CSY/reowolf Changeset - e16722f0d0ac · Centrum Wiskunde & Informatica (CWI)

Changeset - e16722f0d0ac

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Hans-Dieter Hiep - 5 years ago 2020-02-10 15:48:57
hdh@cwi.nl

Lift parser restriction on assignable expressions

3 files changed with 5 insertions and 8 deletions:

src/protocol/parser.rs

testdata/parser/negative/20.txt

testdata/parser/positive/20.pdl

rename

0 comments (0 inline, 0 general)

src/protocol/parser.rs

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@@ @@ -42,1842 +42,1842 @@ trait Visitor: Sized { @@
+    }
     fn visit_local_declaration(&mut self, _h: &mut Heap, _decl: LocalId) -> VisitorResult {
         Ok(())
+    }
     fn visit_statement(&mut self, h: &mut Heap, stmt: StatementId) -> VisitorResult {
         recursive_statement(self, h, stmt)
+    }
     fn visit_local_statement(&mut self, h: &mut Heap, stmt: LocalStatementId) -> VisitorResult {
         recursive_local_statement(self, h, stmt)
+    }
     fn visit_memory_statement(&mut self, h: &mut Heap, stmt: MemoryStatementId) -> VisitorResult {
         recursive_memory_statement(self, h, stmt)
+    }
     fn visit_channel_statement(
         &mut self,
         _h: &mut Heap,
         _stmt: ChannelStatementId,
     ) -> VisitorResult {
         Ok(())
+    }
     fn visit_block_statement(&mut self, h: &mut Heap, stmt: BlockStatementId) -> VisitorResult {
         recursive_block_statement(self, h, stmt)
+    }
     fn visit_labeled_statement(&mut self, h: &mut Heap, stmt: LabeledStatementId) -> VisitorResult {
         recursive_labeled_statement(self, h, stmt)
+    }
     fn visit_skip_statement(&mut self, _h: &mut Heap, _stmt: SkipStatementId) -> VisitorResult {
         Ok(())
+    }
     fn visit_if_statement(&mut self, h: &mut Heap, stmt: IfStatementId) -> VisitorResult {
         recursive_if_statement(self, h, stmt)
+    }
     fn visit_while_statement(&mut self, h: &mut Heap, stmt: WhileStatementId) -> VisitorResult {
         recursive_while_statement(self, h, stmt)
+    }
     fn visit_break_statement(&mut self, _h: &mut Heap, _stmt: BreakStatementId) -> VisitorResult {
         Ok(())
+    }
     fn visit_continue_statement(
         &mut self,
         _h: &mut Heap,
         _stmt: ContinueStatementId,
     ) -> VisitorResult {
         Ok(())
+    }
     fn visit_synchronous_statement(
         &mut self,
         h: &mut Heap,
         stmt: SynchronousStatementId,
     ) -> VisitorResult {
         recursive_synchronous_statement(self, h, stmt)
+    }
     fn visit_return_statement(&mut self, h: &mut Heap, stmt: ReturnStatementId) -> VisitorResult {
         recursive_return_statement(self, h, stmt)
+    }
     fn visit_assert_statement(&mut self, h: &mut Heap, stmt: AssertStatementId) -> VisitorResult {
         recursive_assert_statement(self, h, stmt)
+    }
     fn visit_goto_statement(&mut self, _h: &mut Heap, _stmt: GotoStatementId) -> VisitorResult {
         Ok(())
+    }
     fn visit_new_statement(&mut self, h: &mut Heap, stmt: NewStatementId) -> VisitorResult {
         recursive_new_statement(self, h, stmt)
+    }
     fn visit_put_statement(&mut self, h: &mut Heap, stmt: PutStatementId) -> VisitorResult {
         recursive_put_statement(self, h, stmt)
+    }
     fn visit_expression_statement(
         &mut self,
         h: &mut Heap,
         stmt: ExpressionStatementId,
     ) -> VisitorResult {
         recursive_expression_statement(self, h, stmt)
+    }
     fn visit_expression(&mut self, h: &mut Heap, expr: ExpressionId) -> VisitorResult {
         recursive_expression(self, h, expr)
+    }
     fn visit_assignment_expression(
         &mut self,
         h: &mut Heap,
         expr: AssignmentExpressionId,
     ) -> VisitorResult {
         recursive_assignment_expression(self, h, expr)
+    }
     fn visit_conditional_expression(
         &mut self,
         h: &mut Heap,
         expr: ConditionalExpressionId,
     ) -> VisitorResult {
         recursive_conditional_expression(self, h, expr)
+    }
     fn visit_binary_expression(&mut self, h: &mut Heap, expr: BinaryExpressionId) -> VisitorResult {
         recursive_binary_expression(self, h, expr)
+    }
     fn visit_unary_expression(&mut self, h: &mut Heap, expr: UnaryExpressionId) -> VisitorResult {
         recursive_unary_expression(self, h, expr)
+    }
     fn visit_indexing_expression(
         &mut self,
         h: &mut Heap,
         expr: IndexingExpressionId,
     ) -> VisitorResult {
         recursive_indexing_expression(self, h, expr)
+    }
     fn visit_slicing_expression(
         &mut self,
         h: &mut Heap,
         expr: SlicingExpressionId,
     ) -> VisitorResult {
         recursive_slicing_expression(self, h, expr)
+    }
     fn visit_select_expression(&mut self, h: &mut Heap, expr: SelectExpressionId) -> VisitorResult {
         recursive_select_expression(self, h, expr)
+    }
     fn visit_array_expression(&mut self, h: &mut Heap, expr: ArrayExpressionId) -> VisitorResult {
         recursive_array_expression(self, h, expr)
+    }
     fn visit_call_expression(&mut self, h: &mut Heap, expr: CallExpressionId) -> VisitorResult {
         recursive_call_expression(self, h, expr)
+    }
     fn visit_constant_expression(
         &mut self,
         _h: &mut Heap,
         _expr: ConstantExpressionId,
     ) -> VisitorResult {
         Ok(())
+    }
     fn visit_variable_expression(
         &mut self,
         _h: &mut Heap,
         _expr: VariableExpressionId,
     ) -> VisitorResult {
         Ok(())
+    }
+}
 // Bubble-up helpers
 fn recursive_parameter_as_variable<T: Visitor>(
     this: &mut T,
     h: &mut Heap,
     param: ParameterId,
 ) -> VisitorResult {
     this.visit_variable_declaration(h, param.upcast())
+}
 fn recursive_local_as_variable<T: Visitor>(
     this: &mut T,
     h: &mut Heap,
     local: LocalId,
 ) -> VisitorResult {
     this.visit_variable_declaration(h, local.upcast())
+}
 fn recursive_call_expression_as_expression<T: Visitor>(
     this: &mut T,
     h: &mut Heap,
     call: CallExpressionId,
 ) -> VisitorResult {
     this.visit_expression(h, call.upcast())
+}
 // Recursive procedures
 fn recursive_protocol_description<T: Visitor>(
     this: &mut T,
     h: &mut Heap,
     pd: RootId,
 ) -> VisitorResult {
     for &pragma in h[pd].pragmas.clone().iter() {
         this.visit_pragma(h, pragma)?;
+    }
     for &import in h[pd].imports.clone().iter() {
         this.visit_import(h, import)?;
+    }
     for &def in h[pd].definitions.clone().iter() {
         this.visit_symbol_definition(h, def)?;
+    }
     Ok(())
+}
 fn recursive_symbol_definition<T: Visitor>(
     this: &mut T,
     h: &mut Heap,
     def: DefinitionId,
 ) -> VisitorResult {
     // We clone the definition in case it is modified
     match h[def].clone() {
         Definition::Component(cdef) => this.visit_component_definition(h, cdef.this()),
         Definition::Function(fdef) => this.visit_function_definition(h, fdef.this),
+    }
+}
 fn recursive_component_definition<T: Visitor>(
     this: &mut T,
     h: &mut Heap,
     def: ComponentId,
 ) -> VisitorResult {
     match h[def].clone() {
         Component::Composite(cdef) => this.visit_composite_definition(h, cdef.this),
         Component::Primitive(pdef) => this.visit_primitive_definition(h, pdef.this),
+    }
+}
 fn recursive_composite_definition<T: Visitor>(
     this: &mut T,
     h: &mut Heap,
     def: CompositeId,
 ) -> VisitorResult {
     for &param in h[def].parameters.clone().iter() {
         recursive_parameter_as_variable(this, h, param)?;
+    }
     this.visit_statement(h, h[def].body)
+}
 fn recursive_primitive_definition<T: Visitor>(
     this: &mut T,
     h: &mut Heap,
     def: PrimitiveId,
 ) -> VisitorResult {
     for &param in h[def].parameters.clone().iter() {
         recursive_parameter_as_variable(this, h, param)?;
+    }
     this.visit_statement(h, h[def].body)
+}
 fn recursive_function_definition<T: Visitor>(
     this: &mut T,
     h: &mut Heap,
     def: FunctionId,
 ) -> VisitorResult {
