Arg::new("threads")

                .long("threads")

                .short('t')

                .help("number of runtime threads")

                .default_value("1")

                .takes_value(true)

        )

        .arg(

            Arg::new("debug")

                .long("debug")

                .short('d')

                .help("enable debug logging")

        );

    // Retrieve arguments and convert

    let app = app.get_matches();

    let input_files = app.values_of("input");

    if input_files.is_none() {

        println!("ERROR: Expected at least one input file");

        return;

    }

    let num_threads = app.value_of("threads").unwrap();

    let num_threads = match num_threads.parse::<i32>() {

            }

            num_threads as u32

        },

        Err(err) => {

            println!("ERROR: Failed to parse number of threads\nbecause: {}", err);

            return;

        }

    };

    let debug_enabled = app.is_present("debug");

    // Add input files to file buffer

    let input_files = input_files.unwrap();

    assert!(input_files.len() > 0); // because arg is required

    let mut file_buffer = Vec::with_capacity(4096);

    for input_file in input_files {

        print!("Adding file: {} ... ", input_file);

        let mut file = match File::open(input_file) {

            Ok(file) => file,

            Err(err) => {

                println!("FAILED (to open file)\nbecause:\n{}", err);

                return;

            }

        };

    // Compile the program

    print!("Compiling program ... ");

    let protocol_description = match builder.compile() {

        Ok(pd) => pd,

        Err(err) => {

            println!("FAILED\nbecause:\n{}", err);

            return;

        }

    };

    println!("Success");

    // Make sure there is a nameless module with a main component

    print!("Creating main component ... ");

    if let Err(err) = runtime.create_component(b"", b"main") {

        use rw::ComponentCreationError as CCE;

        let reason = match err {

            CCE::ModuleDoesntExist => "Input files did not contain a nameless module (that should contain the 'main' component)",

            CCE::DefinitionDoesntExist => "Input files did not contain a component called 'main'",

            CCE::DefinitionNotComponent => "Input file contained a 'main' function, but not a 'main' component",

            _ => "Unexpected error"

        };

        println!("FAILED\nbecause:\n{} (raw error: {:?})", reason, err);

        return;

    }

    ModuleDoesntExist,

    DefinitionDoesntExist,

    DefinitionNotComponent,

    InvalidNumArguments,

    InvalidArgumentType(usize),

    UnownedPort,

    InSync,

}

impl ProtocolDescription {

    pub fn parse(buffer: &[u8]) -> Result<Self, String> {

        let source = InputSource::new(String::new(), Vec::from(buffer));

        parser.feed(source).expect("failed to feed source");

        if let Err(err) = parser.parse() {

            println!("ERROR:\n{}", err);

            return Err(format!("{}", err))

        }

        let modules: Vec<Module> = parser.modules.into_iter()

            .map(|module| Module{

                source: module.source,

                root_id: module.root_id,

                name: module.name.map(|(_, name)| name)

    fn performed_get(&mut self, port: PortId) -> Option<ValueGroup>; // None if still waiting on message

    fn fires(&mut self, port: PortId) -> Option<Value>; // None if not yet branched

    fn performed_fork(&mut self) -> Option<bool>; // None if not yet forked

    fn created_channel(&mut self) -> Option<(Value, Value)>; // None if not yet prepared

    fn performed_select_wait(&mut self) -> Option<u32>; // None if not yet notified runtime of select blocker

}

pub struct ProtocolDescriptionBuilder {

    parser: Parser,

}

impl ProtocolDescriptionBuilder {

    }

    pub fn add(&mut self, filename: String, buffer: Vec<u8>) -> Result<(), ParseError> {

        let input = InputSource::new(filename, buffer);

        self.parser.feed(input)?;

        return Ok(())

    }

    pub fn compile(mut self) -> Result<ProtocolDescription, ParseError> {

        self.parser.parse()?;

    // around.

    pass_tokenizer: PassTokenizer,

    pass_symbols: PassSymbols,

    pass_import: PassImport,

    pass_definitions: PassDefinitions,

    pass_validation: PassValidationLinking,

    pass_typing: PassTyping,

    pass_rewriting: PassRewriting,

    pass_stack_size: PassStackSize,

    // Compiler options

    pub write_tokens_to: Option<String>,

    pub write_ast_to: Option<String>,

    pub(crate) arch: TargetArch,

}

impl Parser {

        let mut parser = Parser{

            heap: Heap::new(),

            string_pool: StringPool::new(),

            modules: Vec::new(),

            symbol_table: SymbolTable::new(),

            type_table: TypeTable::new(),

            global_module_index: 0,

            pass_tokenizer: PassTokenizer::new(),

            pass_symbols: PassSymbols::new(),

            pass_import: PassImport::new(),

            pass_definitions: PassDefinitions::new(),

            pass_validation: PassValidationLinking::new(),

            pass_typing: PassTyping::new(),

            pass_rewriting: PassRewriting::new(),

            pass_stack_size: PassStackSize::new(),

            write_tokens_to: None,

            write_ast_to: None,

            arch: TargetArch::new(),

        };

        parser.symbol_table.insert_scope(None, SymbolScope::Global);

        // Insert builtin types

        // TODO: At some point use correct values for size/alignment

        parser.arch.void_type_id    = insert_builtin_type(&mut parser.type_table, vec![ConcreteTypePart::Void], false, 0, 1);

        parser.arch.message_type_id = insert_builtin_type(&mut parser.type_table, vec![ConcreteTypePart::Message], false, 24, 8);

        parser.arch.bool_type_id    = insert_builtin_type(&mut parser.type_table, vec![ConcreteTypePart::Bool], false, 1, 1);

        parser.arch.uint8_type_id   = insert_builtin_type(&mut parser.type_table, vec![ConcreteTypePart::UInt8], false, 1, 1);

        parser.arch.uint16_type_id  = insert_builtin_type(&mut parser.type_table, vec![ConcreteTypePart::UInt16], false, 2, 2);

        // Pair is (name, add_to_global_namespace)

        const FILES: [(&'static str, bool); 3] = [

            ("std.global.pdl", true),

            ("std.internet.pdl", false),

            ("std.random.pdl", false),

        ];

        // Determine base directory

        let (base_path, from_env) = if let Ok(path) = env::var(REOWOLF_PATH_ENV) {

            // Path variable is set

            (path, true)

        } else {

            (path, false)

        };

        // Make sure directory exists

        let path = Path::new(&base_path);

        if !path.exists() {

            return Err(format!("std lib root directory '{}' does not exist", base_path));

        }

        // Try to load all standard library files. We might need a more unified

        // way to do this in the future (i.e. a "std" package, containing all

        // of the modules)

        Self::new(test_name)

            .with_source(source)

            .compile()

            .expect_err()

    }

    pub(crate) fn with_source<S: ToString>(mut self, source: S) -> Self {

        self.sources.push(source.to_string());

        self

    }

    pub(crate) fn compile(self) -> AstTesterResult {

        for source in self.sources.into_iter() {

            let source = source.into_bytes();

            let input_source = InputSource::new(String::from(""), source);

            if let Err(err) = parser.feed(input_source) {

                return AstTesterResult::Err(AstErrTester::new(self.test_name, err))

            }

        }

        if let Err(err) = parser.parse() {

            return AstTesterResult::Err(AstErrTester::new(self.test_name, err))