Changeset - 9e689afc94cb
[Not reviewed]
0 4 0
MH - 3 years ago 2022-02-11 15:40:33
contact@maxhenger.nl
Initial rewrite implementation, pending integration and typesystem refactor
4 files changed with 160 insertions and 120 deletions:
0 comments (0 inline, 0 general)
src/protocol/ast.rs
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@@ -434,1492 +434,1493 @@ pub struct ParserTypeElement {
 
/// are then the children of the node.
 
#[derive(Debug, Clone)]
 
pub struct ParserType {
 
    pub elements: Vec<ParserTypeElement>,
 
    pub full_span: InputSpan,
 
}
 

	
 
impl ParserType {
 
    pub(crate) fn iter_embedded(&self, parent_idx: usize) -> ParserTypeIter {
 
        ParserTypeIter::new(&self.elements, parent_idx)
 
    }
 
}
 

	
 
/// Iterator over the embedded elements of a specific element.
 
pub struct ParserTypeIter<'a> {
 
    pub elements: &'a [ParserTypeElement],
 
    pub cur_embedded_idx: usize,
 
}
 

	
 
impl<'a> ParserTypeIter<'a> {
 
    fn new(elements: &'a [ParserTypeElement], parent_idx: usize) -> Self {
 
        debug_assert!(parent_idx < elements.len(), "parent index exceeds number of elements in ParserType");
 
        if elements[0].variant.num_embedded() == 0 {
 
            // Parent element does not have any embedded types, place
 
            // `cur_embedded_idx` at end so we will always return `None`
 
            Self{ elements, cur_embedded_idx: elements.len() }
 
        } else {
 
            // Parent element has an embedded type
 
            Self{ elements, cur_embedded_idx: parent_idx + 1 }
 
        }
 
    }
 
}
 

	
 
impl<'a> Iterator for ParserTypeIter<'a> {
 
    type Item = &'a [ParserTypeElement];
 

	
 
    fn next(&mut self) -> Option<Self::Item> {
 
        let elements_len = self.elements.len();
 
        if self.cur_embedded_idx >= elements_len {
 
            return None;
 
        }
 

	
 
        // Seek to the end of the subtree
 
        let mut depth = 1;
 
        let start_element = self.cur_embedded_idx;
 
        while self.cur_embedded_idx < elements_len {
 
            let cur_element = &self.elements[self.cur_embedded_idx];
 
            let depth_change = cur_element.variant.num_embedded() as i32 - 1;
 
            depth += depth_change;
 
            debug_assert!(depth >= 0, "illegally constructed ParserType: {:?}", self.elements);
 

	
 
            self.cur_embedded_idx += 1;
 
            if depth == 0 {
 
                break;
 
            }
 
        }
 

	
 
        debug_assert!(depth == 0, "illegally constructed ParserType: {:?}", self.elements);
 
        return Some(&self.elements[start_element..self.cur_embedded_idx]);
 
    }
 
}
 

	
 
/// ConcreteType is the representation of a type after the type inference and
 
/// checker is finished. These are fully typed.
 
#[derive(Debug, Clone, Copy, Eq, PartialEq, Hash)]
 
pub enum ConcreteTypePart {
 
    // Special types (cannot be explicitly constructed by the programmer)
 
    Void,
 
    // Builtin types without nested types
 
    Message,
 
    Bool,
 
    UInt8, UInt16, UInt32, UInt64,
 
    SInt8, SInt16, SInt32, SInt64,
 
    Character, String,
 
    // Builtin types with one nested type
 
    Array,
 
    Slice,
 
    Input,
 
    Output,
 
    // Tuple: variable number of nested types, will never be 1
 
    Tuple(u32),
 
    // User defined type with any number of nested types
 
    Instance(DefinitionId, u32),    // instance of data type
 
    Function(DefinitionId, u32),    // instance of function
 
    Component(DefinitionId, u32),   // instance of a connector
 
}
 

	
 
impl ConcreteTypePart {
 
    pub(crate) fn num_embedded(&self) -> u32 {
 
        use ConcreteTypePart::*;
 

	
 
        match self {
 
            Void | Message | Bool |
 
            UInt8 | UInt16 | UInt32 | UInt64 |
 
            SInt8 | SInt16 | SInt32 | SInt64 |
 
            Character | String =>
 
                0,
 
            Array | Slice | Input | Output =>
 
                1,
 
            Tuple(num_embedded) => *num_embedded,
 
            Instance(_, num_embedded) => *num_embedded,
 
            Function(_, num_embedded) => *num_embedded,
 
            Component(_, num_embedded) => *num_embedded,
 
        }
 
    }
 
}
 

	
 
#[derive(Debug, Clone, Eq, PartialEq)]
 
pub struct ConcreteType {
 
    pub(crate) parts: Vec<ConcreteTypePart>
 
}
 

	
 
impl Default for ConcreteType {
 
    fn default() -> Self {
 
        Self{ parts: Vec::new() }
 
    }
 
}
 

	
 
impl ConcreteType {
 
    /// Returns an iterator over the subtrees that are type arguments (e.g. an
 
    /// array element's type, or a polymorphic type's arguments) to the
 
    /// provided parent type (specified by its index in the `parts` array).
 
    pub(crate) fn embedded_iter(&self, parent_part_idx: usize) -> ConcreteTypeIter {
 
        return ConcreteTypeIter::new(&self.parts, parent_part_idx);
 
    }
 

	
 
    /// Construct a human-readable name for the type. Because this performs
 
    /// a string allocation don't use it for anything else then displaying the
 
    /// type to the user.
 
    pub(crate) fn display_name(&self, heap: &Heap) -> String {
 
        return Self::type_parts_display_name(self.parts.as_slice(), heap);
 
    }
 

	
 
    // --- Utilities that operate on slice of parts
 

	
 
    /// Given the starting position of a type tree, determine the exclusive
 
    /// ending index.
 
    pub(crate) fn type_parts_subtree_end_idx(parts: &[ConcreteTypePart], start_idx: usize) -> usize {
 
        let mut depth = 1;
 
        let num_parts = parts.len();
 
        debug_assert!(start_idx < num_parts);
 

	
 
        for part_idx in start_idx..parts.len() {
 
            let depth_change = parts[part_idx].num_embedded() as i32 - 1;
 
            depth += depth_change;
 
            debug_assert!(depth >= 0);
 

	
 
            if depth == 0 {
 
                return part_idx + 1;
 
            }
 
        }
 

	
 
        debug_assert!(false, "incorrectly constructed ConcreteType instance");
 
        return 0;
 
    }
 

	
 
    /// Produces a human-readable representation of the concrete type parts
 
    fn type_parts_display_name(parts: &[ConcreteTypePart], heap: &Heap) -> String {
 
        let mut name = String::with_capacity(128);
 
        let _final_idx = Self::render_type_part_at(parts, heap, 0, &mut name);
 
        debug_assert_eq!(_final_idx, parts.len());
 

	
 
        return name;
 
    }
 

	
 
    /// Produces a human-readable representation of a single type part. Lower
 
    /// level utility for `type_parts_display_name`.
 
    fn render_type_part_at(parts: &[ConcreteTypePart], heap: &Heap, mut idx: usize, target: &mut String) -> usize {
 
        use ConcreteTypePart as CTP;
 
        use crate::protocol::parser::token_parsing::*;
 

	
 
        let cur_idx = idx;
 
        idx += 1; // increment by 1, because it always happens
 

	
 
        match parts[cur_idx] {
 
            CTP::Void => { target.push_str("void"); },
 
            CTP::Message => { target.push_str(KW_TYPE_MESSAGE_STR); },
 
            CTP::Bool => { target.push_str(KW_TYPE_BOOL_STR); },
 
            CTP::UInt8 => { target.push_str(KW_TYPE_UINT8_STR); },
 
            CTP::UInt16 => { target.push_str(KW_TYPE_UINT16_STR); },
 
            CTP::UInt32 => { target.push_str(KW_TYPE_UINT32_STR); },
 
            CTP::UInt64 => { target.push_str(KW_TYPE_UINT64_STR); },
 
            CTP::SInt8 => { target.push_str(KW_TYPE_SINT8_STR); },
 
            CTP::SInt16 => { target.push_str(KW_TYPE_SINT16_STR); },
 
            CTP::SInt32 => { target.push_str(KW_TYPE_SINT32_STR); },
 
            CTP::SInt64 => { target.push_str(KW_TYPE_SINT64_STR); },
 
            CTP::Character => { target.push_str(KW_TYPE_CHAR_STR); },
 
            CTP::String => { target.push_str(KW_TYPE_STRING_STR); },
 
            CTP::Array | CTP::Slice => {
 
                idx = Self::render_type_part_at(parts, heap, idx, target);
 
                target.push_str("[]");
 
            },
 
            CTP::Input => {
 
                target.push_str(KW_TYPE_IN_PORT_STR);
 
                target.push('<');
 
                idx = Self::render_type_part_at(parts, heap, idx, target);
 
                target.push('>');
 
            },
 
            CTP::Output => {
 
                target.push_str(KW_TYPE_OUT_PORT_STR);
 
                target.push('<');
 
                idx = Self::render_type_part_at(parts, heap, idx, target);
 
                target.push('>');
 
            },
 
            CTP::Tuple(num_parts) => {
 
                target.push('(');
 
                if num_parts != 0 {
 
                    idx = Self::render_type_part_at(parts, heap, idx, target);
 
                    for _ in 1..num_parts {
 
                        target.push(',');
 
                        idx = Self::render_type_part_at(parts, heap, idx, target);
 
                    }
 
                }
 
                target.push(')');
 
            },
 
            CTP::Instance(definition_id, num_poly_args) |
 
            CTP::Function(definition_id, num_poly_args) |
 
            CTP::Component(definition_id, num_poly_args) => {
 
                let definition = &heap[definition_id];
 
                target.push_str(definition.identifier().value.as_str());
 

	
 
                if num_poly_args != 0 {
 
                    target.push('<');
 
                    for poly_arg_idx in 0..num_poly_args {
 
                        if poly_arg_idx != 0 {
 
                            target.push(',');
 
                        }
 
                        idx = Self::render_type_part_at(parts, heap, idx, target);
 
                    }
 
                    target.push('>');
 
                }
 
            }
 
        }
 

	
 
        idx
 
    }
 
}
 

	
 
#[derive(Debug)]
 
pub struct ConcreteTypeIter<'a> {
 
    parts: &'a [ConcreteTypePart],
 
    idx_embedded: u32,
 
    num_embedded: u32,
 
    part_idx: usize,
 
}
 

	
 
impl<'a> ConcreteTypeIter<'a> {
 
    pub(crate) fn new(parts: &'a[ConcreteTypePart], parent_idx: usize) -> Self {
 
        let num_embedded = parts[parent_idx].num_embedded();
 
        return ConcreteTypeIter{
 
            parts,
 
            idx_embedded: 0,
 
            num_embedded,
 
            part_idx: parent_idx + 1,
 
        }
 
    }
 
}
 

	
 
impl<'a> Iterator for ConcreteTypeIter<'a> {
 
    type Item = &'a [ConcreteTypePart];
 

	
 
    fn next(&mut self) -> Option<Self::Item> {
 
        if self.idx_embedded == self.num_embedded {
 
            return None;
 
        }
 

	
 
        // Retrieve the subtree of interest
 
        let start_idx = self.part_idx;
 
        let end_idx = ConcreteType::type_parts_subtree_end_idx(&self.parts, start_idx);
 

	
 
        self.idx_embedded += 1;
 
        self.part_idx = end_idx;
 

	
 
        return Some(&self.parts[start_idx..end_idx]);
 
    }
 
}
 

	
 
#[derive(Debug, Clone, Copy)]
 
pub enum ScopeAssociation {
 
    Definition(DefinitionId),
 
    Block(BlockStatementId),
 
    If(IfStatementId, bool), // if true, then body of "if", otherwise body of "else"
 
    While(WhileStatementId),
 
    Synchronous(SynchronousStatementId),
 
    SelectCase(SelectStatementId, u32), // index is select case
 
}
 

	
 
/// `ScopeNode` is a helper that links scopes in two directions. It doesn't
 
/// actually contain any information associated with the scope, this may be
 
/// found on the AST elements that `Scope` points to.
 
#[derive(Debug, Clone)]
 
pub struct Scope {
 
    // Relation to other scopes
 
    pub this: ScopeId,
 
    pub parent: Option<ScopeId>,
 
    pub nested: Vec<ScopeId>,
 
    // Locally available variables/labels
 
    pub association: ScopeAssociation,
 
    pub variables: Vec<VariableId>,
 
    pub labels: Vec<LabeledStatementId>,
 
    // Location trackers/counters
 
    pub relative_pos_in_parent: i32,
 
    pub first_unique_id_in_scope: i32,
 
    pub next_unique_id_in_scope: i32,
 
}
 

	
 
impl Scope {
 
    pub(crate) fn new(id: ScopeId, association: ScopeAssociation) -> Self {
 
        return Self{
 
            this: id,
 
            parent: None,
 
            nested: Vec::new(),
 
            association,
 
            variables: Vec::new(),
 
            labels: Vec::new(),
 
            relative_pos_in_parent: -1,
 
            first_unique_id_in_scope: -1,
 
            next_unique_id_in_scope: -1,
 
        }
 
    }
 
}
 

	
 
impl Scope {
 
    pub(crate) fn new_invalid(this: ScopeId) -> Self {
 
        return Self{
 
            this,
 
            parent: None,
 
            nested: Vec::new(),
 
            association: ScopeAssociation::Definition(DefinitionId::new_invalid()),
 
            variables: Vec::new(),
 
            labels: Vec::new(),
 
            relative_pos_in_parent: -1,
 
            first_unique_id_in_scope: -1,
 
            next_unique_id_in_scope: -1,
 
        };
 
    }
 
}
 

	
 
#[derive(Debug, Clone, PartialEq, Eq)]
 
pub enum VariableKind {
 
    Parameter,      // in parameter list of function/component
 
    Local,          // declared in function/component body
 
    Binding,        // may be bound to in a binding expression (determined in validator/linker)
 
}
 

	
 
#[derive(Debug, Clone)]
 
pub struct Variable {
 
    pub this: VariableId,
 
    // Parsing
 
    pub kind: VariableKind,
 
    pub parser_type: ParserType,
 
    pub identifier: Identifier,
 
    // Validator/linker
 
    pub relative_pos_in_parent: i32,
 
    pub unique_id_in_scope: i32, // Temporary fix until proper bytecode/asm is generated
 
}
 

	
 
#[derive(Debug, Clone)]
 
pub enum Definition {
 
    Struct(StructDefinition),
 
    Enum(EnumDefinition),
 
    Union(UnionDefinition),
 
    Component(ComponentDefinition),
 
    Function(FunctionDefinition),
 
}
 

	
 
impl Definition {
 
    pub fn is_struct(&self) -> bool {
 
        match self {
 
            Definition::Struct(_) => true,
 
            _ => false
 
        }
 
    }
 
    pub(crate) fn as_struct(&self) -> &StructDefinition {
 
        match self {
 
            Definition::Struct(result) => result,
 
            _ => panic!("Unable to cast 'Definition' to 'StructDefinition'"),
 
        }
 
    }
 
    pub(crate) fn as_struct_mut(&mut self) -> &mut StructDefinition {
 
        match self {
 
            Definition::Struct(result) => result,
 
            _ => panic!("Unable to cast 'Definition' to 'StructDefinition'"),
 
        }
 
    }
 
    pub fn is_enum(&self) -> bool {
 
        match self {
 
            Definition::Enum(_) => true,
 
            _ => false,
 
        }
 
    }
 
    pub(crate) fn as_enum(&self) -> &EnumDefinition {
 
        match self {
 
            Definition::Enum(result) => result,
 
            _ => panic!("Unable to cast 'Definition' to 'EnumDefinition'"),
 
        }
 
    }
 
    pub(crate) fn as_enum_mut(&mut self) -> &mut EnumDefinition {
 
        match self {
 
            Definition::Enum(result) => result,
 
            _ => panic!("Unable to cast 'Definition' to 'EnumDefinition'"),
 
        }
 
    }
 
    pub fn is_union(&self) -> bool {
 
        match self {
 
            Definition::Union(_) => true,
 
            _ => false,
 
        }
 
    }
 
    pub(crate) fn as_union(&self) -> &UnionDefinition {
 
        match self {
 
            Definition::Union(result) => result, 
 
            _ => panic!("Unable to cast 'Definition' to 'UnionDefinition'"),
 
        }
 
    }
 
    pub(crate) fn as_union_mut(&mut self) -> &mut UnionDefinition {
 
        match self {
 
            Definition::Union(result) => result,
 
            _ => panic!("Unable to cast 'Definition' to 'UnionDefinition'"),
 
        }
 
    }
 
    pub fn is_component(&self) -> bool {
 
        match self {
 
            Definition::Component(_) => true,
 
            _ => false,
 
        }
 
    }
 
    pub(crate) fn as_component(&self) -> &ComponentDefinition {
 
        match self {
 
            Definition::Component(result) => result,
 
            _ => panic!("Unable to cast `Definition` to `Component`"),
 
        }
 
    }
 
    pub(crate) fn as_component_mut(&mut self) -> &mut ComponentDefinition {
 
        match self {
 
            Definition::Component(result) => result,
 
            _ => panic!("Unable to cast `Definition` to `Component`"),
 
        }
 
    }
 
    pub fn is_function(&self) -> bool {
 
        match self {
 
            Definition::Function(_) => true,
 
            _ => false,
 
        }
 
    }
 
    pub(crate) fn as_function(&self) -> &FunctionDefinition {
 
        match self {
 
            Definition::Function(result) => result,
 
            _ => panic!("Unable to cast `Definition` to `Function`"),
 
        }
 
    }
 
    pub(crate) fn as_function_mut(&mut self) -> &mut FunctionDefinition {
 
        match self {
 
            Definition::Function(result) => result,
 
            _ => panic!("Unable to cast `Definition` to `Function`"),
 
        }
 
    }
 
    pub fn parameters(&self) -> &Vec<VariableId> {
 
        match self {
 
            Definition::Component(def) => &def.parameters,
 
            Definition::Function(def) => &def.parameters,
 
            _ => panic!("Called parameters() on {:?}", self)
 
        }
 
    }
 
    pub fn defined_in(&self) -> RootId {
 
        match self {
 
            Definition::Struct(def) => def.defined_in,
 
            Definition::Enum(def) => def.defined_in,
 
            Definition::Union(def) => def.defined_in,
 
            Definition::Component(def) => def.defined_in,
 
            Definition::Function(def) => def.defined_in,
 
        }
 
    }
 
    pub fn identifier(&self) -> &Identifier {
 
        match self {
 
            Definition::Struct(def) => &def.identifier,
 
            Definition::Enum(def) => &def.identifier,
 
            Definition::Union(def) => &def.identifier,
 
            Definition::Component(def) => &def.identifier,
 
            Definition::Function(def) => &def.identifier,
 
        }
 
    }
 
    pub fn poly_vars(&self) -> &Vec<Identifier> {
 
        match self {
 
            Definition::Struct(def) => &def.poly_vars,
 
            Definition::Enum(def) => &def.poly_vars,
 
            Definition::Union(def) => &def.poly_vars,
 
            Definition::Component(def) => &def.poly_vars,
 
            Definition::Function(def) => &def.poly_vars,
 
        }
 
    }
 
}
 

	
 
#[derive(Debug, Clone)]
 
pub struct StructFieldDefinition {
 
    pub span: InputSpan,
 
    pub field: Identifier,
 
    pub parser_type: ParserType,
 
}
 

	
 
#[derive(Debug, Clone)]
 
pub struct StructDefinition {
 
    pub this: StructDefinitionId,
 
    pub defined_in: RootId,
 
    // Symbol scanning
 
    pub span: InputSpan,
 
    pub identifier: Identifier,
 
    pub poly_vars: Vec<Identifier>,
 
    // Parsing
 
    pub fields: Vec<StructFieldDefinition>
 
}
 

	
 
impl StructDefinition {
 
    pub(crate) fn new_empty(
 
        this: StructDefinitionId, defined_in: RootId, span: InputSpan,
 
        identifier: Identifier, poly_vars: Vec<Identifier>
 
    ) -> Self {
 
        Self{ this, defined_in, span, identifier, poly_vars, fields: Vec::new() }
 
    }
 
}
 

	
 
#[derive(Debug, Clone, Copy)]
 
pub enum EnumVariantValue {
 
    None,
 
    Integer(i64),
 
}
 

	
 
#[derive(Debug, Clone)]
 
pub struct EnumVariantDefinition {
 
    pub identifier: Identifier,
 
    pub value: EnumVariantValue,
 
}
 

	
 
#[derive(Debug, Clone)]
 
pub struct EnumDefinition {
 
    pub this: EnumDefinitionId,
 
    pub defined_in: RootId,
 
    // Symbol scanning
 
    pub span: InputSpan,
 
    pub identifier: Identifier,
 
    pub poly_vars: Vec<Identifier>,
 
    // Parsing
 
    pub variants: Vec<EnumVariantDefinition>,
 
}
 

	
 
impl EnumDefinition {
 
    pub(crate) fn new_empty(
 
        this: EnumDefinitionId, defined_in: RootId, span: InputSpan,
 
        identifier: Identifier, poly_vars: Vec<Identifier>
 
    ) -> Self {
 
        Self{ this, defined_in, span, identifier, poly_vars, variants: Vec::new() }
 
    }
 
}
 

	
 
#[derive(Debug, Clone)]
 
pub struct UnionVariantDefinition {
 
    pub span: InputSpan,
 
    pub identifier: Identifier,
 
    pub value: Vec<ParserType>, // if empty, then union variant does not contain any embedded types
 
}
 

	
 
#[derive(Debug, Clone)]
 
pub struct UnionDefinition {
 
    pub this: UnionDefinitionId,
 
    pub defined_in: RootId,
 
    // Phase 1: symbol scanning
 
    pub span: InputSpan,
 
    pub identifier: Identifier,
 
    pub poly_vars: Vec<Identifier>,
 
    // Phase 2: parsing
 
    pub variants: Vec<UnionVariantDefinition>,
 
}
 

	
 
impl UnionDefinition {
 
    pub(crate) fn new_empty(
 
        this: UnionDefinitionId, defined_in: RootId, span: InputSpan,
 
        identifier: Identifier, poly_vars: Vec<Identifier>
 
    ) -> Self {
 
        Self{ this, defined_in, span, identifier, poly_vars, variants: Vec::new() }
 
    }
 
}
 

	
 
#[derive(Debug, Clone, Copy)]
 
pub enum ComponentVariant {
 
    Primitive,
 
    Composite,
 
}
 

	
 
#[derive(Debug, Clone)]
 
pub struct ComponentDefinition {
 
    pub this: ComponentDefinitionId,
 
    pub defined_in: RootId,
 
    // Symbol scanning
 
    pub span: InputSpan,
 
    pub variant: ComponentVariant,
 
    pub identifier: Identifier,
 
    pub poly_vars: Vec<Identifier>,
 
    // Parsing
 
    pub parameters: Vec<VariableId>,
 
    pub scope: ScopeId,
 
    pub body: BlockStatementId,
 
    // Validation/linking
 
    pub num_expressions_in_body: i32,
 
}
 

	
 
impl ComponentDefinition {
 
    // Used for preallocation during symbol scanning
 
    pub(crate) fn new_empty(
 
        this: ComponentDefinitionId, defined_in: RootId, span: InputSpan,
 
        variant: ComponentVariant, identifier: Identifier, poly_vars: Vec<Identifier>
 
    ) -> Self {
 
        Self{ 
 
            this, defined_in, span, variant, identifier, poly_vars,
 
            parameters: Vec::new(),
 
            scope: ScopeId::new_invalid(),
 
            body: BlockStatementId::new_invalid(),
 
            num_expressions_in_body: -1,
 
        }
 
    }
 
}
 

	
 
// Note that we will have function definitions for builtin functions as well. In
 
// that case the span, the identifier span and the body are all invalid.
 
#[derive(Debug, Clone)]
 
pub struct FunctionDefinition {
 
    pub this: FunctionDefinitionId,
 
    pub defined_in: RootId,
 
    // Symbol scanning
 
    pub builtin: bool,
 
    pub span: InputSpan,
 
    pub identifier: Identifier,
 
    pub poly_vars: Vec<Identifier>,
 
    // Parser
 
    pub return_type: ParserType,
 
    pub parameters: Vec<VariableId>,
 
    pub scope: ScopeId,
 
    pub body: BlockStatementId,
 
    // Validation/linking
 
    pub num_expressions_in_body: i32,
 
}
 

	
 
impl FunctionDefinition {
 
    pub(crate) fn new_empty(
 
        this: FunctionDefinitionId, defined_in: RootId, span: InputSpan,
 
        identifier: Identifier, poly_vars: Vec<Identifier>
 
    ) -> Self {
 
        Self {
 
            this, defined_in,
 
            builtin: false,
 
            span, identifier, poly_vars,
 
            return_type: ParserType{ elements: Vec::new(), full_span: InputSpan::new() },
 
            parameters: Vec::new(),
 
            scope: ScopeId::new_invalid(),
 
            body: BlockStatementId::new_invalid(),
 
            num_expressions_in_body: -1,
 
        }
 
    }
 
}
 

	
 
#[derive(Debug, Clone)]
 
pub enum Statement {
 
    Block(BlockStatement),
 
    EndBlock(EndBlockStatement),
 
    Local(LocalStatement),
 
    Labeled(LabeledStatement),
 
    If(IfStatement),
 
    EndIf(EndIfStatement),
 
    While(WhileStatement),
 
    EndWhile(EndWhileStatement),
 
    Break(BreakStatement),
 
    Continue(ContinueStatement),
 
    Synchronous(SynchronousStatement),
 
    EndSynchronous(EndSynchronousStatement),
 
    Fork(ForkStatement),
 
    EndFork(EndForkStatement),
 
    Select(SelectStatement),
 
    EndSelect(EndSelectStatement),
 
    Return(ReturnStatement),
 
    Goto(GotoStatement),
 
    New(NewStatement),
 
    Expression(ExpressionStatement),
 
}
 

	
 
impl Statement {
 
    pub fn as_block(&self) -> &BlockStatement {
 
        match self {
 
            Statement::Block(result) => result,
 
            _ => panic!("Unable to cast `Statement` to `BlockStatement`"),
 
        }
 
    }
 
    pub fn as_local(&self) -> &LocalStatement {
 
        match self {
 
            Statement::Local(result) => result,
 
            _ => panic!("Unable to cast `Statement` to `LocalStatement`"),
 
        }
 
    }
 
    pub fn as_memory(&self) -> &MemoryStatement {
 
        self.as_local().as_memory()
 
    }
 
    pub fn as_channel(&self) -> &ChannelStatement {
 
        self.as_local().as_channel()
 
    }
 

	
 
    pub fn as_new(&self) -> &NewStatement {
 
        match self {
 
            Statement::New(result) => result,
 
            _ => panic!("Unable to cast `Statement` to `NewStatement`"),
 
        }
 
    }
 

	
 
    pub fn span(&self) -> InputSpan {
 
        match self {
 
            Statement::Block(v) => v.span,
 
            Statement::Local(v) => v.span(),
 
            Statement::Labeled(v) => v.label.span,
 
            Statement::If(v) => v.span,
 
            Statement::While(v) => v.span,
 
            Statement::Break(v) => v.span,
 
            Statement::Continue(v) => v.span,
 
            Statement::Synchronous(v) => v.span,
 
            Statement::Fork(v) => v.span,
 
            Statement::Select(v) => v.span,
 
            Statement::Return(v) => v.span,
 
            Statement::Goto(v) => v.span,
 
            Statement::New(v) => v.span,
 
            Statement::Expression(v) => v.span,
 
            Statement::EndBlock(_)
 
            | Statement::EndIf(_)
 
            | Statement::EndWhile(_)
 
            | Statement::EndSynchronous(_)
 
            | Statement::EndFork(_)
 
            | Statement::EndSelect(_) => unreachable!(),
 
        }
 
    }
 
    pub fn link_next(&mut self, next: StatementId) {
 
        match self {
 
            Statement::Block(stmt) => stmt.next = next,
 
            Statement::EndBlock(stmt) => stmt.next = next,
 
            Statement::Local(stmt) => match stmt {
 
                LocalStatement::Channel(stmt) => stmt.next = next,
 
                LocalStatement::Memory(stmt) => stmt.next = next,
 
            },
 
            Statement::EndIf(stmt) => stmt.next = next,
 
            Statement::EndWhile(stmt) => stmt.next = next,
 
            Statement::EndSynchronous(stmt) => stmt.next = next,
 
            Statement::EndFork(stmt) => stmt.next = next,
 
            Statement::EndSelect(stmt) => stmt.next = next,
 
            Statement::New(stmt) => stmt.next = next,
 
            Statement::Expression(stmt) => stmt.next = next,
 
            Statement::Return(_)
 
            | Statement::Break(_)
 
            | Statement::Continue(_)
 
            | Statement::Synchronous(_)
 
            | Statement::Fork(_)
 
            | Statement::Select(_)
 
            | Statement::Goto(_)
 
            | Statement::While(_)
 
            | Statement::Labeled(_)
 
            | Statement::If(_) => unreachable!(),
 
        }
 
    }
 

	
 
}
 

	
 
#[derive(Debug, Clone)]
 
pub struct BlockStatement {
 
    pub this: BlockStatementId,
 
    // Phase 1: parser
 
    pub is_implicit: bool,
 
    pub span: InputSpan, // of the complete block
 
    pub statements: Vec<StatementId>,
 
    pub end_block: EndBlockStatementId,
 
    // Phase 2: linker
 
    pub scope: ScopeId,
 
    pub next: StatementId,
 
}
 

	
 
#[derive(Debug, Clone)]
 
pub struct EndBlockStatement {
 
    pub this: EndBlockStatementId,
 
    // Parser
 
    pub start_block: BlockStatementId,
 
    // Validation/Linking
 
    pub next: StatementId,
 
}
 

	
 
#[derive(Debug, Clone)]
 
pub enum LocalStatement {
 
    Memory(MemoryStatement),
 
    Channel(ChannelStatement),
 
}
 

	
 
impl LocalStatement {
 
    pub fn this(&self) -> LocalStatementId {
 
        match self {
 
            LocalStatement::Memory(stmt) => stmt.this.upcast(),
 
            LocalStatement::Channel(stmt) => stmt.this.upcast(),
 
        }
 
    }
 
    pub fn as_memory(&self) -> &MemoryStatement {
 
        match self {
 
            LocalStatement::Memory(result) => result,
 
            _ => panic!("Unable to cast `LocalStatement` to `MemoryStatement`"),
 
        }
 
    }
 
    pub fn as_channel(&self) -> &ChannelStatement {
 
        match self {
 
            LocalStatement::Channel(result) => result,
 
            _ => panic!("Unable to cast `LocalStatement` to `ChannelStatement`"),
 
        }
 
    }
 
    pub fn span(&self) -> InputSpan {
 
        match self {
 
            LocalStatement::Channel(v) => v.span,
 
            LocalStatement::Memory(v) => v.span,
 
        }
 
    }
 
}
 

	
 
#[derive(Debug, Clone)]
 
pub struct MemoryStatement {
 
    pub this: MemoryStatementId,
 
    // Phase 1: parser
 
    pub span: InputSpan,
 
    pub variable: VariableId,
 
    pub initial_expr: AssignmentExpressionId,
 
    // Phase 2: linker
 
    pub next: StatementId,
 
}
 

	
 
/// ChannelStatement is the declaration of an input and output port associated
 
/// with the same channel. Note that the polarity of the ports are from the
 
/// point of view of the component. So an output port is something that a
 
/// component uses to send data over (i.e. it is the "input end" of the
 
/// channel), and vice versa.
 
