added a (very incomplete) C frontend for DSAC

compiler/src/frontend/c/lexer.rs

@@ -0,0 +1,336 @@
+// ============================================================================
+// Token Types
+// ============================================================================
+
+#[derive(Debug, Clone, PartialEq)]
+pub enum TokenType {
+    // Keywords
+    Int,
+    If,
+    Else,
+    While,
+    Return,
+    Include,
+
+    // Identifiers and literals
+    Identifier(String),
+    Number(i32),
+    String(String),
+    Char(char),
+
+    // Operators
+    Plus,
+    Minus,
+    Star,
+    Slash,
+    Assign,
+    Eq,
+    Ne,
+    Lt,
+    Gt,
+    Le,
+    Ge,
+
+    // Delimiters
+    LParen,
+    RParen,
+    LBrace,
+    RBrace,
+    Semicolon,
+    Comma,
+    Colon,
+    Namespace,
+
+    Eof,
+}
+
+#[allow(unused)]
+pub enum Type {
+    Int32,
+    Int16,
+    Int8,
+    Uint32,
+    Uint16,
+    Uint8,
+    Char,
+}
+
+#[derive(Debug, Clone)]
+pub struct Token {
+    pub token_type: TokenType,
+    pub line: usize,
+    pub col: usize,
+}
+
+impl Token {
+    pub fn new(token_type: TokenType, line: usize, col: usize) -> Self {
+        Self {
+            token_type,
+            line,
+            col,
+        }
+    }
+}
+
+// ============================================================================
+// Lexer
+// ============================================================================
+
+pub struct Lexer {
+    source: Vec<char>,
+    pos: usize,
+    line: usize,
+    col: usize,
+}
+
+impl Lexer {
+    pub fn new(source: &str) -> Self {
+        Self {
+            source: source.chars().collect(),
+            pos: 0,
+            line: 1,
+            col: 1,
+        }
+    }
+
+    fn error(&self, msg: &str) -> String {
+        format!(
+            "Lexer error at line {}, col {}: {}",
+            self.line, self.col, msg
+        )
+    }
+
+    fn peek(&self, offset: usize) -> Option<char> {
+        self.source.get(self.pos + offset).copied()
+    }
+
+    fn advance(&mut self) -> Option<char> {
+        if self.pos >= self.source.len() {
+            return None;
+        }
+        let ch = self.source[self.pos];
+        self.pos += 1;
+        if ch == '\n' {
+            self.line += 1;
+            self.col = 1;
+        } else {
+            self.col += 1;
+        }
+        Some(ch)
+    }
+
+    fn skip_whitespace(&mut self) {
+        while let Some(ch) = self.peek(0) {
+            if ch.is_whitespace() {
+                self.advance();
+            } else {
+                break;
+            }
+        }
+    }
+
+    fn skip_comment(&mut self) {
+        if self.peek(0) == Some('/') && self.peek(1) == Some('/') {
+            while let Some(ch) = self.peek(0) {
+                if ch == '\n' {
+                    break;
+                }
+                self.advance();
+            }
+        }
+    }
+
+    fn read_number(&mut self) -> i32 {
+        let mut num_str = String::new();
+        while let Some(ch) = self.peek(0) {
+            if ch.is_ascii_digit() {
+                num_str.push(ch);
+                self.advance();
+            } else {
+                break;
+            }
+        }
+        num_str.parse().unwrap_or(0)
+    }
+
+    fn read_identifier(&mut self) -> String {
+        let mut ident = String::new();
+        while let Some(ch) = self.peek(0) {
+            if ch.is_alphanumeric() || ch == '_' {
+                ident.push(ch);
+                self.advance();
+            } else {
+                break;
+            }
+        }
+        ident
+    }
+
+    fn read_string(&mut self) -> Result<String, String> {
+        let mut string = String::new();
+        self.advance(); // Consume the opening quote
+
+        while let Some(ch) = self.peek(0) {
+            if ch == '"' {
+                self.advance(); // Consume the closing quote
+                return Ok(string);
+            } else if ch == '\\' {
+                self.advance(); // Consume the backslash
+                if let Some(escaped_char) = self.peek(0) {
+                    string.push(escaped_char);
+                    self.advance();
+                }
+            } else {
+                string.push(ch);
+                self.advance();
+            }
+        }
+
+        Err(String::from("Unexpected EOF"))
+    }
+
+    fn read_char(&mut self) -> Result<char, String> {
+        self.advance(); // Consume the opening quote
+
+        if let Some(ch) = self.peek(0) {
+            self.advance();
+            if self.peek(0) == Some('\'') {
+                self.advance();
+                return Ok(ch);
+            } else {
+                Err(String::from("expected closing quote"))
+            }
+        } else {
+            Err(String::from("expected character"))
+        }
+    }
+
+    pub fn tokenize(&mut self) -> Result<Vec<Token>, String> {
+        let mut tokens = Vec::new();
+
+        loop {
+            self.skip_whitespace();
+            self.skip_comment();
+
+            if self.pos >= self.source.len() {
+                break;
+            }
+
+            let line = self.line;
+            let col = self.col;
+            let ch = self.peek(0).unwrap();
+
+            let token_type = if ch.is_ascii_digit() {
+                let num = self.read_number();
