src/error.rs

@@ -1,41 +0,0 @@
-use std::{error::Error, fmt::Display};
-
-#[derive(Debug)]
-pub struct ParseError {
-    message: String
-}
-
-impl ParseError {
-    pub fn new(message: impl Into<String>) -> Self {
-        Self { message: message.into() }
-    }
-}
-
-impl Display for ParseError {
-    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-        write!(f, "parse error: {}", self.message)
-    }
-}
-
-impl Error for ParseError {}
-
-
-
-#[derive(Debug)]
-pub struct LexError {
-    message: String
-}
-
-impl LexError {
-    pub fn new(message: impl Into<String>) -> Self {
-        Self { message: message.into() }
-    }
-}
-
-impl Display for LexError {
-    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-        write!(f, "lex error: {}", self.message)
-    }
-}
-
-impl Error for LexError {}

src/lexer.rs

@@ -1,6 +1,4 @@
-use crate::{error::LexError, token::Token};
+use crate::token::Token;
-
-type LexResult<T> = Result<T, LexError>;
 
 pub struct Lexer {
     source: Vec<u8>,
@@ -29,7 +27,7 @@ impl Lexer {
         self.source.get(self.pos).copied()
     }
 
-    fn number(&mut self) -> LexResult<Token> {
+    fn number(&mut self) -> Option<Token> {
         let mut num = String::new();
 
         while matches!(self.peek(), Some(b'0' ..= b'9')) {
@@ -37,97 +35,42 @@ impl Lexer {
             self.advance();
         }
 
-        Ok(Token::Number(num.parse().unwrap()))
+        Some(Token::Number(num.parse().unwrap()))
     }
 
-    fn ident(&mut self) -> LexResult<Token> {
+    fn ident(&mut self) -> Option<Token> {
         let mut ident = String::new();
 
-        while matches!(self.peek(), Some(b'a' ..= b'z' | b'A' ..= b'Z' | b'0' ..= b'9' | b'_')) {
+        while matches!(self.peek(), Some(b'a' ..= b'z' | b'A' ..= b'Z')) {
             ident.push(self.peek().unwrap() as char);
-            self.advance();
         }
 
-        let tok = match ident.as_str() {
+        Some(Token::Ident(ident))
-            "mov"        => Token::Mov,
-            "if"         => Token::If,
-            "else"       => Token::Else,
-            "loop"       => Token::Loop,
-            "while"      => Token::While,
-            "for"        => Token::For,
-            "in"         => Token::In,
-            "fun"        => Token::Fun,
-            "call"       => Token::Call,
-            "break"      => Token::Break,
-            "continue"   => Token::Continue,
-            "true"       => Token::True,
-            "false"      => Token::False,
-
-            "eq"         => Token::Eq,
-            "new"        => Token::Neq,
-            "lt"         => Token::Lt,
-            "gt"         => Token::Gt,
-            "lte"        => Token::Lte,
-            "gte"        => Token::Gte,
-
-            _            => Token::Ident(ident)
-        };
-
-        Ok(tok)
     }
 
-    fn string(&mut self) -> LexResult<Token> {
+    pub fn next(&mut self) -> Option<Token> {
-        self.advance();
-        let mut s = String::new();
-
-        loop {
-            match self.peek() {
-                Some(b'"') => { self.advance(); break; },
-                Some(c) => { s.push(c as char); self.advance(); }
-                None => { return Err(LexError::new(format!(
-                    "expected closing \""
-                ))); }
-            }
-        }
-
-        Ok(Token::StringLit(s))
-    }
-
-    pub fn next(&mut self) -> LexResult<Token> {
         self.skip_whitespace();
         match self.peek() {
             Some(b'0' ..= b'9') => self.number(),
             Some(b'a' ..= b'z' | b'A' ..= b'Z') => self.ident(),
 
-            Some(b'+') => {self.advance(); Ok(Token::Plus)},
+            Some(b'+') => {self.advance(); Some(Token::Plus)},
-            Some(b'-') => {self.advance(); Ok(Token::Minus)},
+            Some(b'-') => {self.advance(); Some(Token::Minus)},
-            Some(b'*') => {self.advance(); Ok(Token::Asterisk)},
+            Some(b'*') => {self.advance(); Some(Token::Asterisk)},
-            Some(b'/') => {self.advance(); Ok(Token::Slash)},
+            Some(b'/') => {self.advance(); Some(Token::Slash)},
-            Some(b'%') => {self.advance(); Ok(Token::Percent)},
+            Some(b'%') => {self.advance(); Some(Token::Percent)},
-            Some(b'^') => {self.advance(); Ok(Token::Caret)},
+            Some(b'^') => {self.advance(); Some(Token::Caret)},
 
-            Some(b'(') => {self.advance(); Ok(Token::LParen)},
+            Some(b'(') => {self.advance(); Some(Token::LParen)},
-            Some(b')') => {self.advance(); Ok(Token::RParen)},
+            Some(b')') => {self.advance(); Some(Token::RParen)},
-            Some(b'[') => {self.advance(); Ok(Token::LBracket)},
+            Some(b'[') => {self.advance(); Some(Token::LBracket)},
-            Some(b']') => {self.advance(); Ok(Token::RBracket)},
+            Some(b']') => {self.advance(); Some(Token::RBracket)},
-            Some(b'{') => {self.advance(); Ok(Token::LBrace)},
+            Some(b'{') => {self.advance(); Some(Token::LBrace)},
-            Some(b'}') => {self.advance(); Ok(Token::RBrace)},
+            Some(b'}') => {self.advance(); Some(Token::RBrace)},
 