#[derive(Debug, Clone)]
 
pub struct ChannelStatement {
 
    pub this: ChannelStatementId,
 
    // Phase 1: parser
 
    pub span: InputSpan, // of the "channel" keyword
 
    pub from: VariableId, // output
 
    pub to: VariableId,   // input
 
    // Phase 2: linker
 
    pub relative_pos_in_parent: i32,
 
    pub next: StatementId,
 
}
 

	
 
#[derive(Debug, Clone)]
 
pub struct LabeledStatement {
 
    pub this: LabeledStatementId,
 
    // Phase 1: parser
 
    pub label: Identifier,
 
    pub body: StatementId,
 
    // Phase 2: linker
 
    pub relative_pos_in_parent: i32,
 
    pub in_sync: SynchronousStatementId, // may be invalid
 
}
 

	
 
#[derive(Debug, Clone)]
 
pub struct IfStatement {
 
    pub this: IfStatementId,
 
    // Phase 1: parser
 
    pub span: InputSpan, // of the "if" keyword
 
    pub test: ExpressionId,
 
    pub true_case: IfStatementCase,
 
    pub false_case: Option<IfStatementCase>,
 
    pub end_if: EndIfStatementId,
 
}
 

	
 
#[derive(Debug, Clone, Copy)]
 
pub struct IfStatementCase {
 
    pub body: StatementId,
 
    pub scope: ScopeId,
 
}
 

	
 
#[derive(Debug, Clone)]
 
pub struct EndIfStatement {
 
    pub this: EndIfStatementId,
 
    pub start_if: IfStatementId,
 
    pub next: StatementId,
 
}
 

	
 
#[derive(Debug, Clone)]
 
pub struct WhileStatement {
 
    pub this: WhileStatementId,
 
    // Phase 1: parser
 
    pub span: InputSpan, // of the "while" keyword
 
    pub test: ExpressionId,
 
    pub scope: ScopeId,
 
    pub body: StatementId,
 
    pub end_while: EndWhileStatementId,
 
    pub in_sync: SynchronousStatementId, // may be invalid
 
}
 

	
 
#[derive(Debug, Clone)]
 
pub struct EndWhileStatement {
 
    pub this: EndWhileStatementId,
 
    pub start_while: WhileStatementId,
 
    // Phase 2: linker
 
    pub next: StatementId,
 
}
 

	
 
#[derive(Debug, Clone)]
 
pub struct BreakStatement {
 
    pub this: BreakStatementId,
 
    // Phase 1: parser
 
    pub span: InputSpan, // of the "break" keyword
 
    pub label: Option<Identifier>,
 
    // Phase 2: linker
 
    pub target: EndWhileStatementId, // invalid if not yet set
 
}
 

	
 
#[derive(Debug, Clone)]
 
pub struct ContinueStatement {
 
    pub this: ContinueStatementId,
 
    // Phase 1: parser
 
    pub span: InputSpan, // of the "continue" keyword
 
    pub label: Option<Identifier>,
 
    // Phase 2: linker
 
    pub target: WhileStatementId, // invalid if not yet set
 
}
 

	
 
#[derive(Debug, Clone)]
 
pub struct SynchronousStatement {
 
    pub this: SynchronousStatementId,
 
    // Phase 1: parser
 
    pub span: InputSpan, // of the "sync" keyword
 
    pub scope: ScopeId,
 
    pub body: StatementId,
 
    pub end_sync: EndSynchronousStatementId,
 
}
 

	
 
#[derive(Debug, Clone)]
 
pub struct EndSynchronousStatement {
 
    pub this: EndSynchronousStatementId,
 
    pub start_sync: SynchronousStatementId,
 
    // Phase 2: linker
 
    pub next: StatementId,
 
}
 

	
 
#[derive(Debug, Clone)]
 
pub struct ForkStatement {
 
    pub this: ForkStatementId,
 
    // Phase 1: parser
 
    pub span: InputSpan, // of the "fork" keyword
 
    pub left_body: StatementId,
 
    pub right_body: Option<StatementId>,
 
    pub end_fork: EndForkStatementId,
 
}
 

	
 
#[derive(Debug, Clone)]
 
pub struct EndForkStatement {
 
    pub this: EndForkStatementId,
 
    pub start_fork: ForkStatementId,
 
    pub next: StatementId,
 
}
 

	
 
#[derive(Debug, Clone)]
 
pub struct SelectStatement {
 
    pub this: SelectStatementId,
 
    pub span: InputSpan, // of the "select" keyword
 
    pub cases: Vec<SelectCase>,
 
    pub end_select: EndSelectStatementId,
 
    pub relative_pos_in_parent: i32,
 
    pub next: StatementId, // note: the select statement will be transformed into other AST elements, this `next` jumps to those replacement statements
 
}
 

	
 
#[derive(Debug, Clone)]
 
pub struct SelectCase {
 
    // The guard statement of a `select` is either a MemoryStatement or an
 
    // ExpressionStatement. Nothing else is allowed by the initial parsing
 
    pub guard: StatementId,
 
    pub body: StatementId,
 
    pub scope: ScopeId,
 
    // Phase 2: Validation and Linking
 
    pub involved_ports: Vec<(CallExpressionId, ExpressionId)>, // call to `get` and its port argument
 
}
 

	
 
#[derive(Debug, Clone)]
 
pub struct EndSelectStatement {
 
    pub this: EndSelectStatementId,
 
    pub start_select: SelectStatementId,
 
    pub next: StatementId,
 
}
 

	
 
#[derive(Debug, Clone)]
 
pub struct ReturnStatement {
 
    pub this: ReturnStatementId,
 
    // Phase 1: parser
 
    pub span: InputSpan, // of the "return" keyword
 
    pub expressions: Vec<ExpressionId>,
 
}
 

	
 
#[derive(Debug, Clone)]
 
pub struct GotoStatement {
 
    pub this: GotoStatementId,
 
    // Phase 1: parser
 
    pub span: InputSpan, // of the "goto" keyword
 
    pub label: Identifier,
 
    // Phase 2: linker
 
    pub target: LabeledStatementId, // invalid if not yet set
 
}
 

	
 
#[derive(Debug, Clone)]
 
pub struct NewStatement {
 
    pub this: NewStatementId,
 
    // Phase 1: parser
 
    pub span: InputSpan, // of the "new" keyword
 
    pub expression: CallExpressionId,
 
    // Phase 2: linker
 
    pub next: StatementId,
 
}
 

	
 
#[derive(Debug, Clone)]
 
pub struct ExpressionStatement {
 
    pub this: ExpressionStatementId,
 
    // Phase 1: parser
 
    pub span: InputSpan,
 
    pub expression: ExpressionId,
 
    // Phase 2: linker
 
    pub next: StatementId,
 
}
 

	
 
#[derive(Debug, PartialEq, Eq, Clone, Copy)]
 
pub enum ExpressionParent {
 
    None, // only set during initial parsing
 
    Memory(MemoryStatementId),
 
    If(IfStatementId),
 
    While(WhileStatementId),
 
    Return(ReturnStatementId),
 
    New(NewStatementId),
 
    ExpressionStmt(ExpressionStatementId),
 
    Expression(ExpressionId, u32) // index within expression (e.g LHS or RHS of expression, or index in array literal, etc.)
 
}
 

	
 
impl ExpressionParent {
 
    pub fn is_new(&self) -> bool {
 
        match self {
 
            ExpressionParent::New(_) => true,
 
            _ => false,
 
        }
 
    }
 

	
 
    pub fn as_expression(&self) -> ExpressionId {
 
        match self {
 
            ExpressionParent::Expression(id, _) => *id,
 
            _ => panic!("called as_expression() on {:?}", self),
 
        }
 
    }
 
}
 

	
 
#[derive(Debug, Clone)]
 
pub enum Expression {
 
    Assignment(AssignmentExpression),
 
    Binding(BindingExpression),
 
    Conditional(ConditionalExpression),
 
    Binary(BinaryExpression),
 
    Unary(UnaryExpression),
 
    Indexing(IndexingExpression),
 
    Slicing(SlicingExpression),
 
    Select(SelectExpression),
 
    Literal(LiteralExpression),
 
    Cast(CastExpression),
 
    Call(CallExpression),
 
    Variable(VariableExpression),
 
}
 

	
 
impl Expression {
 
    pub fn as_variable(&self) -> &VariableExpression {
 
        match self {
 
            Expression::Variable(result) => result,
 
            _ => panic!("Unable to cast `Expression` to `VariableExpression`"),
 
        }
 
    }
 

	
 
    /// Returns operator span, function name, a binding's "let" span, etc. An
 
    /// indicator for the kind of expression that is being applied.
 
    pub fn operation_span(&self) -> InputSpan {
 
        match self {
 
            Expression::Assignment(expr) => expr.operator_span,
 
            Expression::Binding(expr) => expr.operator_span,
 
            Expression::Conditional(expr) => expr.operator_span,
 
            Expression::Binary(expr) => expr.operator_span,
 
            Expression::Unary(expr) => expr.operator_span,
 
            Expression::Indexing(expr) => expr.operator_span,
 
            Expression::Slicing(expr) => expr.slicing_span,
 
            Expression::Select(expr) => expr.operator_span,
 
            Expression::Literal(expr) => expr.span,
 
            Expression::Cast(expr) => expr.cast_span,
 
            Expression::Call(expr) => expr.func_span,
 
            Expression::Variable(expr) => expr.identifier.span,
 
        }
 
    }
 

	
 
    /// Returns the span covering the entire expression (i.e. including the
 
    /// spans of the arguments as well).
 
    pub fn full_span(&self) -> InputSpan {
 
        match self {
 
            Expression::Assignment(expr) => expr.full_span,
 
            Expression::Binding(expr) => expr.full_span,
 
            Expression::Conditional(expr) => expr.full_span,
 
            Expression::Binary(expr) => expr.full_span,
 
            Expression::Unary(expr) => expr.full_span,
 
            Expression::Indexing(expr) => expr.full_span,
 
            Expression::Slicing(expr) => expr.full_span,
 
            Expression::Select(expr) => expr.full_span,
 
            Expression::Literal(expr) => expr.span,
 
            Expression::Cast(expr) => expr.full_span,
 
            Expression::Call(expr) => expr.full_span,
 
            Expression::Variable(expr) => expr.identifier.span,
 
        }
 
    }
 

	
 
    pub fn parent(&self) -> &ExpressionParent {
 
        match self {
 
            Expression::Assignment(expr) => &expr.parent,
 
            Expression::Binding(expr) => &expr.parent,
 
            Expression::Conditional(expr) => &expr.parent,
 
            Expression::Binary(expr) => &expr.parent,
 
            Expression::Unary(expr) => &expr.parent,
 
            Expression::Indexing(expr) => &expr.parent,
 
            Expression::Slicing(expr) => &expr.parent,
 
            Expression::Select(expr) => &expr.parent,
 
            Expression::Literal(expr) => &expr.parent,
 
            Expression::Cast(expr) => &expr.parent,
 
            Expression::Call(expr) => &expr.parent,
 
            Expression::Variable(expr) => &expr.parent,
 
        }
 
    }
 

	
 
    pub fn parent_mut(&mut self) -> &mut ExpressionParent {
 
        match self {
 
            Expression::Assignment(expr) => &mut expr.parent,
 
            Expression::Binding(expr) => &mut expr.parent,
 
            Expression::Conditional(expr) => &mut expr.parent,
 
            Expression::Binary(expr) => &mut expr.parent,
 
            Expression::Unary(expr) => &mut expr.parent,
 
            Expression::Indexing(expr) => &mut expr.parent,
 
            Expression::Slicing(expr) => &mut expr.parent,
 
            Expression::Select(expr) => &mut expr.parent,
 
            Expression::Literal(expr) => &mut expr.parent,
 
            Expression::Cast(expr) => &mut expr.parent,
 
            Expression::Call(expr) => &mut expr.parent,
 
            Expression::Variable(expr) => &mut expr.parent,
 
        }
 
    }
 

	
 
    pub fn parent_expr_id(&self) -> Option<ExpressionId> {
 
        if let ExpressionParent::Expression(id, _) = self.parent() {
 
            Some(*id)
 
        } else {
 
            None
 
        }
 
    }
 

	
 
    pub fn get_unique_id_in_definition(&self) -> i32 {
 
        match self {
 
            Expression::Assignment(expr) => expr.unique_id_in_definition,
 
            Expression::Binding(expr) => expr.unique_id_in_definition,
 
            Expression::Conditional(expr) => expr.unique_id_in_definition,
 
            Expression::Binary(expr) => expr.unique_id_in_definition,
 
            Expression::Unary(expr) => expr.unique_id_in_definition,
 
            Expression::Indexing(expr) => expr.unique_id_in_definition,
 
            Expression::Slicing(expr) => expr.unique_id_in_definition,
 
            Expression::Select(expr) => expr.unique_id_in_definition,
 
            Expression::Literal(expr) => expr.unique_id_in_definition,
 
            Expression::Cast(expr) => expr.unique_id_in_definition,
 
            Expression::Call(expr) => expr.unique_id_in_definition,
 
            Expression::Variable(expr) => expr.unique_id_in_definition,
 
        }
 
    }
 
}
 

	
 
#[derive(Debug, Clone, Copy)]
 
pub enum AssignmentOperator {
 
    Set,
 
    Concatenated,
 
    Multiplied,
 
    Divided,
 
    Remained,
 
    Added,
 
    Subtracted,
 
    ShiftedLeft,
 
    ShiftedRight,
 
    BitwiseAnded,
 
    BitwiseXored,
 
    BitwiseOred,
 
}
 

	
 
#[derive(Debug, Clone)]
 
pub struct AssignmentExpression {
 
    pub this: AssignmentExpressionId,
 
    // Parsing
 
    pub operator_span: InputSpan,
 
    pub full_span: InputSpan,
 
    pub left: ExpressionId,
 
    pub operation: AssignmentOperator,
 
    pub right: ExpressionId,
 
    // Validator/Linker
 
    pub parent: ExpressionParent,
 
    pub unique_id_in_definition: i32,
 
}
 

	
 
#[derive(Debug, Clone)]
 
pub struct BindingExpression {
 
    pub this: BindingExpressionId,
 
    // Parsing
 
    pub operator_span: InputSpan,
 
    pub full_span: InputSpan,
 
    pub bound_to: ExpressionId,
 
    pub bound_from: ExpressionId,
 
    // Validator/Linker
 
    pub parent: ExpressionParent,
 
    pub unique_id_in_definition: i32,
 
}
 

	
 
#[derive(Debug, Clone)]
 
pub struct ConditionalExpression {
 
    pub this: ConditionalExpressionId,
 
    // Parsing
 
    pub operator_span: InputSpan,
 
    pub full_span: InputSpan,
 
    pub test: ExpressionId,
 
    pub true_expression: ExpressionId,
 
    pub false_expression: ExpressionId,
 
    // Validator/Linking
 
    pub parent: ExpressionParent,
 
    pub unique_id_in_definition: i32,
 
}
 

	
 
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
 
pub enum BinaryOperator {
 
    Concatenate,
 
    LogicalOr,
 
    LogicalAnd,
 
    BitwiseOr,
 
    BitwiseXor,
 
    BitwiseAnd,
 
    Equality,
 
    Inequality,
 
    LessThan,
 
    GreaterThan,
 
    LessThanEqual,
 
    GreaterThanEqual,
 
    ShiftLeft,
 
    ShiftRight,
 
    Add,
 
    Subtract,
 
    Multiply,
 
    Divide,
 
    Remainder,
 
}
 

	
 
#[derive(Debug, Clone)]
 
pub struct BinaryExpression {
 
    pub this: BinaryExpressionId,
 
    // Parsing
 
    pub operator_span: InputSpan,
 
    pub full_span: InputSpan,
 
    pub left: ExpressionId,
 
    pub operation: BinaryOperator,
 
    pub right: ExpressionId,
 
    // Validator/Linker
 
    pub parent: ExpressionParent,
 
    pub unique_id_in_definition: i32,
 
}
 

	
 
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
 
pub enum UnaryOperator {
 
    Positive,
 
    Negative,
 
    BitwiseNot,
 
    LogicalNot,
 
}
 

	
 
#[derive(Debug, Clone)]
 
pub struct UnaryExpression {
 
    pub this: UnaryExpressionId,
 
    // Parsing
 
    pub operator_span: InputSpan,
 
    pub full_span: InputSpan,
 
    pub operation: UnaryOperator,
 
    pub expression: ExpressionId,
 
    // Validator/Linker
 
    pub parent: ExpressionParent,
 
    pub unique_id_in_definition: i32,
 
}
 

	
 
#[derive(Debug, Clone)]
 
pub struct IndexingExpression {
 
    pub this: IndexingExpressionId,
 
    // Parsing
 
    pub operator_span: InputSpan,
 
    pub full_span: InputSpan,
 
    pub subject: ExpressionId,
 
    pub index: ExpressionId,
 
    // Validator/Linker
 
    pub parent: ExpressionParent,
 
    pub unique_id_in_definition: i32,
 
}
 

	
 
#[derive(Debug, Clone)]
 
pub struct SlicingExpression {
 
    pub this: SlicingExpressionId,
 
    // Parsing
 
    pub slicing_span: InputSpan, // from '[' to ']'
 
    pub full_span: InputSpan, // includes subject
 
    pub subject: ExpressionId,
 
    pub from_index: ExpressionId,
 
    pub to_index: ExpressionId,
 
    // Validator/Linker
 
    pub parent: ExpressionParent,
 
    pub unique_id_in_definition: i32,
 
}
 

	
 
#[derive(Debug, Clone)]
 
pub enum SelectKind {
 
    StructField(Identifier),
 
    TupleMember(u64), // u64 is overkill, but space is taken up by `StructField` variant anyway
 
}
 

	
 
#[derive(Debug, Clone)]
 
pub struct SelectExpression {
 
    pub this: SelectExpressionId,
 
    // Parsing
 
    pub operator_span: InputSpan, // of the '.'
 
    pub full_span: InputSpan, // includes subject and field
 
    pub subject: ExpressionId,
 
    pub kind: SelectKind,
 
    // Validator/Linker
 
    pub parent: ExpressionParent,
 
    pub unique_id_in_definition: i32,
 
}
 

	
 
#[derive(Debug, Clone)]
 
pub struct CastExpression {
 
    pub this: CastExpressionId,
 
    // Parsing
 
    pub cast_span: InputSpan, // of the "cast" keyword,
 
    pub full_span: InputSpan, // includes the cast subject
 
    pub to_type: ParserType,
 
    pub subject: ExpressionId,
 
    // Validator/linker
 
    pub parent: ExpressionParent,
 
    pub unique_id_in_definition: i32,
 
}
 

	
 
#[derive(Debug, Clone)]
 
pub struct CallExpression {
 
    pub this: CallExpressionId,
 
    // Parsing
 
    pub func_span: InputSpan, // of the function name
 
    pub full_span: InputSpan, // includes the arguments and parentheses
 
    pub parser_type: ParserType, // of the function call, not the return type
 
    pub method: Method,
 
    pub arguments: Vec<ExpressionId>,
 
    pub definition: DefinitionId,
 
    // Validator/Linker
 
    pub parent: ExpressionParent,
 
    pub unique_id_in_definition: i32,
 
}
 

	
 
#[derive(Debug, Clone, PartialEq, Eq)]
 
pub enum Method {
 
    // Builtin, accessible by programmer
 
    Get,
 
    Put,
 
    Fires,
 
    Create,
 
    Length,
 
    Assert,
 
    Print,
 
    // Builtin, not accessible by programmer
 
    SelectStart, // SelectStart(total_num_cases, total_num_ports)
 
    SelectRegisterCasePort, // SelectRegisterCasePort(case_index, port_index, port_id)
 
    SelectWait, // SelectWait() -> u32
 
    // User-defined
 
    UserFunction,
 
    UserComponent,
 
}
 

	
 
#[derive(Debug, Clone)]
 
pub struct MethodSymbolic {
 
    pub(crate) parser_type: ParserType,
 
    pub(crate) definition: DefinitionId
 
}
 

	
 
#[derive(Debug, Clone)]
 
pub struct LiteralExpression {
 
    pub this: LiteralExpressionId,
 
    // Parsing
 
    pub span: InputSpan,
 
    pub value: Literal,
 
    // Validator/Linker
 
    pub parent: ExpressionParent,
 
    pub unique_id_in_definition: i32,
 
}
 

	
 
#[derive(Debug, Clone)]
 
pub enum Literal {
 
    Null, // message
 
    True,
 
    False,
 
    Character(char),
 
    String(StringRef<'static>),
 
    Integer(LiteralInteger),
 
    Struct(LiteralStruct),
 
    Enum(LiteralEnum),
 
    Union(LiteralUnion),
 
    Array(Vec<ExpressionId>),
 
    Tuple(Vec<ExpressionId>),
 
}
 

	
 
impl Literal {
 
    pub(crate) fn as_struct(&self) -> &LiteralStruct {
 
        if let Literal::Struct(literal) = self{
 
            literal
 
        } else {
 
            unreachable!("Attempted to obtain {:?} as Literal::Struct", self)
 
        }
 
    }
 

	
 
    pub(crate) fn as_enum(&self) -> &LiteralEnum {
 
        if let Literal::Enum(literal) = self {
 
            literal
 
        } else {
 
            unreachable!("Attempted to obtain {:?} as Literal::Enum", self)
 
        }
 
    }
 

	
 
    pub(crate) fn as_union(&self) -> &LiteralUnion {
 
        if let Literal::Union(literal) = self {
 
            literal
 
        } else {
 
            unreachable!("Attempted to obtain {:?} as Literal::Union", self)
 
        }
 
    }
 
}
 

	
 
#[derive(Debug, Clone)]
 
pub struct LiteralInteger {
 
    pub(crate) unsigned_value: u64,
 
    pub(crate) negated: bool, // for constant expression evaluation, TODO: @Int
 
}
 

	
 
#[derive(Debug, Clone)]
 
pub struct LiteralStructField {
 
    // Phase 1: parser
 
    pub(crate) identifier: Identifier,
 
    pub(crate) value: ExpressionId,
 
    // Phase 2: linker
 
    pub(crate) field_idx: usize, // in struct definition
 
}
 

	
 
#[derive(Debug, Clone)]
 
pub struct LiteralStruct {
 
    // Phase 1: parser
 
    pub(crate) parser_type: ParserType,
 
    pub(crate) fields: Vec<LiteralStructField>,
 
    pub(crate) definition: DefinitionId,
 
}
 

	
 
#[derive(Debug, Clone)]
 
pub struct LiteralEnum {
 
    // Phase 1: parser
 
    pub(crate) parser_type: ParserType,
 
    pub(crate) variant: Identifier,
 
    pub(crate) definition: DefinitionId,
 
    // Phase 2: linker
 
    pub(crate) variant_idx: usize, // as present in the type table
 
}
 

	
 
#[derive(Debug, Clone)]
 
pub struct LiteralUnion {
 
    // Phase 1: parser
 
    pub(crate) parser_type: ParserType,
 
    pub(crate) variant: Identifier,
 
    pub(crate) values: Vec<ExpressionId>,
 
    pub(crate) definition: DefinitionId,
 
    // Phase 2: linker
 
    pub(crate) variant_idx: usize, // as present in type table
 
}
 

	
 
#[derive(Debug, Clone)]
 
pub struct VariableExpression {
 
    pub this: VariableExpressionId,
 
    // Parsing
 
    pub identifier: Identifier,
 
    // Validator/Linker
 
    pub declaration: Option<VariableId>,
 
    pub used_as_binding_target: bool,
 
    pub parent: ExpressionParent,
 
    pub unique_id_in_definition: i32, // used to index into type table after all types are determined
 
}
 
\ No newline at end of file
src/protocol/parser/pass_definitions.rs
Show inline comments
 
use crate::protocol::ast::*;
 
use super::symbol_table::*;
 
use super::{Module, ModuleCompilationPhase, PassCtx};
 
use super::tokens::*;
 
use super::token_parsing::*;
 
use super::pass_definitions_types::*;
 

	
 
use crate::protocol::input_source::{InputSource, InputPosition, InputSpan, ParseError};
 
use crate::collections::*;
 

	
 
/// Parses all the tokenized definitions into actual AST nodes.
 
pub(crate) struct PassDefinitions {
 
    // State associated with the definition currently being processed
 
    cur_definition: DefinitionId,
 
    // Itty bitty parsing machines
 
    type_parser: ParserTypeParser,
 
    // Temporary buffers of various kinds
 
    buffer: String,
 
    struct_fields: ScopedBuffer<StructFieldDefinition>,
 
    enum_variants: ScopedBuffer<EnumVariantDefinition>,
 
    union_variants: ScopedBuffer<UnionVariantDefinition>,
 
    variables: ScopedBuffer<VariableId>,
 
    expressions: ScopedBuffer<ExpressionId>,
 
    statements: ScopedBuffer<StatementId>,
 
    parser_types: ScopedBuffer<ParserType>,
 
}
 

	
 
impl PassDefinitions {
 
    pub(crate) fn new() -> Self {
 
        Self{
 
            cur_definition: DefinitionId::new_invalid(),
 
            type_parser: ParserTypeParser::new(),
 
            buffer: String::with_capacity(128),
 
            struct_fields: ScopedBuffer::with_capacity(128),
 
            enum_variants: ScopedBuffer::with_capacity(128),
 
            union_variants: ScopedBuffer::with_capacity(128),
 
            variables: ScopedBuffer::with_capacity(128),
 
            expressions: ScopedBuffer::with_capacity(128),
 
            statements: ScopedBuffer::with_capacity(128),
 
            parser_types: ScopedBuffer::with_capacity(128),
 
        }
 
    }
 

	
 
    pub(crate) fn parse(&mut self, modules: &mut [Module], module_idx: usize, ctx: &mut PassCtx) -> Result<(), ParseError> {
 
        let module = &modules[module_idx];
 
        let module_range = &module.tokens.ranges[0];
 
        debug_assert_eq!(module.phase, ModuleCompilationPhase::ImportsResolved);
 
        debug_assert_eq!(module_range.range_kind, TokenRangeKind::Module);
 

	
 
        // Although we only need to parse the definitions, we want to go through
 
        // code ranges as well such that we can throw errors if we get
 
        // unexpected tokens at the module level of the source.
 
        let mut range_idx = module_range.first_child_idx;
 
        loop {
 
            let range_idx_usize = range_idx as usize;
 
            let cur_range = &module.tokens.ranges[range_idx_usize];
 

	
 
            match cur_range.range_kind {
 
                TokenRangeKind::Module => unreachable!(), // should not be reachable
 
                TokenRangeKind::Pragma | TokenRangeKind::Import => {
 
                    // Already fully parsed, fall through and go to next range
 
                },
 
                TokenRangeKind::Definition | TokenRangeKind::Code => {
 
                    // Visit range even if it is a "code" range to provide
 
                    // proper error messages.
 
                    self.visit_range(modules, module_idx, ctx, range_idx_usize)?;
 
                },
 
            }
 

	
 
            if cur_range.next_sibling_idx == NO_SIBLING {
 
                break;
 
            } else {
 
                range_idx = cur_range.next_sibling_idx;
 
            }
 
        }
 

	
 
        modules[module_idx].phase = ModuleCompilationPhase::DefinitionsParsed;
 

	
 
        Ok(())
 
    }
 

	
 
    fn visit_range(
 
        &mut self, modules: &[Module], module_idx: usize, ctx: &mut PassCtx, range_idx: usize
 
