ralix 0.2.0

A simple, type-safe, tree walking interpreter
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use crate::{
    Expression, Parser, ParserDiagnostic, ParserResult, Statement, Token,
    parser::expressions::Precedence, statements::Binding, types::Type,
};

impl Parser<'_> {
    /// Not really a function statement it's just a binding statement that
    /// the binding value and type is a function
    pub fn parse_function_statement(&mut self) -> ParserResult<Statement> {
        if self.is_peek_token(Token::LParen) || self.is_peek_token(Token::LBracket) {
            return Ok(Statement::Expression(self.parse_function_expression()?));
        }
        self.expect_ident()?;

        let ident = self.parse_identifier()?;

        let generics = if self.is_peek_token(Token::LBracket) {
            self.next_token();
            self.parse_generics()?
        } else {
            Vec::new()
        };

        // Define generics so while parsing arguments we don't get errors
        self.symbol_table.enter_scope();
        for g in &generics {
            self.symbol_table
                .define(g.name.clone(), Type::TypeVar(g.clone()), false);
        }

        self.expect_token(Token::LParen)?;
        let parameters = self.parse_function_parameters()?;
        self.consume_current_token(Token::RParen);

        let mut return_type = Type::Void;
        if !self.is_current_token(Token::Colon) {
            if !self.is_current_token(Token::ThinArrow) {
                self.symbol_table.leave_scope();
                return Err(ParserDiagnostic::SyntaxError {
                    expected: Token::ThinArrow,
                    got: self.current_token.clone(),
                });
            }
            self.consume_current_token(Token::ThinArrow);
            return_type = self.parse_type_definition()?;
            self.expect_token(Token::Colon)?;
        } else {
            self.next_token();
        }

        let body = Box::new(self.parse_expression(Precedence::Lowest)?);

        self.consume_peek_token(Token::SemiColon);

        // Drop generics
        self.symbol_table.leave_scope();

        Ok(Statement::Binding(Binding {
            ident,
            type_annotation: None,
            is_constant: false,
            value: Expression::Function {
                generics,
                parameters,
                return_type,
                body,
            },
        }))
    }
}