+                TokenType::Number(num)
+            } else if ch == '"' {
+                let string = self.read_string()?;
+                TokenType::String(string)
+            } else if ch == '\'' {
+                let char = self.read_char()?;
+                TokenType::Char(char)
+            } else if ch.is_alphabetic() || ch == '_' {
+                let ident = self.read_identifier();
+                match ident.as_str() {
+                    "int" => TokenType::Int,
+                    "if" => TokenType::If,
+                    "else" => TokenType::Else,
+                    "while" => TokenType::While,
+                    "return" => TokenType::Return,
+                    "include" => TokenType::Include,
+                    _ => TokenType::Identifier(ident),
+                }
+            } else {
+                match ch {
+                    ':' if self.peek(1) == Some(':') => {
+                        self.advance();
+                        self.advance();
+                        TokenType::Namespace
+                    }
+                    ':' => {
+                        self.advance();
+                        TokenType::Colon
+                    }
+                    '=' if self.peek(1) == Some('=') => {
+                        self.advance();
+                        self.advance();
+                        TokenType::Eq
+                    }
+                    '!' if self.peek(1) == Some('=') => {
+                        self.advance();
+                        self.advance();
+                        TokenType::Ne
+                    }
+                    '<' if self.peek(1) == Some('=') => {
+                        self.advance();
+                        self.advance();
+                        TokenType::Le
+                    }
+                    '>' if self.peek(1) == Some('=') => {
+                        self.advance();
+                        self.advance();
+                        TokenType::Ge
+                    }
+                    '+' => {
+                        self.advance();
+                        TokenType::Plus
+                    }
+                    '-' => {
+                        self.advance();
+                        TokenType::Minus
+                    }
+                    '*' => {
+                        self.advance();
+                        TokenType::Star
+                    }
+                    '/' => {
+                        self.advance();
+                        TokenType::Slash
+                    }
+                    '=' => {
+                        self.advance();
+                        TokenType::Assign
+                    }
+                    '<' => {
+                        self.advance();
+                        TokenType::Lt
+                    }
+                    '>' => {
+                        self.advance();
+                        TokenType::Gt
+                    }
+                    '(' => {
+                        self.advance();
+                        TokenType::LParen
+                    }
+                    ')' => {
+                        self.advance();
+                        TokenType::RParen
+                    }
+                    '{' => {
+                        self.advance();
+                        TokenType::LBrace
+                    }
+                    '}' => {
+                        self.advance();
+                        TokenType::RBrace
+                    }
+                    ';' => {
+                        self.advance();
+                        TokenType::Semicolon
+                    }
+                    ',' => {
+                        self.advance();
+                        TokenType::Comma
+                    }
+                    _ => return Err(self.error(&format!("Unexpected character: {}", ch))),
+                }
+            };
+
+            tokens.push(Token::new(token_type, line, col));
+        }
+
+        tokens.push(Token::new(TokenType::Eof, self.line, self.col));
+        Ok(tokens)
+    }
+}

compiler/src/frontend/c/mod.rs

@@ -0,0 +1,25 @@
+use common::logging::log;
+
+use crate::model::{CompilerError, Program};
+use parser::Parser;
+
+pub mod lexer;
+pub mod parser;
+
+pub fn generate_ast(input: &str) -> Result<Program, CompilerError> {
+    log("Tokenising Input...");
+
+    let mut lexer = lexer::Lexer::new(&input);
+    let tokens = lexer.tokenize().map_err(|e| CompilerError::Generic(e))?;
+    // println!("{tokens:?}");
+
+    log(&format!("Parsing {} Tokens...", tokens.len()));
+
+    let mut parser = Parser::new(tokens);
+    let ast = match parser.parse() {
+        Ok(ast) => ast,
+        Err(e) => return Err(CompilerError::Generic(e)),
+    };
+
+    Ok(ast)
+}

compiler/src/frontend/c/parser.rs

@@ -0,0 +1,471 @@
+// ============================================================================
+// AST Node Types
+// ============================================================================
+
+use crate::model::{
+    BinaryOperator, Block, ConstExpr, Declaration, Dependency, Expression, Name, Program,
+    Statement, TypeId, UnaryOperator, Variable,
+};
+
+use super::lexer::{Token, TokenType};
+
+// ============================================================================
+// Parser