    ) -> Result<(), ParseError> {
 
        let module = &modules[module_idx];
 
        let cur_range = &module.tokens.ranges[range_idx];
 
        debug_assert!(cur_range.range_kind == TokenRangeKind::Definition || cur_range.range_kind == TokenRangeKind::Code);
 

	
 
        // Detect which definition we're parsing
 
        let mut iter = module.tokens.iter_range(cur_range);
 
        loop {
 
            let next = iter.next();
 
            if next.is_none() {
 
                return Ok(())
 
            }
 

	
 
            // Token was not None, so peek_ident returns None if not an ident
 
            let ident = peek_ident(&module.source, &mut iter);
 
            match ident {
 
                Some(KW_STRUCT) => self.visit_struct_definition(module, &mut iter, ctx)?,
 
                Some(KW_ENUM) => self.visit_enum_definition(module, &mut iter, ctx)?,
 
                Some(KW_UNION) => self.visit_union_definition(module, &mut iter, ctx)?,
 
                Some(KW_FUNCTION) => self.visit_function_definition(module, &mut iter, ctx)?,
 
                Some(KW_PRIMITIVE) | Some(KW_COMPOSITE) => self.visit_component_definition(module, &mut iter, ctx)?,
 
                _ => return Err(ParseError::new_error_str_at_pos(
 
                    &module.source, iter.last_valid_pos(),
 
                    "unexpected symbol, expected a keyword marking the start of a definition"
 
                )),
 
            }
 
        }
 
    }
 

	
 
    fn visit_struct_definition(
 
        &mut self, module: &Module, iter: &mut TokenIter, ctx: &mut PassCtx
 
    ) -> Result<(), ParseError> {
 
        consume_exact_ident(&module.source, iter, KW_STRUCT)?;
 
        let (ident_text, _) = consume_ident(&module.source, iter)?;
 

	
 
        // Retrieve preallocated DefinitionId
 
        let module_scope = SymbolScope::Module(module.root_id);
 
        let definition_id = ctx.symbols.get_symbol_by_name_defined_in_scope(module_scope, ident_text)
 
            .unwrap().variant.as_definition().definition_id;
 
        self.cur_definition = definition_id;
 

	
 
        // Parse struct definition
 
        consume_polymorphic_vars_spilled(&module.source, iter, ctx)?;
 

	
 
        let mut fields_section = self.struct_fields.start_section();
 
        consume_comma_separated(
 
            TokenKind::OpenCurly, TokenKind::CloseCurly, &module.source, iter, ctx,
 
            |source, iter, ctx| {
 
                let poly_vars = ctx.heap[definition_id].poly_vars();
 

	
 
                let start_pos = iter.last_valid_pos();
 
                let parser_type = self.type_parser.consume_parser_type(
 
                    iter, &ctx.heap, source, &ctx.symbols, poly_vars, definition_id,
 
                    module_scope, false, None
 
                )?;
 
                let field = consume_ident_interned(source, iter, ctx)?;
 
                Ok(StructFieldDefinition{
 
                    span: InputSpan::from_positions(start_pos, field.span.end),
 
                    field, parser_type
 
                })
 
            },
 
            &mut fields_section, "a struct field", "a list of struct fields", None
 
        )?;
 

	
 
        // Transfer to preallocated definition
 
        let struct_def = ctx.heap[definition_id].as_struct_mut();
 
        struct_def.fields = fields_section.into_vec();
 

	
 
        Ok(())
 
    }
 

	
 
    fn visit_enum_definition(
 
        &mut self, module: &Module, iter: &mut TokenIter, ctx: &mut PassCtx
 
    ) -> Result<(), ParseError> {
 
        consume_exact_ident(&module.source, iter, KW_ENUM)?;
 
        let (ident_text, _) = consume_ident(&module.source, iter)?;
 

	
 
        // Retrieve preallocated DefinitionId
 
        let module_scope = SymbolScope::Module(module.root_id);
 
        let definition_id = ctx.symbols.get_symbol_by_name_defined_in_scope(module_scope, ident_text)
 
            .unwrap().variant.as_definition().definition_id;
 
        self.cur_definition = definition_id;
 

	
 
        // Parse enum definition
 
        consume_polymorphic_vars_spilled(&module.source, iter, ctx)?;
 

	
 
        let mut enum_section = self.enum_variants.start_section();
 
        consume_comma_separated(
 
            TokenKind::OpenCurly, TokenKind::CloseCurly, &module.source, iter, ctx,
 
            |source, iter, ctx| {
 
                let identifier = consume_ident_interned(source, iter, ctx)?;
 
                let value = if iter.next() == Some(TokenKind::Equal) {
 
                    iter.consume();
 
                    let (variant_number, _) = consume_integer_literal(source, iter, &mut self.buffer)?;
 
                    EnumVariantValue::Integer(variant_number as i64) // TODO: @int
 
                } else {
 
                    EnumVariantValue::None
 
                };
 
                Ok(EnumVariantDefinition{ identifier, value })
 
            },
 
            &mut enum_section, "an enum variant", "a list of enum variants", None
 
        )?;
 

	
 
        // Transfer to definition
 
        let enum_def = ctx.heap[definition_id].as_enum_mut();
 
        enum_def.variants = enum_section.into_vec();
 

	
 
        Ok(())
 
    }
 

	
 
    fn visit_union_definition(
 
        &mut self, module: &Module, iter: &mut TokenIter, ctx: &mut PassCtx
 
    ) -> Result<(), ParseError> {
 
        consume_exact_ident(&module.source, iter, KW_UNION)?;
 
        let (ident_text, _) = consume_ident(&module.source, iter)?;
 

	
 
        // Retrieve preallocated DefinitionId
 
        let module_scope = SymbolScope::Module(module.root_id);
 
        let definition_id = ctx.symbols.get_symbol_by_name_defined_in_scope(module_scope, ident_text)
 
            .unwrap().variant.as_definition().definition_id;
 
        self.cur_definition = definition_id;
 

	
 
        // Parse union definition
 
        consume_polymorphic_vars_spilled(&module.source, iter, ctx)?;
 

	
 
        let mut variants_section = self.union_variants.start_section();
 
        consume_comma_separated(
 
            TokenKind::OpenCurly, TokenKind::CloseCurly, &module.source, iter, ctx,
 
            |source, iter, ctx| {
 
                let identifier = consume_ident_interned(source, iter, ctx)?;
 
                let mut close_pos = identifier.span.end;
 

	
 
                let mut types_section = self.parser_types.start_section();
 

	
 
                let has_embedded = maybe_consume_comma_separated(
 
                    TokenKind::OpenParen, TokenKind::CloseParen, source, iter, ctx,
 
                    |source, iter, ctx| {
 
                        let poly_vars = ctx.heap[definition_id].poly_vars();
 
                        self.type_parser.consume_parser_type(
 
                            iter, &ctx.heap, source, &ctx.symbols, poly_vars, definition_id,
 
                            module_scope, false, None
 
                        )
 
                    },
 
                    &mut types_section, "an embedded type", Some(&mut close_pos)
 
                )?;
 
                let value = if has_embedded {
 
                    types_section.into_vec()
 
                } else {
 
                    types_section.forget();
 
                    Vec::new()
 
                };
 

	
 
                Ok(UnionVariantDefinition{
 
                    span: InputSpan::from_positions(identifier.span.begin, close_pos),
 
                    identifier,
 
                    value
 
                })
 
            },
 
            &mut variants_section, "a union variant", "a list of union variants", None
 
        )?;
 

	
 
        // Transfer to AST
 
        let union_def = ctx.heap[definition_id].as_union_mut();
 
        union_def.variants = variants_section.into_vec();
 

	
 
        Ok(())
 
    }
 

	
 
    fn visit_function_definition(
 
        &mut self, module: &Module, iter: &mut TokenIter, ctx: &mut PassCtx
 
    ) -> Result<(), ParseError> {
 
        // Retrieve function name
 
        consume_exact_ident(&module.source, iter, KW_FUNCTION)?;
 
        let (ident_text, _) = consume_ident(&module.source, iter)?;
 

	
 
        // Retrieve preallocated DefinitionId
 
        let module_scope = SymbolScope::Module(module.root_id);
 
        let definition_id = ctx.symbols.get_symbol_by_name_defined_in_scope(module_scope, ident_text)
 
            .unwrap().variant.as_definition().definition_id;
 
        self.cur_definition = definition_id;
 

	
 
        consume_polymorphic_vars_spilled(&module.source, iter, ctx)?;
 

	
 
        // Parse function's argument list
 
        let mut parameter_section = self.variables.start_section();
 
        consume_parameter_list(
 
            &mut self.type_parser, &module.source, iter, ctx, &mut parameter_section, module_scope, definition_id
 
        )?;
 
        let parameters = parameter_section.into_vec();
 

	
 
        // Consume return types
 
        consume_token(&module.source, iter, TokenKind::ArrowRight)?;
 
        let poly_vars = ctx.heap[definition_id].poly_vars();
 
        let parser_type = self.type_parser.consume_parser_type(
 
            iter, &ctx.heap, &module.source, &ctx.symbols, poly_vars, definition_id,
 
            module_scope, false, None
 
        )?;
 

	
 
        // Consume block and the definition's scope
 
        let body_id = self.consume_block_statement(module, iter, ctx)?;
 
        let scope_id = ctx.heap.alloc_scope(|this| Scope::new(this, ScopeAssociation::Definition(definition_id)));
 

	
 
        // Assign everything in the preallocated AST node
 
        let function = ctx.heap[definition_id].as_function_mut();
 
        function.return_type = parser_type;
 
        function.parameters = parameters;
 
        function.scope = scope_id;
 
        function.body = body_id;
 

	
 
        Ok(())
 
    }
 

	
 
    fn visit_component_definition(
 
        &mut self, module: &Module, iter: &mut TokenIter, ctx: &mut PassCtx
 
    ) -> Result<(), ParseError> {
 
        // Consume component variant and name
 
        let (_variant_text, _) = consume_any_ident(&module.source, iter)?;
 
        debug_assert!(_variant_text == KW_PRIMITIVE || _variant_text == KW_COMPOSITE);
 
        let (ident_text, _) = consume_ident(&module.source, iter)?;
 

	
 
        // Retrieve preallocated definition
 
        let module_scope = SymbolScope::Module(module.root_id);
 
        let definition_id = ctx.symbols.get_symbol_by_name_defined_in_scope(module_scope, ident_text)
 
            .unwrap().variant.as_definition().definition_id;
 
        self.cur_definition = definition_id;
 

	
 
        consume_polymorphic_vars_spilled(&module.source, iter, ctx)?;
 

	
 
        // Parse component's argument list
 
        let mut parameter_section = self.variables.start_section();
 
        consume_parameter_list(
 
            &mut self.type_parser, &module.source, iter, ctx, &mut parameter_section, module_scope, definition_id
 
        )?;
 
        let parameters = parameter_section.into_vec();
 

	
 
        // Consume block
 
        let body_id = self.consume_block_statement(module, iter, ctx)?;
 
        let scope_id = ctx.heap.alloc_scope(|this| Scope::new(this, ScopeAssociation::Definition(definition_id)));
 

	
 
        // Assign everything in the AST node
 
        let component = ctx.heap[definition_id].as_component_mut();
 
        component.parameters = parameters;
 
        component.scope = scope_id;
 
        component.body = body_id;
 

	
 
        Ok(())
 
    }
 

	
 
    /// Consumes a statement and returns a boolean indicating whether it was a
 
    /// block or not.
 
    fn consume_statement(&mut self, module: &Module, iter: &mut TokenIter, ctx: &mut PassCtx) -> Result<StatementId, ParseError> {
 
        let next = iter.next().expect("consume_statement has a next token");
 

	
 
        if next == TokenKind::OpenCurly {
 
            let id = self.consume_block_statement(module, iter, ctx)?;
 
            return Ok(id.upcast());
 
        } else if next == TokenKind::Ident {
 
            let ident = peek_ident(&module.source, iter).unwrap();
 
            if ident == KW_STMT_IF {
 
                // Consume if statement and place end-if statement directly
 
                // after it.
 
                let id = self.consume_if_statement(module, iter, ctx)?;
 
                return Ok(id.upcast());
 
            } else if ident == KW_STMT_WHILE {
 
                let id = self.consume_while_statement(module, iter, ctx)?;
 
                return Ok(id.upcast());
 
            } else if ident == KW_STMT_BREAK {
 
                let id = self.consume_break_statement(module, iter, ctx)?;
 
                return Ok(id.upcast());
 
            } else if ident == KW_STMT_CONTINUE {
 
                let id = self.consume_continue_statement(module, iter, ctx)?;
 
                return Ok(id.upcast());
 
            } else if ident == KW_STMT_SYNC {
 
                let id = self.consume_synchronous_statement(module, iter, ctx)?;
 
                return Ok(id.upcast());
 
            } else if ident == KW_STMT_FORK {
 
                let id = self.consume_fork_statement(module, iter, ctx)?;
 

	
 
                let end_fork = ctx.heap.alloc_end_fork_statement(|this| EndForkStatement {
 
                    this,
 
                    start_fork: id,
 
                    next: StatementId::new_invalid(),
 
                });
 

	
 
                let fork_stmt = &mut ctx.heap[id];
 
                fork_stmt.end_fork = end_fork;
 

	
 
                return Ok(id.upcast());
 
            } else if ident == KW_STMT_SELECT {
 
                let id = self.consume_select_statement(module, iter, ctx)?;
 
                return Ok(id.upcast());
 
            } else if ident == KW_STMT_RETURN {
 
                let id = self.consume_return_statement(module, iter, ctx)?;
 
                return Ok(id.upcast());
 
            } else if ident == KW_STMT_GOTO {
 
                let id = self.consume_goto_statement(module, iter, ctx)?;
 
                return Ok(id.upcast());
 
            } else if ident == KW_STMT_NEW {
 
                let id = self.consume_new_statement(module, iter, ctx)?;
 
                return Ok(id.upcast());
 
            } else if ident == KW_STMT_CHANNEL {
 
                let id = self.consume_channel_statement(module, iter, ctx)?;
 
                return Ok(id.upcast().upcast());
 
            } else if iter.peek() == Some(TokenKind::Colon) {
 
                let id = self.consume_labeled_statement(module, iter, ctx)?;
 
                return Ok(id.upcast());
 
            } else {
 
                // Two fallback possibilities: the first one is a memory
 
                // declaration, the other one is to parse it as a normal
 
                // expression. This is a bit ugly.
 
                if let Some(memory_stmt_id) = self.maybe_consume_memory_statement_without_semicolon(module, iter, ctx)? {
 
                    consume_token(&module.source, iter, TokenKind::SemiColon)?;
 
                    return Ok(memory_stmt_id.upcast().upcast());
 
                } else {
 
                    let id = self.consume_expression_statement(module, iter, ctx)?;
 
                    return Ok(id.upcast());
 
                }
 
            }
 
        } else if next == TokenKind::OpenParen {
 
            // Same as above: memory statement or normal expression
 
            if let Some(memory_stmt_id) = self.maybe_consume_memory_statement_without_semicolon(module, iter, ctx)? {
 
                consume_token(&module.source, iter, TokenKind::SemiColon)?;
 
                return Ok(memory_stmt_id.upcast().upcast());
 
            } else {
 
                let id = self.consume_expression_statement(module, iter, ctx)?;
 
                return Ok(id.upcast());
 
            }
 
        } else {
 
            let id = self.consume_expression_statement(module, iter, ctx)?;
 
            return Ok(id.upcast());
 
        }
 
    }
 

	
 
    fn consume_block_statement(
 
        &mut self, module: &Module, iter: &mut TokenIter, ctx: &mut PassCtx
 
    ) -> Result<BlockStatementId, ParseError> {
 
        let open_curly_span = consume_token(&module.source, iter, TokenKind::OpenCurly)?;
 

	
 
        let mut stmt_section = self.statements.start_section();
 
        let mut next = iter.next();
 
        while next != Some(TokenKind::CloseCurly) {
 
            if next.is_none() {
 
                return Err(ParseError::new_error_str_at_pos(
 
                    &module.source, iter.last_valid_pos(), "expected a statement or '}'"
 
                ));
 
            }
 
            let stmt_id = self.consume_statement(module, iter, ctx)?;
 
            stmt_section.push(stmt_id);
 
            next = iter.next();
 
        }
 

	
 
        let statements = stmt_section.into_vec();
 
        let mut block_span = consume_token(&module.source, iter, TokenKind::CloseCurly)?;
 
        block_span.begin = open_curly_span.begin;
 

	
 
        let block_id = ctx.heap.alloc_block_statement(|this| BlockStatement{
 
            this,
 
            is_implicit: false,
 
            span: block_span,
 
            statements,
 
            end_block: EndBlockStatementId::new_invalid(),
 
            scope: ScopeId::new_invalid(),
 
            next: StatementId::new_invalid(),
 
        });
 
        let scope_id = ctx.heap.alloc_scope(|this| Scope::new(this, ScopeAssociation::Block(block_id)));
 

	
 
        let end_block_id = ctx.heap.alloc_end_block_statement(|this| EndBlockStatement{
 
            this, start_block: block_id, next: StatementId::new_invalid()
 
        });
 

	
 
        let block_stmt = &mut ctx.heap[block_id];
 
        block_stmt.end_block = end_block_id;
 
        block_stmt.scope = scope_id;
 

	
 
        Ok(block_id)
 
    }
 

	
 
    fn consume_if_statement(
 
        &mut self, module: &Module, iter: &mut TokenIter, ctx: &mut PassCtx
 
    ) -> Result<IfStatementId, ParseError> {
 
        let if_span = consume_exact_ident(&module.source, iter, KW_STMT_IF)?;
 
        consume_token(&module.source, iter, TokenKind::OpenParen)?;
 
        let test = self.consume_expression(module, iter, ctx)?;
 
        consume_token(&module.source, iter, TokenKind::CloseParen)?;
 

	
 
        // Consume bodies of if-statement
 
        let true_body = IfStatementCase{
 
            body: self.consume_statement(module, iter, ctx)?,
 
            scope: ScopeId::new_invalid(),
 
        };
 

	
 
        let false_body = if has_ident(&module.source, iter, KW_STMT_ELSE) {
 
            iter.consume();
 
            let false_body = IfStatementCase{
 
                body: self.consume_statement(module, iter, ctx)?,
 
                scope: ScopeId::new_invalid(),
 
            };
 

	
 
            let false_body_scope_id = false_body.scope;
 
            Some(false_body)
 
        } else {
 
            None
 
        };
 

	
 
        // Construct AST elements
 
        let if_stmt_id = ctx.heap.alloc_if_statement(|this| IfStatement{
 
            this,
 
            span: if_span,
 
            test,
 
            true_case: true_body,
 
            false_case: false_body,
 
            end_if: EndIfStatementId::new_invalid(),
 
        });
 
        let end_if_stmt_id = ctx.heap.alloc_end_if_statement(|this| EndIfStatement{
 
            this,
 
            start_if: if_stmt_id,
 
            next: StatementId::new_invalid(),
 
        });
 
        let true_scope_id = ctx.heap.alloc_scope(|this| Scope::new(this, ScopeAssociation::If(if_stmt_id, true)));
 
        let false_scope_id = if false_body.is_some() {
 
            Some(ctx.heap.alloc_scope(|this| Scope::new(this, ScopeAssociation::If(if_stmt_id, false))))
 
        } else {
 
            None
 
        };
 

	
 
        let if_stmt = &mut ctx.heap[if_stmt_id];
 
        if_stmt.end_if = end_if_stmt_id;
 
        if_stmt.true_case.scope = true_scope_id;
 
        if let Some(false_case) = &mut if_stmt.false_case {
 
            false_case.scope = false_scope_id.unwrap();
 
        }
 

	
 
        return Ok(if_stmt_id);
 
    }
 

	
 
    fn consume_while_statement(
 
        &mut self, module: &Module, iter: &mut TokenIter, ctx: &mut PassCtx
 
    ) -> Result<WhileStatementId, ParseError> {
 
        let while_span = consume_exact_ident(&module.source, iter, KW_STMT_WHILE)?;
 
        consume_token(&module.source, iter, TokenKind::OpenParen)?;
 
        let test = self.consume_expression(module, iter, ctx)?;
 
        consume_token(&module.source, iter, TokenKind::CloseParen)?;
 
        let body = self.consume_statement(module, iter, ctx)?;
 

	
 
        let while_stmt_id = ctx.heap.alloc_while_statement(|this| WhileStatement{
 
            this,
 
            span: while_span,
 
            test,
 
            scope: ScopeId::new_invalid(),
 
            body,
 
            end_while: EndWhileStatementId::new_invalid(),
 
            in_sync: SynchronousStatementId::new_invalid(),
 
        });
 
        let end_while_stmt_id = ctx.heap.alloc_end_while_statement(|this| EndWhileStatement{
 
            this,
 
            start_while: while_stmt_id,
 
            next: StatementId::new_invalid(),
 
        });
 
        let scope_id = ctx.heap.alloc_scope(|this| Scope::new(this, ScopeAssociation::While(while_stmt_id)));
 

	
 
        let while_stmt = &mut ctx.heap[while_stmt_id];
 
        while_stmt.scope = scope_id;
 
        while_stmt.end_while = end_while_stmt_id;
 

	
 
        Ok(while_stmt_id)
 
    }
 

	
 
    fn consume_break_statement(
 
        &mut self, module: &Module, iter: &mut TokenIter, ctx: &mut PassCtx
 
    ) -> Result<BreakStatementId, ParseError> {
 
        let break_span = consume_exact_ident(&module.source, iter, KW_STMT_BREAK)?;
 
        let label = if Some(TokenKind::Ident) == iter.next() {
 
            let label = consume_ident_interned(&module.source, iter, ctx)?;
 
            Some(label)
 
        } else {
 
            None
 
        };
 
        consume_token(&module.source, iter, TokenKind::SemiColon)?;
 
        Ok(ctx.heap.alloc_break_statement(|this| BreakStatement{
 
            this,
 
            span: break_span,
 
            label,
 
            target: EndWhileStatementId::new_invalid(),
 
        }))
 
    }
 

	
 
    fn consume_continue_statement(
 
        &mut self, module: &Module, iter: &mut TokenIter, ctx: &mut PassCtx
 
    ) -> Result<ContinueStatementId, ParseError> {
 
        let continue_span = consume_exact_ident(&module.source, iter, KW_STMT_CONTINUE)?;
 
        let label=  if Some(TokenKind::Ident) == iter.next() {
 
            let label = consume_ident_interned(&module.source, iter, ctx)?;
 
            Some(label)
 
        } else {
 
            None
 
        };
 
        consume_token(&module.source, iter, TokenKind::SemiColon)?;
 
        Ok(ctx.heap.alloc_continue_statement(|this| ContinueStatement{
 
            this,
 
            span: continue_span,
 
            label,
 
            target: WhileStatementId::new_invalid(),
 
        }))
 
    }
 

	
 
    fn consume_synchronous_statement(
 
        &mut self, module: &Module, iter: &mut TokenIter, ctx: &mut PassCtx
 
    ) -> Result<SynchronousStatementId, ParseError> {
 
        let synchronous_span = consume_exact_ident(&module.source, iter, KW_STMT_SYNC)?;
 
        let body = self.consume_statement(module, iter, ctx)?;
 

	
 
        let sync_stmt_id = ctx.heap.alloc_synchronous_statement(|this| SynchronousStatement{
 
            this,
 
            span: synchronous_span,
 
            scope: ScopeId::new_invalid(),
 
            body,
 
            end_sync: EndSynchronousStatementId::new_invalid(),
 
        });
 
        let end_sync_stmt_id = ctx.heap.alloc_end_synchronous_statement(|this| EndSynchronousStatement{
 
            this,
 
            start_sync: sync_stmt_id,
 
            next: StatementId::new_invalid(),
 
        });
 
        let scope_id = ctx.heap.alloc_scope(|this| Scope::new(this, ScopeAssociation::Synchronous(sync_stmt_id)));
 

	
 
        let sync_stmt = &mut ctx.heap[sync_stmt_id];
 
        sync_stmt.scope = scope_id;
 
        sync_stmt.end_sync = end_sync_stmt_id;
 

	
 
        return Ok(sync_stmt_id);
 
    }
 

	
 
    fn consume_fork_statement(
 
        &mut self, module: &Module, iter: &mut TokenIter, ctx: &mut PassCtx
 
    ) -> Result<ForkStatementId, ParseError> {
 
        let fork_span = consume_exact_ident(&module.source, iter, KW_STMT_FORK)?;
 
        let left_body = self.consume_statement(module, iter, ctx)?;
 

	
 
        let right_body = if has_ident(&module.source, iter, KW_STMT_OR) {
 
            iter.consume();
 
            let right_body = self.consume_statement(module, iter, ctx)?;
 
            Some(right_body)
 
        } else {
 
            None
 
        };
 

	
 
        Ok(ctx.heap.alloc_fork_statement(|this| ForkStatement{
 
            this,
 
            span: fork_span,
 
            left_body,
 
            right_body,
 
            end_fork: EndForkStatementId::new_invalid(),
 
        }))
 
    }
 

	
 
    fn consume_select_statement(
 
        &mut self, module: &Module, iter: &mut TokenIter, ctx: &mut PassCtx
 
    ) -> Result<SelectStatementId, ParseError> {
 
        let select_span = consume_exact_ident(&module.source, iter, KW_STMT_SELECT)?;
 
        consume_token(&module.source, iter, TokenKind::OpenCurly)?;
 

	
 
        let mut cases = Vec::new();
 
        let mut next = iter.next();
 

	
 
        while Some(TokenKind::CloseCurly) != next {
 
            let guard = match self.maybe_consume_memory_statement_without_semicolon(module, iter, ctx)? {
 
                Some(guard_mem_stmt) => guard_mem_stmt.upcast().upcast(),
 
                None => {
 
                    let start_pos = iter.last_valid_pos();
 
                    let expr = self.consume_expression(module, iter, ctx)?;
 
                    let end_pos = iter.last_valid_pos();
 

	
 
                    let guard_expr_stmt = ctx.heap.alloc_expression_statement(|this| ExpressionStatement{
 
                        this,
 
                        span: InputSpan::from_positions(start_pos, end_pos),
 
                        expression: expr,
 
                        next: StatementId::new_invalid(),
 
                    });
 

	
 
                    guard_expr_stmt.upcast()
 
                },
 
            };
 
            consume_token(&module.source, iter, TokenKind::ArrowRight)?;
 
            let block = self.consume_statement(module, iter, ctx)?;
 
            cases.push(SelectCase{
 
                guard,
 
                body: block,
 
                scope: ScopeId::new_invalid(),
 
                involved_ports: Vec::with_capacity(1)
 
            });
 

	
 
            next = iter.next();
 
        }
 

	
 
        consume_token(&module.source, iter, TokenKind::CloseCurly)?;
 

	
 
        let num_cases = cases.len();
 
        let select_stmt_id = ctx.heap.alloc_select_statement(|this| SelectStatement{
 
            this,
 
            span: select_span,
 
            cases,
 
            end_select: EndSelectStatementId::new_invalid(),
 
            relative_pos_in_parent: -1,
 
            next: StatementId::new_invalid(),
 
        });
 

	
 
        let end_select_stmt_id = ctx.heap.alloc_end_select_statement(|this| EndSelectStatement{
 
            this,
 
            start_select: select_stmt_id,
 
            next: StatementId::new_invalid(),
 
        });
 

	
 
        let select_stmt = &mut ctx.heap[select_stmt_id];
 
        select_stmt.end_select = end_select_stmt_id;
 

	
 
        for case_index in 0..num_cases {
 
            let scope_id = ctx.heap.alloc_scope(|this| Scope::new(this, ScopeAssociation::SelectCase(select_stmt_id, case_index as u32)));
 
            let select_stmt = &mut ctx.heap[select_stmt_id];
 
            let select_case = &mut select_stmt.cases[case_index];
 
            select_case.scope = scope_id;
 
        }
 

	
 
        return Ok(select_stmt_id)
 
    }
 

	
 
    fn consume_return_statement(
 
        &mut self, module: &Module, iter: &mut TokenIter, ctx: &mut PassCtx
 
    ) -> Result<ReturnStatementId, ParseError> {
 
        let return_span = consume_exact_ident(&module.source, iter, KW_STMT_RETURN)?;
 
        let mut scoped_section = self.expressions.start_section();
 

	
 
        consume_comma_separated_until(
 
            TokenKind::SemiColon, &module.source, iter, ctx,
 
            |_source, iter, ctx| self.consume_expression(module, iter, ctx),
 
            &mut scoped_section, "an expression", None
 
        )?;
 
        let expressions = scoped_section.into_vec();
 

	
 
        if expressions.is_empty() {
 
            return Err(ParseError::new_error_str_at_span(&module.source, return_span, "expected at least one return value"));
 
        } else if expressions.len() > 1 {
 
            return Err(ParseError::new_error_str_at_span(&module.source, return_span, "multiple return values are not (yet) supported"))
 
        }
 

	
 
        Ok(ctx.heap.alloc_return_statement(|this| ReturnStatement{
 
            this,
 
            span: return_span,
 
            expressions
 
        }))
 
    }
 

	
 
    fn consume_goto_statement(
 
        &mut self, module: &Module, iter: &mut TokenIter, ctx: &mut PassCtx
 
    ) -> Result<GotoStatementId, ParseError> {
 
        let goto_span = consume_exact_ident(&module.source, iter, KW_STMT_GOTO)?;
 
        let label = consume_ident_interned(&module.source, iter, ctx)?;
 
        consume_token(&module.source, iter, TokenKind::SemiColon)?;
 