     for &param in h[def].parameters.clone().iter() {
         recursive_parameter_as_variable(this, h, param)?;
+    }
     this.visit_statement(h, h[def].body)
+}
 fn recursive_variable_declaration<T: Visitor>(
     this: &mut T,
     h: &mut Heap,
     decl: VariableId,
 ) -> VisitorResult {
     match h[decl].clone() {
         Variable::Parameter(decl) => this.visit_parameter_declaration(h, decl.this),
         Variable::Local(decl) => this.visit_local_declaration(h, decl.this),
+    }
+}
 fn recursive_statement<T: Visitor>(this: &mut T, h: &mut Heap, stmt: StatementId) -> VisitorResult {
     match h[stmt].clone() {
         Statement::Block(stmt) => this.visit_block_statement(h, stmt.this),
         Statement::Local(stmt) => this.visit_local_statement(h, stmt.this()),
         Statement::Skip(stmt) => this.visit_skip_statement(h, stmt.this),
         Statement::Labeled(stmt) => this.visit_labeled_statement(h, stmt.this),
         Statement::If(stmt) => this.visit_if_statement(h, stmt.this),
         Statement::EndIf(stmt) => unreachable!(), // pseudo-statement
         Statement::While(stmt) => this.visit_while_statement(h, stmt.this),
         Statement::EndWhile(stmt) => unreachable!(), // pseudo-statement
         Statement::Break(stmt) => this.visit_break_statement(h, stmt.this),
         Statement::Continue(stmt) => this.visit_continue_statement(h, stmt.this),
         Statement::Synchronous(stmt) => this.visit_synchronous_statement(h, stmt.this),
         Statement::EndSynchronous(stmt) => unreachable!(), // pseudo-statement
         Statement::Return(stmt) => this.visit_return_statement(h, stmt.this),
         Statement::Assert(stmt) => this.visit_assert_statement(h, stmt.this),
         Statement::Goto(stmt) => this.visit_goto_statement(h, stmt.this),
         Statement::New(stmt) => this.visit_new_statement(h, stmt.this),
         Statement::Put(stmt) => this.visit_put_statement(h, stmt.this),
         Statement::Expression(stmt) => this.visit_expression_statement(h, stmt.this),
+    }
+}
 fn recursive_block_statement<T: Visitor>(
     this: &mut T,
     h: &mut Heap,
     block: BlockStatementId,
 ) -> VisitorResult {
     for &local in h[block].locals.clone().iter() {
         recursive_local_as_variable(this, h, local)?;
+    }
     for &stmt in h[block].statements.clone().iter() {
         this.visit_statement(h, stmt)?;
+    }
     Ok(())
+}
 fn recursive_local_statement<T: Visitor>(
     this: &mut T,
     h: &mut Heap,
     stmt: LocalStatementId,
 ) -> VisitorResult {
     match h[stmt].clone() {
         LocalStatement::Channel(stmt) => this.visit_channel_statement(h, stmt.this),
         LocalStatement::Memory(stmt) => this.visit_memory_statement(h, stmt.this),
+    }
+}
 fn recursive_memory_statement<T: Visitor>(
     this: &mut T,
     h: &mut Heap,
     stmt: MemoryStatementId,
 ) -> VisitorResult {
     this.visit_expression(h, h[stmt].initial)
+}
 fn recursive_labeled_statement<T: Visitor>(
     this: &mut T,
     h: &mut Heap,
     stmt: LabeledStatementId,
 ) -> VisitorResult {
     this.visit_statement(h, h[stmt].body)
+}
 fn recursive_if_statement<T: Visitor>(
     this: &mut T,
     h: &mut Heap,
     stmt: IfStatementId,
 ) -> VisitorResult {
     this.visit_expression(h, h[stmt].test)?;
     this.visit_statement(h, h[stmt].true_body)?;
     this.visit_statement(h, h[stmt].false_body)
+}
 fn recursive_while_statement<T: Visitor>(
     this: &mut T,
     h: &mut Heap,
     stmt: WhileStatementId,
 ) -> VisitorResult {
     this.visit_expression(h, h[stmt].test)?;
     this.visit_statement(h, h[stmt].body)
+}
 fn recursive_synchronous_statement<T: Visitor>(
     this: &mut T,
     h: &mut Heap,
     stmt: SynchronousStatementId,
 ) -> VisitorResult {
     for &param in h[stmt].parameters.clone().iter() {
         recursive_parameter_as_variable(this, h, param)?;
+    }
     this.visit_statement(h, h[stmt].body)
+}
 fn recursive_return_statement<T: Visitor>(
     this: &mut T,
     h: &mut Heap,
     stmt: ReturnStatementId,
 ) -> VisitorResult {
     this.visit_expression(h, h[stmt].expression)
+}
 fn recursive_assert_statement<T: Visitor>(
     this: &mut T,
     h: &mut Heap,
     stmt: AssertStatementId,
 ) -> VisitorResult {
     this.visit_expression(h, h[stmt].expression)
+}
 fn recursive_new_statement<T: Visitor>(
     this: &mut T,
     h: &mut Heap,
     stmt: NewStatementId,
 ) -> VisitorResult {
     recursive_call_expression_as_expression(this, h, h[stmt].expression)
+}
 fn recursive_put_statement<T: Visitor>(
     this: &mut T,
     h: &mut Heap,
     stmt: PutStatementId,
 ) -> VisitorResult {
     this.visit_expression(h, h[stmt].port)?;
     this.visit_expression(h, h[stmt].message)
+}
 fn recursive_expression_statement<T: Visitor>(
     this: &mut T,
     h: &mut Heap,
     stmt: ExpressionStatementId,
 ) -> VisitorResult {
     this.visit_expression(h, h[stmt].expression)
+}
 fn recursive_expression<T: Visitor>(
     this: &mut T,
     h: &mut Heap,
     expr: ExpressionId,
 ) -> VisitorResult {
     match h[expr].clone() {
         Expression::Assignment(expr) => this.visit_assignment_expression(h, expr.this),
         Expression::Conditional(expr) => this.visit_conditional_expression(h, expr.this),
         Expression::Binary(expr) => this.visit_binary_expression(h, expr.this),
         Expression::Unary(expr) => this.visit_unary_expression(h, expr.this),
         Expression::Indexing(expr) => this.visit_indexing_expression(h, expr.this),
         Expression::Slicing(expr) => this.visit_slicing_expression(h, expr.this),
         Expression::Select(expr) => this.visit_select_expression(h, expr.this),
         Expression::Array(expr) => this.visit_array_expression(h, expr.this),
         Expression::Constant(expr) => this.visit_constant_expression(h, expr.this),
         Expression::Call(expr) => this.visit_call_expression(h, expr.this),
         Expression::Variable(expr) => this.visit_variable_expression(h, expr.this),
+    }
+}
 fn recursive_assignment_expression<T: Visitor>(
     this: &mut T,
     h: &mut Heap,
     expr: AssignmentExpressionId,
 ) -> VisitorResult {
     this.visit_expression(h, h[expr].left)?;
     this.visit_expression(h, h[expr].right)
+}
 fn recursive_conditional_expression<T: Visitor>(
     this: &mut T,
     h: &mut Heap,
     expr: ConditionalExpressionId,
 ) -> VisitorResult {
     this.visit_expression(h, h[expr].test)?;
     this.visit_expression(h, h[expr].true_expression)?;
     this.visit_expression(h, h[expr].false_expression)
+}
 fn recursive_binary_expression<T: Visitor>(
     this: &mut T,
     h: &mut Heap,
     expr: BinaryExpressionId,
 ) -> VisitorResult {
     this.visit_expression(h, h[expr].left)?;
     this.visit_expression(h, h[expr].right)
+}
 fn recursive_unary_expression<T: Visitor>(
     this: &mut T,
     h: &mut Heap,
     expr: UnaryExpressionId,
 ) -> VisitorResult {
     this.visit_expression(h, h[expr].expression)
+}
 fn recursive_indexing_expression<T: Visitor>(
     this: &mut T,
     h: &mut Heap,
     expr: IndexingExpressionId,
 ) -> VisitorResult {
     this.visit_expression(h, h[expr].subject)?;
     this.visit_expression(h, h[expr].index)
+}
 fn recursive_slicing_expression<T: Visitor>(
     this: &mut T,
     h: &mut Heap,
     expr: SlicingExpressionId,
 ) -> VisitorResult {
     this.visit_expression(h, h[expr].subject)?;
     this.visit_expression(h, h[expr].from_index)?;
     this.visit_expression(h, h[expr].to_index)
+}
 fn recursive_select_expression<T: Visitor>(
     this: &mut T,
     h: &mut Heap,
     expr: SelectExpressionId,
 ) -> VisitorResult {
     this.visit_expression(h, h[expr].subject)
+}
 fn recursive_array_expression<T: Visitor>(
     this: &mut T,
     h: &mut Heap,
     expr: ArrayExpressionId,
 ) -> VisitorResult {
     for &expr in h[expr].elements.clone().iter() {
         this.visit_expression(h, expr)?;
+    }
     Ok(())
+}
 fn recursive_call_expression<T: Visitor>(
     this: &mut T,
     h: &mut Heap,
     expr: CallExpressionId,
 ) -> VisitorResult {
     for &expr in h[expr].arguments.clone().iter() {