+// ============================================================================
+
+pub struct Parser {
+    tokens: Vec<Token>,
+    pos: usize,
+}
+
+impl Parser {
+    pub fn new(tokens: Vec<Token>) -> Self {
+        Self { tokens, pos: 0 }
+    }
+
+    fn error(&self, msg: &str) -> String {
+        let token = self.current();
+        format!(
+            "Parser error at line {}, col {}: {}",
+            token.line, token.col, msg
+        )
+    }
+
+    fn current(&self) -> &Token {
+        self.tokens
+            .get(self.pos)
+            .unwrap_or_else(|| self.tokens.last().unwrap())
+    }
+
+    fn peek(&self, offset: usize) -> &Token {
+        self.tokens
+            .get(self.pos + offset)
+            .unwrap_or_else(|| self.tokens.last().unwrap())
+    }
+
+    fn advance(&mut self) -> &Token {
+        if self.pos < self.tokens.len() - 1 {
+            self.pos += 1;
+        }
+        self.current()
+    }
+
+    fn expect(&mut self, expected: TokenType) -> Result<Token, String> {
+        let token = self.current().clone();
+        if std::mem::discriminant(&token.token_type) != std::mem::discriminant(&expected)
+        {
+            return Err(self.error(&format!(
+                "Expected {:?}, got {:?}",
+                expected, token.token_type
+            )));
+        }
+        self.advance();
+        Ok(token)
+    }
+
+    pub fn parse(&mut self) -> Result<Program, String> {
+        let mut declarations = Vec::new();
+
+        while !matches!(self.current().token_type, TokenType::Eof) {
+            declarations.push(self.parse_declaration()?);
+        }
+
+        Ok(Program { declarations })
+    }
+
+    fn parse_declaration(&mut self) -> Result<Declaration, String> {
+        // check for an import
+        if let TokenType::Include = self.current().token_type {
+            self.advance();
+
+            let name =
+                if let TokenType::Identifier(id) = self.current().clone().token_type {
+                    Some(id)
+                } else {
+                    None
+                }
+                .ok_or(String::from("Expected identifier"))?;
+
+            self.advance();
+            self.expect(TokenType::Colon)?;
+
+            let path = if let TokenType::String(id) = self.current().clone().token_type {
+                Some(id)
+            } else {
+                None
+            }
+            .ok_or(String::from("Expected string literal"))?;
+
+            self.advance();
+            return Ok(Declaration::Dependency(Dependency { name, path }));
+        }
+
+        self.expect(TokenType::Int)?;
+
+        let name = match &self.current().token_type {
+            TokenType::Identifier(s) => s.clone(),
+            _ => return Err(self.error("Expected identifier")),
+        };
+        self.advance();
+
+        match &self.current().token_type {
+            TokenType::LParen => {
+                // Function declaration
+                self.advance();
+                let mut params = Vec::<Variable>::new();
+
+                if !matches!(self.current().token_type, TokenType::RParen) {
+                    self.expect(TokenType::Int)?;
+
+                    match &self.current().token_type {
+                        TokenType::Identifier(s) => {
+                            params.push(Variable {
+                                name: s.clone(),
+                                type_id: TypeId::U32,
+                            });
+                            self.advance();
+                        }
+                        _ => return Err(self.error("Expected parameter name")),
+                    }
+
+                    while matches!(self.current().token_type, TokenType::Comma) {
+                        self.advance();
+                        self.expect(TokenType::Int)?;
+
+                        match &self.current().token_type {
+                            TokenType::Identifier(s) => {
+                                params.push(Variable {
+                                    name: s.clone(),
+                                    type_id: TypeId::U32,
+                                });
+                                self.advance();
+                            }
+                            _ => return Err(self.error("Expected parameter name")),
+                        }
+                    }
+                }
+
+                self.expect(TokenType::RParen)?;
+                let body = self.parse_block()?;
+
+                Ok(Declaration::Function {
+                    name,
+                    params,
+                    body,
+                    return_type: TypeId::U32,
+                })
+            }
+            _ => {
+                // Variable declaration
+                let init = if matches!(self.current().token_type, TokenType::Assign) {
+                    self.advance();
+
+                    if let TokenType::Number(n) = self.current().token_type {
+                        self.advance();
+                        Some(ConstExpr::Number(n))
+                    } else {
+                        return Err(self
+                            .error("Expected constant in global variable declaration"));
+                    }
+                } else {
+                    None
+                };
+