        Ok(ctx.heap.alloc_goto_statement(|this| GotoStatement{
 
            this,
 
            span: goto_span,
 
            label,
 
            target: LabeledStatementId::new_invalid(),
 
        }))
 
    }
 

	
 
    fn consume_new_statement(
 
        &mut self, module: &Module, iter: &mut TokenIter, ctx: &mut PassCtx
 
    ) -> Result<NewStatementId, ParseError> {
 
        let new_span = consume_exact_ident(&module.source, iter, KW_STMT_NEW)?;
 

	
 
        let start_pos = iter.last_valid_pos();
 
        let expression_id = self.consume_primary_expression(module, iter, ctx)?;
 
        let expression = &ctx.heap[expression_id];
 
        let mut valid = false;
 

	
 
        let mut call_id = CallExpressionId::new_invalid();
 
        if let Expression::Call(expression) = expression {
 
            // Allow both components and functions, as it makes more sense to
 
            // check their correct use in the validation and linking pass
 
            if expression.method == Method::UserComponent || expression.method == Method::UserFunction {
 
                call_id = expression.this;
 
                valid = true;
 
            }
 
        }
 

	
 
        if !valid {
 
            return Err(ParseError::new_error_str_at_span(
 
                &module.source, InputSpan::from_positions(start_pos, iter.last_valid_pos()), "expected a call expression"
 
            ));
 
        }
 
        consume_token(&module.source, iter, TokenKind::SemiColon)?;
 

	
 
        debug_assert!(!call_id.is_invalid());
 
        Ok(ctx.heap.alloc_new_statement(|this| NewStatement{
 
            this,
 
            span: new_span,
 
            expression: call_id,
 
            next: StatementId::new_invalid(),
 
        }))
 
    }
 

	
 
    fn consume_channel_statement(
 
        &mut self, module: &Module, iter: &mut TokenIter, ctx: &mut PassCtx
 
    ) -> Result<ChannelStatementId, ParseError> {
 
        // Consume channel specification
 
        let channel_span = consume_exact_ident(&module.source, iter, KW_STMT_CHANNEL)?;
 
        let (inner_port_type, end_pos) = if Some(TokenKind::OpenAngle) == iter.next() {
 
            // Retrieve the type of the channel, we're cheating a bit here by
 
            // consuming the first '<' and setting the initial angle depth to 1
 
            // such that our final '>' will be consumed as well.
 
            let angle_start_pos = iter.next_start_position();
 
            iter.consume();
 
            let definition_id = self.cur_definition;
 
            let poly_vars = ctx.heap[definition_id].poly_vars();
 
            let parser_type = self.type_parser.consume_parser_type(
 
                iter, &ctx.heap, &module.source, &ctx.symbols, poly_vars,
 
                definition_id, SymbolScope::Module(module.root_id),
 
                true, Some(angle_start_pos)
 
            )?;
 

	
 
            (parser_type.elements, parser_type.full_span.end)
 
        } else {
 
            // Assume inferred
 
            (
 
                vec![ParserTypeElement{
 
                    element_span: channel_span,
 
                    variant: ParserTypeVariant::Inferred
 
                }],
 
                channel_span.end
 
            )
 
        };
 

	
 
        let from_identifier = consume_ident_interned(&module.source, iter, ctx)?;
 
        consume_token(&module.source, iter, TokenKind::ArrowRight)?;
 
        let to_identifier = consume_ident_interned(&module.source, iter, ctx)?;
 
        consume_token(&module.source, iter, TokenKind::SemiColon)?;
 

	
 
        // Construct ports
 
        let port_type_span = InputSpan::from_positions(channel_span.begin, end_pos);
 
        let port_type_len = inner_port_type.len() + 1;
 
        let mut from_port_type = ParserType{ elements: Vec::with_capacity(port_type_len), full_span: port_type_span };
 
        from_port_type.elements.push(ParserTypeElement{
 
            element_span: channel_span,
 
            variant: ParserTypeVariant::Output,
 
        });
 
        from_port_type.elements.extend_from_slice(&inner_port_type);
 
        let from = ctx.heap.alloc_variable(|this| Variable{
 
            this,
 
            kind: VariableKind::Local,
 
            identifier: from_identifier,
 
            parser_type: from_port_type,
 
            relative_pos_in_parent: 0,
 
            unique_id_in_scope: -1,
 
        });
 

	
 
        let mut to_port_type = ParserType{ elements: Vec::with_capacity(port_type_len), full_span: port_type_span };
 
        to_port_type.elements.push(ParserTypeElement{
 
            element_span: channel_span,
 
            variant: ParserTypeVariant::Input
 
        });
 
        to_port_type.elements.extend_from_slice(&inner_port_type);
 
        let to = ctx.heap.alloc_variable(|this|Variable{
 
            this,
 
            kind: VariableKind::Local,
 
            identifier: to_identifier,
 
            parser_type: to_port_type,
 
            relative_pos_in_parent: 0,
 
            unique_id_in_scope: -1,
 
        });
 

	
 
        // Construct the channel
 
        Ok(ctx.heap.alloc_channel_statement(|this| ChannelStatement{
 
            this,
 
            span: channel_span,
 
            from, to,
 
            relative_pos_in_parent: 0,
 
            next: StatementId::new_invalid(),
 
        }))
 
    }
 

	
 
    fn consume_labeled_statement(&mut self, module: &Module, iter: &mut TokenIter, ctx: &mut PassCtx) -> Result<LabeledStatementId, ParseError> {
 
        let label = consume_ident_interned(&module.source, iter, ctx)?;
 
        consume_token(&module.source, iter, TokenKind::Colon)?;
 

	
 
        let inner_stmt_id = self.consume_statement(module, iter, ctx)?;
 
        let stmt_id = ctx.heap.alloc_labeled_statement(|this| LabeledStatement {
 
            this,
 
            label,
 
            body: inner_stmt_id,
 
            relative_pos_in_parent: 0,
 
            in_sync: SynchronousStatementId::new_invalid(),
 
        });
 

	
 
        return Ok(stmt_id);
 
    }
 

	
 
    /// Attempts to consume a memory statement (a statement along the lines of
 
    /// `type var_name = initial_expr`). Will return `Ok(None)` if it didn't
 
    /// seem like there was a memory statement, `Ok(Some(...))` if there was
 
    /// one, and `Err(...)` if its reasonable to assume that there was a memory
 
    /// statement, but we failed to parse it.
 
    fn maybe_consume_memory_statement_without_semicolon(
 
        &mut self, module: &Module, iter: &mut TokenIter, ctx: &mut PassCtx
 
    ) -> Result<Option<MemoryStatementId>, ParseError> {
 
        // This is a bit ugly. It would be nicer if we could somehow
 
        // consume the expression with a type hint if we do get a valid
 
        // type, but we don't get an identifier following it
 
        let iter_state = iter.save();
 
        let definition_id = self.cur_definition;
 
        let poly_vars = ctx.heap[definition_id].poly_vars();
 

	
 
        let parser_type = self.type_parser.consume_parser_type(
 
            iter, &ctx.heap, &module.source, &ctx.symbols, poly_vars,
 
            definition_id, SymbolScope::Definition(definition_id), true, None
 
        );
 

	
 
        if let Ok(parser_type) = parser_type {
 
            if Some(TokenKind::Ident) == iter.next() {
 
                // Assume this is a proper memory statement
 
                let identifier = consume_ident_interned(&module.source, iter, ctx)?;
 
                let memory_span = InputSpan::from_positions(parser_type.full_span.begin, identifier.span.end);
 
                let assign_span = consume_token(&module.source, iter, TokenKind::Equal)?;
 

	
 
                let initial_expr_id = self.consume_expression(module, iter, ctx)?;
 
                let initial_expr_end_pos = iter.last_valid_pos();
 

	
 
                // Create the AST variable
 
                let local_id = ctx.heap.alloc_variable(|this| Variable{
 
                    this,
 
                    kind: VariableKind::Local,
 
                    identifier: identifier.clone(),
 
                    parser_type,
 
                    relative_pos_in_parent: 0,
 
                    unique_id_in_scope: -1,
 
                });
 

	
 
                // Create the initial assignment expression
 
                // Note: we set the initial variable declaration here
 
                let variable_expr_id = ctx.heap.alloc_variable_expression(|this| VariableExpression{
 
                    this,
 
                    identifier,
 
                    declaration: Some(local_id),
 
                    used_as_binding_target: false,
 
                    parent: ExpressionParent::None,
 
                    unique_id_in_definition: -1,
 
                });
 
                let assignment_expr_id = ctx.heap.alloc_assignment_expression(|this| AssignmentExpression{
 
                    this,
 
                    operator_span: assign_span,
 
                    full_span: InputSpan::from_positions(memory_span.begin, initial_expr_end_pos),
 
                    left: variable_expr_id.upcast(),
 
                    operation: AssignmentOperator::Set,
 
                    right: initial_expr_id,
 
                    parent: ExpressionParent::None,
 
                    unique_id_in_definition: -1,
 
                });
 

	
 
                // Put both together in the memory statement
 
                let memory_stmt_id = ctx.heap.alloc_memory_statement(|this| MemoryStatement{
 
                    this,
 
                    span: memory_span,
 
                    variable: local_id,
 
                    initial_expr: assignment_expr_id,
 
                    next: StatementId::new_invalid()
 
                });
 

	
 
                return Ok(Some(memory_stmt_id));
 
            }
 
        }
 

	
 
        // If here then one of the preconditions for a memory statement was not
 
        // met. So recover the iterator and return
 
        iter.load(iter_state);
 
        Ok(None)
 
    }
 

	
 
    fn consume_expression_statement(
 
        &mut self, module: &Module, iter: &mut TokenIter, ctx: &mut PassCtx
 
    ) -> Result<ExpressionStatementId, ParseError> {
 
        let start_pos = iter.last_valid_pos();
 
        let expression = self.consume_expression(module, iter, ctx)?;
 
        let end_pos = iter.last_valid_pos();
 
        consume_token(&module.source, iter, TokenKind::SemiColon)?;
 

	
 
        Ok(ctx.heap.alloc_expression_statement(|this| ExpressionStatement{
 
            this,
 
            span: InputSpan::from_positions(start_pos, end_pos),
 
            expression,
 
            next: StatementId::new_invalid(),
 
        }))
 
    }
 

	
 
    //--------------------------------------------------------------------------
 
    // Expression Parsing
 
    //--------------------------------------------------------------------------
 

	
 
    // TODO: @Cleanup This is fine for now. But I prefer my stacktraces not to
 
    //  look like enterprise Java code...
 
    fn consume_expression(
 
        &mut self, module: &Module, iter: &mut TokenIter, ctx: &mut PassCtx
 
    ) -> Result<ExpressionId, ParseError> {
 
        self.consume_assignment_expression(module, iter, ctx)
 
    }
 

	
 
    fn consume_assignment_expression(
 
        &mut self, module: &Module, iter: &mut TokenIter, ctx: &mut PassCtx
 
    ) -> Result<ExpressionId, ParseError> {
 
        // Utility to convert token into assignment operator
 
        fn parse_assignment_operator(token: Option<TokenKind>) -> Option<AssignmentOperator> {
 
            use TokenKind as TK;
 
            use AssignmentOperator as AO;
 

	
 
            if token.is_none() {
 
                return None
 
            }
 

	
 
            match token.unwrap() {
 
                TK::Equal               => Some(AO::Set),
 
                TK::AtEquals            => Some(AO::Concatenated),
 
                TK::StarEquals          => Some(AO::Multiplied),
 
                TK::SlashEquals         => Some(AO::Divided),
 
                TK::PercentEquals       => Some(AO::Remained),
 
                TK::PlusEquals          => Some(AO::Added),
 
                TK::MinusEquals         => Some(AO::Subtracted),
 
                TK::ShiftLeftEquals     => Some(AO::ShiftedLeft),
 
                TK::ShiftRightEquals    => Some(AO::ShiftedRight),
 
                TK::AndEquals           => Some(AO::BitwiseAnded),
 
                TK::CaretEquals         => Some(AO::BitwiseXored),
 
                TK::OrEquals            => Some(AO::BitwiseOred),
 
                _                       => None
 
            }
 
        }
 

	
 
        let expr = self.consume_conditional_expression(module, iter, ctx)?;
 
        if let Some(operation) = parse_assignment_operator(iter.next()) {
 
            let operator_span = iter.next_span();
 
            iter.consume();
 

	
 
            let left = expr;
 
            let right = self.consume_expression(module, iter, ctx)?;
 

	
 
            let full_span = InputSpan::from_positions(
 
                ctx.heap[left].full_span().begin,
 
                ctx.heap[right].full_span().end,
 
            );
 

	
 
            Ok(ctx.heap.alloc_assignment_expression(|this| AssignmentExpression{
 
                this, operator_span, full_span, left, operation, right,
 
                parent: ExpressionParent::None,
 
                unique_id_in_definition: -1,
 
            }).upcast())
 
        } else {
 
            Ok(expr)
 
        }
 
    }
 

	
 
    fn consume_conditional_expression(
 
        &mut self, module: &Module, iter: &mut TokenIter, ctx: &mut PassCtx
 
    ) -> Result<ExpressionId, ParseError> {
 
        let result = self.consume_concat_expression(module, iter, ctx)?;
 
        if let Some(TokenKind::Question) = iter.next() {
 
            let operator_span = iter.next_span();
 
            iter.consume();
 

	
 
            let test = result;
 
            let true_expression = self.consume_expression(module, iter, ctx)?;
 
            consume_token(&module.source, iter, TokenKind::Colon)?;
 
            let false_expression = self.consume_expression(module, iter, ctx)?;
 

	
 
            let full_span = InputSpan::from_positions(
 
                ctx.heap[test].full_span().begin,
 
                ctx.heap[false_expression].full_span().end,
 
            );
 

	
 
            Ok(ctx.heap.alloc_conditional_expression(|this| ConditionalExpression{
 
                this, operator_span, full_span, test, true_expression, false_expression,
 
                parent: ExpressionParent::None,
 
                unique_id_in_definition: -1,
 
            }).upcast())
 
        } else {
 
            Ok(result)
 
        }
 
    }
 

	
 
    fn consume_concat_expression(
 
        &mut self, module: &Module, iter: &mut TokenIter, ctx: &mut PassCtx
 
    ) -> Result<ExpressionId, ParseError> {
 
        self.consume_generic_binary_expression(
 
            module, iter, ctx,
 
            |token| match token {
 
                Some(TokenKind::At) => Some(BinaryOperator::Concatenate),
 
                _ => None
 
            },
 
            Self::consume_logical_or_expression
 
        )
 
    }
 

	
 
    fn consume_logical_or_expression(
 
        &mut self, module: &Module, iter: &mut TokenIter, ctx: &mut PassCtx
 
    ) -> Result<ExpressionId, ParseError> {
 
        self.consume_generic_binary_expression(
 
            module, iter, ctx,
 
            |token| match token {
 
                Some(TokenKind::OrOr) => Some(BinaryOperator::LogicalOr),
 
                _ => None
 
            },
 
            Self::consume_logical_and_expression
 
        )
 
    }
 

	
 
    fn consume_logical_and_expression(
 
        &mut self, module: &Module, iter: &mut TokenIter, ctx: &mut PassCtx
 
    ) -> Result<ExpressionId, ParseError> {
 
        self.consume_generic_binary_expression(
 
            module, iter, ctx,
 
            |token| match token {
 
                Some(TokenKind::AndAnd) => Some(BinaryOperator::LogicalAnd),
 
                _ => None
 
            },
 
            Self::consume_bitwise_or_expression
 
        )
 
    }
 

	
 
    fn consume_bitwise_or_expression(
 
        &mut self, module: &Module, iter: &mut TokenIter, ctx: &mut PassCtx
 
    ) -> Result<ExpressionId, ParseError> {
 
        self.consume_generic_binary_expression(
 
            module, iter, ctx,
 
            |token| match token {
 
                Some(TokenKind::Or) => Some(BinaryOperator::BitwiseOr),
 
                _ => None
 
            },
 
            Self::consume_bitwise_xor_expression
 
        )
 
    }
 

	
 
    fn consume_bitwise_xor_expression(
 
        &mut self, module: &Module, iter: &mut TokenIter, ctx: &mut PassCtx
 
    ) -> Result<ExpressionId, ParseError> {
 
        self.consume_generic_binary_expression(
 
            module, iter, ctx,
 
            |token| match token {
 
                Some(TokenKind::Caret) => Some(BinaryOperator::BitwiseXor),
 
                _ => None
 
            },
 
            Self::consume_bitwise_and_expression
 
        )
 
    }
 

	
 
    fn consume_bitwise_and_expression(
 
        &mut self, module: &Module, iter: &mut TokenIter, ctx: &mut PassCtx
 
    ) -> Result<ExpressionId, ParseError> {
 
        self.consume_generic_binary_expression(
 
            module, iter, ctx,
 
            |token| match token {
 
                Some(TokenKind::And) => Some(BinaryOperator::BitwiseAnd),
 
                _ => None
 
            },
 
            Self::consume_equality_expression
 
        )
 
    }
 

	
 
    fn consume_equality_expression(
 
        &mut self, module: &Module, iter: &mut TokenIter, ctx: &mut PassCtx
 
    ) -> Result<ExpressionId, ParseError> {
 
        self.consume_generic_binary_expression(
 
            module, iter, ctx,
 
            |token| match token {
 
                Some(TokenKind::EqualEqual) => Some(BinaryOperator::Equality),
 
                Some(TokenKind::NotEqual) => Some(BinaryOperator::Inequality),
 
                _ => None
 
            },
 
            Self::consume_relational_expression
 
        )
 
    }
 

	
 
    fn consume_relational_expression(
 
        &mut self, module: &Module, iter: &mut TokenIter, ctx: &mut PassCtx
 
    ) -> Result<ExpressionId, ParseError> {
 
        self.consume_generic_binary_expression(
 
            module, iter, ctx,
 
            |token| match token {
 
                Some(TokenKind::OpenAngle) => Some(BinaryOperator::LessThan),
 
                Some(TokenKind::CloseAngle) => Some(BinaryOperator::GreaterThan),
 
                Some(TokenKind::LessEquals) => Some(BinaryOperator::LessThanEqual),
 
                Some(TokenKind::GreaterEquals) => Some(BinaryOperator::GreaterThanEqual),
 
                _ => None
 
            },
 
            Self::consume_shift_expression
 
        )
 
    }
 

	
 
    fn consume_shift_expression(
 
        &mut self, module: &Module, iter: &mut TokenIter, ctx: &mut PassCtx
 
    ) -> Result<ExpressionId, ParseError> {
 
        self.consume_generic_binary_expression(
 
            module, iter, ctx,
 
            |token| match token {
 
                Some(TokenKind::ShiftLeft) => Some(BinaryOperator::ShiftLeft),
 
                Some(TokenKind::ShiftRight) => Some(BinaryOperator::ShiftRight),
 
                _ => None
 
            },
 
            Self::consume_add_or_subtract_expression
 
        )
 
    }
 

	
 
    fn consume_add_or_subtract_expression(
 
        &mut self, module: &Module, iter: &mut TokenIter, ctx: &mut PassCtx
 
    ) -> Result<ExpressionId, ParseError> {
 
        self.consume_generic_binary_expression(
 
            module, iter, ctx,
 
            |token| match token {
 
                Some(TokenKind::Plus) => Some(BinaryOperator::Add),
 
                Some(TokenKind::Minus) => Some(BinaryOperator::Subtract),
 
                _ => None,
 
            },
 
            Self::consume_multiply_divide_or_modulus_expression
 
        )
 
    }
 

	
 
    fn consume_multiply_divide_or_modulus_expression(
 
        &mut self, module: &Module, iter: &mut TokenIter, ctx: &mut PassCtx
 
    ) -> Result<ExpressionId, ParseError> {
 
        self.consume_generic_binary_expression(
 
            module, iter, ctx,
 
            |token| match token {
 
                Some(TokenKind::Star) => Some(BinaryOperator::Multiply),
 
                Some(TokenKind::Slash) => Some(BinaryOperator::Divide),
 
                Some(TokenKind::Percent) => Some(BinaryOperator::Remainder),
 
                _ => None
 
            },
 
            Self::consume_prefix_expression
 
        )
 
    }
 

	
 
    fn consume_prefix_expression(
 
        &mut self, module: &Module, iter: &mut TokenIter, ctx: &mut PassCtx
 
    ) -> Result<ExpressionId, ParseError> {
 
        fn parse_prefix_token(token: Option<TokenKind>) -> Option<UnaryOperator> {
 
            use TokenKind as TK;
 
            use UnaryOperator as UO;
 
            match token {
 
                Some(TK::Plus) => Some(UO::Positive),
 
                Some(TK::Minus) => Some(UO::Negative),
 
                Some(TK::Tilde) => Some(UO::BitwiseNot),
 
                Some(TK::Exclamation) => Some(UO::LogicalNot),
 
                _ => None
 
            }
 
        }
 

	
 
        let next = iter.next();
 
        if let Some(operation) = parse_prefix_token(next) {
 
            let operator_span = iter.next_span();
 
            iter.consume();
 

	
 
            let expression = self.consume_prefix_expression(module, iter, ctx)?;
 
            let full_span = InputSpan::from_positions(
 
                operator_span.begin, ctx.heap[expression].full_span().end,
 
            );
 
            Ok(ctx.heap.alloc_unary_expression(|this| UnaryExpression {
 
                this, operator_span, full_span, operation, expression,
 
                parent: ExpressionParent::None,
 
                unique_id_in_definition: -1,
 
            }).upcast())
 
        } else if next == Some(TokenKind::PlusPlus) {
 
            return Err(ParseError::new_error_str_at_span(
 
                &module.source, iter.next_span(), "prefix increment is not supported in the language"
 
            ));
 
        } else if next == Some(TokenKind::MinusMinus) {
 
            return Err(ParseError::new_error_str_at_span(
 
                &module.source, iter.next_span(), "prefix decrement is not supported in this language"
 
            ));
 
        } else {
 
            self.consume_postfix_expression(module, iter, ctx)
 
        }
 
    }
 

	
 
    fn consume_postfix_expression(
 
        &mut self, module: &Module, iter: &mut TokenIter, ctx: &mut PassCtx
 
    ) -> Result<ExpressionId, ParseError> {
 
        fn has_matching_postfix_token(token: Option<TokenKind>) -> bool {
 
            use TokenKind as TK;
 

	
 
            if token.is_none() { return false; }
 
            match token.unwrap() {
 
                TK::PlusPlus | TK::MinusMinus | TK::OpenSquare | TK::Dot => true,
 
                _ => false
 
            }
 
        }
 

	
 
        let mut result = self.consume_primary_expression(module, iter, ctx)?;
 
        let mut next = iter.next();
 
        while has_matching_postfix_token(next) {
 
            let token = next.unwrap();
 
            let mut operator_span = iter.next_span();
 
            iter.consume();
 

	
 
            if token == TokenKind::PlusPlus {
 
                return Err(ParseError::new_error_str_at_span(
 
                    &module.source, operator_span, "postfix increment is not supported in this language"
 
                ));
 
            } else if token == TokenKind::MinusMinus {
 
                return Err(ParseError::new_error_str_at_span(
 
                    &module.source, operator_span, "prefix increment is not supported in this language"
 
                ));
 
            } else if token == TokenKind::OpenSquare {
 
                let subject = result;
 
                let from_index = self.consume_expression(module, iter, ctx)?;
 

	
 
                // Check if we have an indexing or slicing operation
 
                next = iter.next();
 
                if Some(TokenKind::DotDot) == next {
 
                    iter.consume();
 

	
 
                    let to_index = self.consume_expression(module, iter, ctx)?;
 
                    let end_span = consume_token(&module.source, iter, TokenKind::CloseSquare)?;
 
                    operator_span.end = end_span.end;
 
                    let full_span = InputSpan::from_positions(
 
                        ctx.heap[subject].full_span().begin, operator_span.end
 
                    );
 

	
 
                    result = ctx.heap.alloc_slicing_expression(|this| SlicingExpression{
 
                        this,
 
                        slicing_span: operator_span,
 
                        full_span, subject, from_index, to_index,
 
                        parent: ExpressionParent::None,
 
                        unique_id_in_definition: -1,
 
                    }).upcast();
 
                } else if Some(TokenKind::CloseSquare) == next {
 
                    let end_span = consume_token(&module.source, iter, TokenKind::CloseSquare)?;
 
                    operator_span.end = end_span.end;
 

	
 
                    let full_span = InputSpan::from_positions(
 
                        ctx.heap[subject].full_span().begin, operator_span.end
 
                    );
 

	
 
                    result = ctx.heap.alloc_indexing_expression(|this| IndexingExpression{
 
                        this, operator_span, full_span, subject,
 
                        index: from_index,
 
                        parent: ExpressionParent::None,
 
                        unique_id_in_definition: -1,
 
                    }).upcast();
 
                } else {
 
                    return Err(ParseError::new_error_str_at_pos(
 
                        &module.source, iter.last_valid_pos(), "unexpected token: expected ']' or '..'"
 
                    ));
 
                }
 
            } else {
 
                // Can be a select expression for struct fields, or a select
 
                // for a tuple element.
 
                debug_assert_eq!(token, TokenKind::Dot);
 
                let subject = result;
 

	
 
                let next = iter.next();
 
                let (select_kind, full_span) = if Some(TokenKind::Integer) == next {
 
                    // Tuple member
 
                    let (index, index_span) = consume_integer_literal(&module.source, iter, &mut self.buffer)?;
 
                    let full_span = InputSpan::from_positions(
 
                        ctx.heap[subject].full_span().begin, index_span.end
 
                    );
 

	
 
                    (SelectKind::TupleMember(index), full_span)
 
                } else if Some(TokenKind::Ident) == next {
 
                    // Struct field
 
                    let field_name = consume_ident_interned(&module.source, iter, ctx)?;
 

	
 
                    let full_span = InputSpan::from_positions(
 
                        ctx.heap[subject].full_span().begin, field_name.span.end
 
                    );
 

	
 
                    (SelectKind::StructField(field_name), full_span)
 
                } else {
 
                    return Err(ParseError::new_error_str_at_pos(
 
                        &module.source, iter.last_valid_pos(), "unexpected token: expected integer or identifier"
 
                    ));
 
                };
 

	
 
                result = ctx.heap.alloc_select_expression(|this| SelectExpression{
 
                    this, operator_span, full_span, subject,
 
                    kind: select_kind,
 
                    parent: ExpressionParent::None,
 
                    unique_id_in_definition: -1,
 
                }).upcast();
 
            }
 

	
 
            next = iter.next();
 
        }
 

	
 
        Ok(result)
 
    }
 

	
 
    fn consume_primary_expression(
 
        &mut self, module: &Module, iter: &mut TokenIter, ctx: &mut PassCtx
 
    ) -> Result<ExpressionId, ParseError> {
 
        let next = iter.next();
 

	
 
        let result = if next == Some(TokenKind::OpenParen) {
 
            // Something parenthesized. This can mean several things: we have
 
            // a parenthesized expression or we have a tuple literal. They are
 
            // ambiguous when the tuple has one member. But like the tuple type
 
            // parsing we interpret all one-tuples as parenthesized expressions.
 