         this.visit_expression(h, expr)?;
+    }
     Ok(())
+}
 // ====================
 // Grammar Rules
 // ====================
 struct NestedSynchronousStatements {
     illegal: bool,
+}
 impl NestedSynchronousStatements {
     fn new() -> Self {
         NestedSynchronousStatements { illegal: false }
+    }
+}
 impl Visitor for NestedSynchronousStatements {
     fn visit_composite_definition(&mut self, h: &mut Heap, def: CompositeId) -> VisitorResult {
         assert!(!self.illegal);
         self.illegal = true;
         recursive_composite_definition(self, h, def)?;
         self.illegal = false;
         Ok(())
+    }
     fn visit_function_definition(&mut self, h: &mut Heap, def: FunctionId) -> VisitorResult {
         assert!(!self.illegal);
         self.illegal = true;
         recursive_function_definition(self, h, def)?;
         self.illegal = false;
         Ok(())
+    }
     fn visit_synchronous_statement(
         &mut self,
         h: &mut Heap,
         stmt: SynchronousStatementId,
     ) -> VisitorResult {
         if self.illegal {
             return Err(ParseError::new(
                 h[stmt].position(),
                 "Illegal nested synchronous statement",
             ));
+        }
         self.illegal = true;
         recursive_synchronous_statement(self, h, stmt)?;
         self.illegal = false;
         Ok(())
+    }
     fn visit_expression(&mut self, _h: &mut Heap, _expr: ExpressionId) -> VisitorResult {
         Ok(())
+    }
+}
 struct ChannelStatementOccurrences {
     illegal: bool,
+}
 impl ChannelStatementOccurrences {
     fn new() -> Self {
         ChannelStatementOccurrences { illegal: false }
+    }
+}
 impl Visitor for ChannelStatementOccurrences {
     fn visit_primitive_definition(&mut self, h: &mut Heap, def: PrimitiveId) -> VisitorResult {
         assert!(!self.illegal);
         self.illegal = true;
         recursive_primitive_definition(self, h, def)?;
         self.illegal = false;
         Ok(())
+    }
     fn visit_function_definition(&mut self, h: &mut Heap, def: FunctionId) -> VisitorResult {
         assert!(!self.illegal);
         self.illegal = true;
         recursive_function_definition(self, h, def)?;
         self.illegal = false;
         Ok(())
+    }
     fn visit_channel_statement(&mut self, h: &mut Heap, stmt: ChannelStatementId) -> VisitorResult {
         if self.illegal {
             return Err(ParseError::new(h[stmt].position(), "Illegal channel delcaration"));
+        }
         Ok(())
+    }
     fn visit_expression(&mut self, _h: &mut Heap, _expr: ExpressionId) -> VisitorResult {
         Ok(())
+    }
+}
 struct FunctionStatementReturns {}
 impl FunctionStatementReturns {
     fn new() -> Self {
         FunctionStatementReturns {}
+    }
     fn function_error(&self, position: InputPosition) -> VisitorResult {
         Err(ParseError::new(position, "Function definition must return"))
+    }
+}
 impl Visitor for FunctionStatementReturns {
     fn visit_component_definition(&mut self, _h: &mut Heap, _def: ComponentId) -> VisitorResult {
         Ok(())
+    }
     fn visit_variable_declaration(&mut self, _h: &mut Heap, _decl: VariableId) -> VisitorResult {
         Ok(())
+    }
     fn visit_block_statement(&mut self, h: &mut Heap, block: BlockStatementId) -> VisitorResult {
         let len = h[block].statements.len();
         assert!(len > 0);
         self.visit_statement(h, h[block].statements[len - 1])
+    }
     fn visit_skip_statement(&mut self, h: &mut Heap, stmt: SkipStatementId) -> VisitorResult {
         self.function_error(h[stmt].position)
+    }
     fn visit_break_statement(&mut self, h: &mut Heap, stmt: BreakStatementId) -> VisitorResult {
         self.function_error(h[stmt].position)
+    }
     fn visit_continue_statement(
         &mut self,
         h: &mut Heap,
         stmt: ContinueStatementId,
     ) -> VisitorResult {
         self.function_error(h[stmt].position)
+    }
     fn visit_assert_statement(&mut self, h: &mut Heap, stmt: AssertStatementId) -> VisitorResult {
         self.function_error(h[stmt].position)
+    }
     fn visit_new_statement(&mut self, h: &mut Heap, stmt: NewStatementId) -> VisitorResult {
         self.function_error(h[stmt].position)
+    }
     fn visit_expression_statement(
         &mut self,
         h: &mut Heap,
         stmt: ExpressionStatementId,
     ) -> VisitorResult {
         self.function_error(h[stmt].position)
+    }
     fn visit_expression(&mut self, _h: &mut Heap, _expr: ExpressionId) -> VisitorResult {
         Ok(())
+    }
+}
 struct ComponentStatementReturnNew {
     illegal_new: bool,
     illegal_return: bool,
+}
 impl ComponentStatementReturnNew {
     fn new() -> Self {
         ComponentStatementReturnNew { illegal_new: false, illegal_return: false }
+    }
+}
 impl Visitor for ComponentStatementReturnNew {
     fn visit_component_definition(&mut self, h: &mut Heap, def: ComponentId) -> VisitorResult {
         assert!(!(self.illegal_new || self.illegal_return));
         self.illegal_return = true;
         recursive_component_definition(self, h, def)?;
         self.illegal_return = false;
         Ok(())
+    }
     fn visit_primitive_definition(&mut self, h: &mut Heap, def: PrimitiveId) -> VisitorResult {
         assert!(!self.illegal_new);
         self.illegal_new = true;
         recursive_primitive_definition(self, h, def)?;
         self.illegal_new = false;
         Ok(())
+    }
     fn visit_function_definition(&mut self, h: &mut Heap, def: FunctionId) -> VisitorResult {
         assert!(!(self.illegal_new || self.illegal_return));
         self.illegal_new = true;
         recursive_function_definition(self, h, def)?;
         self.illegal_new = false;
         Ok(())
+    }
     fn visit_variable_declaration(&mut self, _h: &mut Heap, _decl: VariableId) -> VisitorResult {
         Ok(())
+    }
     fn visit_return_statement(&mut self, h: &mut Heap, stmt: ReturnStatementId) -> VisitorResult {
         if self.illegal_return {
             Err(ParseError::new(h[stmt].position, "Component definition must not return"))
         } else {
             recursive_return_statement(self, h, stmt)
+        }
+    }
     fn visit_new_statement(&mut self, h: &mut Heap, stmt: NewStatementId) -> VisitorResult {
         if self.illegal_new {
             Err(ParseError::new(
                 h[stmt].position,
                 "Symbol definition contains illegal new statement",
             ))
         } else {
             recursive_new_statement(self, h, stmt)
+        }
+    }
     fn visit_expression(&mut self, _h: &mut Heap, _expr: ExpressionId) -> VisitorResult {
         Ok(())
+    }
+}
 struct CheckBuiltinOccurrences {
     legal: bool,
+}
 impl CheckBuiltinOccurrences {
     fn new() -> Self {
         CheckBuiltinOccurrences { legal: false }
+    }
+}
 impl Visitor for CheckBuiltinOccurrences {
     fn visit_synchronous_statement(
         &mut self,
         h: &mut Heap,
         stmt: SynchronousStatementId,
     ) -> VisitorResult {
         assert!(!self.legal);
         self.legal = true;
         recursive_synchronous_statement(self, h, stmt)?;
         self.legal = false;
         Ok(())
+    }
     fn visit_call_expression(&mut self, h: &mut Heap, expr: CallExpressionId) -> VisitorResult {
         match h[expr].method {
             Method::Get | Method::Fires => {
                 if !self.legal {
                     return Err(ParseError::new(h[expr].position, "Illegal built-in occurrence"));
+                }
+            }
             _ => {}
+        }
         recursive_call_expression(self, h, expr)
+    }
+}
 struct BuildSymbolDeclarations {
     declarations: Vec<DeclarationId>,
+}
 impl BuildSymbolDeclarations {
     fn new() -> Self {
         BuildSymbolDeclarations { declarations: Vec::new() }
+    }
     fn checked_add(&mut self, h: &mut Heap, decl: DeclarationId) -> VisitorResult {
         for &old in self.declarations.iter() {
             let id = h[decl].identifier();
             if h[id] == h[h[old].identifier()] {
                 return match h[decl].clone() {