+                self.expect(TokenType::Semicolon)?;
+                Ok(Declaration::Variable {
+                    var: Variable {
+                        name,
+                        type_id: TypeId::U32,
+                    },
+                    init,
+                    is_const: false,
+                })
+            }
+        }
+    }
+
+    fn parse_block(&mut self) -> Result<Block, String> {
+        self.expect(TokenType::LBrace)?;
+        let mut statements = Vec::new();
+
+        while !matches!(self.current().token_type, TokenType::RBrace) {
+            statements.push(self.parse_statement()?);
+        }
+
+        self.expect(TokenType::RBrace)?;
+        Ok(statements)
+    }
+
+    fn parse_statement(&mut self) -> Result<Statement, String> {
+        match &self.current().token_type {
+            TokenType::LBrace => Ok(Statement::Block(self.parse_block()?)),
+            TokenType::If => self.parse_if_stmt(),
+            TokenType::While => self.parse_while_stmt(),
+            TokenType::Return => self.parse_return_stmt(),
+            TokenType::Identifier(name) => {
+                let name = name.clone();
+
+                // peek ahead for open paren (func call expr)
+                if matches!(self.peek(1).token_type, TokenType::LParen) {
+                    let expr = self.parse_expression()?; // a function call expr
+                    self.expect(TokenType::Semicolon)?;
+                    return Ok(Statement::Expression { expr });
+                }
+
+                self.advance(); // advance past identifier
+
+                // assignment expression
+                if matches!(self.current().token_type, TokenType::Assign) {
+                    self.advance();
+                    let expr = self.parse_expression()?;
+
+                    self.expect(TokenType::Semicolon)?;
+                    Ok(Statement::Assign {
+                        varname: name,
+                        value: expr,
+                    })
+                }
+                // var expression
+                else {
+                    self.expect(TokenType::Semicolon)?;
+                    Ok(Statement::Expression {
+                        expr: Expression::Variable {
+                            name: Name {
+                                name,
+                                namespace: None,
+                            },
+                            expr_type: None,
+                        },
+                    })
+                }
+            }
+            TokenType::Int => {
+                // Local variable declaration
+                self.advance();
+                let name = match &self.current().token_type {
+                    TokenType::Identifier(s) => s.clone(),
+                    _ => return Err(self.error("Expected variable name")),
+                };
+                self.advance();
+
+                let init = if matches!(self.current().token_type, TokenType::Assign) {
+                    self.advance();
+                    Some(self.parse_expression()?)
+                } else {
+                    None
+                };
+
+                self.expect(TokenType::Semicolon)?;
+
+                // Convert to assignment expression statement
+                let expr = if let Some(init_expr) = init {
+                    Statement::Assign {
+                        varname: name,
+                        value: init_expr,
+                    }
+                } else {
+                    Statement::Assign {
+                        varname: name,
+                        value: Expression::Empty,
+                    }
+                };
+
+                Ok(expr)
+            }
+            _ => {
+                let expr = if matches!(self.current().token_type, TokenType::Semicolon) {
+                    Expression::Empty
+                } else {
+                    self.parse_expression()?
+                };
+
+                self.expect(TokenType::Semicolon)?;
+                Ok(Statement::Expression { expr })
+            }
+        }
+    }
+
+    fn parse_if_stmt(&mut self) -> Result<Statement, String> {
+        self.expect(TokenType::If)?;
+        self.expect(TokenType::LParen)?;
+        let condition = self.parse_expression()?;
+        self.expect(TokenType::RParen)?;
+        let then_stmt = self.parse_block()?;
+
+        let else_stmt = if matches!(self.current().token_type, TokenType::Else) {
+            self.advance();
+            self.parse_block()?
+        } else {
+            Vec::new()
+        };
+
+        Ok(Statement::If {
+            condition,
+            then_stmt,
+            else_stmt,
+        })
+    }
+
+    fn parse_while_stmt(&mut self) -> Result<Statement, String> {
+        self.expect(TokenType::While)?;
+        self.expect(TokenType::LParen)?;
+        let condition = self.parse_expression()?;
+        self.expect(TokenType::RParen)?;
+        let body = self.parse_block()?;
+
+        Ok(Statement::While { condition, body })
+    }
+
+    fn parse_return_stmt(&mut self) -> Result<Statement, String> {
+        self.expect(TokenType::Return)?;
+
+        let expr = if matches!(self.current().token_type, TokenType::Semicolon) {
+            None
+        } else {
+            Some(self.parse_expression()?)