            //
 
            // Practically (to prevent unnecessary `consume_expression` calls)
 
            // we distinguish the zero-tuple, the parenthesized expression, and
 
            // the N-tuple (for N > 1).
 
            let open_paren_pos = iter.next_start_position();
 
            iter.consume();
 
            let result = if Some(TokenKind::CloseParen) == iter.next() {
 
                // Zero-tuple
 
                let (_, close_paren_pos) = iter.next_positions();
 
                iter.consume();
 

	
 
                let literal_id = ctx.heap.alloc_literal_expression(|this| LiteralExpression{
 
                    this,
 
                    span: InputSpan::from_positions(open_paren_pos, close_paren_pos),
 
                    value: Literal::Tuple(Vec::new()),
 
                    parent: ExpressionParent::None,
 
                    unique_id_in_definition: -1,
 
                });
 

	
 
                literal_id.upcast()
 
            } else {
 
                // Start by consuming one expression, then check for a comma
 
                let expr_id = self.consume_expression(module, iter, ctx)?;
 
                if Some(TokenKind::Comma) == iter.next() && Some(TokenKind::CloseParen) != iter.peek() {
 
                    // Must be an N-tuple
 
                    iter.consume(); // the comma
 
                    let mut scoped_section = self.expressions.start_section();
 
                    scoped_section.push(expr_id);
 

	
 
                    let mut close_paren_pos = open_paren_pos;
 
                    consume_comma_separated_until(
 
                        TokenKind::CloseParen, &module.source, iter, ctx,
 
                        |_source, iter, ctx| self.consume_expression(module, iter, ctx),
 
                        &mut scoped_section, "an expression", Some(&mut close_paren_pos)
 
                    )?;
 
                    debug_assert!(scoped_section.len() > 1); // peeked token wasn't CloseParen, must be expression
 

	
 
                    let literal_id = ctx.heap.alloc_literal_expression(|this| LiteralExpression{
 
                        this,
 
                        span: InputSpan::from_positions(open_paren_pos, close_paren_pos),
 
                        value: Literal::Tuple(scoped_section.into_vec()),
 
                        parent: ExpressionParent::None,
 
                        unique_id_in_definition: -1,
 
                    });
 

	
 
                    literal_id.upcast()
 
                } else {
 
                    // Assume we're dealing with a normal expression
 
                    consume_token(&module.source, iter, TokenKind::CloseParen)?;
 

	
 
                    expr_id
 
                }
 
            };
 

	
 
            result
 
        } else if next == Some(TokenKind::OpenCurly) {
 
            // Array literal
 
            let (start_pos, mut end_pos) = iter.next_positions();
 
            let mut scoped_section = self.expressions.start_section();
 
            consume_comma_separated(
 
                TokenKind::OpenCurly, TokenKind::CloseCurly, &module.source, iter, ctx,
 
                |_source, iter, ctx| self.consume_expression(module, iter, ctx),
 
                &mut scoped_section, "an expression", "a list of expressions", Some(&mut end_pos)
 
            )?;
 

	
 
            ctx.heap.alloc_literal_expression(|this| LiteralExpression{
 
                this,
 
                span: InputSpan::from_positions(start_pos, end_pos),
 
                value: Literal::Array(scoped_section.into_vec()),
 
                parent: ExpressionParent::None,
 
                unique_id_in_definition: -1,
 
            }).upcast()
 
        } else if next == Some(TokenKind::Integer) {
src/protocol/parser/pass_rewriting.rs
Show inline comments
 
use crate::collections::*;
 
use crate::protocol::*;
 

	
 
use super::visitor::*;
 

	
 
pub(crate) struct PassRewriting {
 
    current_scope: BlockStatementId,
 
    current_scope: ScopeId,
 
    statement_buffer: ScopedBuffer<StatementId>,
 
    call_expr_buffer: ScopedBuffer<CallExpressionId>,
 
    expression_buffer: ScopedBuffer<ExpressionId>,
 
    scope_buffer: ScopedBuffer<ScopeId>,
 
}
 

	
 
impl PassRewriting {
 
    pub(crate) fn new() -> Self {
 
        Self{
 
            current_scope: BlockStatementId::new_invalid(),
 
            statement_buffer: ScopedBuffer::with_capacity(16),
 
            call_expr_buffer: ScopedBuffer::with_capacity(16),
 
            expression_buffer: ScopedBuffer::with_capacity(16),
 
            current_scope: ScopeId::new_invalid(),
 
            statement_buffer: ScopedBuffer::with_capacity(BUFFER_INIT_CAP_SMALL),
 
            call_expr_buffer: ScopedBuffer::with_capacity(BUFFER_INIT_CAP_SMALL),
 
            expression_buffer: ScopedBuffer::with_capacity(BUFFER_INIT_CAP_SMALL),
 
            scope_buffer: ScopedBuffer::with_capacity(BUFFER_INIT_CAP_SMALL),
 
        }
 
    }
 
}
 

	
 
impl Visitor for PassRewriting {
 
    // --- Visiting procedures
 

	
 
    fn visit_component_definition(&mut self, ctx: &mut Ctx, id: ComponentDefinitionId) -> VisitorResult {
 
        let def = &ctx.heap[id];
 
        let body_id = def.body;
 
        self.current_scope = def.scope;
 
        return self.visit_block_stmt(ctx, body_id);
 
    }
 

	
 
    fn visit_function_definition(&mut self, ctx: &mut Ctx, id: FunctionDefinitionId) -> VisitorResult {
 
        let def = &ctx.heap[id];
 
        let body_id = def.body;
 
        self.current_scope = def.scope;
 
        return self.visit_block_stmt(ctx, body_id);
 
    }
 

	
 
    // --- Visiting statements (that are not the select statement)
 

	
 
    fn visit_block_stmt(&mut self, ctx: &mut Ctx, id: BlockStatementId) -> VisitorResult {
 
        let block_stmt = &ctx.heap[id];
 
        let stmt_section = self.statement_buffer.start_section_initialized(&block_stmt.statements);
 

	
 
        self.current_scope = id;
 
        self.current_scope = block_stmt.scope;
 
        for stmt_idx in 0..stmt_section.len() {
 
            self.visit_stmt(ctx, stmt_section[stmt_idx])?;
 
        }
 

	
 
        stmt_section.forget();
 
        return Ok(())
 
    }
 

	
 
    fn visit_labeled_stmt(&mut self, ctx: &mut Ctx, id: LabeledStatementId) -> VisitorResult {
 
        let labeled_stmt = &ctx.heap[id];
 
        let body_id = labeled_stmt.body;
 
        return self.visit_stmt(ctx, body_id);
 
    }
 

	
 
    fn visit_if_stmt(&mut self, ctx: &mut Ctx, id: IfStatementId) -> VisitorResult {
 
        let if_stmt = &ctx.heap[id];
 
        let true_body_id = if_stmt.true_case;
 
        let false_body_id = if_stmt.false_case;
 

	
 
        self.visit_stmt(ctx, true_body_id.body)?;
 
        if let Some(false_body_id) = false_body_id {
 
            self.visit_stmt(ctx, false_body_id.body)?;
 
        let true_case = if_stmt.true_case;
 
        let false_case = if_stmt.false_case;
 

	
 
        self.current_scope = true_case.scope;
 
        self.visit_stmt(ctx, true_case.body)?;
 
        if let Some(false_case) = false_case {
 
            self.current_scope = false_case.scope;
 
            self.visit_stmt(ctx, false_case.body)?;
 
        }
 

	
 
        return Ok(())
 
    }
 

	
 
    fn visit_while_stmt(&mut self, ctx: &mut Ctx, id: WhileStatementId) -> VisitorResult {
 
        let while_stmt = &ctx.heap[id];
 
        let body_id = while_stmt.body;
 
        self.current_scope = while_stmt.scope;
 
        return self.visit_stmt(ctx, body_id);
 
    }
 

	
 
    fn visit_synchronous_stmt(&mut self, ctx: &mut Ctx, id: SynchronousStatementId) -> VisitorResult {
 
        let sync_stmt = &ctx.heap[id];
 
        let body_id = sync_stmt.body;
 
        self.current_scope = sync_stmt.scope;
 
        return self.visit_stmt(ctx, body_id);
 
    }
 

	
 
    // --- Visiting the select statement
 

	
 
    fn visit_select_stmt(&mut self, ctx: &mut Ctx, id: SelectStatementId) -> VisitorResult {
 
        // Utility for the last stage of rewriting process. Note that caller
 
        // still needs to point the end of the if-statement to the end of the
 
        // replacement statement of the select statement.
 
        fn transform_select_case_code(ctx: &mut Ctx, select_id: SelectStatementId, case_index: usize, select_var_id: VariableId) -> (IfStatementId, EndIfStatementId) {
 
            // Retrieve statement IDs associated with case
 
            let case = &ctx.heap[select_id].cases[case_index];
 
            let case_guard_id = case.guard;
 
            let case_body_id = case.body;
 
            let case_scope_id = case.scope;
 

	
 
            // Create the if-statement for the result of the select statement
 
            let compare_expr_id = create_ast_equality_comparison_expr(ctx, select_var_id, case_index as u64);
 
            let true_case = IfStatementCase{
 
                body: case_guard_id, // which is linked up to the body
 
                scope: case_scope_id,
 
            };
 
            let (if_stmt_id, end_if_stmt_id) = create_ast_if_stmt(ctx, compare_expr_id.upcast(), true_case, None);
 

	
 
            // Link up body statement to end-if
 
            set_ast_statement_next(ctx, case_body_id, end_if_stmt_id.upcast());
 

	
 
            return (if_stmt_id, end_if_stmt_id)
 
        }
 

	
 
        // We're going to transform the select statement by a block statement
 
        // containing builtin runtime-calls. And to do so we create temporary
 
        // variables and move some other statements around.
 
        // Precreate the block that will end up containing all of the
 
        // transformed statements. Also precreate the scope associated with it
 
        let (outer_block_id, outer_end_block_id, outer_scope_id) =
 
            create_ast_block_stmt(ctx, Vec::new());
 

	
 
        // The "select" and the "end select" statement will act like trampolines
 
        // that jump to the replacement block. So set the child/parent
 
        // relationship already.
 
        // --- for the statements
 
        let select_stmt = &mut ctx.heap[id];
 
        select_stmt.next = outer_block_id.upcast();
 
        let end_select_stmt_id = select_stmt.end_select;
 
        let select_stmt_relative_pos = select_stmt.relative_pos_in_parent;
 

	
 
        let outer_end_block_stmt = &mut ctx.heap[outer_end_block_id];
 
        outer_end_block_stmt.next = end_select_stmt_id.upcast();
 

	
 
        // --- for the scopes
 
        link_existing_child_to_new_parent_scope(ctx, &mut self.scope_buffer, self.current_scope, outer_scope_id, select_stmt_relative_pos);
 

	
 
        // Create statements that will create temporary variables for all of the
 
        // ports passed to the "get" calls in the select case guards.
 
        let select_stmt = &ctx.heap[id];
 
        let total_num_cases = select_stmt.cases.len();
 
        let mut total_num_ports = 0;
 
        let end_select_stmt_id = select_stmt.end_select;
 
        let end_select = &ctx.heap[end_select_stmt_id];
 
        let stmt_id_after_select_stmt = end_select.next;
 

	
 
        // Put heap IDs into temporary buffers to handle borrowing rules
 
        let mut call_id_section = self.call_expr_buffer.start_section();
 
        let mut expr_id_section = self.expression_buffer.start_section();
 

	
 
        for case in select_stmt.cases.iter() {
 
            total_num_ports += case.involved_ports.len();
 
            for (call_id, expr_id) in case.involved_ports.iter().copied() {
 
                call_id_section.push(call_id);
 
                expr_id_section.push(expr_id);
 
            }
 
        }
 

	
 
        // Transform all of the call expressions by takings its argument (the
 
        // port from which we `get`) and turning it into a temporary variable.
 
        let mut transformed_stmts = Vec::with_capacity(total_num_ports); // TODO: Recompute this preallocated length, put assert at the end
 
        let mut locals = Vec::with_capacity(total_num_ports);
 

	
 
        for port_var_idx in 0..call_id_section.len() {
 
            let get_call_expr_id = call_id_section[port_var_idx];
 
            let port_expr_id = expr_id_section[port_var_idx];
 

	
 
            // Move the port expression such that it gets assigned to a temporary variable
 
            let variable_id = create_ast_variable(ctx);
 
            let variable_id = create_ast_variable(ctx, outer_scope_id);
 
            let variable_decl_stmt_id = create_ast_variable_declaration_stmt(ctx, variable_id, port_expr_id);
 

	
 
            // Replace the original port expression in the call with a reference
 
            // to the replacement variable
 
            let variable_expr_id = create_ast_variable_expr(ctx, variable_id);
 
            let call_expr = &mut ctx.heap[get_call_expr_id];
 
            call_expr.arguments[0] = variable_expr_id.upcast();
 

	
 
            transformed_stmts.push(variable_decl_stmt_id.upcast().upcast());
 
            locals.push(variable_id);
 
        }
 

	
 
        // Insert runtime calls that facilitate the semantics of the select
 
        // block.
 

	
 
        // Create the call that indicates the start of the select block
 
        {
 
            let num_cases_expression_id = create_ast_literal_integer_expr(ctx, total_num_cases as u64);
 
            let num_ports_expression_id = create_ast_literal_integer_expr(ctx, total_num_ports as u64);
 
            let arguments = vec![
 
                num_cases_expression_id.upcast(),
 
                num_ports_expression_id.upcast()
 
            ];
 

	
 
            let call_expression_id = create_ast_call_expr(ctx, Method::SelectStart, &mut self.expression_buffer, arguments);
 
            let call_statement_id = create_ast_expression_stmt(ctx, call_expression_id.upcast());
 

	
 
            transformed_stmts.push(call_statement_id.upcast());
 
        }
 

	
 
        // Create calls for each select case that will register the ports that
 
        // we are waiting on at the runtime.
 
        {
 
            let mut total_port_index = 0;
 
            for case_index in 0..total_num_cases {
 
                let case = &ctx.heap[id].cases[case_index];
 
                let case_num_ports = case.involved_ports.len();
 

	
 
                for case_port_index in 0..case_num_ports {
 
                    // Arguments to runtime call
 
                    let port_variable_id = locals[total_port_index]; // so far this variable contains the temporary variables for the port expressions
 
                    let case_index_expr_id = create_ast_literal_integer_expr(ctx, case_index as u64);
 
                    let port_index_expr_id = create_ast_literal_integer_expr(ctx, case_port_index as u64);
 
                    let port_variable_expr_id = create_ast_variable_expr(ctx, port_variable_id);
 
                    let runtime_call_arguments = vec![
 
                        case_index_expr_id.upcast(),
 
                        port_index_expr_id.upcast(),
 
                        port_variable_expr_id.upcast()
 
                    ];
 

	
 
                    // Create runtime call, then store it
 
                    let runtime_call_expr_id = create_ast_call_expr(ctx, Method::SelectRegisterCasePort, &mut self.expression_buffer, runtime_call_arguments);
 
                    let runtime_call_stmt_id = create_ast_expression_stmt(ctx, runtime_call_expr_id.upcast());
 

	
 
                    transformed_stmts.push(runtime_call_stmt_id.upcast());
 

	
 
                    total_port_index += 1;
 
                }
 
            }
 
        }
 

	
 
        // Create the variable that will hold the result of a completed select
 
        // block. Then create the runtime call that will produce this result
 
        let select_variable_id = create_ast_variable(ctx);
 
        let select_variable_id = create_ast_variable(ctx, outer_scope_id);
 
        locals.push(select_variable_id);
 

	
 
        {
 
            let runtime_call_expr_id = create_ast_call_expr(ctx, Method::SelectWait, &mut self.expression_buffer, Vec::new());
 
            let variable_stmt_id = create_ast_variable_declaration_stmt(ctx, select_variable_id, runtime_call_expr_id.upcast());
 
            transformed_stmts.push(variable_stmt_id.upcast().upcast());
 
        }
 

	
 
        call_id_section.forget();
 
        expr_id_section.forget();
 

	
 
        // Precreate the block statement that will be the replacement of the
 
        // select statement. Do not set its members yet.
 
        let replacement_stmt_id = ctx.heap.alloc_block_statement(|this| BlockStatement{
 
            this,
 
            is_implicit: true,
 
            span: InputSpan::new(),
 
            statements: Vec::new(),
 
            end_block: EndBlockStatementId::new_invalid(),
 
            scope: ScopeId::new_invalid(),
 
            next: StatementId::new_invalid(),
 
        });
 
        let end_block_id = ctx.heap.alloc_end_block_statement(|this| EndBlockStatement{
 
            this,
 
            start_block: replacement_stmt_id,
 
            next: stmt_id_after_select_stmt,
 
        });
 

	
 
        // Now we transform each of the select block case's guard and code into
 
        // a chained if-else statement.
 
        if total_num_cases > 0 {
 
            let (if_stmt_id, end_if_stmt_id) = transform_select_case_code(ctx, id, 0, select_variable_id);
 
            let first_end_if_stmt = &mut ctx.heap[end_if_stmt_id];
 
            first_end_if_stmt.next = outer_end_block_id.upcast();
 

	
 
            let mut last_if_stmt_id = if_stmt_id;
 
            let mut last_end_if_stmt_id = end_if_stmt_id;
 
            transformed_stmts.push(last_if_stmt_id.upcast());
 

	
 
            for case_index in 1..total_num_cases {
 
                let (if_stmt_id, end_if_stmt_id) = transform_select_case_code(ctx, id, case_index, select_variable_id);
 
                let last_if_stmt = &mut ctx.heap[last_if_stmt_id];
 
                // last_if_stmt.false_case = Some(if_stmt_id.upcast());
 

	
 
                // TODO:
 
                //  1. Change scoping such that it is a separate datastructure with separate IDs
 
                //  2. Change statements that contain "implicit scopes" to explicitly point to the appropriate scopes
 
                //  3. Continue here setting the true-body and false-body.
 
                //  4. Figure out how we're going to link everything up again
 
                let false_case_scope_id = ctx.heap.alloc_scope(|this| Scope::new(this, ScopeAssociation::If(last_if_stmt_id, false)));
 
                set_ast_if_statement_false_body(ctx, last_if_stmt_id, last_end_if_stmt_id, IfStatementCase{ body: if_stmt_id.upcast(), scope: false_case_scope_id });
 

	
 
                let end_if_stmt = &mut ctx.heap[end_if_stmt_id];
 
                end_if_stmt.next = last_end_if_stmt_id.upcast();
 

	
 
                last_if_stmt_id = if_stmt_id;
 
                last_end_if_stmt_id = end_if_stmt_id;
 
            }
 
        }
 

	
 
        // let block = ctx.heap.alloc_block_statement(|this| BlockStatement{
 
        //     this,
 
        //     is_implicit: true,
 
        //     span: stmt.span,
 
        //     statements: vec![],
 
        //     end_block: EndBlockStatementId(),
 
        //     scope_node: ScopeNode {},
 
        //     first_unique_id_in_scope: 0,
 
        //     next_unique_id_in_scope: 0,
 
        //     locals,
 
        //     labels: vec![],
 
        //     next: ()
 
        // });
 
        // Final steps: set the statements of the replacement block statement,
 
        // and link all of those statements together
 
        let mut last_stmt_id = transformed_stmts[0];
 
        for stmt_id in transformed_stmts.iter().skip(1).copied() {
 
            set_ast_statement_next(ctx, last_stmt_id, stmt_id);
 
            last_stmt_id = stmt_id;
 
        }
 

	
 
        let outer_block_stmt = &mut ctx.heap[outer_block_id];
 
        outer_block_stmt.statements = transformed_stmts;
 

	
 
        return Ok(())
 
    }
 
}
 

	
 
impl PassRewriting {
 
    fn create_runtime_call_statement(&self, ctx: &mut Ctx, method: Method, arguments: Vec<ExpressionId>) -> (CallExpressionId, ExpressionStatementId) {
 
        let call_expr_id = ctx.heap.alloc_call_expression(|this| CallExpression{
 
            this,
 
            func_span: InputSpan::new(),
 
            full_span: InputSpan::new(),
 
            parser_type: ParserType{
 
                elements: Vec::new(),
 
                full_span: InputSpan::new(),
 
            },
 
            method,
 
            arguments,
 
            definition: DefinitionId::new_invalid(),
 
            parent: ExpressionParent::None,
 
            unique_id_in_definition: -1,
 
        });
 
        let call_stmt_id = ctx.heap.alloc_expression_statement(|this| ExpressionStatement{
 
            this,
 
            span: InputSpan::new(),
 
            expression: call_expr_id.upcast(),
 
            next: StatementId::new_invalid(),
 
        });
 

	
 
        let call_expr = &mut ctx.heap[call_expr_id];
 
        call_expr.parent = ExpressionParent::ExpressionStmt(call_stmt_id);
 

	
 
        return (call_expr_id, call_stmt_id);
 
    }
 

	
 
    fn create_runtime_select_wait_variable_and_statement(&self, ctx: &mut Ctx) -> (VariableId, MemoryStatementId) {
 
        let variable_id = create_ast_variable(ctx);
 
        let variable_expr_id = create_ast_variable_expr(ctx, variable_id);
 
        let runtime_call_expr_id = ctx.heap.alloc_call_expression(|this| CallExpression{
 
            this,
 
            func_span: InputSpan::new(),
 
            full_span: InputSpan::new(),
 
            parser_type: ParserType{
 
                elements: Vec::new(),
 
                full_span: InputSpan::new(),
 
            },
 
            method: Method::SelectWait,
 
            arguments: Vec::new(),
 
            definition: DefinitionId::new_invalid(),
 
            parent: ExpressionParent::None,
 
            unique_id_in_definition: -1
 
        });
 
        let initial_expr_id = ctx.heap.alloc_assignment_expression(|this| AssignmentExpression{
 
            this,
 
            operator_span: InputSpan::new(),
 
            full_span: InputSpan::new(),
 
            left: variable_expr_id.upcast(),
 
            operation: AssignmentOperator::Set,
 
            right: runtime_call_expr_id.upcast(),
 
            parent: ExpressionParent::None,
 
            unique_id_in_definition: -1
 
        });
 

	
 
        let variable_statement_id = ctx.heap.alloc_memory_statement(|this| MemoryStatement{
 
            this,
 
            span: InputSpan::new(),
 
            variable: variable_id,
 
            initial_expr: initial_expr_id,
 
            next: StatementId::new_invalid()
 
        });
 

	
 
        let variable_expr = &mut ctx.heap[variable_expr_id];
 
        variable_expr.parent = ExpressionParent::Expression(initial_expr_id.upcast(), 0);
 
        let runtime_call_expr = &mut ctx.heap[runtime_call_expr_id];
 
        runtime_call_expr.parent = ExpressionParent::Expression(initial_expr_id.upcast(), 1);
 
        let initial_expr = &mut ctx.heap[initial_expr_id];
 
        initial_expr.parent = ExpressionParent::Memory(variable_statement_id);
 

	
 
        return (variable_id, variable_statement_id);
 
    }
 
}
 

	
 
// -----------------------------------------------------------------------------
 
// Utilities to create compiler-generated AST nodes
 
// -----------------------------------------------------------------------------
 

	
 
fn create_ast_variable(ctx: &mut Ctx) -> VariableId {
 
    return ctx.heap.alloc_variable(|this| Variable{
 
fn create_ast_variable(ctx: &mut Ctx, scope_id: ScopeId) -> VariableId {
 
    let variable_id = ctx.heap.alloc_variable(|this| Variable{
 
        this,
 
        kind: VariableKind::Local,
 
        parser_type: ParserType{
 
            elements: Vec::new(),
 
            full_span: InputSpan::new(),
 
        },
 
        identifier: Identifier::new_empty(InputSpan::new()),
 
        relative_pos_in_parent: -1,
 
        unique_id_in_scope: -1,
 
    });
 
    let scope = &mut ctx.heap[scope_id];
 
    scope.variables.push(variable_id);
 

	
 
    return variable_id;
 
}
 

	
 
fn create_ast_variable_expr(ctx: &mut Ctx, variable_id: VariableId) -> VariableExpressionId {
 
    return ctx.heap.alloc_variable_expression(|this| VariableExpression{
 
        this,
 
        identifier: Identifier::new_empty(InputSpan::new()),
 
        declaration: Some(variable_id),
 
        used_as_binding_target: false,
 
        parent: ExpressionParent::None,
 
        unique_id_in_definition: -1
 
    });
 
}
 

	
 
fn create_ast_call_expr(ctx: &mut Ctx, method: Method, buffer: &mut ScopedBuffer<ExpressionId>, arguments: Vec<ExpressionId>) -> CallExpressionId {
 
    let expression_ids = buffer.start_section_initialized(&arguments);
 
    let call_expression_id = ctx.heap.alloc_call_expression(|this| CallExpression{
 
        this,
 
        func_span: InputSpan::new(),
 
        full_span: InputSpan::new(),
 
        parser_type: ParserType{
 
            elements: Vec::new(),
 
            full_span: InputSpan::new(),
 
        },
 
        method,
 
        arguments,
 
        definition: DefinitionId::new_invalid(),
 
        parent: ExpressionParent::None,
 
        unique_id_in_definition: -1,
 
    });
 

	
 
    for argument_index in 0..expression_ids.len() {
 
        let argument_id = expression_ids[argument_index];
 
        let argument_expr = &mut ctx.heap[argument_id];
 
        *argument_expr.parent_mut() = ExpressionParent::Expression(call_expression_id.upcast(), argument_index as u32);
 
    }
 

	
 
    return call_expression_id;
 
}
 

	
 
fn create_ast_literal_integer_expr(ctx: &mut Ctx, unsigned_value: u64) -> LiteralExpressionId {
 
    return ctx.heap.alloc_literal_expression(|this| LiteralExpression{
 
        this,
 
        span: InputSpan::new(),
 
        value: Literal::Integer(LiteralInteger{
 
            unsigned_value,
 
            negated: false,
 
        }),
 
        parent: ExpressionParent::None,
 
        unique_id_in_definition: -1
 
    });
 
}
 

	
 
fn create_ast_equality_comparison_expr(ctx: &mut Ctx, variable_id: VariableId, value: u64) -> BinaryExpressionId {
 
    let var_expr_id = create_ast_variable_expr(ctx, variable_id);
 
    let int_expr_id = create_ast_literal_integer_expr(ctx, value);
 
    let cmp_expr_id = ctx.heap.alloc_binary_expression(|this| BinaryExpression{
 
        this,
 
        operator_span: InputSpan::new(),
 
        full_span: InputSpan::new(),
 
        left: var_expr_id.upcast(),
 
        operation: BinaryOperator::Equality,
 
        right: int_expr_id.upcast(),
 
        parent: ExpressionParent::None,
 
        unique_id_in_definition: -1,
 
    });
 

	
 
    let var_expr = &mut ctx.heap[var_expr_id];
 
    var_expr.parent = ExpressionParent::Expression(cmp_expr_id.upcast(), 0);
 
    let int_expr = &mut ctx.heap[int_expr_id];
 
    int_expr.parent = ExpressionParent::Expression(cmp_expr_id.upcast(), 1);
 

	
 
    return cmp_expr_id;
 
}
 

	
 
fn create_ast_expression_stmt(ctx: &mut Ctx, expression_id: ExpressionId) -> ExpressionStatementId {
 
    let statement_id = ctx.heap.alloc_expression_statement(|this| ExpressionStatement{
 
        this,
 
        span: InputSpan::new(),
 
        expression: expression_id,
 
        next: StatementId::new_invalid(),
 
    });
 

	
 
    let expression = &mut ctx.heap[expression_id];
 
    *expression.parent_mut() = ExpressionParent::ExpressionStmt(statement_id);
 

	
 
    return statement_id;
 
}
 

	
 
fn create_ast_variable_declaration_stmt(ctx: &mut Ctx, variable_id: VariableId, initial_value_expr_id: ExpressionId) -> MemoryStatementId {
 
    // Create the assignment expression, assigning the initial value to the variable
 
    let variable_expr_id = create_ast_variable_expr(ctx, variable_id);
 
    let assignment_expr_id = ctx.heap.alloc_assignment_expression(|this| AssignmentExpression{
 
        this,
 
        operator_span: InputSpan::new(),
 
        full_span: InputSpan::new(),
 
        left: variable_expr_id.upcast(),
 
        operation: AssignmentOperator::Set,
 
        right: initial_value_expr_id,
 
        parent: ExpressionParent::None,
 
        unique_id_in_definition: -1,
 
    });
 

	
 
    // Create the memory statement
 
    let memory_stmt_id = ctx.heap.alloc_memory_statement(|this| MemoryStatement{
 
        this,
 
        span: InputSpan::new(),
 
        variable: variable_id,
 
        initial_expr: assignment_expr_id,
 
        next: StatementId::new_invalid(),
 
    });
 

	
 
    // Set all parents which we can access
 
    let variable_expr = &mut ctx.heap[variable_expr_id];
 
    variable_expr.parent = ExpressionParent::Expression(assignment_expr_id.upcast(), 0);
 
    let value_expr = &mut ctx.heap[initial_value_expr_id];
 
    *value_expr.parent_mut() = ExpressionParent::Expression(assignment_expr_id.upcast(), 1);
 
    let assignment_expr = &mut ctx.heap[assignment_expr_id];
 
    assignment_expr.parent = ExpressionParent::Memory(memory_stmt_id);
 

	
 
    return memory_stmt_id;
 
}
 

	
 
fn create_ast_block_stmt(ctx: &mut Ctx, statements: Vec<StatementId>) -> (BlockStatementId, EndBlockStatementId, ScopeId) {
 
    let block_stmt_id = ctx.heap.alloc_block_statement(|this| BlockStatement{
 
        this,
 
        span: InputSpan::new(),
 
        statements,
 
        end_block: EndBlockStatementId::new_invalid(),
 
        scope: ScopeId::new_invalid(),
 
        next: StatementId::new_invalid(),
 
    });
 
    let end_block_stmt_id = ctx.heap.alloc_end_block_statement(|this| EndBlockStatement{
 
        this,
 
        start_block: block_stmt_id,
 
        next: StatementId::new_invalid(),
 
    });
 
    let scope_id = ctx.heap.alloc_scope(|this| Scope::new(this, ScopeAssociation::Block(block_stmt_id)));
 

	
 
    let block_stmt = &mut ctx.heap[block_stmt_id];
 
    block_stmt.end_block = end_block_stmt_id;
 
    block_stmt.scope = scope_id;
 

	
 
    return (block_stmt_id, end_block_stmt_id, scope_id);
 
}
 

	
 
fn create_ast_if_stmt(ctx: &mut Ctx, condition_expression_id: ExpressionId, true_case: IfStatementCase, false_case: Option<IfStatementCase>) -> (IfStatementId, EndIfStatementId) {
 
    // Create if statement and the end-if statement
 
    let if_stmt_id = ctx.heap.alloc_if_statement(|this| IfStatement{
 
        this,
 
        span: InputSpan::new(),
 
        test: condition_expression_id,
 
        true_case,
 
        false_case,
 
        end_if: EndIfStatementId::new_invalid()
 
    });
 

	
 
    let end_if_stmt_id = ctx.heap.alloc_end_if_statement(|this| EndIfStatement{
 
        this,
 
        start_if: if_stmt_id,
 
        next: StatementId::new_invalid(),
 
    });
 

	
 
    // Link the statements up as much as we can
 
    let if_stmt = &mut ctx.heap[if_stmt_id];
 
    if_stmt.end_if = end_if_stmt_id;
 

	
 
    let condition_expr = &mut ctx.heap[condition_expression_id];
 
    *condition_expr.parent_mut() = ExpressionParent::If(if_stmt_id);
 

	
 

	
 

	
 
    return (if_stmt_id, end_if_stmt_id);
 
}
 

	
 
fn set_ast_if_statement_false_body(ctx: &mut Ctx, if_statement_id: IfStatementId, end_if_statement_id: EndIfStatementId, false_body_id: StatementId) {
 