                     Declaration::Defined(defined) => Err(ParseError::new(
                         h[defined.definition].position(),
                         format!("Defined symbol clash: {}", h[id]),
                     )),
                     Declaration::Imported(imported) => Err(ParseError::new(
                         h[imported.import].position(),
                         format!("Imported symbol clash: {}", h[id]),
                     )),
                 };
+            }
+        }
         self.declarations.push(decl);
         Ok(())
+    }
+}
 impl Visitor for BuildSymbolDeclarations {
     fn visit_protocol_description(&mut self, h: &mut Heap, pd: RootId) -> VisitorResult {
         recursive_protocol_description(self, h, pd)?;
         // Move all collected declarations to the protocol description
         h[pd].declarations.append(&mut self.declarations);
         Ok(())
+    }
     fn visit_import(&mut self, h: &mut Heap, import: ImportId) -> VisitorResult {
         let vec = library::get_declarations(h, import)?;
         // Destructively iterate over the vector
         for decl in vec {
             self.checked_add(h, decl)?;
+        }
         Ok(())
+    }
     fn visit_symbol_definition(&mut self, h: &mut Heap, definition: DefinitionId) -> VisitorResult {
         let signature = Signature::from_definition(h, definition);
         let decl = h
             .alloc_defined_declaration(|this| DefinedDeclaration { this, definition, signature })
             .upcast();
         self.checked_add(h, decl)?;
         Ok(())
+    }
+}
 struct LinkCallExpressions {
     pd: Option<RootId>,
     composite: bool,
     new_statement: bool,
+}
 impl LinkCallExpressions {
     fn new() -> Self {
         LinkCallExpressions { pd: None, composite: false, new_statement: false }
+    }
     fn get_declaration(
         &self,
         h: &Heap,
         id: SourceIdentifierId,
     ) -> Result<DeclarationId, ParseError> {
         match h[self.pd.unwrap()].get_declaration(h, id.upcast()) {
             Some(id) => Ok(id),
             None => Err(ParseError::new(h[id].position, "Unresolved method")),
+        }
+    }
+}
 impl Visitor for LinkCallExpressions {
     fn visit_protocol_description(&mut self, h: &mut Heap, pd: RootId) -> VisitorResult {
         self.pd = Some(pd);
         recursive_protocol_description(self, h, pd)?;
         self.pd = None;
         Ok(())
+    }
     fn visit_composite_definition(&mut self, h: &mut Heap, def: CompositeId) -> VisitorResult {
         assert!(!self.composite);
         self.composite = true;
         recursive_composite_definition(self, h, def)?;
         self.composite = false;
         Ok(())
+    }
     fn visit_new_statement(&mut self, h: &mut Heap, stmt: NewStatementId) -> VisitorResult {
         assert!(self.composite);
         assert!(!self.new_statement);
         self.new_statement = true;
         recursive_new_statement(self, h, stmt)?;
         self.new_statement = false;
         Ok(())
+    }
     fn visit_call_expression(&mut self, h: &mut Heap, expr: CallExpressionId) -> VisitorResult {
         if let Method::Symbolic(id) = h[expr].method {
             let decl = self.get_declaration(h, id)?;
             if self.new_statement && h[decl].is_function() {
                 return Err(ParseError::new(h[id].position, "Illegal call expression"));
+            }
             if !self.new_statement && h[decl].is_component() {
                 return Err(ParseError::new(h[id].position, "Illegal call expression"));
+            }
             // Set the corresponding declaration of the call
             h[expr].declaration = Some(decl);
+        }
         // A new statement's call expression may have as arguments function calls
         let old = self.new_statement;
         self.new_statement = false;
         recursive_call_expression(self, h, expr)?;
         self.new_statement = old;
         Ok(())
+    }
+}
 struct BuildScope {
     scope: Option<Scope>,
+}
 impl BuildScope {
     fn new() -> Self {
         BuildScope { scope: None }
+    }
+}
 impl Visitor for BuildScope {
     fn visit_symbol_definition(&mut self, h: &mut Heap, def: DefinitionId) -> VisitorResult {
         assert!(self.scope.is_none());
         self.scope = Some(Scope::Definition(def));
         recursive_symbol_definition(self, h, def)?;
         self.scope = None;
         Ok(())
+    }
     fn visit_block_statement(&mut self, h: &mut Heap, stmt: BlockStatementId) -> VisitorResult {
         assert!(!self.scope.is_none());
         let old = self.scope;
         // First store the current scope
         h[stmt].parent_scope = self.scope;
         // Then move scope down to current block
         self.scope = Some(Scope::Block(stmt));
         recursive_block_statement(self, h, stmt)?;
         // Move scope back up
         self.scope = old;
         Ok(())
+    }
     fn visit_synchronous_statement(
         &mut self,
         h: &mut Heap,
         stmt: SynchronousStatementId,
     ) -> VisitorResult {
         assert!(!self.scope.is_none());
         let old = self.scope;
         // First store the current scope
         h[stmt].parent_scope = self.scope;
         // Then move scope down to current sync
         self.scope = Some(Scope::Synchronous(stmt));
         recursive_synchronous_statement(self, h, stmt)?;
         // Move scope back up
         self.scope = old;
         Ok(())
+    }
     fn visit_expression(&mut self, h: &mut Heap, expr: ExpressionId) -> VisitorResult {
         Ok(())
+    }
+}
 struct ResolveVariables {
     scope: Option<Scope>,
+}
 impl ResolveVariables {
     fn new() -> Self {
         ResolveVariables { scope: None }
+    }
     fn get_variable(&self, h: &Heap, id: SourceIdentifierId) -> Result<VariableId, ParseError> {
         if let Some(var) = self.find_variable(h, id) {
             Ok(var)
         } else {
             Err(ParseError::new(h[id].position, "Unresolved variable"))
+        }
+    }
     fn find_variable(&self, h: &Heap, id: SourceIdentifierId) -> Option<VariableId> {
         ResolveVariables::find_variable_impl(h, self.scope, id)
+    }
     fn find_variable_impl(
         h: &Heap,
         scope: Option<Scope>,
         id: SourceIdentifierId,
     ) -> Option<VariableId> {
         if let Some(scope) = scope {
             // The order in which we check for variables is important:
             // otherwise, two variables with the same name are shadowed.
             if let Some(var) = ResolveVariables::find_variable_impl(h, scope.parent_scope(h), id) {
                 Some(var)
             } else {
                 scope.get_variable(h, id)
+            }
         } else {
             None
+        }
+    }
+}
 impl Visitor for ResolveVariables {
     fn visit_symbol_definition(&mut self, h: &mut Heap, def: DefinitionId) -> VisitorResult {
         assert!(self.scope.is_none());
         self.scope = Some(Scope::Definition(def));
         recursive_symbol_definition(self, h, def)?;
         self.scope = None;
         Ok(())
+    }
     fn visit_variable_declaration(&mut self, h: &mut Heap, decl: VariableId) -> VisitorResult {
         // This is only called for parameters of definitions and synchronous statements,
         // since the local variables of block statements are still empty
         // the moment it is traversed. After resolving variables, this
         // function is also called for every local variable declaration.
         // We want to make sure that the resolved variable is the variable declared itself;
         // otherwise, there is some variable defined in the parent scope. This check
         // imposes that the order in which find_variable looks is significant!
         let id = h[decl].identifier();
         let check_same = self.find_variable(h, id);
         if let Some(check_same) = check_same {
             if check_same != decl {
                 return Err(ParseError::new(h[id].position, "Declared variable clash"));
+            }
+        }
         recursive_variable_declaration(self, h, decl)
+    }