+        };
+
+        self.expect(TokenType::Semicolon)?;
+        Ok(Statement::Return(expr))
+    }
+
+    fn parse_expression(&mut self) -> Result<Expression, String> {
+        self.parse_comparison()
+    }
+
+    fn parse_comparison(&mut self) -> Result<Expression, String> {
+        let mut expr = self.parse_additive()?;
+
+        while let Some(op) = match &self.current().token_type {
+            TokenType::Eq => Some(BinaryOperator::Eq),
+            TokenType::Ne => Some(BinaryOperator::Ne),
+            TokenType::Lt => Some(BinaryOperator::Lt),
+            TokenType::Gt => Some(BinaryOperator::Gt),
+            TokenType::Le => Some(BinaryOperator::Le),
+            TokenType::Ge => Some(BinaryOperator::Ge),
+            _ => None,
+        } {
+            self.advance();
+            let right = Box::new(self.parse_additive()?);
+            expr = Expression::Binary {
+                op,
+                left: Box::new(expr),
+                right,
+            };
+        }
+
+        Ok(expr)
+    }
+
+    fn parse_additive(&mut self) -> Result<Expression, String> {
+        let mut expr = self.parse_multiplicative()?;
+
+        while let Some(op) = match &self.current().token_type {
+            TokenType::Plus => Some(BinaryOperator::Add),
+            TokenType::Minus => Some(BinaryOperator::Sub),
+            _ => None,
+        } {
+            self.advance();
+            let right = Box::new(self.parse_multiplicative()?);
+            expr = Expression::Binary {
+                op,
+                left: Box::new(expr),
+                right,
+            };
+        }
+
+        Ok(expr)
+    }
+
+    fn parse_multiplicative(&mut self) -> Result<Expression, String> {
+        let mut expr = self.parse_unary()?;
+
+        while let Some(op) = match &self.current().token_type {
+            TokenType::Star => Some(BinaryOperator::Mul),
+            TokenType::Slash => Some(BinaryOperator::Div),
+            _ => None,
+        } {
+            self.advance();
+            let right = Box::new(self.parse_unary()?);
+            expr = Expression::Binary {
+                op,
+                left: Box::new(expr),
+                right,
+            };
+        }
+
+        Ok(expr)
+    }
+
+    fn parse_unary(&mut self) -> Result<Expression, String> {
+        let op = match &self.current().token_type {
+            TokenType::Plus => Some(UnaryOperator::Plus),
+            TokenType::Minus => Some(UnaryOperator::Minus),
+            _ => None,
+        };
+
+        if let Some(op) = op {
+            self.advance();
+            let operand = Box::new(self.parse_unary()?);
+            return Ok(Expression::Unary { op, operand });
+        }
+
+        self.parse_primary()
+    }
+
+    fn parse_primary(&mut self) -> Result<Expression, String> {
+        match &self.current().token_type.clone() {
+            TokenType::Number(n) => {
+                let value = *n;
+                self.advance();
+                Ok(Expression::Number(value as isize))
+            }
+            TokenType::Identifier(name) => {
+                let name = name.clone();
+                self.advance();
+
+                if matches!(self.current().token_type, TokenType::LParen) {
+                    // Function call
+                    self.advance();
+                    let mut args = Vec::new();
+
+                    if !matches!(self.current().token_type, TokenType::RParen) {
+                        args.push(self.parse_expression()?);
+
+                        while matches!(self.current().token_type, TokenType::Comma) {
+                            self.advance();
+                            args.push(self.parse_expression()?);
+                        }
+                    }
+
+                    self.expect(TokenType::RParen)?;
+                    Ok(Expression::Call {
+                        name: Name {
+                            name,
+                            namespace: None,
+                        },
+                        args,
+                    })
+                } else {
+                    Ok(Expression::Variable {
+                        name: Name {
+                            name,
+                            namespace: None,
+                        },
+                        expr_type: None,
+                    })
+                }
+            }
+            TokenType::LParen => {
+                self.advance();
+                let expr = self.parse_expression()?;
+                self.expect(TokenType::RParen)?;
+                Ok(expr)
+            }
+            _ => Err(self.error(&format!(
+                "Unexpected token: {:?}",
+                self.current().token_type
+            ))),
+        }
+    }
+}