/// Sets the false body for a given
 
fn set_ast_if_statement_false_body(ctx: &mut Ctx, if_statement_id: IfStatementId, end_if_statement_id: EndIfStatementId, false_case: IfStatementCase) {
 
    // Point if-statement to "false body"
 
    todo!("set scopes");
 
    let if_stmt = &mut ctx.heap[if_statement_id];
 
    debug_assert!(if_stmt.false_case.is_none()); // simplifies logic, not necessary
 
    if_stmt.false_case = Some(IfStatementCase{
 
        body: false_body_id,
 
        scope: ScopeId::new_invalid(),
 
    });
 
    if_stmt.false_case = Some(false_case);
 

	
 
    // Point end of false body to the end of the if statement
 
    set_ast_statement_next(ctx, false_body_id, end_if_statement_id.upcast());
 
    set_ast_statement_next(ctx, false_case.body, end_if_statement_id.upcast());
 
}
 

	
 
/// Sets the specified AST statement's control flow such that it will be
 
/// followed by the target statement. This may seem obvious, but may imply that
 
/// a statement associated with, but different from, the source statement is
 
/// modified.
 
fn set_ast_statement_next(ctx: &mut Ctx, source_stmt_id: StatementId, target_stmt_id: StatementId) {
 
    let source_stmt = &mut ctx.heap[source_stmt_id];
 
    match source_stmt {
 
        Statement::Block(stmt) => {
 
            let end_id = stmt.end_block;
 
            ctx.heap[end_id].next = target_stmt_id
 
        },
 
        Statement::EndBlock(stmt) => stmt.next = target_stmt_id,
 
        Statement::Local(stmt) => {
 
            match stmt {
 
                LocalStatement::Memory(stmt) => stmt.next = target_stmt_id,
 
                LocalStatement::Channel(stmt) => stmt.next = target_stmt_id,
 
            }
 
        },
 
        Statement::Labeled(stmt) => {
 
            let body_id = stmt.body;
 
            set_ast_statement_next(ctx, body_id, target_stmt_id);
 
        },
 
        Statement::If(stmt) => {
 
            let end_id = stmt.end_if;
 
            ctx.heap[end_id].next = target_stmt_id;
 
        },
 
        Statement::EndIf(stmt) => stmt.next = target_stmt_id,
 
        Statement::While(stmt) => {
 
            let end_id = stmt.end_while;
 
            ctx.heap[end_id].next = target_stmt_id;
 
        },
 
        Statement::EndWhile(stmt) => stmt.next = target_stmt_id,
 

	
 
        Statement::Break(_stmt) => {},
 
        Statement::Continue(_stmt) => {},
 
        Statement::Synchronous(stmt) => {
 
            let end_id = stmt.end_sync;
 
            ctx.heap[end_id].next = target_stmt_id;
 
        },
 
        Statement::EndSynchronous(stmt) => {
 
            stmt.next = target_stmt_id;
 
        },
 
        Statement::Fork(_) | Statement::EndFork(_) => {
 
            todo!("remove fork from language");
 
        },
 
        Statement::Select(stmt) => {
 
            let end_id = stmt.end_select;
 
            ctx.heap[end_id].next = target_stmt_id;
 
        },
 
        Statement::EndSelect(stmt) => stmt.next = target_stmt_id,
 
        Statement::Return(_stmt) => {},
 
        Statement::Goto(_stmt) => {},
 
        Statement::New(stmt) => stmt.next = target_stmt_id,
 
        Statement::Expression(stmt) => stmt.next = target_stmt_id,
 
    }
 
}
 
\ No newline at end of file
 
}
 

	
 
/// Links a new scope to an existing scope as its child.
 
fn link_new_child_to_existing_parent_scope(ctx: &mut Ctx, scope_buffer: &mut ScopedBuffer<ScopeId>, parent_scope_id: ScopeId, child_scope_id: ScopeId, relative_pos_hint: i32) {
 
    let child_scope = &mut ctx.heap[child_scope_id];
 
    debug_assert!(child_scope.parent.is_none());
 

	
 
    child_scope.parent = Some(parent_scope_id);
 
    child_scope.relative_pos_in_parent = relative_pos_hint;
 

	
 
    add_child_scope_to_parent(ctx, scope_buffer, parent_scope_id, child_scope_id, relative_pos_hint);
 
}
 

	
 
/// Relinks an existing scope to a new scope as its child. Will also break the
 
/// link of the child scope's old parent.
 
fn link_existing_child_to_new_parent_scope(ctx: &mut Ctx, scope_buffer: &mut ScopedBuffer<ScopeId>, new_parent_scope_id: ScopeId, child_scope_id: ScopeId, new_relative_pos_in_parent: i32) {
 
    let child_scope = &mut ctx.heap[child_scope_id];
 
    let old_parent_scope_id = child_scope.parent.unwrap();
 
    child_scope.parent = Some(new_parent_scope_id);
 
    child_scope.relative_pos_in_parent = new_relative_pos_in_parent;
 

	
 
    // Remove from old parent
 
    let old_parent = &mut ctx.heap[old_parent_scope_id];
 
    let scope_index = old_parent.nested.iter()
 
        .position(|v| *v == child_scope_id)
 
        .unwrap();
 
    old_parent.nested.remove(scope_index);
 

	
 
    // Add to new parent
 
    add_child_scope_to_parent(ctx, scope_buffer, new_parent_scope_id, child_scope_id, new_relative_pos_in_parent);
 
}
 

	
 
/// Will add a child scope to a parent scope using the relative position hint.
 
fn add_child_scope_to_parent(ctx: &mut Ctx, scope_buffer: &mut ScopedBuffer<ScopeId>, parent_scope_id: ScopeId, child_scope_id: ScopeId, relative_pos_hint: i32) {
 
    let child_scope = &ctx.heap[child_scope_id];
 

	
 
    let existing_scope_ids = scope_buffer.start_section_initialized(&child_scope.nested);
 
    let mut insert_pos = existing_scope_ids.len();
 
    for index in 0..existing_scope_ids.len() {
 
        let existing_scope_id = existing_scope_ids[index];
 
        let existing_scope = &ctx.heap[existing_scope_id];
 
        if relative_pos_hint <= existing_scope.relative_pos_in_parent {
 
            insert_pos = index;
 
            break;
 
        }
 
    }
 
    existing_scope_ids.forget();
 

	
 
    let parent_scope = &mut ctx.heap[parent_scope_id];
 
    parent_scope.nested.insert(insert_pos, child_scope_id);
 
}
src/protocol/parser/pass_validation_linking.rs
Show inline comments
 
/*
 
 * pass_validation_linking.rs
 
 *
 
 * The pass that will validate properties of the AST statements (one is not
 
 * allowed to nest synchronous statements, instantiating components occurs in
 
 * the right places, etc.) and expressions (assignments may not occur in
 
 * arbitrary expressions).
 
 *
 
 * Furthermore, this pass will also perform "linking", in the sense of: some AST
 
 * nodes have something to do with one another, so we link them up in this pass
 
 * (e.g. setting the parents of expressions, linking the control flow statements
 
 * like `continue` and `break` up to the respective loop statement, etc.).
 
 *
 
 * There are several "confusing" parts about this pass:
 
 *
 
 * Setting expression parents: this is the simplest one. The pass struct acts
 
 * like a little state machine. When visiting an expression it will set the
 
 * "parent expression" field of the pass to itself, then visit its child. The
 
 * child will look at this "parent expression" field to determine its parent.
 
 *
 
 * Setting the `next` statement: the AST is a tree, but during execution we walk
 
 * a linear path through all statements. So where appropriate a statement may
 
 * set the "previous statement" field of the pass to itself. When visiting the
 
 * subsequent statement it will check this "previous statement", and if set, it
 
 * will link this previous statement up to itself. Not every statement has a
 
 * previous statement. Hence there are two patterns that occur: assigning the
 
 * `next` value, then clearing the "previous statement" field. And assigning the
 
 * `next` value, and then putting the current statement's ID in the "previous
 
 * statement" field. Because it is so common, this file contain two macros that
 
 * perform that operation.
 
 *
 
 * To make storing types for polymorphic procedures simpler and more efficient,
 
 * we assign to each expression in the procedure a unique ID. This is what the
 
 * "next expression index" field achieves. Each expression simply takes the
 
 * current value, and then increments this counter.
 
 */
 

	
 
use crate::collections::{ScopedBuffer};
 
use crate::protocol::ast::*;
 
use crate::protocol::input_source::*;
 
use crate::protocol::parser::symbol_table::*;
 
use crate::protocol::parser::type_table::*;
 

	
 
use super::visitor::{
 
    BUFFER_INIT_CAP_SMALL,
 
    BUFFER_INIT_CAP_LARGE,
 
    Ctx,
 
    Visitor,
 
    VisitorResult
 
};
 
use crate::protocol::parser::ModuleCompilationPhase;
 

	
 
#[derive(PartialEq, Eq)]
 
enum DefinitionType {
 
    Primitive(ComponentDefinitionId),
 
    Composite(ComponentDefinitionId),
 
    Function(FunctionDefinitionId)
 
}
 

	
 
impl DefinitionType {
 
    fn is_primitive(&self) -> bool { if let Self::Primitive(_) = self { true } else { false } }
 
    fn is_composite(&self) -> bool { if let Self::Composite(_) = self { true } else { false } }
 
    fn is_function(&self) -> bool { if let Self::Function(_) = self { true } else { false } }
 
    fn definition_id(&self) -> DefinitionId {
 
        match self {
 
            DefinitionType::Primitive(v) => v.upcast(),
 
            DefinitionType::Composite(v) => v.upcast(),
 
            DefinitionType::Function(v) => v.upcast(),
 
        }
 
    }
 
}
 

	
 
struct ControlFlowStatement {
 
    in_sync: SynchronousStatementId,
 
    in_while: WhileStatementId,
 
    in_scope: ScopeId,
 
    statement: StatementId, // of 'break', 'continue' or 'goto'
 
}
 

	
 
/// This particular visitor will go through the entire AST in a recursive manner
 
/// and check if all statements and expressions are legal (e.g. no "return"
 
/// statements in component definitions), and will link certain AST nodes to
 
/// their appropriate targets (e.g. goto statements, or function calls).
 
///
 
/// This visitor will not perform control-flow analysis (e.g. making sure that
 
/// each function actually returns) and will also not perform type checking. So
 
/// the linking of function calls and component instantiations will be checked
 
/// and linked to the appropriate definitions, but the return types and/or
 
/// arguments will not be checked for validity.
 
///
 
/// The main idea is, because we're visiting nodes in a tree, to do as much as
 
/// we can while we have the memory in cache.
 
pub(crate) struct PassValidationLinking {
 
    // Traversal state, all valid IDs if inside a certain AST element. Otherwise
 
    // `id.is_invalid()` returns true.
 
    in_sync: SynchronousStatementId,
 
    in_while: WhileStatementId, // to resolve labeled continue/break
 
    in_select_guard: SelectStatementId, // for detection/rejection of builtin calls
 
    in_select_arm: u32,
 
    in_test_expr: StatementId, // wrapping if/while stmt id
 
    in_binding_expr: BindingExpressionId, // to resolve variable expressions
 
    in_binding_expr_lhs: bool,
 
    // Traversal state, current scope (which can be used to find the parent
 
    // scope) and the definition variant we are considering.
 
    cur_scope: ScopeId,
 
    def_type: DefinitionType,
 
    // "Trailing" traversal state, set be child/prev stmt/expr used by next one
 
    prev_stmt: StatementId,
 
    expr_parent: ExpressionParent,
 
    // Set by parent to indicate that child expression must be assignable. The
 
    // child will throw an error if it is not assignable. The stored span is
 
    // used for the error's position
 
    must_be_assignable: Option<InputSpan>,
 
    // Keeping track of relative positions and unique IDs.
 
    relative_pos_in_parent: i32, // of statements: to determine when variables are visible
 
    next_expr_index: i32, // to arrive at a unique ID for all expressions within a definition
 
    // Control flow statements that require label resolving
 
    control_flow_stmts: Vec<ControlFlowStatement>,
 
    // Various temporary buffers for traversal. Essentially working around
 
    // Rust's borrowing rules since it cannot understand we're modifying AST
 
    // members but not the AST container.
 
    variable_buffer: ScopedBuffer<VariableId>,
 
    definition_buffer: ScopedBuffer<DefinitionId>,
 
    statement_buffer: ScopedBuffer<StatementId>,
 
    expression_buffer: ScopedBuffer<ExpressionId>,
 
    scope_buffer: ScopedBuffer<ScopeId>,
 
}
 

	
 
impl PassValidationLinking {
 
    pub(crate) fn new() -> Self {
 
        Self{
 
            in_sync: SynchronousStatementId::new_invalid(),
 
            in_while: WhileStatementId::new_invalid(),
 
            in_select_guard: SelectStatementId::new_invalid(),
 
            in_select_arm: 0,
 
            in_test_expr: StatementId::new_invalid(),
 
            in_binding_expr: BindingExpressionId::new_invalid(),
 
            in_binding_expr_lhs: false,
 
            cur_scope: ScopeId::new_invalid(),
 
            prev_stmt: StatementId::new_invalid(),
 
            expr_parent: ExpressionParent::None,
 
            def_type: DefinitionType::Function(FunctionDefinitionId::new_invalid()),
 
            must_be_assignable: None,
 
            relative_pos_in_parent: 0,
 
            next_expr_index: 0,
 
            control_flow_stmts: Vec::with_capacity(BUFFER_INIT_CAP_SMALL),
 
            variable_buffer: ScopedBuffer::with_capacity(BUFFER_INIT_CAP_SMALL),
 
            definition_buffer: ScopedBuffer::with_capacity(BUFFER_INIT_CAP_SMALL),
 
            statement_buffer: ScopedBuffer::with_capacity(BUFFER_INIT_CAP_LARGE),
 
            expression_buffer: ScopedBuffer::with_capacity(BUFFER_INIT_CAP_LARGE),
 
            scope_buffer: ScopedBuffer::with_capacity(BUFFER_INIT_CAP_SMALL),
 
        }
 
    }
 

	
 
    fn reset_state(&mut self) {
 
        self.in_sync = SynchronousStatementId::new_invalid();
 
        self.in_while = WhileStatementId::new_invalid();
 
        self.in_select_guard = SelectStatementId::new_invalid();
 
        self.in_test_expr = StatementId::new_invalid();
 
        self.in_binding_expr = BindingExpressionId::new_invalid();
 
        self.in_binding_expr_lhs = false;
 
        self.cur_scope = ScopeId::new_invalid();
 
        self.def_type = DefinitionType::Function(FunctionDefinitionId::new_invalid());
 
        self.prev_stmt = StatementId::new_invalid();
 
        self.expr_parent = ExpressionParent::None;
 
        self.must_be_assignable = None;
 
        self.relative_pos_in_parent = 0;
 
        self.next_expr_index = 0;
 
        self.control_flow_stmts.clear();
 
    }
 
}
 

	
 
macro_rules! assign_then_erase_next_stmt {
 
    ($self:ident, $ctx:ident, $stmt_id:expr) => {
 
        if !$self.prev_stmt.is_invalid() {
 
            $ctx.heap[$self.prev_stmt].link_next($stmt_id);
 
            $self.prev_stmt = StatementId::new_invalid();
 
        }
 
    }
 
}
 

	
 
macro_rules! assign_and_replace_next_stmt {
 
    ($self:ident, $ctx:ident, $stmt_id:expr) => {
 
        if !$self.prev_stmt.is_invalid() {
 
            $ctx.heap[$self.prev_stmt].link_next($stmt_id);
 
        }
 
        $self.prev_stmt = $stmt_id;
 
    }
 
}
 

	
 
impl Visitor for PassValidationLinking {
 
    fn visit_module(&mut self, ctx: &mut Ctx) -> VisitorResult {
 
        debug_assert_eq!(ctx.module().phase, ModuleCompilationPhase::TypesAddedToTable);
 

	
 
        let root = &ctx.heap[ctx.module().root_id];
 
        let section = self.definition_buffer.start_section_initialized(&root.definitions);
 
        for definition_id in section.iter_copied() {
 
            self.visit_definition(ctx, definition_id)?;
 
        }
 
        section.forget();
 

	
 
        ctx.module_mut().phase = ModuleCompilationPhase::ValidatedAndLinked;
 
        Ok(())
 
    }
 
    //--------------------------------------------------------------------------
 
    // Definition visitors
 
    //--------------------------------------------------------------------------
 

	
 
    fn visit_component_definition(&mut self, ctx: &mut Ctx, id: ComponentDefinitionId) -> VisitorResult {
 
        self.reset_state();
 

	
 
        let definition = &ctx.heap[id];
 
        self.def_type = match &definition.variant {
 
            ComponentVariant::Primitive => DefinitionType::Primitive(id),
 
            ComponentVariant::Composite => DefinitionType::Composite(id),
 
        };
 
        self.expr_parent = ExpressionParent::None;
 

	
 
        // Visit parameters and assign a unique scope ID
 
        let definition_scope_id = definition.scope;
 
        let old_scope = self.push_scope(ctx, true, definition_scope_id);
 

	
 
        let definition = &ctx.heap[id];
 
        let body_id = definition.body;
 
        let section = self.variable_buffer.start_section_initialized(&definition.parameters);
 
        for variable_idx in 0..section.len() {
 
            let variable_id = section[variable_idx];
 
            self.checked_at_single_scope_add_local(ctx, self.cur_scope, -1, variable_id)?;
 
        }
 
        self.relative_pos_in_parent = section.len() as i32;
 

	
 
        section.forget();
 

	
 
        // Visit statements in component body
 
        self.visit_block_stmt(ctx, body_id)?;
 
        self.pop_scope(old_scope);
 

	
 
        // Assign total number of expressions and assign an in-block unique ID
 
        // to each of the locals in the procedure.
 
        let definition = &mut ctx.heap[id];
 
        let definition_scope = definition.scope;
 
        definition.num_expressions_in_body = self.next_expr_index;
 

	
 
        self.visit_scope_and_assign_local_ids(ctx, definition_scope, 0);
 
        self.resolve_pending_control_flow_targets(ctx)?;
 

	
 
        Ok(())
 
    }
 

	
 
    fn visit_function_definition(&mut self, ctx: &mut Ctx, id: FunctionDefinitionId) -> VisitorResult {
 
        self.reset_state();
 

	
 
        // Set internal statement indices
 
        self.def_type = DefinitionType::Function(id);
 
        self.expr_parent = ExpressionParent::None;
 

	
 
        // Visit parameters and assign a unique scope ID
 
        let definition = &ctx.heap[id];
 
        let definition_scope_id = definition.scope;
 
        let old_scope = self.push_scope(ctx, true, definition_scope_id);
 

	
 
        let definition = &ctx.heap[id];
 
        let body_id = definition.body;
 
        let section = self.variable_buffer.start_section_initialized(&definition.parameters);
 
        for variable_idx in 0..section.len() {
 
            let variable_id = section[variable_idx];
 
            self.checked_at_single_scope_add_local(ctx, self.cur_scope, -1, variable_id)?;
 
        }
 
        section.forget();
 

	
 
        // Visit statements in function body
 
        self.visit_block_stmt(ctx, body_id)?;
 
        self.pop_scope(old_scope);
 

	
 
        // Assign total number of expressions and assign an in-block unique ID
 
        // to each of the locals in the procedure.
 
        let definition = &mut ctx.heap[id];
 
        let definition_scope = definition.scope;
 
        definition.num_expressions_in_body = self.next_expr_index;
 
        self.visit_scope_and_assign_local_ids(ctx, definition_scope, 0);
 
        self.resolve_pending_control_flow_targets(ctx)?;
 

	
 
        Ok(())
 
    }
 

	
 
    //--------------------------------------------------------------------------
 
    // Statement visitors
 
    //--------------------------------------------------------------------------
 

	
 
    fn visit_block_stmt(&mut self, ctx: &mut Ctx, id: BlockStatementId) -> VisitorResult {
 
        // Get end of block
 
        let block_stmt = &ctx.heap[id];
 
        let end_block_id = block_stmt.end_block;
 
        let scope_id = block_stmt.scope;
 

	
 
        // Traverse statements in block
 
        let statement_section = self.statement_buffer.start_section_initialized(&block_stmt.statements);
 
        let old_scope = self.push_scope(ctx, false, scope_id);
 
        assign_and_replace_next_stmt!(self, ctx, id.upcast());
 

	
 
        for stmt_idx in 0..statement_section.len() {
 
            self.relative_pos_in_parent = stmt_idx as i32;
 
            self.visit_stmt(ctx, statement_section[stmt_idx])?;
 
        }
 

	
 
        statement_section.forget();
 
        assign_and_replace_next_stmt!(self, ctx, end_block_id.upcast());
 

	
 
        self.pop_scope(old_scope);
 
        Ok(())
 
    }
 

	
 
    fn visit_local_memory_stmt(&mut self, ctx: &mut Ctx, id: MemoryStatementId) -> VisitorResult {
 
        let stmt = &ctx.heap[id];
 
        let expr_id = stmt.initial_expr;
 
        let variable_id = stmt.variable;
 

	
 
        if ctx.heap[variable_id].identifier.value.as_str() == "counter" {
 
            let a = 1;
 
        }
 
        self.checked_add_local(ctx, self.cur_scope, self.relative_pos_in_parent, variable_id)?;
 

	
 
        assign_and_replace_next_stmt!(self, ctx, id.upcast().upcast());
 
        debug_assert_eq!(self.expr_parent, ExpressionParent::None);
 
        self.expr_parent = ExpressionParent::Memory(id);
 
        self.visit_assignment_expr(ctx, expr_id)?;
 
        self.expr_parent = ExpressionParent::None;
 

	
 
        Ok(())
 
    }
 

	
 
    fn visit_local_channel_stmt(&mut self, ctx: &mut Ctx, id: ChannelStatementId) -> VisitorResult {
 
        let stmt = &ctx.heap[id];
 
        let from_id = stmt.from;
 
        let to_id = stmt.to;
 

	
 
        self.checked_add_local(ctx, self.cur_scope, self.relative_pos_in_parent, from_id)?;
 
        self.checked_add_local(ctx, self.cur_scope, self.relative_pos_in_parent, to_id)?;
 

	
 
        assign_and_replace_next_stmt!(self, ctx, id.upcast().upcast());
 
        Ok(())
 
    }
 

	
 
    fn visit_labeled_stmt(&mut self, ctx: &mut Ctx, id: LabeledStatementId) -> VisitorResult {
 
        let stmt = &ctx.heap[id];
 
        let body_id = stmt.body;
 

	
 
        self.checked_add_label(ctx, self.relative_pos_in_parent, self.in_sync, id)?;
 

	
 
        self.visit_stmt(ctx, body_id)?;
 
        Ok(())
 
    }
 

	
 
    fn visit_if_stmt(&mut self, ctx: &mut Ctx, id: IfStatementId) -> VisitorResult {
 
        let if_stmt = &ctx.heap[id];
 
        let end_if_id = if_stmt.end_if;
 
        let test_expr_id = if_stmt.test;
 
        let true_case = if_stmt.true_case;
 
        let false_case = if_stmt.false_case;
 

	
 
        // Visit test expression
 
        debug_assert_eq!(self.expr_parent, ExpressionParent::None);
 
        debug_assert!(self.in_test_expr.is_invalid());
 

	
 
        self.in_test_expr = id.upcast();
 
        self.expr_parent = ExpressionParent::If(id);
 
        self.visit_expr(ctx, test_expr_id)?;
 
        self.in_test_expr = StatementId::new_invalid();
 

	
 
        self.expr_parent = ExpressionParent::None;
 

	
 
        // Visit true and false branch. Executor chooses next statement based on
 
        // test expression, not on if-statement itself. Hence the if statement
 
        // does not have a static subsequent statement.
 
        assign_then_erase_next_stmt!(self, ctx, id.upcast());
 
        let old_scope = self.push_scope(ctx, false, true_case.scope);
 
        self.visit_stmt(ctx, true_case.body)?;
 
        self.pop_scope(old_scope);
 
        assign_then_erase_next_stmt!(self, ctx, end_if_id.upcast());
 

	
 
        if let Some(false_case) = false_case {
 
            let old_scope = self.push_scope(ctx, false, false_case.scope);
 
            self.visit_stmt(ctx, false_case.body)?;
 
            self.pop_scope(old_scope);
 
            assign_then_erase_next_stmt!(self, ctx, end_if_id.upcast());
 
        }
 

	
 
        self.prev_stmt = end_if_id.upcast();
 
        Ok(())
 
    }
 

	
 
    fn visit_while_stmt(&mut self, ctx: &mut Ctx, id: WhileStatementId) -> VisitorResult {
 
        let stmt = &ctx.heap[id];
 
        let end_while_id = stmt.end_while;
 
        let test_expr_id = stmt.test;
 
        let body_stmt_id = stmt.body;
 
        let scope_id = stmt.scope;
 

	
 
        let old_while = self.in_while;
 
        self.in_while = id;
 

	
 
        // Visit test expression
 
        debug_assert_eq!(self.expr_parent, ExpressionParent::None);
 
        debug_assert!(self.in_test_expr.is_invalid());
 
        self.in_test_expr = id.upcast();
 
        self.expr_parent = ExpressionParent::While(id);
 
        self.visit_expr(ctx, test_expr_id)?;
 
        self.in_test_expr = StatementId::new_invalid();
 

	
 
        // Link up to body statement
 
        assign_then_erase_next_stmt!(self, ctx, id.upcast());
 

	
 
        self.expr_parent = ExpressionParent::None;
 
        let old_scope = self.push_scope(ctx, false, scope_id);
 
        self.visit_stmt(ctx, body_stmt_id)?;
 
        self.pop_scope(old_scope);
 
        self.in_while = old_while;
 

	
 
        // Link final entry in while's block statement back to the while. The
 
        // executor will go to the end-while statement if the test expression
 
        // is false, so put that in as the new previous stmt
 
        assign_then_erase_next_stmt!(self, ctx, id.upcast());
 
        self.prev_stmt = end_while_id.upcast();
 

	
 
        Ok(())
 
    }
 

	
 
    fn visit_break_stmt(&mut self, ctx: &mut Ctx, id: BreakStatementId) -> VisitorResult {
 
        self.control_flow_stmts.push(ControlFlowStatement{
 
            in_sync: self.in_sync,
 
            in_while: self.in_while,
 
            in_scope: self.cur_scope,
 
            statement: id.upcast()
 
        });
 
        assign_then_erase_next_stmt!(self, ctx, id.upcast());
 

	
 
        Ok(())
 
    }
 

	
 
    fn visit_continue_stmt(&mut self, ctx: &mut Ctx, id: ContinueStatementId) -> VisitorResult {
 
        self.control_flow_stmts.push(ControlFlowStatement{
 
            in_sync: self.in_sync,
 
            in_while: self.in_while,
 
            in_scope: self.cur_scope,
 
            statement: id.upcast()
 
        });
 
        assign_then_erase_next_stmt!(self, ctx, id.upcast());
 

	
 
        Ok(())
 
    }
 

	
 
    fn visit_synchronous_stmt(&mut self, ctx: &mut Ctx, id: SynchronousStatementId) -> VisitorResult {
 
        // Check for validity of synchronous statement
 
        let sync_stmt = &ctx.heap[id];
 
        let end_sync_id = sync_stmt.end_sync;
 
        let cur_sync_span = sync_stmt.span;
 
        let scope_id = sync_stmt.scope;
 

	
 
        if !self.in_sync.is_invalid() {
 
            // Nested synchronous statement
 
            let old_sync_span = ctx.heap[self.in_sync].span;
 
            return Err(ParseError::new_error_str_at_span(
 
                &ctx.module().source, cur_sync_span, "Illegal nested synchronous statement"
 
            ).with_info_str_at_span(
 
                &ctx.module().source, old_sync_span, "It is nested in this synchronous statement"
 
            ));
 
        }
 

	
 
        if !self.def_type.is_primitive() {
 
            return Err(ParseError::new_error_str_at_span(
 
                &ctx.module().source, cur_sync_span,
 
                "synchronous statements may only be used in primitive components"
 
            ));
 
        }
 

	
 
        // Synchronous statement implicitly moves to its block
 
        assign_then_erase_next_stmt!(self, ctx, id.upcast());
 

	
 
        // Visit block statement. Note that we explicitly push the scope here
 
        // (and the `visit_block_stmt` will also push, but without effect) to
 
        // ensure the scope contains the sync ID.
 
        let sync_body = ctx.heap[id].body;
 
        debug_assert!(self.in_sync.is_invalid());
 
        self.in_sync = id;
 
        let old_scope = self.push_scope(ctx, false, scope_id);
 
        self.visit_stmt(ctx, sync_body)?;
 
        self.pop_scope(old_scope);
 
        assign_and_replace_next_stmt!(self, ctx, end_sync_id.upcast());
 

	
 
        self.in_sync = SynchronousStatementId::new_invalid();
 

	
 
        Ok(())
 
    }
 

	
 
    fn visit_fork_stmt(&mut self, ctx: &mut Ctx, id: ForkStatementId) -> VisitorResult {
 
        let fork_stmt = &ctx.heap[id];
 
        let end_fork_id = fork_stmt.end_fork;
 
        let left_body_id = fork_stmt.left_body;
 
        let right_body_id = fork_stmt.right_body;
 

	
 
        // Fork statements may only occur inside sync blocks
 
        if self.in_sync.is_invalid() {
 
            return Err(ParseError::new_error_str_at_span(
 
                &ctx.module().source, fork_stmt.span,
 
                "Forking may only occur inside sync blocks"
 