     fn visit_memory_statement(&mut self, h: &mut Heap, stmt: MemoryStatementId) -> VisitorResult {
         assert!(!self.scope.is_none());
         let var = h[stmt].variable;
         let id = h[var].identifier;
         // First check whether variable with same identifier is in scope
         let check_duplicate = self.find_variable(h, id);
         if !check_duplicate.is_none() {
             return Err(ParseError::new(h[id].position, "Declared variable clash"));
+        }
         // Then check the expression's variables (this should not refer to own variable)
         recursive_memory_statement(self, h, stmt)?;
         // Finally, we may add the variable to the scope, which is guaranteed to be a block
+        {
             let mut block = &mut h[self.scope.unwrap().to_block()];
             block.locals.push(var);
+        }
         Ok(())
+    }
     fn visit_channel_statement(&mut self, h: &mut Heap, stmt: ChannelStatementId) -> VisitorResult {
         assert!(!self.scope.is_none());
         // First handle the from variable
+        {
             let var = h[stmt].from;
             let id = h[var].identifier;
             let check_duplicate = self.find_variable(h, id);
             if !check_duplicate.is_none() {
                 return Err(ParseError::new(h[id].position, "Declared variable clash"));
+            }
             let mut block = &mut h[self.scope.unwrap().to_block()];
             block.locals.push(var);
+        }
         // Then handle the to variable (which may not be the same as the from)
+        {
             let var = h[stmt].to;
             let id = h[var].identifier;
             let check_duplicate = self.find_variable(h, id);
             if !check_duplicate.is_none() {
                 return Err(ParseError::new(h[id].position, "Declared variable clash"));
+            }
             let mut block = &mut h[self.scope.unwrap().to_block()];
             block.locals.push(var);
+        }
         Ok(())
+    }
     fn visit_block_statement(&mut self, h: &mut Heap, stmt: BlockStatementId) -> VisitorResult {
         assert!(!self.scope.is_none());
         let old = self.scope;
         self.scope = Some(Scope::Block(stmt));
         recursive_block_statement(self, h, stmt)?;
         self.scope = old;
         Ok(())
+    }
     fn visit_synchronous_statement(
         &mut self,
         h: &mut Heap,
         stmt: SynchronousStatementId,
     ) -> VisitorResult {
         assert!(!self.scope.is_none());
         let old = self.scope;
         self.scope = Some(Scope::Synchronous(stmt));
         recursive_synchronous_statement(self, h, stmt)?;
         self.scope = old;
         Ok(())
+    }
     fn visit_variable_expression(
         &mut self,
         h: &mut Heap,
         expr: VariableExpressionId,
     ) -> VisitorResult {
         let var = self.get_variable(h, h[expr].identifier)?;
         h[expr].declaration = Some(var);
         Ok(())
+    }
+}
 struct UniqueStatementId(StatementId);
 struct LinkStatements {
     prev: Option<UniqueStatementId>,
+}
 impl LinkStatements {
     fn new() -> Self {
         LinkStatements { prev: None }
+    }
+}
 impl Visitor for LinkStatements {
     fn visit_symbol_definition(&mut self, h: &mut Heap, def: DefinitionId) -> VisitorResult {
         assert!(self.prev.is_none());
         recursive_symbol_definition(self, h, def)?;
         // Clear out last statement
         self.prev = None;
         Ok(())
+    }
     fn visit_statement(&mut self, h: &mut Heap, stmt: StatementId) -> VisitorResult {
         if let Some(UniqueStatementId(prev)) = self.prev.take() {
             h[prev].link_next(stmt);
+        }
         recursive_statement(self, h, stmt)
+    }
     fn visit_local_statement(&mut self, _h: &mut Heap, stmt: LocalStatementId) -> VisitorResult {
         self.prev = Some(UniqueStatementId(stmt.upcast()));
         Ok(())
+    }
     fn visit_labeled_statement(&mut self, h: &mut Heap, stmt: LabeledStatementId) -> VisitorResult {
         recursive_labeled_statement(self, h, stmt)
+    }
     fn visit_skip_statement(&mut self, _h: &mut Heap, stmt: SkipStatementId) -> VisitorResult {
         self.prev = Some(UniqueStatementId(stmt.upcast()));
         Ok(())
+    }
     fn visit_if_statement(&mut self, h: &mut Heap, stmt: IfStatementId) -> VisitorResult {
         // We allocate a pseudo-statement, which combines both branches into one next statement
         let position = h[stmt].position;
         let pseudo =
             h.alloc_end_if_statement(|this| EndIfStatement { this, position, next: None }).upcast();
         assert!(self.prev.is_none());
         self.visit_statement(h, h[stmt].true_body)?;
         if let Some(UniqueStatementId(prev)) = self.prev.take() {
             h[prev].link_next(pseudo);
+        }
         assert!(self.prev.is_none());
         self.visit_statement(h, h[stmt].false_body)?;
         if let Some(UniqueStatementId(prev)) = self.prev.take() {
             h[prev].link_next(pseudo);
+        }
         // Use the pseudo-statement as the statement where to update the next pointer
         self.prev = Some(UniqueStatementId(pseudo));
         Ok(())
+    }
     fn visit_while_statement(&mut self, h: &mut Heap, stmt: WhileStatementId) -> VisitorResult {
         // We allocate a pseudo-statement, to which the break statement finds its target
         let position = h[stmt].position;
         let pseudo =
             h.alloc_end_while_statement(|this| EndWhileStatement { this, position, next: None });
         // Update the while's next statement to point to the pseudo-statement
         h[stmt].next = Some(pseudo);
         assert!(self.prev.is_none());
         self.visit_statement(h, h[stmt].body)?;
         // The body's next statement loops back to the while statement itself
         // Note: continue statements also loop back to the while statement itself
         if let Some(UniqueStatementId(prev)) = std::mem::replace(&mut self.prev, None) {
             h[prev].link_next(stmt.upcast());
+        }
         // Use the while statement as the statement where the next pointer is updated
         self.prev = Some(UniqueStatementId(pseudo.upcast()));
         Ok(())
+    }
     fn visit_break_statement(&mut self, _h: &mut Heap, _stmt: BreakStatementId) -> VisitorResult {
         Ok(())
+    }
     fn visit_continue_statement(
         &mut self,
         _h: &mut Heap,
         _stmt: ContinueStatementId,
     ) -> VisitorResult {
         Ok(())
+    }
     fn visit_synchronous_statement(
         &mut self,
         h: &mut Heap,
         stmt: SynchronousStatementId,
     ) -> VisitorResult {
         // Allocate a pseudo-statement, that is added for helping the evaluator to issue a command
         // that marks the end of the synchronous block. Every evaluation has to pause at this
         // point, only to resume later when the thread is selected as unique thread to continue.
         let position = h[stmt].position;
         let pseudo = h
             .alloc_end_synchronous_statement(|this| EndSynchronousStatement {
                 this,
                 position,
                 next: None,
             })
             .upcast();
         assert!(self.prev.is_none());
         self.visit_statement(h, h[stmt].body)?;
         // The body's next statement points to the pseudo element
         if let Some(UniqueStatementId(prev)) = std::mem::replace(&mut self.prev, None) {
             h[prev].link_next(pseudo);
+        }
         // Use the pseudo-statement as the statement where the next pointer is updated
         self.prev = Some(UniqueStatementId(pseudo));
         Ok(())
+    }
     fn visit_return_statement(&mut self, h: &mut Heap, stmt: ReturnStatementId) -> VisitorResult {
         Ok(())
+    }
     fn visit_assert_statement(&mut self, h: &mut Heap, stmt: AssertStatementId) -> VisitorResult {
         self.prev = Some(UniqueStatementId(stmt.upcast()));
         Ok(())
+    }
     fn visit_goto_statement(&mut self, _h: &mut Heap, _stmt: GotoStatementId) -> VisitorResult {
         Ok(())
+    }
