parse blocks

src/codegen.rs

@@ -83,6 +83,21 @@ section .note.GNU-stack
                 env.locals.insert(name.lexeme, offset);
                 writeln!(&mut self.output, "    mov QWORD [rbp-{}], rax", offset)?;
             }
+            Stmt::Block(statements) => {
+                let mut env = Env::new();
+                for stmt in statements {
+                    self.compile_stmt(&mut env, stmt)?;
+                }
+            }
+            Stmt::If {
+                condition: _,
+                then_branch: _,
+                else_branch: _,
+            } => todo!(),
+            Stmt::While {
+                condition: _,
+                body: _,
+            } => todo!(),
         }
         Ok(())
     }

src/parser.rs

@@ -1,10 +1,25 @@
+use std::error::Error;
+
 use crate::tokenizer::{MotError, Token, TokenType, error};
 
 #[derive(Debug, Clone)]
 pub enum Stmt {
     Expression(Expr),
     Print(Expr),
-    Var { name: Token, initializer: Expr },
+    Var {
+        name: Token,
+        initializer: Expr,
+    },
+    Block(Vec<Stmt>),
+    If {
+        condition: Expr,
+        then_branch: Box<Stmt>,
+        else_branch: Option<Box<Stmt>>,
+    },
+    While {
+        condition: Expr,
+        body: Box<Stmt>,
+    },
 }
 
 #[derive(Debug, Clone)]
@@ -37,7 +52,7 @@ impl Parser {
         Parser { tokens, current: 0 }
     }
 
-    pub fn parse(mut self) -> Result<Vec<Stmt>, MotError> {
+    pub fn parse(mut self) -> Result<Vec<Stmt>, Box<dyn Error>> {
         let mut statements = vec![];
         while !self.eof() {
             statements.push(self.declaration()?);
@@ -45,7 +60,7 @@ impl Parser {
         Ok(statements)
     }
 
-    fn declaration(&mut self) -> Result<Stmt, MotError> {
+    fn declaration(&mut self) -> Result<Stmt, Box<dyn Error>> {
         // TODO: synchronization after parse error
         if self.match_token(&[TokenType::KeywordLet]) {
             self.let_declaration()
@@ -54,27 +69,70 @@ impl Parser {
         }
     }
 
-    fn let_declaration(&mut self) -> Result<Stmt, MotError> {
+    fn let_declaration(&mut self) -> Result<Stmt, Box<dyn Error>> {
         let name = self.consume(TokenType::Identifier, "expected variable name")?;
         self.consume(TokenType::Equal, "expected '=' after variable name")?;
         let initializer = self.expression()?;
         Ok(Stmt::Var { name, initializer })
     }
 
-    fn statement(&mut self) -> Result<Stmt, MotError> {
+    fn block(&mut self) -> Result<Stmt, Box<dyn Error>> {
+        self.consume(TokenType::Indent, "expected an indent")?;
+
+        let mut statements = vec![];
+        while !self.eof() && !self.match_token(&[TokenType::Dedent]) {
+            statements.push(self.declaration()?);
+        }
+
+        Ok(Stmt::Block(statements))
+    }
+
+    fn statement(&mut self) -> Result<Stmt, Box<dyn Error>> {
         if self.match_token(&[TokenType::KeywordPrint]) {
             Ok(Stmt::Print(self.expression()?))
+        } else if self.match_token(&[TokenType::KeywordIf]) {
+            self.if_statement()
+        } else if self.match_token(&[TokenType::KeywordWhile]) {
+            self.while_statement()
         } else {
             Ok(Stmt::Expression(self.expression()?))
         }
     }
 
-    fn expression(&mut self) -> Result<Expr, MotError> {
+    fn if_statement(&mut self) -> Result<Stmt, Box<dyn Error>> {
+        let condition = self.expression()?;
+        let then_branch = self.block()?;
+        let else_branch = if self.match_token(&[TokenType::KeywordElse]) {
+            if self.match_token(&[TokenType::KeywordIf]) {
+                Some(Box::new(self.if_statement()?))
+            } else {
+                Some(Box::new(self.block()?))
+            }
+        } else {
+            None
+        };
+        Ok(Stmt::If {
+            condition,
+            then_branch: Box::new(then_branch),
+            else_branch,
+        })
+    }
+
+    fn while_statement(&mut self) -> Result<Stmt, Box<dyn Error>> {
+        let condition = self.expression()?;
+        let body = self.block()?;
+        Ok(Stmt::While {
+            condition,
+            body: Box::new(body),
+        })
+    }
+
+    fn expression(&mut self) -> Result<Expr, Box<dyn Error>> {
         self.assignment()
     }
 