            ));
 
        }
 

	
 
        // Visit the respective bodies. Like the if statement, a fork statement
 
        // does not have a single static subsequent statement. It forks and then
 
        // each fork has a different next statement.
 
        assign_then_erase_next_stmt!(self, ctx, id.upcast());
 
        self.visit_stmt(ctx, left_body_id)?;
 
        assign_then_erase_next_stmt!(self, ctx, end_fork_id.upcast());
 

	
 
        if let Some(right_body_id) = right_body_id {
 
            self.visit_stmt(ctx, right_body_id)?;
 
            assign_then_erase_next_stmt!(self, ctx, end_fork_id.upcast());
 
        }
 

	
 
        self.prev_stmt = end_fork_id.upcast();
 
        Ok(())
 
    }
 

	
 
    fn visit_select_stmt(&mut self, ctx: &mut Ctx, id: SelectStatementId) -> VisitorResult {
 
        let select_stmt = &mut ctx.heap[id];
 
        select_stmt.relative_pos_in_parent = self.relative_pos_in_parent;
 
        self.relative_pos_in_parent += 1;
 

	
 
        let select_stmt = &ctx.heap[id];
 
        let end_select_id = select_stmt.end_select;
 

	
 
        // Select statements may only occur inside sync blocks
 
        if self.in_sync.is_invalid() {
 
            return Err(ParseError::new_error_str_at_span(
 
                &ctx.module().source, select_stmt.span,
 
                "select statements may only occur inside sync blocks"
 
            ));
 
        }
 

	
 
        if !self.def_type.is_primitive() {
 
            return Err(ParseError::new_error_str_at_span(
 
                &ctx.module().source, select_stmt.span,
 
                "select statements may only be used in primitive components"
 
            ));
 
        }
 

	
 
        // Visit the various arms in the select block
 
        let mut case_stmt_ids = self.statement_buffer.start_section();
 
        let mut case_scope_ids = self.scope_buffer.start_section();
 
        let num_cases = select_stmt.cases.len();
 
        for case in &select_stmt.cases {
 
            // We add them in pairs, so the subsequent for-loop retrieves in pairs
 
            case_stmt_ids.push(case.guard);
 
            case_stmt_ids.push(case.body);
 
            case_scope_ids.push(case.scope);
 
        }
 

	
 
        assign_then_erase_next_stmt!(self, ctx, id.upcast());
 

	
 
        for index in 0..num_cases {
 
            let base_index = 2 * index;
 
            let guard_id     = case_stmt_ids[base_index];
 
            let case_body_id = case_stmt_ids[base_index + 1];
 
            let case_scope_id = case_scope_ids[index];
 

	
 
            // The guard statement ends up belonging to the block statement
 
            // following the arm. The reason we parse it separately is to
 
            // extract all of the "get" calls.
 
            let old_scope = self.push_scope(ctx, false, case_scope_id);
 

	
 
            // Visit the guard of this arm
 
            debug_assert!(self.in_select_guard.is_invalid());
 
            self.in_select_guard = id;
 
            self.in_select_arm = index as u32;
 
            self.visit_stmt(ctx, guard_id)?;
 
            self.in_select_guard = SelectStatementId::new_invalid();
 

	
 
            // Visit the code associated with the guard
 
            self.relative_pos_in_parent += 1;
 
            self.visit_stmt(ctx, case_body_id)?;
 
            self.pop_scope(old_scope);
 

	
 
            // Link up last statement in block to EndSelect
 
            assign_then_erase_next_stmt!(self, ctx, end_select_id.upcast());
 
        }
 

	
 
        self.in_select_guard = SelectStatementId::new_invalid();
 
        self.prev_stmt = end_select_id.upcast();
 
        Ok(())
 
    }
 

	
 
    fn visit_return_stmt(&mut self, ctx: &mut Ctx, id: ReturnStatementId) -> VisitorResult {
 
        // Check if "return" occurs within a function
 
        let stmt = &ctx.heap[id];
 
        if !self.def_type.is_function() {
 
            return Err(ParseError::new_error_str_at_span(
 
                &ctx.module().source, stmt.span,
 
                "return statements may only appear in function bodies"
 
            ));
 
        }
 

	
 
        // If here then we are within a function
 
        assign_then_erase_next_stmt!(self, ctx, id.upcast());
 
        debug_assert_eq!(self.expr_parent, ExpressionParent::None);
 
        debug_assert_eq!(ctx.heap[id].expressions.len(), 1);
 
        self.expr_parent = ExpressionParent::Return(id);
 
        self.visit_expr(ctx, ctx.heap[id].expressions[0])?;
 
        self.expr_parent = ExpressionParent::None;
 

	
 
        Ok(())
 
    }
 

	
 
    fn visit_goto_stmt(&mut self, ctx: &mut Ctx, id: GotoStatementId) -> VisitorResult {
 
        self.control_flow_stmts.push(ControlFlowStatement{
 
            in_sync: self.in_sync,
 
            in_while: self.in_while,
 
            in_scope: self.cur_scope,
 
            statement: id.upcast(),
 
        });
 
        assign_then_erase_next_stmt!(self, ctx, id.upcast());
 

	
 
        Ok(())
 
    }
 

	
 
    fn visit_new_stmt(&mut self, ctx: &mut Ctx, id: NewStatementId) -> VisitorResult {
 
        // Make sure the new statement occurs inside a composite component
 
        if !self.def_type.is_composite() {
 
            let new_stmt = &ctx.heap[id];
 
            return Err(ParseError::new_error_str_at_span(
 
                &ctx.module().source, new_stmt.span,
 
                "instantiating components may only be done in composite components"
 
            ));
 
        }
 

	
 
        // Recurse into call expression (which will check the expression parent
 
        // to ensure that the "new" statment instantiates a component)
 
        let call_expr_id = ctx.heap[id].expression;
 

	
 
        assign_and_replace_next_stmt!(self, ctx, id.upcast());
 
        debug_assert_eq!(self.expr_parent, ExpressionParent::None);
 
        self.expr_parent = ExpressionParent::New(id);
 
        self.visit_call_expr(ctx, call_expr_id)?;
 
        self.expr_parent = ExpressionParent::None;
 

	
 
        Ok(())
 
    }
 

	
 
    fn visit_expr_stmt(&mut self, ctx: &mut Ctx, id: ExpressionStatementId) -> VisitorResult {
 
        let expr_id = ctx.heap[id].expression;
 

	
 
        assign_and_replace_next_stmt!(self, ctx, id.upcast());
 
        debug_assert_eq!(self.expr_parent, ExpressionParent::None);
 
        self.expr_parent = ExpressionParent::ExpressionStmt(id);
 
        self.visit_expr(ctx, expr_id)?;
 
        self.expr_parent = ExpressionParent::None;
 

	
 
        Ok(())
 
    }
 

	
 

	
 
    //--------------------------------------------------------------------------
 
    // Expression visitors
 
    //--------------------------------------------------------------------------
 

	
 
    fn visit_assignment_expr(&mut self, ctx: &mut Ctx, id: AssignmentExpressionId) -> VisitorResult {
 
        let upcast_id = id.upcast();
 

	
 
        let assignment_expr = &mut ctx.heap[id];
 

	
 
        // Although we call assignment an expression to simplify the compiler's
 
        // code (mainly typechecking), we disallow nested use in expressions
 
        match self.expr_parent {
 
            // Look at us: lying through our teeth while providing error messages.
 
            ExpressionParent::Memory(_) => {},
 
            ExpressionParent::ExpressionStmt(_) => {},
 
            _ => {
 
                let assignment_span = assignment_expr.full_span;
 
                return Err(ParseError::new_error_str_at_span(
 
                    &ctx.module().source, assignment_span,
 
                    "assignments are statements, and cannot be used in expressions"
 
                ))
 
            },
 
        }
 

	
 
        let left_expr_id = assignment_expr.left;
 
        let right_expr_id = assignment_expr.right;
 
        let old_expr_parent = self.expr_parent;
 
        assignment_expr.parent = old_expr_parent;
 
        assignment_expr.unique_id_in_definition = self.next_expr_index;
 
        self.next_expr_index += 1;
 

	
 
        self.expr_parent = ExpressionParent::Expression(upcast_id, 0);
 
        self.must_be_assignable = Some(assignment_expr.operator_span);
 
        self.visit_expr(ctx, left_expr_id)?;
 
        self.expr_parent = ExpressionParent::Expression(upcast_id, 1);
 
        self.must_be_assignable = None;
 
        self.visit_expr(ctx, right_expr_id)?;
 
        self.expr_parent = old_expr_parent;
 
        Ok(())
 
    }
 

	
 
    fn visit_binding_expr(&mut self, ctx: &mut Ctx, id: BindingExpressionId) -> VisitorResult {
 
        let upcast_id = id.upcast();
 

	
 
        // Check for valid context of binding expression
 
        if let Some(span) = self.must_be_assignable {
 
            return Err(ParseError::new_error_str_at_span(
 
                &ctx.module().source, span, "cannot assign to the result from a binding expression"
 
            ));
 
        }
 

	
 
        if self.in_test_expr.is_invalid() {
 
            let binding_expr = &ctx.heap[id];
 
            return Err(ParseError::new_error_str_at_span(
 
                &ctx.module().source, binding_expr.full_span,
 
                "binding expressions can only be used inside the testing expression of 'if' and 'while' statements"
 
            ));
 
        }
 

	
 
        if !self.in_binding_expr.is_invalid() {
 
            let binding_expr = &ctx.heap[id];
 
            let previous_expr = &ctx.heap[self.in_binding_expr];
 
            return Err(ParseError::new_error_str_at_span(
 
                &ctx.module().source, binding_expr.full_span,
 
                "nested binding expressions are not allowed"
 
            ).with_info_str_at_span(
 
                &ctx.module().source, previous_expr.operator_span,
 
                "the outer binding expression is found here"
 
            ));
 
        }
 

	
 
        let mut seeking_parent = self.expr_parent;
 
        loop {
 
            // Perform upward search to make sure only LogicalAnd is applied to
 
            // the binding expression
 
            let valid = match seeking_parent {
 
                ExpressionParent::If(_) | ExpressionParent::While(_) => {
 
                    // Every parent expression (if any) were LogicalAnd.
 
                    break;
 
                }
 
                ExpressionParent::Expression(parent_id, _) => {
 
                    let parent_expr = &ctx.heap[parent_id];
 
                    match parent_expr {
 
                        Expression::Binary(parent_expr) => {
 
                            // Set new parent to continue the search. Otherwise
 
                            // halt and provide an error using the current
 
                            // parent.
 
                            if parent_expr.operation == BinaryOperator::LogicalAnd {
 
                                seeking_parent = parent_expr.parent;
 
                                true
 
                            } else {
 
                                false
 
                            }
 
                        },
 
                        _ => false,
 
                    }
 
                },
 
                _ => unreachable!(), // nested under if/while, so always expressions as parents
 
            };
 

	
 
            if !valid {
 
                let binding_expr = &ctx.heap[id];
 
                let parent_expr = &ctx.heap[seeking_parent.as_expression()];
 
                return Err(ParseError::new_error_str_at_span(
 
                    &ctx.module().source, binding_expr.full_span,
 
                    "only the logical-and operator (&&) may be applied to binding expressions"
 
                ).with_info_str_at_span(
 
                    &ctx.module().source, parent_expr.operation_span(),
 
                    "this was the disallowed operation applied to the result from a binding expression"
 
                ));
 
            }
 
        }
 

	
 
        // Perform all of the index/parent assignment magic
 
        let binding_expr = &mut ctx.heap[id];
 

	
 
        let old_expr_parent = self.expr_parent;
 
        binding_expr.parent = old_expr_parent;
 
        binding_expr.unique_id_in_definition = self.next_expr_index;
 
        self.next_expr_index += 1;
 
        self.in_binding_expr = id;
 

	
 
        // Perform preliminary check on children: binding expressions only make
 
        // sense if the left hand side is just a variable expression, or if it
 
        // is a literal of some sort. The typechecker will take care of the rest
 
        let bound_to_id = binding_expr.bound_to;
 
        let bound_from_id = binding_expr.bound_from;
 

	
 
        match &ctx.heap[bound_to_id] {
 
            // Variables may not be binding variables, and literals may
 
            // actually not contain binding variables. But in that case we just
 
            // perform an equality check.
 
            Expression::Variable(_) => {}
 
            Expression::Literal(_) => {},
 
            _ => {
 
                let binding_expr = &ctx.heap[id];
 
                return Err(ParseError::new_error_str_at_span(
 
                    &ctx.module().source, binding_expr.operator_span,
 
                    "the left hand side of a binding expression may only be a variable or a literal expression"
 
                ));
 
            },
 
        }
 

	
 
        // Visit the children themselves
 
        self.in_binding_expr_lhs = true;
 
        self.expr_parent = ExpressionParent::Expression(upcast_id, 0);
 
        self.visit_expr(ctx, bound_to_id)?;
 
        self.in_binding_expr_lhs = false;
 
        self.expr_parent = ExpressionParent::Expression(upcast_id, 1);
 
        self.visit_expr(ctx, bound_from_id)?;
 

	
 
        self.expr_parent = old_expr_parent;
 
        self.in_binding_expr = BindingExpressionId::new_invalid();
 

	
 
        Ok(())
 
    }
 

	
 
    fn visit_conditional_expr(&mut self, ctx: &mut Ctx, id: ConditionalExpressionId) -> VisitorResult {
 
        let upcast_id = id.upcast();
 
        let conditional_expr = &mut ctx.heap[id];
 

	
 
        if let Some(span) = self.must_be_assignable {
 
            return Err(ParseError::new_error_str_at_span(
 
                &ctx.module().source, span, "cannot assign to the result from a conditional expression"
 
            ))
 
        }
 

	
 
        let test_expr_id = conditional_expr.test;
 
        let true_expr_id = conditional_expr.true_expression;
 
        let false_expr_id = conditional_expr.false_expression;
 

	
 
        let old_expr_parent = self.expr_parent;
 
        conditional_expr.parent = old_expr_parent;
 
        conditional_expr.unique_id_in_definition = self.next_expr_index;
 
        self.next_expr_index += 1;
 

	
 
        self.expr_parent = ExpressionParent::Expression(upcast_id, 0);
 
        self.visit_expr(ctx, test_expr_id)?;
 
        self.expr_parent = ExpressionParent::Expression(upcast_id, 1);
 
        self.visit_expr(ctx, true_expr_id)?;
 
        self.expr_parent = ExpressionParent::Expression(upcast_id, 2);
 
        self.visit_expr(ctx, false_expr_id)?;
 
        self.expr_parent = old_expr_parent;
 

	
 
        Ok(())
 
    }
 

	
 
    fn visit_binary_expr(&mut self, ctx: &mut Ctx, id: BinaryExpressionId) -> VisitorResult {
 
        let upcast_id = id.upcast();
 
        let binary_expr = &mut ctx.heap[id];
 

	
 
        if let Some(span) = self.must_be_assignable {
 
            return Err(ParseError::new_error_str_at_span(
 
                &ctx.module().source, span, "cannot assign to the result from a binary expression"
 
            ))
 
        }
 

	
 
        let left_expr_id = binary_expr.left;
 
        let right_expr_id = binary_expr.right;
 

	
 
        let old_expr_parent = self.expr_parent;
 
        binary_expr.parent = old_expr_parent;
 
        binary_expr.unique_id_in_definition = self.next_expr_index;
 
        self.next_expr_index += 1;
 

	
 
        self.expr_parent = ExpressionParent::Expression(upcast_id, 0);
 
        self.visit_expr(ctx, left_expr_id)?;
 
        self.expr_parent = ExpressionParent::Expression(upcast_id, 1);
 
        self.visit_expr(ctx, right_expr_id)?;
 
        self.expr_parent = old_expr_parent;
 

	
 
        Ok(())
 
    }
 

	
 
    fn visit_unary_expr(&mut self, ctx: &mut Ctx, id: UnaryExpressionId) -> VisitorResult {
 
        let unary_expr = &mut ctx.heap[id];
 
        let expr_id = unary_expr.expression;
 

	
 
        if let Some(span) = self.must_be_assignable {
 
            return Err(ParseError::new_error_str_at_span(
 
                &ctx.module().source, span, "cannot assign to the result from a unary expression"
 
            ))
 
        }
 

	
 
        let old_expr_parent = self.expr_parent;
 
        unary_expr.parent = old_expr_parent;
 
        unary_expr.unique_id_in_definition = self.next_expr_index;
 
        self.next_expr_index += 1;
 

	
 
        self.expr_parent = ExpressionParent::Expression(id.upcast(), 0);
 
        self.visit_expr(ctx, expr_id)?;
 
        self.expr_parent = old_expr_parent;
 

	
 
        Ok(())
 
    }
 

	
 
    fn visit_indexing_expr(&mut self, ctx: &mut Ctx, id: IndexingExpressionId) -> VisitorResult {
 
        let upcast_id = id.upcast();
 
        let indexing_expr = &mut ctx.heap[id];
 

	
 
        let subject_expr_id = indexing_expr.subject;
 
        let index_expr_id = indexing_expr.index;
 

	
 
        let old_expr_parent = self.expr_parent;
 
        indexing_expr.parent = old_expr_parent;
 
        indexing_expr.unique_id_in_definition = self.next_expr_index;
 
        self.next_expr_index += 1;
 

	
 
        self.expr_parent = ExpressionParent::Expression(upcast_id, 0);
 
        self.visit_expr(ctx, subject_expr_id)?;
 

	
 
        let old_assignable = self.must_be_assignable.take();
 
        self.expr_parent = ExpressionParent::Expression(upcast_id, 1);
 
        self.visit_expr(ctx, index_expr_id)?;
 

	
 
        self.must_be_assignable = old_assignable;
 
        self.expr_parent = old_expr_parent;
 

	
 
        Ok(())
 
    }
 

	
 
    fn visit_slicing_expr(&mut self, ctx: &mut Ctx, id: SlicingExpressionId) -> VisitorResult {
 
        let upcast_id = id.upcast();
 
        let slicing_expr = &mut ctx.heap[id];
 

	
 
        if let Some(span) = self.must_be_assignable {
 
            // TODO: @Slicing
 
            return Err(ParseError::new_error_str_at_span(
 
                &ctx.module().source, span, "assignment to slices should be valid in the final language, but is currently not implemented"
 
            ));
 
        }
 

	
 
        let subject_expr_id = slicing_expr.subject;
 
        let from_expr_id = slicing_expr.from_index;
 
        let to_expr_id = slicing_expr.to_index;
 

	
 
        let old_expr_parent = self.expr_parent;
 
        slicing_expr.parent = old_expr_parent;
 
        slicing_expr.unique_id_in_definition = self.next_expr_index;
 
        self.next_expr_index += 1;
 

	
 
        self.expr_parent = ExpressionParent::Expression(upcast_id, 0);
 
        self.visit_expr(ctx, subject_expr_id)?;
 

	
 
        let old_assignable = self.must_be_assignable.take();
 
        self.expr_parent = ExpressionParent::Expression(upcast_id, 1);
 
        self.visit_expr(ctx, from_expr_id)?;
 
        self.expr_parent = ExpressionParent::Expression(upcast_id, 2);
 
        self.visit_expr(ctx, to_expr_id)?;
 

	
 
        self.must_be_assignable = old_assignable;
 
        self.expr_parent = old_expr_parent;
 

	
 
        Ok(())
 
    }
 

	
 
    fn visit_select_expr(&mut self, ctx: &mut Ctx, id: SelectExpressionId) -> VisitorResult {
 
        let select_expr = &mut ctx.heap[id];
 
        let expr_id = select_expr.subject;
 

	
 
        let old_expr_parent = self.expr_parent;
 
        select_expr.parent = old_expr_parent;
 
        select_expr.unique_id_in_definition = self.next_expr_index;
 
        self.next_expr_index += 1;
 

	
 
        self.expr_parent = ExpressionParent::Expression(id.upcast(), 0);
 
        self.visit_expr(ctx, expr_id)?;
 
        self.expr_parent = old_expr_parent;
 

	
 
        Ok(())
 
    }
 

	
 
    fn visit_literal_expr(&mut self, ctx: &mut Ctx, id: LiteralExpressionId) -> VisitorResult {
 
        let literal_expr = &mut ctx.heap[id];
 
        let old_expr_parent = self.expr_parent;
 
        literal_expr.parent = old_expr_parent;
 
        literal_expr.unique_id_in_definition = self.next_expr_index;
 
        self.next_expr_index += 1;
 

	
 
        if let Some(span) = self.must_be_assignable {
 
            return Err(ParseError::new_error_str_at_span(
 
                &ctx.module().source, span, "cannot assign to a literal expression"
 
            ))
 
        }
 

	
 
        match &mut literal_expr.value {
 
            Literal::Null | Literal::True | Literal::False |
 
            Literal::Character(_) | Literal::String(_) | Literal::Integer(_) => {
 
                // Just the parent has to be set, done above
 
            },
 
            Literal::Struct(literal) => {
 
                let upcast_id = id.upcast();
 
                // Retrieve type definition
 
                let type_definition = ctx.types.get_base_definition(&literal.definition).unwrap();
 
                let struct_definition = type_definition.definition.as_struct();
 

	
 
                // Make sure all fields are specified, none are specified twice
 
                // and all fields exist on the struct definition
 
                let mut specified = Vec::new(); // TODO: @performance
 
                specified.resize(struct_definition.fields.len(), false);
 

	
 
                for field in &mut literal.fields {
 
                    // Find field in the struct definition
 
                    let field_idx = struct_definition.fields.iter().position(|v| v.identifier == field.identifier);
 
                    if field_idx.is_none() {
 
                        let field_span = field.identifier.span;
 
                        let literal = ctx.heap[id].value.as_struct();
 
                        let ast_definition = &ctx.heap[literal.definition];
 
                        return Err(ParseError::new_error_at_span(
 
                            &ctx.module().source, field_span, format!(
 
                                "This field does not exist on the struct '{}'",
 
                                ast_definition.identifier().value.as_str()
 
                            )
 
                        ));
 
                    }
 
                    field.field_idx = field_idx.unwrap();
 

	
 
                    // Check if specified more than once
 
                    if specified[field.field_idx] {
 
                        let field_span = field.identifier.span;
 
                        return Err(ParseError::new_error_str_at_span(
 
                            &ctx.module().source, field_span,
 
                            "This field is specified more than once"
 
                        ));
 
                    }
 

	
 
                    specified[field.field_idx] = true;
 
                }
 

	
 
                if !specified.iter().all(|v| *v) {
 
                    // Some fields were not specified
 
                    let mut not_specified = String::new();
 
                    let mut num_not_specified = 0;
 
                    for (def_field_idx, is_specified) in specified.iter().enumerate() {
 
                        if !is_specified {
 
                            if !not_specified.is_empty() { not_specified.push_str(", ") }
 
                            let field_ident = &struct_definition.fields[def_field_idx].identifier;
 
                            not_specified.push_str(field_ident.value.as_str());
 
                            num_not_specified += 1;
 
                        }
 
                    }
 

	
 
                    debug_assert!(num_not_specified > 0);
 
                    let msg = if num_not_specified == 1 {
 
                        format!("not all fields are specified, '{}' is missing", not_specified)
 
                    } else {
 
                        format!("not all fields are specified, [{}] are missing", not_specified)
 
                    };
 

	
 
                    let literal_span = literal.parser_type.full_span;
 
                    return Err(ParseError::new_error_at_span(
 
                        &ctx.module().source, literal_span, msg
 
                    ));
 
                }
 

	
 
                // Need to traverse fields expressions in struct and evaluate
 
                // the poly args
 
                let mut expr_section = self.expression_buffer.start_section();
 
                for field in &literal.fields {
 
                    expr_section.push(field.value);
 
                }
 

	
 
                for expr_idx in 0..expr_section.len() {
 
                    let expr_id = expr_section[expr_idx];
 
                    self.expr_parent = ExpressionParent::Expression(upcast_id, expr_idx as u32);
 
                    self.visit_expr(ctx, expr_id)?;
 
                }
 

	
 
                expr_section.forget();
 
            },
 
            Literal::Enum(literal) => {
 
                // Make sure the variant exists
 
                let type_definition = ctx.types.get_base_definition(&literal.definition).unwrap();
 
                let enum_definition = type_definition.definition.as_enum();
 

	
 
                let variant_idx = enum_definition.variants.iter().position(|v| {
 
                    v.identifier == literal.variant
 
                });
 

	
 
                if variant_idx.is_none() {
 
                    let literal = ctx.heap[id].value.as_enum();
 
                    let ast_definition = ctx.heap[literal.definition].as_enum();
 
                    return Err(ParseError::new_error_at_span(
 
                        &ctx.module().source, literal.parser_type.full_span, format!(
 
                            "the variant '{}' does not exist on the enum '{}'",
 
                            literal.variant.value.as_str(), ast_definition.identifier.value.as_str()
 
                        )
 
                    ));
 
                }
 

	
 
                literal.variant_idx = variant_idx.unwrap();
 
            },
 
            Literal::Union(literal) => {
 
                // Make sure the variant exists
 
                let type_definition = ctx.types.get_base_definition(&literal.definition).unwrap();
 
                let union_definition = type_definition.definition.as_union();
 

	
 
                let variant_idx = union_definition.variants.iter().position(|v| {
 
                    v.identifier == literal.variant
 
                });
 
                if variant_idx.is_none() {
 
                    let literal = ctx.heap[id].value.as_union();
 
                    let ast_definition = ctx.heap[literal.definition].as_union();
 
                    return Err(ParseError::new_error_at_span(
 
                        &ctx.module().source, literal.parser_type.full_span, format!(
 
                            "the variant '{}' does not exist on the union '{}'",
 
                            literal.variant.value.as_str(), ast_definition.identifier.value.as_str()
 
                        )
 
                    ));
 
                }
 

	
 
                literal.variant_idx = variant_idx.unwrap();
 

	
 
                // Make sure the number of specified values matches the expected
 
                // number of embedded values in the union variant.
 
                let union_variant = &union_definition.variants[literal.variant_idx];
 
                if union_variant.embedded.len() != literal.values.len() {
 
                    let literal = ctx.heap[id].value.as_union();
 
                    let ast_definition = ctx.heap[literal.definition].as_union();
 
                    return Err(ParseError::new_error_at_span(
 
                        &ctx.module().source, literal.parser_type.full_span, format!(
 
                            "The variant '{}' of union '{}' expects {} embedded values, but {} were specified",
 
                            literal.variant.value.as_str(), ast_definition.identifier.value.as_str(),
 
                            union_variant.embedded.len(), literal.values.len()
 
                        ),
 
                    ))
 
                }
 

	
 
                // Traverse embedded values of union (if any) and evaluate the
 
                // polymorphic arguments
 
                let upcast_id = id.upcast();
 
                let mut expr_section = self.expression_buffer.start_section();
 
                for value in &literal.values {
 
                    expr_section.push(*value);
 
                }
 

	
 
                for expr_idx in 0..expr_section.len() {
 
                    let expr_id = expr_section[expr_idx];
 
                    self.expr_parent = ExpressionParent::Expression(upcast_id, expr_idx as u32);
 
                    self.visit_expr(ctx, expr_id)?;
 
                }
 

	
 
                expr_section.forget();
 
            },
 
            Literal::Array(literal) | Literal::Tuple(literal) => {
 
                // Visit all expressions in the array
 
                let upcast_id = id.upcast();
 
                let expr_section = self.expression_buffer.start_section_initialized(literal);
 
                for expr_idx in 0..expr_section.len() {
 
                    let expr_id = expr_section[expr_idx];
 
                    self.expr_parent = ExpressionParent::Expression(upcast_id, expr_idx as u32);
 
                    self.visit_expr(ctx, expr_id)?;
 
                }
 

	
 
                expr_section.forget();
 
            }
 
        }
 

	
 
        self.expr_parent = old_expr_parent;
 

	
 
        Ok(())
 
    }
 

	
 
    fn visit_cast_expr(&mut self, ctx: &mut Ctx, id: CastExpressionId) -> VisitorResult {
 
        let cast_expr = &mut ctx.heap[id];
 

	
 
        if let Some(span) = self.must_be_assignable {
 
            return Err(ParseError::new_error_str_at_span(
 
                &ctx.module().source, span, "cannot assign to the result from a cast expression"
 
            ))
 
        }
 

	
 
        let upcast_id = id.upcast();
 
        let old_expr_parent = self.expr_parent;
 
        cast_expr.parent = old_expr_parent;
 
        cast_expr.unique_id_in_definition = self.next_expr_index;
 
        self.next_expr_index += 1;
 

	
 
        // Recurse into the thing that we're casting
 
        self.expr_parent = ExpressionParent::Expression(upcast_id, 0);
 
        let subject_id = cast_expr.subject;
 
        self.visit_expr(ctx, subject_id)?;
 
        self.expr_parent = old_expr_parent;
 

	
 
        Ok(())
 
    }
 

	
 
    fn visit_call_expr(&mut self, ctx: &mut Ctx, id: CallExpressionId) -> VisitorResult {
 
        let call_expr = &ctx.heap[id];
 

	
 
        if let Some(span) = self.must_be_assignable {
 
            return Err(ParseError::new_error_str_at_span(
 
                &ctx.module().source, span, "cannot assign to the result from a call expression"
 
            ))
 
        }
 

	
 
        // Check whether the method is allowed to be called within the code's
 
        // context (in sync, definition type, etc.)
 
        let mut expecting_wrapping_new_stmt = false;
 
        let mut expecting_primitive_def = false;
 
        let mut expecting_wrapping_sync_stmt = false;
 
        let mut expecting_no_select_stmt = false;
 

	
 
        match call_expr.method {
 
            Method::Get => {
 
                expecting_primitive_def = true;
 
                expecting_wrapping_sync_stmt = true;
 
                if !self.in_select_guard.is_invalid() {
 
                    // In a select guard. Take the argument (i.e. the port we're
 
                    // retrieving from) and add it to the list of involved ports
 
                    // of the guard
 
                    if call_expr.arguments.len() == 1 {
 
                        // We're checking the number of arguments later, for now
 
                        // assume it is correct.
 