-            Some(b';') => {self.advance(); Ok(Token::Semicolon)},
+            Some(b';') => {self.advance(); Some(Token::Semicolon)}
-            Some(b',') => {self.advance(); Ok(Token::Comma)},
-            Some(b'.') => {
-                self.advance();
             
-                match self.peek() {
+            _ => None
-                    Some(b'.') => { self.advance(); Ok(Token::DotDot) },
-                    c => Err(LexError::new(format!(
-                        "unexpected character after '.': {c:?}"
-                    )))
-                }
-            },
-            Some(b'"') => self.string(),
-
-            _ => Ok(Token::EOF)
         }
     }
 }

src/main.rs

@@ -3,7 +3,6 @@ use std::{fs::File, io::Read};
 mod token;
 mod expr;
 mod lexer;
-mod error;
 use lexer::Lexer;
 mod parser;
 use parser::Parser;
@@ -21,8 +20,7 @@ fn main() -> std::io::Result<()> {
     let mut lexer = Lexer::new(&source);
 
     let mut tokens = Vec::new();
-    while let Ok(tok) = lexer.next() {
+    while let Some(tok) = lexer.next() {
-        if tok == token::Token::EOF { break; }
         print!("{tok:?}, ");
         tokens.push(tok);
     }
@@ -31,7 +29,7 @@ fn main() -> std::io::Result<()> {
 
     let mut parser = Parser::new(tokens);
     loop {
-        let parsed = parser.parse().unwrap_or(expr::Expr::EOL);
+        let parsed = parser.parse();
         match parsed {
             expr::Expr::EOL => break,
             _ => {

src/parser.rs

@@ -1,8 +1,5 @@
 use crate::token::Token;
 use crate::expr::{Expr, UnaryOp, BinaryOp, infix_bp, prefix_bp};
-use crate::error::ParseError;
-
-type ParseResult<T> = Result<T, ParseError>;
 
 pub struct Parser {
     tokens: Vec<Token>,
@@ -31,49 +28,39 @@ impl Parser {
         tok
     }
 
-    fn expect(&mut self, expected: &Token) -> ParseResult<Token> {
+    fn parse_atom(&mut self) -> Expr {
         match self.next() {
-            Some(tok) if &tok == expected => Ok(tok),
+            Some(Token::Number(n)) => Expr::Number(n),
-            other => Err(ParseError::new(format!(
+            Some(Token::Ident(id)) => Expr::Ident(id),
-                "expected {expected:?}, got {other:?}"
-            )))
-        }
-    }
-
-    fn parse_atom(&mut self) -> ParseResult<Expr> {
-        match self.next() {
-            Some(Token::Number(n)) => Ok(Expr::Number(n)),
-            Some(Token::Ident(id)) => Ok(Expr::Ident(id)),
             Some(Token::LParen) => {
-                let expr = self.parse_expr(0)?;
+                let expr = self.parse_expr(0);
 
-                self.expect(&Token::RParen)?;
+                match self.next() {
-
+                    Some(Token::RParen) => expr,
-                Ok(expr)
+                    _ => panic!("expected ')'")
+                }
             },
-            tok => Err(ParseError::new(format!(
+            tok => panic!("unknown token: {tok:?}")
-                "unexpected token: {tok:?}"
-            )))
         }
     }
 
-    fn parse_prefix(&mut self) -> ParseResult<Expr> {
+    fn parse_prefix(&mut self) -> Expr {
         match self.peek() {
             Some(Token::Minus) => {
                 self.advance();
                 let op = UnaryOp::Neg;
 
                 let bp = prefix_bp(&op);
-                let rhs = self.parse_expr(bp)?;
+                let rhs = self.parse_expr(bp);
 
-                Ok(Expr::Unary { op, right: Box::new(rhs) })
+                Expr::Unary { op, right: Box::new(rhs) }
             },
             _ => self.parse_atom()
         }
     }
 
-    fn parse_expr(&mut self, min_bp: u8) -> ParseResult<Expr> {
+    fn parse_expr(&mut self, min_bp: u8) -> Expr {
-        let mut lhs = self.parse_prefix()?;
+        let mut lhs = self.parse_prefix();
 
         loop {
             let op = match self.peek() {
@@ -94,16 +81,16 @@ impl Parser {
 
             self.advance();
 
-            let rhs = self.parse_expr(right_bp)?;
+            let rhs = self.parse_expr(right_bp);
 
             lhs = Expr::Binary { left: Box::new(lhs), op, right: Box::new(rhs) }
         }
 
-        Ok(lhs)
+        lhs
     }
 
-    pub fn parse(&mut self) -> ParseResult<Expr> {
+    pub fn parse(&mut self) -> Expr {
-        if self.peek().is_none() {return Ok(Expr::EOL)}
+        if self.peek().is_none() {return Expr::EOL}
         self.parse_expr(0)
     }
 }

src/token.rs

@@ -2,7 +2,6 @@
 pub enum Token {
     Number(i64),
     Ident(String),
-    StringLit(String),
 
     // Operators
     Plus,
@@ -20,33 +19,5 @@ pub enum Token {
     LBracket,
     RBracket,
 
-    // Separators
+    Semicolon
-    Semicolon,
-    Comma,
-
-    // Keywords
-    Mov,
-    If,
-    Else,
-    Loop,
-    While,
-    For,
-    In,
-    Fun,
-    Call,
-    Break,
-    Continue,
-    True,
-    False,
-    DotDot,
-
-    // Conditionals
-    Eq,
-    Neq,
-    Lt,
-    Gt,
-    Lte,
-    Gte,
-
-    EOF
 }