-    fn assignment(&mut self) -> Result<Expr, MotError> {
+    fn assignment(&mut self) -> Result<Expr, Box<dyn Error>> {
-        let expr = self.equality()?;
+        let expr = self.logical_or()?;
 
         if self.match_token(&[TokenType::Equal]) {
             let equals = self.previous().clone();
@@ -92,7 +150,39 @@ impl Parser {
         Ok(expr)
     }
 
-    fn equality(&mut self) -> Result<Expr, MotError> {
+    fn logical_or(&mut self) -> Result<Expr, Box<dyn Error>> {
+        let mut expr = self.logical_and()?;
+
+        while self.match_token(&[TokenType::Or]) {
+            let op = self.previous().clone();
+            let right = self.logical_and()?;
+            expr = Expr::Binary {
+                left: Box::new(expr),
+                op,
+                right: Box::new(right),
+            }
+        }
+
+        Ok(expr)
+    }
+
+    fn logical_and(&mut self) -> Result<Expr, Box<dyn Error>> {
+        let mut expr = self.equality()?;
+
+        while self.match_token(&[TokenType::And]) {
+            let op = self.previous().clone();
+            let right = self.equality()?;
+            expr = Expr::Binary {
+                left: Box::new(expr),
+                op,
+                right: Box::new(right),
+            }
+        }
+
+        Ok(expr)
+    }
+
+    fn equality(&mut self) -> Result<Expr, Box<dyn Error>> {
         let mut expr = self.comparison()?;
 
         while self.match_token(&[TokenType::DoubleEqual, TokenType::NotEqual]) {
@@ -108,7 +198,7 @@ impl Parser {
         Ok(expr)
     }
 
-    fn comparison(&mut self) -> Result<Expr, MotError> {
+    fn comparison(&mut self) -> Result<Expr, Box<dyn Error>> {
         let mut expr = self.term()?;
 
         while self.match_token(&[
@@ -129,7 +219,7 @@ impl Parser {
         Ok(expr)
     }
 
-    fn term(&mut self) -> Result<Expr, MotError> {
+    fn term(&mut self) -> Result<Expr, Box<dyn Error>> {
         let mut expr = self.factor()?;
 
         while self.match_token(&[TokenType::Plus, TokenType::Minus, TokenType::Xor]) {
@@ -145,7 +235,7 @@ impl Parser {
         Ok(expr)
     }
 
-    fn factor(&mut self) -> Result<Expr, MotError> {
+    fn factor(&mut self) -> Result<Expr, Box<dyn Error>> {
         let mut expr = self.unary()?;
 
         while self.match_token(&[TokenType::Star, TokenType::Slash, TokenType::Mod]) {
@@ -161,7 +251,7 @@ impl Parser {
         Ok(expr)
     }
 
-    fn unary(&mut self) -> Result<Expr, MotError> {
+    fn unary(&mut self) -> Result<Expr, Box<dyn Error>> {
         if self.match_token(&[TokenType::Bang, TokenType::Minus]) {
             let op = self.previous().clone();
             let right = self.unary()?;
@@ -174,7 +264,7 @@ impl Parser {
         self.primary()
     }
 
-    fn primary(&mut self) -> Result<Expr, MotError> {
+    fn primary(&mut self) -> Result<Expr, Box<dyn Error>> {
         if self.match_token(&[TokenType::Number, TokenType::String]) {
             Ok(Expr::Literal(self.previous().clone()))
         } else if self.match_token(&[TokenType::LeftParen]) {
@@ -188,7 +278,7 @@ impl Parser {
         }
     }
 
-    fn consume(&mut self, token_type: TokenType, message: &str) -> Result<Token, MotError> {
+    fn consume(&mut self, token_type: TokenType, message: &str) -> Result<Token, Box<dyn Error>> {
         if self.check(&token_type) {
             Ok(self.advance().clone())
         } else {

src/tokenizer.rs

@@ -1,4 +1,4 @@
-use std::fmt;
+use std::{cmp::Ordering, error::Error, fmt};
 
 #[derive(Debug, Clone, PartialEq)]
 pub enum TokenType {
@@ -32,7 +32,12 @@ pub enum TokenType {
 
     KeywordPrint,
     KeywordLet,
+    KeywordIf,
+    KeywordElse,
+    KeywordWhile,
 