                        let argument = call_expr.arguments[0];
 
                        let select_stmt = &mut ctx.heap[self.in_select_guard];
 
                        let select_case = &mut select_stmt.cases[self.in_select_arm as usize];
 
                        select_case.involved_ports.push((id, argument));
 
                    }
 
                }
 
            },
 
            Method::Put => {
 
                expecting_primitive_def = true;
 
                expecting_wrapping_sync_stmt = true;
 
                expecting_no_select_stmt = true;
 
            },
 
            Method::Fires => {
 
                expecting_primitive_def = true;
 
                expecting_wrapping_sync_stmt = true;
 
            },
 
            Method::Create => {},
 
            Method::Length => {},
 
            Method::Assert => {
 
                expecting_wrapping_sync_stmt = true;
 
                expecting_no_select_stmt = true;
 
                if self.def_type.is_function() {
 
                    let call_span = call_expr.func_span;
 
                    return Err(ParseError::new_error_str_at_span(
 
                        &ctx.module().source, call_span,
 
                        "assert statement may only occur in components"
 
                    ));
 
                }
 
            },
 
            Method::Print => {},
 
            Method::SelectStart
 
            | Method::SelectRegisterCasePort
 
            | Method::SelectWait => unreachable!(), // not usable by programmer directly
 
            Method::UserFunction => {},
 
            Method::UserComponent => {
 
                expecting_wrapping_new_stmt = true;
 
            },
 
        }
 

	
 
        let call_expr = &mut ctx.heap[id];
 

	
 
        fn get_span_and_name<'a>(ctx: &'a Ctx, id: CallExpressionId) -> (InputSpan, String) {
 
            let call = &ctx.heap[id];
 
            let span = call.func_span;
 
            let name = String::from_utf8_lossy(ctx.module().source.section_at_span(span)).to_string();
 
            return (span, name);
 
        }
 
        if expecting_primitive_def {
 
            if !self.def_type.is_primitive() {
 
                let (call_span, func_name) = get_span_and_name(ctx, id);
 
                return Err(ParseError::new_error_at_span(
 
                    &ctx.module().source, call_span,
 
                    format!("a call to '{}' may only occur in primitive component definitions", func_name)
 
                ));
 
            }
 
        }
 

	
 
        if expecting_wrapping_sync_stmt {
 
            if self.in_sync.is_invalid() {
 
                let (call_span, func_name) = get_span_and_name(ctx, id);
 
                return Err(ParseError::new_error_at_span(
 
                    &ctx.module().source, call_span,
 
                    format!("a call to '{}' may only occur inside synchronous blocks", func_name)
 
                ))
 
            }
 
        }
 

	
 
        if expecting_no_select_stmt {
 
            if !self.in_select_guard.is_invalid() {
 
                let (call_span, func_name) = get_span_and_name(ctx, id);
 
                return Err(ParseError::new_error_at_span(
 
                    &ctx.module().source, call_span,
 
                    format!("a call to '{}' may not occur in a select statement's guard", func_name)
 
                ));
 
            }
 
        }
 

	
 
        if expecting_wrapping_new_stmt {
 
            if !self.expr_parent.is_new() {
 
                let call_span = call_expr.func_span;
 
                return Err(ParseError::new_error_str_at_span(
 
                    &ctx.module().source, call_span,
 
                    "cannot call a component, it can only be instantiated by using 'new'"
 
                ));
 
            }
 
        } else {
 
            if self.expr_parent.is_new() {
 
                let call_span = call_expr.func_span;
 
                return Err(ParseError::new_error_str_at_span(
 
                    &ctx.module().source, call_span,
 
                    "only components can be instantiated, this is a function"
 
                ));
 
            }
 
        }
 

	
 
        // Check the number of arguments
 
        let call_definition = ctx.types.get_base_definition(&call_expr.definition).unwrap();
 
        let num_expected_args = match &call_definition.definition {
 
            DefinedTypeVariant::Function(definition) => definition.arguments.len(),
 
            DefinedTypeVariant::Component(definition) => definition.arguments.len(),
 
            v => unreachable!("encountered {} type in call expression", v.type_class()),
 
        };
 

	
 
        let num_provided_args = call_expr.arguments.len();
 
        if num_provided_args != num_expected_args {
 
            let argument_text = if num_expected_args == 1 { "argument" } else { "arguments" };
 
            let call_span = call_expr.full_span;
 
            return Err(ParseError::new_error_at_span(
 
                &ctx.module().source, call_span, format!(
 
                    "expected {} {}, but {} were provided",
 
                    num_expected_args, argument_text, num_provided_args
 
                )
 
            ));
 
        }
 

	
 
        // Recurse into all of the arguments and set the expression's parent
 
        let upcast_id = id.upcast();
 

	
 
        let section = self.expression_buffer.start_section_initialized(&call_expr.arguments);
 
        let old_expr_parent = self.expr_parent;
 
        call_expr.parent = old_expr_parent;
 
        call_expr.unique_id_in_definition = self.next_expr_index;
 
        self.next_expr_index += 1;
 

	
 
        for arg_expr_idx in 0..section.len() {
 
            let arg_expr_id = section[arg_expr_idx];
 
            self.expr_parent = ExpressionParent::Expression(upcast_id, arg_expr_idx as u32);
 
            self.visit_expr(ctx, arg_expr_id)?;
 
        }
 

	
 
        section.forget();
 
        self.expr_parent = old_expr_parent;
 

	
 
        Ok(())
 
    }
 

	
 
    fn visit_variable_expr(&mut self, ctx: &mut Ctx, id: VariableExpressionId) -> VisitorResult {
 
        let var_expr = &ctx.heap[id];
 

	
 
        // Check if declaration was already resolved (this occurs for the
 
        // variable expr that is on the LHS of the assignment expr that is
 
        // associated with a variable declaration)
 
        let mut variable_id = var_expr.declaration;
 
        let mut is_binding_target = false;
 

	
 
        // Otherwise try to find it
 
        if var_expr.identifier.value.as_str() == "new_value" {
 
            let a = 0; // TODO: REMOVE!
 
        }
 

	
 
        if variable_id.is_none() {
 
            variable_id = self.find_variable(ctx, self.relative_pos_in_parent, &var_expr.identifier);
 
        }
 

	
 
        // Otherwise try to see if is a variable introduced by a binding expr
 
        let variable_id = if let Some(variable_id) = variable_id {
 
            variable_id
 
        } else {
 
            if self.in_binding_expr.is_invalid() || !self.in_binding_expr_lhs {
 
                return Err(ParseError::new_error_str_at_span(
 
                    &ctx.module().source, var_expr.identifier.span, "unresolved variable"
 
                ));
 
            }
 

	
 
            // This is a binding variable, but it may only appear in very
 
            // specific locations.
 
            let is_valid_binding = match self.expr_parent {
 
                ExpressionParent::Expression(expr_id, idx) => {
 
                    match &ctx.heap[expr_id] {
 
                        Expression::Binding(_binding_expr) => {
 
                            // Nested binding is disallowed, and because of
 
                            // the check above we know we're directly at the
 
                            // LHS of the binding expression
 
                            debug_assert_eq!(_binding_expr.this, self.in_binding_expr);
 
                            debug_assert_eq!(idx, 0);
 
                            true
 
                        }
 
                        Expression::Literal(lit_expr) => {
 
                            // Only struct, unions, tuples and arrays can
 
                            // have subexpressions, so we're always fine
 
                            if cfg!(debug_assertions) {
 
                                match lit_expr.value {
 
                                    Literal::Struct(_) | Literal::Union(_) | Literal::Array(_) | Literal::Tuple(_) => {},
 
                                    _ => unreachable!(),
 
                                }
 
                            }
 

	
 
                            true
 
                        },
 
                        _ => false,
 
                    }
 
                },
 
                _ => {
 
                    false
 
                }
 
            };
 

	
 
            if !is_valid_binding {
 
                let binding_expr = &ctx.heap[self.in_binding_expr];
 
                return Err(ParseError::new_error_str_at_span(
 
                    &ctx.module().source, var_expr.identifier.span,
 
                    "illegal location for binding variable: binding variables may only be nested under a binding expression, or a struct, union or array literal"
 
                ).with_info_at_span(
 
                    &ctx.module().source, binding_expr.operator_span, format!(
 
                        "'{}' was interpreted as a binding variable because the variable is not declared and it is nested under this binding expression",
 
                        var_expr.identifier.value.as_str()
 
                    )
 
                ));
 
            }
 

	
 
            // By now we know that this is a valid binding expression. Given
 
            // that a binding expression must be nested under an if/while
 
            // statement, we now add the variable to the scope associated with
 
            // that statement.
 
            let bound_identifier = var_expr.identifier.clone();
 
            let bound_variable_id = ctx.heap.alloc_variable(|this| Variable {
 
                this,
 
                kind: VariableKind::Binding,
 
                parser_type: ParserType {
 
                    elements: vec![ParserTypeElement {
 
                        element_span: bound_identifier.span,
 
                        variant: ParserTypeVariant::Inferred
 
                    }],
 
                    full_span: bound_identifier.span
 
                },
 
                identifier: bound_identifier,
 
                relative_pos_in_parent: 0,
 
                unique_id_in_scope: -1,
 
            });
 

	
 
            let scope_id = match &ctx.heap[self.in_test_expr] {
 
                Statement::If(stmt) => stmt.true_case.scope,
 
                Statement::While(stmt) => stmt.scope,
 
                _ => unreachable!(),
 
            };
 

	
 
            self.checked_at_single_scope_add_local(ctx, scope_id, -1, bound_variable_id)?; // add at -1 such that first statement can find the variable if needed
 

	
 
            is_binding_target = true;
 
            bound_variable_id
 
        };
 

	
 
        let var_expr = &mut ctx.heap[id];
 
        var_expr.declaration = Some(variable_id);
 
        var_expr.used_as_binding_target = is_binding_target;
 
        var_expr.parent = self.expr_parent;
 
        var_expr.unique_id_in_definition = self.next_expr_index;
 
        self.next_expr_index += 1;
 

	
 
        Ok(())
 
    }
 
}
 

	
 
impl PassValidationLinking {
 
    //--------------------------------------------------------------------------
 
    // Special traversal
 
    //--------------------------------------------------------------------------
 

	
 
    /// Pushes a new scope associated with a particular statement. If that
 
    /// statement already has an associated scope (i.e. scope associated with
 
    /// sync statement or select statement's arm) then we won't do anything.
 
    /// In all cases the caller must call `pop_statement_scope` with the scope
 
    /// and relative scope position returned by this function.
 
    fn push_scope(&mut self, ctx: &mut Ctx, is_top_level_scope: bool, pushed_scope_id: ScopeId) -> (ScopeId, i32) {
 
        // Set the properties of the pushed scope (it is already created during
 
        // AST construction, but most values are not yet set to their correct
 
        // values)
 
        let old_scope_id = self.cur_scope;
 

	
 
        let scope = &mut ctx.heap[pushed_scope_id];
 
        if !is_top_level_scope {
 
            scope.parent = Some(old_scope_id);
 
        }
 

	
 
        scope.relative_pos_in_parent = self.relative_pos_in_parent;
 
        let old_relative_pos = self.relative_pos_in_parent;
 
        self.relative_pos_in_parent = 0;
 

	
 
        // Link up scopes
 
        if !is_top_level_scope {
 
            let old_scope = &mut ctx.heap[old_scope_id];
 
            old_scope.nested.push(pushed_scope_id);
 
        }
 

	
 
        // Set as current traversal scope, then return old scope
 
        self.cur_scope = pushed_scope_id;
 
        return (old_scope_id, old_relative_pos)
 
    }
 

	
 
    fn pop_scope(&mut self, scope_to_restore: (ScopeId, i32)) {
 
        self.cur_scope = scope_to_restore.0;
 
        self.relative_pos_in_parent = scope_to_restore.1;
 
    }
 

	
 
    fn visit_scope_and_assign_local_ids(&mut self, ctx: &mut Ctx, scope_id: ScopeId, mut variable_counter: i32) {
 
        let scope = &mut ctx.heap[scope_id];
 
        scope.first_unique_id_in_scope = variable_counter;
 

	
 
        let variable_section = self.variable_buffer.start_section_initialized(&scope.variables);
 
        let child_scope_section = self.scope_buffer.start_section_initialized(&scope.nested);
 

	
 
        let mut variable_index = 0;
 
        let mut child_scope_index = 0;
 

	
 
        loop {
 
            // Determine relative positions of variable and scope to determine
 
            // which one occurs first within the current scope.
 
            let variable_relative_pos;
 
            if variable_index < variable_section.len() {
 
                let variable_id = variable_section[variable_index];
 
                let variable = &ctx.heap[variable_id];
 
                variable_relative_pos = variable.relative_pos_in_parent;
 
            } else {
 
                variable_relative_pos = i32::MAX;
 
            }
 

	
 
            let child_scope_relative_pos;
 
            if child_scope_index < child_scope_section.len() {
 
                let child_scope_id = child_scope_section[child_scope_index];
 
                let child_scope = &ctx.heap[child_scope_id];
 
                child_scope_relative_pos = child_scope.relative_pos_in_parent;
 
            } else {
 
                child_scope_relative_pos = i32::MAX;
 
            }
 

	
 
            if variable_relative_pos == i32::MAX && child_scope_relative_pos == i32::MAX {
 
                // Done, no more elements in the scope to consider
 
                break;
 
            }
 

	
 
            // Label the variable/scope, whichever comes first. When dealing
 
            // with binding variables, where both variable and scope are
 
            // considered to have the same position in the scope, we treat the
 
            // variable first.
 
            // TODO: Think about this some more, isn't it correct that we
 
            //  consider it part of the fresh scope? So we'll have to deal with
 
            //  the scope first, and add the variable to that scope?
 
            if variable_relative_pos <= child_scope_relative_pos {
 
                let variable = &mut ctx.heap[variable_section[variable_index]];
 
                variable.unique_id_in_scope = variable_counter;
 
                variable_counter += 1;
 
                variable_index += 1;
 
            } else {
 
                let child_scope_id = child_scope_section[child_scope_index];
 
                self.visit_scope_and_assign_local_ids(ctx, child_scope_id, variable_counter);
 
                child_scope_index += 1;
 
            }
 
        }
 

	
 
        variable_section.forget();
 
        child_scope_section.forget();
 

	
 
        let scope = &mut ctx.heap[scope_id];
 
        scope.next_unique_id_in_scope = variable_counter;
 
    }
 

	
 
    fn resolve_pending_control_flow_targets(&mut self, ctx: &mut Ctx) -> Result<(), ParseError> {
 
        for entry in &self.control_flow_stmts {
 
            let stmt = &ctx.heap[entry.statement];
 

	
 
            match stmt {
 
                Statement::Break(stmt) => {
 
                    let stmt_id = stmt.this;
 
                    let target_while_id = Self::resolve_break_or_continue_target(ctx, entry, stmt.span, &stmt.label)?;
 
                    let target_while_stmt = &ctx.heap[target_while_id];
 
                    let target_end_while_id = target_while_stmt.end_while;
 
                    debug_assert!(!target_end_while_id.is_invalid());
 

	
 
                    let break_stmt = &mut ctx.heap[stmt_id];
 
                    break_stmt.target = target_end_while_id;
 
                },
 
                Statement::Continue(stmt) => {
 
                    let stmt_id = stmt.this;
 
                    let target_while_id = Self::resolve_break_or_continue_target(ctx, entry, stmt.span, &stmt.label)?;
 

	
 
                    let continue_stmt = &mut ctx.heap[stmt_id];
 
                    continue_stmt.target = target_while_id;
 
                },
 
                Statement::Goto(stmt) => {
 
                    let stmt_id = stmt.this;
 
                    let target_id = Self::find_label(entry.in_scope, ctx, &stmt.label)?;
 
                    let target_stmt = &ctx.heap[target_id];
 
                    if entry.in_sync != target_stmt.in_sync {
 
                        // Nested sync not allowed. And goto can only go to
 
                        // outer scopes, so we must be escaping from a sync.
 
                        debug_assert!(target_stmt.in_sync.is_invalid());    // target not in sync
 
                        debug_assert!(!entry.in_sync.is_invalid()); // but the goto is in sync
 
                        let goto_stmt = &ctx.heap[stmt_id];
 
                        let sync_stmt = &ctx.heap[entry.in_sync];
 
                        return Err(
 
                            ParseError::new_error_str_at_span(&ctx.module().source, goto_stmt.span, "goto may not escape the surrounding synchronous block")
 
                            .with_info_str_at_span(&ctx.module().source, target_stmt.label.span, "this is the target of the goto statement")
 
                            .with_info_str_at_span(&ctx.module().source, sync_stmt.span, "which will jump past this statement")
 
                        );
 
                    }
 

	
 
                    let goto_stmt = &mut ctx.heap[stmt_id];
 
                    goto_stmt.target = target_id;
 
                },
 
                _ => unreachable!("cannot resolve control flow target for {:?}", stmt),
 
            }
 
        }
 

	
 
        return Ok(())
 
    }
 

	
 
    //--------------------------------------------------------------------------
 
    // Utilities
 
    //--------------------------------------------------------------------------
 

	
 
    /// Adds a local variable to the current scope. It will also annotate the
 
    /// `Local` in the AST with its relative position in the block.
 
    fn checked_add_local(&mut self, ctx: &mut Ctx, target_scope_id: ScopeId, target_relative_pos: i32, new_variable_id: VariableId) -> Result<(), ParseError> {
 
        let new_variable = &ctx.heap[new_variable_id];
 

	
 
        // We immediately go to the parent scope. We check the target scope
 
        // in the call at the end. That is also where we check for collisions
 
        // with symbols.
 
        let mut scope = &ctx.heap[target_scope_id];
 
        let mut cur_relative_pos = scope.relative_pos_in_parent;
 
        while let Some(scope_parent_id) = scope.parent {
 
            scope = &ctx.heap[scope_parent_id];
 

	
 
            // Check for collisions
 
            for variable_id in scope.variables.iter().copied() {
 
                let existing_variable = &ctx.heap[variable_id];
 
                if existing_variable.identifier == new_variable.identifier &&
 
                    existing_variable.this != new_variable_id &&
 
                    cur_relative_pos >= existing_variable.relative_pos_in_parent {
 
                    return Err(
 
                        ParseError::new_error_str_at_span(
 
                            &ctx.module().source, new_variable.identifier.span, "Local variable name conflicts with another variable"
 
                        ).with_info_str_at_span(
 
                            &ctx.module().source, existing_variable.identifier.span, "Previous variable is found here"
 
                        )
 
                    );
 
                }
 
            }
 

	
 
            cur_relative_pos = scope.relative_pos_in_parent;
 
        }
 

	
 
        // No collisions in any of the parent scope, attempt to add to scope
 
        self.checked_at_single_scope_add_local(ctx, target_scope_id, target_relative_pos, new_variable_id)
 
    }
 

	
 
    /// Adds a local variable to the specified scope. Will check the specified
 
    /// scope for variable conflicts and the symbol table for global conflicts.
 
    /// Will NOT check parent scopes of the specified scope.
 
    fn checked_at_single_scope_add_local(
 
        &mut self, ctx: &mut Ctx, scope_id: ScopeId, relative_pos: i32, new_variable_id: VariableId
 
    ) -> Result<(), ParseError> {
 
        // Check the symbol table for conflicts
 
        {
 
            let cur_scope = SymbolScope::Definition(self.def_type.definition_id());
 
            let ident = &ctx.heap[new_variable_id].identifier;
 
            if let Some(symbol) = ctx.symbols.get_symbol_by_name(cur_scope, &ident.value.as_bytes()) {
 
                return Err(ParseError::new_error_str_at_span(
 
                    &ctx.module().source, ident.span,
 
                    "local variable declaration conflicts with symbol"
 
                ).with_info_str_at_span(
 
                    &ctx.module().source, symbol.variant.span_of_introduction(&ctx.heap), "the conflicting symbol is introduced here"
 
                ));
 
            }
 
        }
 

	
 
        // Check the specified scope for conflicts
 
        let new_variable = &ctx.heap[new_variable_id];
 
        let scope = &ctx.heap[scope_id];
 

	
 
        for variable_id in scope.variables.iter().copied() {
 
            let old_variable = &ctx.heap[variable_id];
 
            if new_variable.this != old_variable.this &&
 
                // relative_pos >= other_local.relative_pos_in_block &&
 
                new_variable.identifier == old_variable.identifier {
 
                // Collision
 
                return Err(
 
                    ParseError::new_error_str_at_span(
 
                        &ctx.module().source, new_variable.identifier.span, "Local variable name conflicts with another variable"
 
                    ).with_info_str_at_span(
 
                        &ctx.module().source, old_variable.identifier.span, "Previous variable is found here"
 
                    )
 
                );
 
            }
 
        }
 

	
 
        // No collisions
 
        let scope = &mut ctx.heap[scope_id];
 
        scope.variables.push(new_variable_id);
 

	
 
        let variable = &mut ctx.heap[new_variable_id];
 
        variable.relative_pos_in_parent = relative_pos;
 

	
 
        Ok(())
 
    }
 

	
 
    /// Finds a variable in the visitor's scope that must appear before the
 
    /// specified relative position within that block.
 
    fn find_variable(&self, ctx: &Ctx, mut relative_pos: i32, identifier: &Identifier) -> Option<VariableId> {
 
        let mut scope_id = self.cur_scope;
 

	
 
        loop {
 
            // Check if we can find the variable in the current scope
 
            let scope = &ctx.heap[scope_id];
 
            
 
            for variable_id in scope.variables.iter().copied() {
 
                let variable = &ctx.heap[variable_id];
 
                
 
                if variable.relative_pos_in_parent < relative_pos && identifier == &variable.identifier {
 
                    return Some(variable_id);
 
                }
 
            }
 

	
 
            // Could not find variable, move to parent scope and try again
 
            if scope.parent.is_none() {
 
                return None;
 
            }
 

	
 
            scope_id = scope.parent.unwrap();
 
            relative_pos = scope.relative_pos_in_parent;
 
        }
 
    }
 

	
 
    /// Adds a particular label to the current scope. Will return an error if
 
    /// there is another label with the same name visible in the current scope.
 
    fn checked_add_label(&mut self, ctx: &mut Ctx, relative_pos: i32, in_sync: SynchronousStatementId, new_label_id: LabeledStatementId) -> Result<(), ParseError> {
 
        // Make sure label is not defined within the current scope or any of the
 
        // parent scope.
 
        let new_label = &mut ctx.heap[new_label_id];
 
        new_label.relative_pos_in_parent = relative_pos;
 
        new_label.in_sync = in_sync;
 

	
 
        let new_label = &ctx.heap[new_label_id];
 
        let mut scope_id = self.cur_scope;
 

	
 
        loop {
 
            let scope = &ctx.heap[scope_id];
 
            for existing_label_id in scope.labels.iter().copied() {
 
                let existing_label = &ctx.heap[existing_label_id];
 
                if existing_label.label == new_label.label {
 
                    // Collision
 
                    return Err(ParseError::new_error_str_at_span(
 
                        &ctx.module().source, new_label.label.span, "label name is used more than once"
 
                    ).with_info_str_at_span(
 
                        &ctx.module().source, existing_label.label.span, "the other label is found here"
 
                    ));
 
                }
 
            }
 

	
 
            if scope.parent.is_none() {
 
                break;
 
            }
 

	
 
            scope_id = scope.parent.unwrap();
 
        }
 

	
 
        // No collisions
 
        let scope = &mut ctx.heap[self.cur_scope];
 
        scope.labels.push(new_label_id);
 

	
 
        Ok(())
 
    }
 

	
 
    /// Finds a particular labeled statement by its identifier. Once found it
 
    /// will make sure that the target label does not skip over any variable
 
    /// declarations within the scope in which the label was found.
 
    fn find_label(mut scope_id: ScopeId, ctx: &Ctx, identifier: &Identifier) -> Result<LabeledStatementId, ParseError> {
 
        loop {
 
            let scope = &ctx.heap[scope_id];
 
            let relative_scope_pos = scope.relative_pos_in_parent;
 

	
 
            for label_id in scope.labels.iter().copied() {
 
                let label = &ctx.heap[label_id];
 
                if label.label == *identifier {
 
                    // Found the target label, now make sure that the jump to
 
                    // the label doesn't imply a skipped variable declaration
 
                    for variable_id in scope.variables.iter().copied() {
 
                        // TODO: Better to do this in control flow analysis, it
 
                        //  is legal to skip over a variable declaration if it
 
                        //  is not actually being used.
 
                        let variable = &ctx.heap[variable_id];
 
                        if variable.relative_pos_in_parent > relative_scope_pos && variable.relative_pos_in_parent < label.relative_pos_in_parent {
 
                            return Err(
 
                                ParseError::new_error_str_at_span(&ctx.module().source, identifier.span, "this target label skips over a variable declaration")
 
                                .with_info_str_at_span(&ctx.module().source, label.label.span, "because it jumps to this label")
 
                                .with_info_str_at_span(&ctx.module().source, variable.identifier.span, "which skips over this variable")
 
                            );
 
                        }
 
                    }
 
                    return Ok(label_id);
 
                }
 
            }
 

	
 
            if scope.parent.is_none() {
 
                return Err(ParseError::new_error_str_at_span(
 
                    &ctx.module().source, identifier.span, "could not find this label"
 
                ));
 
            }
 

	
 
            scope_id = scope.parent.unwrap();
 
        }
 
    }
 

	
 
    /// This function will check if the provided scope has a parent that belongs
 
    /// to a while statement.
 
    fn scope_is_nested_in_while_statement(mut scope_id: ScopeId, ctx: &Ctx, expected_while_id: WhileStatementId) -> bool {
 
        let while_stmt = &ctx.heap[expected_while_id];
 

	
 
        loop {
 
            let scope = &ctx.heap[scope_id];
 
            if scope.this == while_stmt.scope {
 
                return true;
 
            }
 

	
 
            match scope.parent {
 
                Some(new_scope_id) => scope_id = new_scope_id,
 
                None => return false, // walked all the way up, not encountering the while statement
 
            }
 
        }
 
    }
 

	
 
    /// This function should be called while dealing with break/continue
 
    /// statements. It will try to find the targeted while statement, using the
 
    /// target label if provided. If a valid target is found then the loop's
 
    /// ID will be returned, otherwise a parsing error is constructed.
 
    /// The provided input position should be the position of the break/continue
 
    /// statement.
 
    fn resolve_break_or_continue_target(ctx: &Ctx, control_flow: &ControlFlowStatement, span: InputSpan, label: &Option<Identifier>) -> Result<WhileStatementId, ParseError> {
 
        let target = match label {
 
            Some(label) => {
 
                let target_id = Self::find_label(control_flow.in_scope, ctx, label)?;
 

	
 
                // Make sure break target is a while statement
 
                let target = &ctx.heap[target_id];
 
                if let Statement::While(target_stmt) = &ctx.heap[target.body] {
 
                    // Even though we have a target while statement, the control
 
                    // flow statement might not be present underneath this
 
                    // particular labeled while statement.
 
                    if !Self::scope_is_nested_in_while_statement(control_flow.in_scope, ctx, target_stmt.this) {
 
                        return Err(ParseError::new_error_str_at_span(
 
                            &ctx.module().source, label.span, "break statement is not nested under the target label's while statement"
 
                        ).with_info_str_at_span(
 
                            &ctx.module().source, target.label.span, "the targeted label is found here"
 
                        ));
 
                    }
 

	
 
                    target_stmt.this
 
                } else {
 
                    return Err(ParseError::new_error_str_at_span(
 
                        &ctx.module().source, label.span, "incorrect break target label, it must target a while loop"
 
                    ).with_info_str_at_span(
 
                        &ctx.module().source, target.label.span, "The targeted label is found here"
 
                    ));
 
                }
 
            },
 
            None => {
 
                // Use the enclosing while statement, the break must be
 
                // nested within that while statement
 
                if control_flow.in_while.is_invalid() {
 
                    return Err(ParseError::new_error_str_at_span(
 
                        &ctx.module().source, span, "Break statement is not nested under a while loop"
 
                    ));
 
                }
 

	
 
                control_flow.in_while
 
            }
 
        };
 

	
 
        // We have a valid target for the break statement. But we need to
 
        // make sure we will not break out of a synchronous block
 
        {
 
            let target_while = &ctx.heap[target];
 
            if target_while.in_sync != control_flow.in_sync {
 
                // Break is nested under while statement, so can only escape a
 
                // sync block if the sync is nested inside the while statement.
 
                debug_assert!(!control_flow.in_sync.is_invalid());
 
                let sync_stmt = &ctx.heap[control_flow.in_sync];
 
                return Err(
 
                    ParseError::new_error_str_at_span(&ctx.module().source, span, "break may not escape the surrounding synchronous block")
 
                        .with_info_str_at_span(&ctx.module().source, target_while.span, "the break escapes out of this loop")
 
                        .with_info_str_at_span(&ctx.module().source, sync_stmt.span, "And would therefore escape this synchronous block")
 
                );
 
            }
 
        }
 

	
 
        Ok(target)
 
    }
 
}
 
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