START OF COMPILER

src/parser/mod.rs

@@ -0,0 +1,14 @@
+mod v1;
+mod v2;
+
+pub fn main() {
+    let arg = std::env::args_os().nth(1);
+    if let Some(path) = arg {
+        let file = std::fs::read_to_string(path).expect("failed to read file");
+        println!("{file}");
+        v1::parse_file(&file);
+        // v2::parse_file(&file);
+    } else {
+        v1::run_stdin();
+    }
+}

src/parser/v1/body.rs

@@ -0,0 +1,131 @@
+use std::fmt::{Debug, Write};
+
+use super::{
+    token::{Keyword, Symbol, Token},
+    Node, Parsable, ParserErrors,
+};
+use crate::util::Padder;
+
+use super::{Expr, ParserError, TokenCursor};
+
+#[derive(Clone)]
+pub struct Body {
+    statements: Vec<Node<Statement>>,
+}
+
+#[derive(Clone)]
+pub enum Statement {
+    Let(String, Node<Expr>),
+    Return(Node<Expr>),
+    Expr(Node<Expr>),
+}
+
+impl Statement {
+    pub fn ended_with_error(&self) -> bool {
+        let expr = match self {
+            Statement::Let(_, e) => e,
+            Statement::Return(e) => e,
+            Statement::Expr(e) => e,
+        };
+        expr.is_err() || expr.as_ref().is_ok_and(|e| e.ended_with_error())
+    }
+}
+
+impl Parsable for Body {
+    fn parse(cursor: &mut TokenCursor, errors: &mut ParserErrors) -> Result<Self, ParserError> {
+        let mut statements = Vec::new();
+        let statement_end = &[Symbol::Semicolon, Symbol::CloseCurly];
+        cursor.expect_sym(Symbol::OpenCurly)?;
+        if cursor.expect_peek()?.is_symbol(Symbol::CloseCurly) {
+            cursor.next();
+            return Ok(Self { statements });
+        }
+        let mut expect_semi = false;
+        loop {
+            let next = cursor.expect_peek()?;
+            if next.is_symbol(Symbol::CloseCurly) {
+                cursor.next();
+                return Ok(Self { statements });
+            }
+            if next.is_symbol(Symbol::Semicolon) {
+                cursor.next();
+                expect_semi = false;
+                continue;
+            } else if expect_semi {
+                errors.add(ParserError {
+                    msg: "expected ';'".to_string(),
+                    spans: vec![cursor.next_pos().char_span()],
+                });
+            }
+            let statement: Node<Statement> = Node::parse(cursor, errors);
+            expect_semi = true;
+            if statement.is_err() || statement.as_ref().is_ok_and(|s| s.ended_with_error()) {
+                let res = cursor
+                    .seek(|t| t.is_symbol_and(|s| statement_end.contains(&s)))
+                    .ok_or(ParserError::unexpected_end())?;
+            }
+            statements.push(statement);
+        }
+    }
+}
+
+impl Parsable for Statement {
+    fn parse(cursor: &mut TokenCursor, errors: &mut ParserErrors) -> Result<Self, ParserError> {
+        let next = cursor.expect_peek()?;
+        Ok(match next.token {
+            Token::Keyword(Keyword::Let) => {
+                cursor.next();
+                let name = cursor.expect_ident()?;
+                cursor.expect_sym(Symbol::Equals)?;
+                let expr = Node::parse(cursor, errors);
+                Self::Let(name, expr)
+            }
+            Token::Keyword(Keyword::Return) => {
+                cursor.next();
+                Self::Return(Node::parse(cursor, errors))
+            }
+            _ => Self::Expr(Node::parse(cursor, errors)),
+        })
+    }
+}
+
+impl Debug for Statement {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            Statement::Let(n, e) => {
+                f.write_str("let ")?;
+                f.write_str(n)?;
+                f.write_str(" = ")?;
+                e.fmt(f)?;
+                f.write_char(';')?;
+            }
+            Statement::Return(e) => {
+                f.write_str("return ")?;
+                e.fmt(f)?;
+                f.write_char(';')?;
+            }
+            Statement::Expr(e) => {
+                e.fmt(f)?;
+                f.write_char(';')?;
+            }
+        }
+        Ok(())
+    }
+}
+
+impl Debug for Body {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        if self.statements.first().is_some() {
+            f.write_str("{\n    ")?;
+            let mut padder = Padder::new(f);
+            for s in &self.statements {
+                // they don't expose wrap_buf :grief:
+                padder.write_str(&format!("{s:?}\n"))?;
+            }
+            f.write_char('}')?;
+        } else {
+            f.write_str("{}")?;
+        }
+        Ok(())
+    }
+}