+    Indent,
+    Dedent,
     Eof,
 }
 
@@ -52,10 +57,10 @@ impl std::error::Error for MotError {}
 
 macro_rules! error {
     ($loc:expr, $msg:expr) => {
-        Err(MotError {
+        Err(Box::new(MotError {
             loc: $loc.clone(),
             message: $msg.into(),
-        })
+        }))
     };
 }
 
@@ -84,6 +89,8 @@ pub struct Token {
 pub struct Tokenizer {
     source: Vec<char>,
     tokens: Vec<Token>,
+    indent_stack: Vec<usize>,
+    current_indent: usize,
     start: usize,
     current: usize,
     loc: Loc,
@@ -94,6 +101,8 @@ impl Tokenizer {
         Tokenizer {
             source: source.chars().collect(),
             tokens: vec![],
+            indent_stack: vec![0],
+            current_indent: 0,
             start: 0,
             current: 0,
             loc: Loc {
@@ -104,7 +113,7 @@ impl Tokenizer {
         }
     }
 
-    pub fn tokenize(mut self) -> Result<Vec<Token>, MotError> {
+    pub fn tokenize(mut self) -> Result<Vec<Token>, Box<dyn Error>> {
         while !self.eof() {
             self.start = self.current;
             self.scan_token()?;
@@ -118,7 +127,7 @@ impl Tokenizer {
         Ok(self.tokens)
     }
 
-    fn scan_token(&mut self) -> Result<(), MotError> {
+    fn scan_token(&mut self) -> Result<(), Box<dyn Error>> {
         match self.advance() {
             '(' => self.add_token(TokenType::LeftParen),
             ')' => self.add_token(TokenType::RightParen),
@@ -202,6 +211,7 @@ impl Tokenizer {
             '\n' => {
                 self.loc.line += 1;
                 self.loc.column = 1;
+                self.handle_indentation()?;
             }
             '0'..='9' => self.scan_number(),
             'A'..='Z' | 'a'..='z' | '_' => self.scan_identifier(),
@@ -210,6 +220,59 @@ impl Tokenizer {
         Ok(())
     }
 
+    fn handle_indentation(&mut self) -> Result<(), Box<dyn Error>> {
+        if self.peek() == '\n' {
+            return Ok(());
+        }
+        let new_indent = self.count_indentation();
+
+        match new_indent.cmp(&self.current_indent) {
+            Ordering::Greater => {
+                self.indent_stack.push(new_indent);
+                self.tokens.push(Token {
+                    token_type: TokenType::Indent,
+                    lexeme: String::new(),
+                    loc: self.loc.clone(),
+                });
+            }
+            Ordering::Less => {
+                while !self.indent_stack.is_empty()
+                    && *self.indent_stack.last().unwrap() > new_indent
+                {
+                    self.indent_stack.pop();
+                    self.tokens.push(Token {
+                        token_type: TokenType::Dedent,
+                        lexeme: String::new(),
+                        loc: self.loc.clone(),
+                    });
+                }
+                if self.indent_stack.is_empty() || *self.indent_stack.last().unwrap() != new_indent
+                {
+                    return error!(self.loc, "invalid indentation");
+                }
+            }
+            Ordering::Equal => {}
+        }
+
+        self.current_indent = new_indent;
+        Ok(())
+    }
+
+    fn count_indentation(&mut self) -> usize {
+        let mut count = 0;
+
+        while self.peek() == ' ' || self.peek() == '\t' {
+            if self.peek() == ' ' {
+                count += 1;
+            }
+            if self.peek() == '\t' {
+                count += 4;
+            }
+            self.advance();
+        }
+        count
+    }
+
     fn scan_number(&mut self) {
         while self.peek().is_ascii_digit() {
             self.advance();
@@ -234,6 +297,9 @@ impl Tokenizer {
         self.add_token(match lexeme.as_str() {
             "print" => TokenType::KeywordPrint,
             "let" => TokenType::KeywordLet,
+            "if" => TokenType::KeywordIf,
+            "else" => TokenType::KeywordElse,
+            "while" => TokenType::KeywordWhile,
             _ => TokenType::Identifier,
         })
     }

test.mot

@@ -1,6 +1,8 @@
-let a = 5
+let a = 0
-let b = 7
+let b = 1
-print(b - a)
+let temp = 0
-a = 4
+
-print(b - a)
+while a < 10000
-print(b)
+    print a
+    temp = a
+    b = temp + b