     fn visit_new_statement(&mut self, h: &mut Heap, stmt: NewStatementId) -> VisitorResult {
         self.prev = Some(UniqueStatementId(stmt.upcast()));
         Ok(())
+    }
     fn visit_put_statement(&mut self, h: &mut Heap, stmt: PutStatementId) -> VisitorResult {
         self.prev = Some(UniqueStatementId(stmt.upcast()));
         Ok(())
+    }
     fn visit_expression_statement(
         &mut self,
         h: &mut Heap,
         stmt: ExpressionStatementId,
     ) -> VisitorResult {
         self.prev = Some(UniqueStatementId(stmt.upcast()));
         Ok(())
+    }
     fn visit_expression(&mut self, h: &mut Heap, expr: ExpressionId) -> VisitorResult {
         Ok(())
+    }
+}
 struct BuildLabels {
     block: Option<BlockStatementId>,
     sync_enclosure: Option<SynchronousStatementId>,
+}
 impl BuildLabels {
     fn new() -> Self {
         BuildLabels { block: None, sync_enclosure: None }
+    }
+}
 impl Visitor for BuildLabels {
     fn visit_block_statement(&mut self, h: &mut Heap, stmt: BlockStatementId) -> VisitorResult {
         assert_eq!(self.block, h[stmt].parent_block(h));
         let old = self.block;
         self.block = Some(stmt);
         recursive_block_statement(self, h, stmt)?;
         self.block = old;
         Ok(())
+    }
     fn visit_labeled_statement(&mut self, h: &mut Heap, stmt: LabeledStatementId) -> VisitorResult {
         assert!(!self.block.is_none());
         // Store label in current block (on the fly)
         h[self.block.unwrap()].labels.push(stmt);
         // Update synchronous scope of label
         h[stmt].in_sync = self.sync_enclosure;
         recursive_labeled_statement(self, h, stmt)
+    }
     fn visit_while_statement(&mut self, h: &mut Heap, stmt: WhileStatementId) -> VisitorResult {
         h[stmt].in_sync = self.sync_enclosure;
         recursive_while_statement(self, h, stmt)
+    }
     fn visit_synchronous_statement(
         &mut self,
         h: &mut Heap,
         stmt: SynchronousStatementId,
     ) -> VisitorResult {
         assert!(self.sync_enclosure.is_none());
         self.sync_enclosure = Some(stmt);
         recursive_synchronous_statement(self, h, stmt)?;
         self.sync_enclosure = None;
         Ok(())
+    }
     fn visit_expression(&mut self, h: &mut Heap, expr: ExpressionId) -> VisitorResult {
         Ok(())
+    }
+}
 struct ResolveLabels {
     block: Option<BlockStatementId>,
     while_enclosure: Option<WhileStatementId>,
     sync_enclosure: Option<SynchronousStatementId>,
+}
 impl ResolveLabels {
     fn new() -> Self {
         ResolveLabels { block: None, while_enclosure: None, sync_enclosure: None }
+    }
     fn check_duplicate_impl(
         h: &Heap,
         block: Option<BlockStatementId>,
         stmt: LabeledStatementId,
     ) -> VisitorResult {
         if let Some(block) = block {
             // Checking the parent first is important. Otherwise, labels
             // overshadow previously defined labels: and this is illegal!
             ResolveLabels::check_duplicate_impl(h, h[block].parent_block(h), stmt)?;
             // For the current block, check for a duplicate.
             for &other_stmt in h[block].labels.iter() {
                 if other_stmt == stmt {
                     continue;
                 } else {
                     if h[h[other_stmt].label] == h[h[stmt].label] {
                         return Err(ParseError::new(h[stmt].position, "Duplicate label"));
+                    }
+                }
+            }
+        }
         Ok(())
+    }
     fn check_duplicate(&self, h: &Heap, stmt: LabeledStatementId) -> VisitorResult {
         ResolveLabels::check_duplicate_impl(h, self.block, stmt)
+    }
     fn get_target(
         &self,
         h: &Heap,
         id: SourceIdentifierId,
     ) -> Result<LabeledStatementId, ParseError> {
         if let Some(stmt) = ResolveLabels::find_target(h, self.block, id) {
             Ok(stmt)
         } else {
             Err(ParseError::new(h[id].position, "Unresolved label"))
+        }
+    }
     fn find_target(
         h: &Heap,
         block: Option<BlockStatementId>,
         id: SourceIdentifierId,
     ) -> Option<LabeledStatementId> {
         if let Some(block) = block {
             // It does not matter in what order we find the labels.
             // If there are duplicates: that is checked elsewhere.
             for &stmt in h[block].labels.iter() {
                 if h[h[stmt].label] == h[id] {
                     return Some(stmt);
+                }
+            }
             if let Some(stmt) = ResolveLabels::find_target(h, h[block].parent_block(h), id) {
                 return Some(stmt);
+            }
+        }
         None
+    }
+}
 impl Visitor for ResolveLabels {
     fn visit_block_statement(&mut self, h: &mut Heap, stmt: BlockStatementId) -> VisitorResult {
         assert_eq!(self.block, h[stmt].parent_block(h));
         let old = self.block;
         self.block = Some(stmt);
         recursive_block_statement(self, h, stmt)?;
         self.block = old;
         Ok(())
+    }
     fn visit_labeled_statement(&mut self, h: &mut Heap, stmt: LabeledStatementId) -> VisitorResult {
         assert!(!self.block.is_none());
         self.check_duplicate(h, stmt)?;
         recursive_labeled_statement(self, h, stmt)
+    }
     fn visit_while_statement(&mut self, h: &mut Heap, stmt: WhileStatementId) -> VisitorResult {
         let old = self.while_enclosure;
         self.while_enclosure = Some(stmt);
         recursive_while_statement(self, h, stmt)?;
         self.while_enclosure = old;
         Ok(())
+    }
     fn visit_break_statement(&mut self, h: &mut Heap, stmt: BreakStatementId) -> VisitorResult {
         let the_while;
         if let Some(label) = h[stmt].label {
             let target = self.get_target(h, label)?;
             let target = &h[h[target].body];
             if !target.is_while() {
                 return Err(ParseError::new(
                     h[stmt].position,
                     "Illegal break: target not a while statement",
                 ));
+            }
             the_while = target.as_while();
         // TODO: check if break is nested under while
         } else {
             if self.while_enclosure.is_none() {
                 return Err(ParseError::new(
                     h[stmt].position,
                     "Illegal break: no surrounding while statement",
                 ));
+            }
             the_while = &h[self.while_enclosure.unwrap()];
             // break is always nested under while, by recursive vistor
+        }
         if the_while.in_sync != self.sync_enclosure {
             return Err(ParseError::new(
                 h[stmt].position,
                 "Illegal break: synchronous statement escape",
             ));
+        }
         h[stmt].target = the_while.next;
         Ok(())
+    }
     fn visit_continue_statement(
         &mut self,
         h: &mut Heap,
         stmt: ContinueStatementId,
     ) -> VisitorResult {
         let the_while;
         if let Some(label) = h[stmt].label {
             let target = self.get_target(h, label)?;
             let target = &h[h[target].body];
             if !target.is_while() {
                 return Err(ParseError::new(
                     h[stmt].position,
                     "Illegal continue: target not a while statement",
                 ));
+            }
             the_while = target.as_while();
         // TODO: check if continue is nested under while
         } else {
             if self.while_enclosure.is_none() {
                 return Err(ParseError::new(
                     h[stmt].position,
                     "Illegal continue: no surrounding while statement",
                 ));
+            }
             the_while = &h[self.while_enclosure.unwrap()];
             // continue is always nested under while, by recursive vistor
+        }
         if the_while.in_sync != self.sync_enclosure {
             return Err(ParseError::new(
                 h[stmt].position,