src/parser/v1/cursor.rs

@@ -0,0 +1,90 @@
+use super::error::ParserError;
+use super::token::{CharCursor, Keyword, Symbol, Token, TokenInstance};
+use super::FilePos;
+
+pub struct TokenCursor<'a> {
+    cursor: CharCursor<'a>,
+    next: Option<TokenInstance>,
+    next_pos: FilePos,
+    prev_end: FilePos,
+}
+
+impl<'a> TokenCursor<'a> {
+    pub fn next(&mut self) -> Option<TokenInstance> {
+        self.prev_end = self.cursor.prev_pos();
+        self.next_pos = self.cursor.next_pos();
+        std::mem::replace(&mut self.next, TokenInstance::parse(&mut self.cursor))
+    }
+    pub fn expect_next(&mut self) -> Result<TokenInstance, ParserError> {
+        self.peek().ok_or(ParserError::unexpected_end())?;
+        Ok(self.next().unwrap())
+    }
+    pub fn expect_token(&mut self, t: Token) -> Result<(), ParserError> {
+        let next = self.expect_next()?;
+        if t == next.token {
+            Ok(())
+        } else {
+            Err(ParserError::unexpected_token(&next, &format!("{t:?}")))
+        }
+    }
+    pub fn expect_sym(&mut self, symbol: Symbol) -> Result<(), ParserError> {
+        self.expect_token(Token::Symbol(symbol))
+    }
+    pub fn seek_sym(&mut self, symbol: Symbol) {
+        while self
+            .next()
+            .is_some_and(|n| n.token != Token::Symbol(symbol))
+        {}
+    }
+    pub fn seek(&mut self, f: impl Fn(&TokenInstance) -> bool) -> Option<&TokenInstance> {
+        loop {
+            if f(self.peek()?) {
+                return self.peek();
+            }
+            self.next();
+        }
+    }
+    pub fn expect_kw(&mut self, kw: Keyword) -> Result<(), ParserError> {
+        self.expect_token(Token::Keyword(kw))
+    }
+    pub fn peek(&self) -> Option<&TokenInstance> {
+        self.next.as_ref()
+    }
+    pub fn expect_peek(&mut self) -> Result<&TokenInstance, ParserError> {
+        self.peek().ok_or(ParserError::unexpected_end())
+    }
+    pub fn expect_ident(&mut self) -> Result<String, ParserError> {
+        let i = self.expect_next()?;
+        let Token::Ident(n) = &i.token else {
+            return Err(ParserError::unexpected_token(&i, "an identifier"));
+        };
+        Ok(n.to_string())
+    }
+    pub fn chars(&mut self) -> &mut CharCursor<'a> {
+        &mut self.cursor
+    }
+    pub fn prev_end(&self) -> FilePos {
+        self.prev_end
+    }
+    pub fn next_pos(&self) -> FilePos {
+        self.next_pos
+    }
+}
+
+impl<'a> From<&'a str> for TokenCursor<'a> {
+    fn from(string: &'a str) -> Self {
+        Self::from(CharCursor::from(string))
+    }
+}
+
+impl<'a> From<CharCursor<'a>> for TokenCursor<'a> {
+    fn from(mut cursor: CharCursor<'a>) -> Self {
+        let cur = TokenInstance::parse(&mut cursor);
+        Self {
+            cursor,
+            next: cur,
+            next_pos: FilePos::start(),
+            prev_end: FilePos::start(),
+        }
+    }
+}

src/parser/v1/error.rs

@@ -0,0 +1,62 @@
+use super::{
+    token::{FileSpan, TokenInstance},
+    FilePos,
+};
+
+#[derive(Debug, Clone)]
+pub struct ParserError {
+    pub msg: String,
+    pub spans: Vec<FileSpan>,
+}
+
+pub struct ParserErrors {
+    pub errs: Vec<ParserError>,
+}
+
+impl ParserError {
+    pub fn from_instances(instances: &[&TokenInstance], msg: String) -> Self {
+        ParserError {
+            msg,
+            spans: instances.iter().map(|i| i.span).collect(),
+        }
+    }
+    pub fn from_msg(msg: String) -> Self {
+        Self {
+            msg,
+            spans: Vec::new(),
+        }
+    }
+    pub fn at(pos: FilePos, msg: String) -> Self {
+        Self {
+            msg,
+            spans: vec![FileSpan::at(pos)],
+        }
+    }
+    pub fn unexpected_end() -> Self {
+        Self::from_msg("unexpected end of input".to_string())
+    }
+    pub fn unexpected_token(inst: &TokenInstance, expected: &str) -> Self {
+        let t = &inst.token;
+        ParserError::from_instances(
+            &[inst],
+            format!("unexpected token {t:?}; expected {expected}"),
+        )
+    }
+    pub fn write_for(&self, writer: &mut impl std::io::Write, file: &str) -> std::io::Result<()> {
+        let after = if self.spans.is_empty() { "" } else { ":" };
+        writeln!(writer, "error: {}{}", self.msg, after)?;
+        for span in &self.spans {
+            span.write_for(writer, file)?;
+        }
+        Ok(())
+    }
+}
+
+impl ParserErrors {
+    pub fn new() -> Self {
+        Self { errs: Vec::new() }
+    }
+    pub fn add(&mut self, err: ParserError) {
+        self.errs.push(err);
+    }
+}