                 "Illegal continue: synchronous statement escape",
             ));
+        }
         h[stmt].target = Some(the_while.this);
         Ok(())
+    }
     fn visit_synchronous_statement(
         &mut self,
         h: &mut Heap,
         stmt: SynchronousStatementId,
     ) -> VisitorResult {
         assert!(self.sync_enclosure.is_none());
         self.sync_enclosure = Some(stmt);
         recursive_synchronous_statement(self, h, stmt)?;
         self.sync_enclosure = None;
         Ok(())
+    }
     fn visit_goto_statement(&mut self, h: &mut Heap, stmt: GotoStatementId) -> VisitorResult {
         let target = self.get_target(h, h[stmt].label)?;
         if h[target].in_sync != self.sync_enclosure {
             return Err(ParseError::new(
                 h[stmt].position,
                 "Illegal goto: synchronous statement escape",
             ));
+        }
         h[stmt].target = Some(target);
         Ok(())
+    }
     fn visit_expression(&mut self, h: &mut Heap, expr: ExpressionId) -> VisitorResult {
         Ok(())
+    }
+}
 struct AssignableExpressions {
     assignable: bool,
+}
 impl AssignableExpressions {
     fn new() -> Self {
         AssignableExpressions { assignable: false }
+    }
     fn error(&self, position: InputPosition) -> VisitorResult {
         Err(ParseError::new(position, "Unassignable expression"))
+    }
+}
 impl Visitor for AssignableExpressions {
     fn visit_assignment_expression(
         &mut self,
         h: &mut Heap,
         expr: AssignmentExpressionId,
     ) -> VisitorResult {
         if self.assignable {
             self.error(h[expr].position)
         } else {
             self.assignable = true;
             self.visit_expression(h, h[expr].left)?;
             self.assignable = false;
             self.visit_expression(h, h[expr].right)
+        }
+    }
     fn visit_conditional_expression(
         &mut self,
         h: &mut Heap,
         expr: ConditionalExpressionId,
     ) -> VisitorResult {
         if self.assignable {
             self.error(h[expr].position)
         } else {
             recursive_conditional_expression(self, h, expr)
+        }
+    }
     fn visit_binary_expression(&mut self, h: &mut Heap, expr: BinaryExpressionId) -> VisitorResult {
         if self.assignable {
             self.error(h[expr].position)
         } else {
             recursive_binary_expression(self, h, expr)
+        }
+    }
     fn visit_unary_expression(&mut self, h: &mut Heap, expr: UnaryExpressionId) -> VisitorResult {
         if self.assignable {
             self.error(h[expr].position)
         } else {
             match h[expr].operation {
                 UnaryOperation::PostDecrement
                 | UnaryOperation::PreDecrement
                 | UnaryOperation::PostIncrement
                 | UnaryOperation::PreIncrement => {
                     self.assignable = true;
                     recursive_unary_expression(self, h, expr)?;
                     self.assignable = false;
                     Ok(())
+                }
                 _ => recursive_unary_expression(self, h, expr),
+            }
+        }
+    }
     fn visit_indexing_expression(
         &mut self,
         h: &mut Heap,
         expr: IndexingExpressionId,
     ) -> VisitorResult {
         let old = self.assignable;
         self.assignable = false;
         recursive_indexing_expression(self, h, expr)?;
         self.assignable = old;
         Ok(())
+    }
     fn visit_slicing_expression(
         &mut self,
         h: &mut Heap,
         expr: SlicingExpressionId,
     ) -> VisitorResult {
         let old = self.assignable;
         self.assignable = false;
         recursive_slicing_expression(self, h, expr)?;
         self.assignable = old;
         Ok(())
+    }
     fn visit_select_expression(&mut self, h: &mut Heap, expr: SelectExpressionId) -> VisitorResult {
         if h[expr].field.is_length() && self.assignable {
             return self.error(h[expr].position);
+        }
         let old = self.assignable;
         self.assignable = false;
         recursive_select_expression(self, h, expr)?;
         self.assignable = old;
         Ok(())
+    }
     fn visit_array_expression(&mut self, h: &mut Heap, expr: ArrayExpressionId) -> VisitorResult {
         if self.assignable {
             self.error(h[expr].position)
         } else {
             recursive_array_expression(self, h, expr)
+        }
+    }
     fn visit_call_expression(&mut self, h: &mut Heap, expr: CallExpressionId) -> VisitorResult {
         if self.assignable {
             self.error(h[expr].position)
         } else {
             recursive_call_expression(self, h, expr)
+        }
+    }
     fn visit_constant_expression(
         &mut self,
         h: &mut Heap,
         expr: ConstantExpressionId,
     ) -> VisitorResult {
         if self.assignable {
             self.error(h[expr].position)
         } else {
             Ok(())
+        }
+    }
     fn visit_variable_expression(
         &mut self,
         h: &mut Heap,
         expr: VariableExpressionId,
     ) -> VisitorResult {
         Ok(())
+    }
+}
 struct IndexableExpressions {
     indexable: bool,
+}
 impl IndexableExpressions {
     fn new() -> Self {
         IndexableExpressions { indexable: false }
+    }
     fn new() -> Self {  IndexableExpressions { indexable: false }  }
     fn error(&self, position: InputPosition) -> VisitorResult {
         Err(ParseError::new(position, "Unindexable expression"))
+    }
+}
 impl Visitor for IndexableExpressions {
     fn visit_assignment_expression(
         &mut self,
         h: &mut Heap,
         expr: AssignmentExpressionId,
     ) -> VisitorResult {
         if self.indexable {
             self.error(h[expr].position)
         } else {
             recursive_assignment_expression(self, h, expr)
+        }
+    }
     fn visit_conditional_expression(
         &mut self,
         h: &mut Heap,
         expr: ConditionalExpressionId,
     ) -> VisitorResult {
         let old = self.indexable;
         self.indexable = false;
         self.visit_expression(h, h[expr].test)?;
         self.indexable = old;
         self.visit_expression(h, h[expr].true_expression)?;
         self.visit_expression(h, h[expr].false_expression)
+    }
     fn visit_binary_expression(&mut self, h: &mut Heap, expr: BinaryExpressionId) -> VisitorResult {
         if self.indexable && h[expr].operation != BinaryOperator::Concatenate {
             self.error(h[expr].position)
         } else {
             recursive_binary_expression(self, h, expr)
+        }
+    }
     fn visit_unary_expression(&mut self, h: &mut Heap, expr: UnaryExpressionId) -> VisitorResult {
         if self.indexable {
             self.error(h[expr].position)
         } else {
             recursive_unary_expression(self, h, expr)
+        }
+    }
     fn visit_indexing_expression(
         &mut self,
         h: &mut Heap,
         expr: IndexingExpressionId,
     ) -> VisitorResult {
         let old = self.indexable;
-        self.indexable = false;
+        self.indexable = true;
         self.visit_expression(h, h[expr].subject)?;
         self.indexable = false;
         self.visit_expression(h, h[expr].index)?;
         self.indexable = old;
-        self.visit_expression(h, h[expr].index)
+        Ok(())
+    }
     fn visit_slicing_expression(
         &mut self,
         h: &mut Heap,
         expr: SlicingExpressionId,
     ) -> VisitorResult {
         let old = self.indexable;
         self.indexable = true;
         self.visit_expression(h, h[expr].subject)?;
         self.indexable = false;
         self.visit_expression(h, h[expr].from_index)?;
         self.visit_expression(h, h[expr].to_index)?;
         self.indexable = old;
         Ok(())
+    }
     fn visit_select_expression(&mut self, h: &mut Heap, expr: SelectExpressionId) -> VisitorResult {
         let old = self.indexable;
         self.indexable = false;
         recursive_select_expression(self, h, expr)?;
         self.indexable = old;
         Ok(())
+    }
     fn visit_array_expression(&mut self, h: &mut Heap, expr: ArrayExpressionId) -> VisitorResult {
         let old = self.indexable;
         self.indexable = false;
         recursive_array_expression(self, h, expr)?;
         self.indexable = old;
         Ok(())
+    }
     fn visit_call_expression(&mut self, h: &mut Heap, expr: CallExpressionId) -> VisitorResult {
         let old = self.indexable;
         self.indexable = false;
         recursive_call_expression(self, h, expr)?;
         self.indexable = old;
         Ok(())
+    }
     fn visit_constant_expression(
         &mut self,
         h: &mut Heap,
         expr: ConstantExpressionId,
     ) -> VisitorResult {
         if self.indexable {
             self.error(h[expr].position)
         } else {
             Ok(())
+        }
+    }
+}
 struct SelectableExpressions {
     selectable: bool,
+}
 impl SelectableExpressions {
     fn new() -> Self {
         SelectableExpressions { selectable: false }
+    }
     fn error(&self, position: InputPosition) -> VisitorResult {
         Err(ParseError::new(position, "Unselectable expression"))
+    }
+}
 impl Visitor for SelectableExpressions {
     fn visit_assignment_expression(
         &mut self,
         h: &mut Heap,
         expr: AssignmentExpressionId,
     ) -> VisitorResult {
         // left-hand side of assignment can be skipped
         let old = self.selectable;
         self.selectable = false;
         self.visit_expression(h, h[expr].right)?;
         self.selectable = old;
         Ok(())
+    }
     fn visit_conditional_expression(
         &mut self,
         h: &mut Heap,
         expr: ConditionalExpressionId,
     ) -> VisitorResult {
         let old = self.selectable;
         self.selectable = false;
         self.visit_expression(h, h[expr].test)?;
         self.selectable = old;
         self.visit_expression(h, h[expr].true_expression)?;
         self.visit_expression(h, h[expr].false_expression)
+    }
     fn visit_binary_expression(&mut self, h: &mut Heap, expr: BinaryExpressionId) -> VisitorResult {
         if self.selectable && h[expr].operation != BinaryOperator::Concatenate {
             self.error(h[expr].position)
         } else {
             recursive_binary_expression(self, h, expr)
+        }
+    }
     fn visit_unary_expression(&mut self, h: &mut Heap, expr: UnaryExpressionId) -> VisitorResult {
         if self.selectable {
             self.error(h[expr].position)
         } else {
             recursive_unary_expression(self, h, expr)
+        }
+    }
     fn visit_indexing_expression(
         &mut self,
         h: &mut Heap,
         expr: IndexingExpressionId,
     ) -> VisitorResult {
         let old = self.selectable;
         self.selectable = false;
         recursive_indexing_expression(self, h, expr)?;
         self.selectable = old;
         Ok(())
+    }
     fn visit_slicing_expression(
         &mut self,
         h: &mut Heap,
         expr: SlicingExpressionId,
     ) -> VisitorResult {
         let old = self.selectable;
         self.selectable = false;
         recursive_slicing_expression(self, h, expr)?;
         self.selectable = old;
         Ok(())
+    }
     fn visit_select_expression(&mut self, h: &mut Heap, expr: SelectExpressionId) -> VisitorResult {
         let old = self.selectable;
         self.selectable = false;
         recursive_select_expression(self, h, expr)?;
         self.selectable = old;
         Ok(())
+    }
     fn visit_array_expression(&mut self, h: &mut Heap, expr: ArrayExpressionId) -> VisitorResult {
         let old = self.selectable;
         self.selectable = false;
         recursive_array_expression(self, h, expr)?;
         self.selectable = old;
         Ok(())
+    }
     fn visit_call_expression(&mut self, h: &mut Heap, expr: CallExpressionId) -> VisitorResult {
         let old = self.selectable;
         self.selectable = false;
         recursive_call_expression(self, h, expr)?;
         self.selectable = old;
         Ok(())
+    }
     fn visit_constant_expression(
         &mut self,
         h: &mut Heap,
         expr: ConstantExpressionId,
     ) -> VisitorResult {
         if self.selectable {
             self.error(h[expr].position)
         } else {
             Ok(())
+        }
+    }
+}
 pub struct Parser<'a> {
     source: &'a mut InputSource,
+}
 impl<'a> Parser<'a> {
     pub fn new(source: &'a mut InputSource) -> Self {
         Parser { source }
+    }
     pub fn parse(&mut self, h: &mut Heap) -> Result<RootId, ParseError> {
         let mut lex = Lexer::new(self.source);
         let pd = lex.consume_protocol_description(h)?;
         NestedSynchronousStatements::new().visit_protocol_description(h, pd)?;
         ChannelStatementOccurrences::new().visit_protocol_description(h, pd)?;
         FunctionStatementReturns::new().visit_protocol_description(h, pd)?;
         ComponentStatementReturnNew::new().visit_protocol_description(h, pd)?;
         CheckBuiltinOccurrences::new().visit_protocol_description(h, pd)?;
         BuildSymbolDeclarations::new().visit_protocol_description(h, pd)?;
         LinkCallExpressions::new().visit_protocol_description(h, pd)?;
         BuildScope::new().visit_protocol_description(h, pd)?;
         ResolveVariables::new().visit_protocol_description(h, pd)?;
         LinkStatements::new().visit_protocol_description(h, pd)?;
         BuildLabels::new().visit_protocol_description(h, pd)?;
         ResolveLabels::new().visit_protocol_description(h, pd)?;
         AssignableExpressions::new().visit_protocol_description(h, pd)?;
         IndexableExpressions::new().visit_protocol_description(h, pd)?;
         SelectableExpressions::new().visit_protocol_description(h, pd)?;
         Ok(pd)
+    }
+}
 #[cfg(test)]
 mod tests {
     extern crate test_generator;
     use std::fs::File;
     use std::io::Read;
     use std::path::Path;
     use test_generator::test_resources;
     use super::*;
     #[test_resources("testdata/parser/positive/*.pdl")]
     fn batch1(resource: &str) {
         let path = Path::new(resource);
         let mut heap = Heap::new();
         let mut source = InputSource::from_file(&path).unwrap();
         let mut parser = Parser::new(&mut source);
         match parser.parse(&mut heap) {
             Ok(_) => {}
             Err(err) => {
                 println!("{}", err.display(&source));
                 println!("{:?}", err);
                 assert!(false);
+            }
+        }
+    }
     #[test_resources("testdata/parser/negative/*.pdl")]
     fn batch2(resource: &str) {
         let path = Path::new(resource);
         let expect = path.with_extension("txt");
         let mut heap = Heap::new();
         let mut source = InputSource::from_file(&path).unwrap();
         let mut parser = Parser::new(&mut source);
         match parser.parse(&mut heap) {
             Ok(pd) => {
                 println!("{:?}", heap[pd]);
                 println!("Expected parse error:");
                 let mut cev: Vec<u8> = Vec::new();
                 let mut f = File::open(expect).unwrap();
                 f.read_to_end(&mut cev).unwrap();
                 println!("{}", String::from_utf8_lossy(&cev));
                 assert!(false);
+            }
             Err(err) => {
                 println!("{:?}", err);
                 let mut vec: Vec<u8> = Vec::new();
                 err.write(&source, &mut vec).unwrap();
                 println!("{}", String::from_utf8_lossy(&vec));
                 let mut cev: Vec<u8> = Vec::new();
                 let mut f = File::open(expect).unwrap();
                 f.read_to_end(&mut cev).unwrap();
                 println!("{}", String::from_utf8_lossy(&cev));
                 assert_eq!(vec, cev);
+            }
+        }
+    }
+}

testdata/parser/negative/20.txt

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testdata/parser/positive/20.pdl

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file renamed from testdata/parser/negative/20.pdl to testdata/parser/positive/20.pdl

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