src/parser/v1/expr.rs

@@ -0,0 +1,203 @@
+use std::fmt::{Debug, Write};
+
+use super::token::{Symbol, Token};
+use super::{Body, Node, Parsable, ParserError, ParserErrors, TokenCursor, Literal};
+
+pub type ExprNode = Node<Box<Expr>>;
+
+#[derive(Clone)]
+pub enum Expr {
+    Lit(Node<Literal>),
+    Ident(String),
+    BinaryOp(Operator, ExprNode, ExprNode),
+    Block(Node<Body>),
+    Call(ExprNode, Vec<Node<Expr>>),
+    Group(ExprNode),
+}
+
+#[derive(Debug, PartialEq, Eq, Clone, Copy)]
+pub enum Operator {
+    Add,
+    Sub,
+    Mul,
+    Div,
+    LessThan,
+    GreaterThan,
+    Access,
+    Assign,
+}
+
+impl Expr {
+    pub fn ended_with_error(&self) -> bool {
+        match self {
+            Expr::Lit(_) => false,
+            Expr::Ident(_) => false,
+            Expr::BinaryOp(_, _, e) => e.is_err() || e.as_ref().is_ok_and(|e| e.ended_with_error()),
+            Expr::Block(b) => b.is_err(),
+            Expr::Call(_, _) => false,
+            Expr::Group(_) => false,
+        }
+    }
+}
+
+impl Parsable for Expr {
+    fn parse(cursor: &mut TokenCursor, errors: &mut ParserErrors) -> Result<Self, ParserError> {
+        let start = cursor.next_pos();
+        let next = cursor.expect_peek()?;
+        let mut e1 = if next.is_symbol(Symbol::OpenParen) {
+            cursor.next();
+            if cursor.expect_peek()?.is_symbol(Symbol::CloseParen) {
+                cursor.next();
+                return Ok(Expr::Lit(Node::new(
+                    Literal::Unit,
+                    cursor.next_pos().char_span(),
+                )));
+            }
+            let expr = Node::parse(cursor, errors).bx();
+            if expr.is_err() {
+                cursor.seek_sym(Symbol::CloseParen);
+            }
+            cursor.expect_sym(Symbol::CloseParen)?;
+            Self::Group(expr)
+        } else if next.is_symbol(Symbol::OpenCurly) {
+            Self::Block(Node::parse(cursor, errors))
+        } else if let Some(val) = Node::maybe_parse(cursor, errors) {
+            Self::Lit(val)
+        } else {
+            let next = cursor.peek().unwrap();
+            match &next.token {
+                Token::Ident(name) => {
+                    let name = name.to_string();
+                    cursor.next();
+                    Self::Ident(name)
+                }
+                _ => {
+                    return Err(ParserError::unexpected_token(next, "an expression"));
+                }
+            }
+        };
+        let Some(mut next) = cursor.peek() else {
+            return Ok(e1);
+        };
+        while next.is_symbol(Symbol::OpenParen) {
+            cursor.next();
+            let inner = Node::parse(cursor, errors);
+            cursor.expect_sym(Symbol::CloseParen)?;
+            let end = cursor.prev_end();
+            e1 = Self::Call(Node::new(Box::new(e1), start.to(end)), vec![inner]);
+            let Some(next2) = cursor.peek() else {
+                return Ok(e1);
+            };
+            next = next2
+        }
+        let end = cursor.prev_end();
+        Ok(if let Some(mut op) = Operator::from_token(&next.token) {
+            cursor.next();
+            let mut n1 = Node::new(Box::new(e1), start.to(end));
+            let mut n2 = Node::parse(cursor, errors).bx();
+            if let Ok(box Self::BinaryOp(op2, n21, n22)) = n2.as_ref() {
+                if op.presedence() > op2.presedence() {
+                    n1 = Node::new(
+                        Box::new(Self::BinaryOp(op, n1, n21.clone())),
+                        start.to(n21.span.end),
+                    );
+                    op = *op2;
+                    n2 = n22.clone();
+                }
+            }
+            Self::BinaryOp(op, n1, n2)
+        } else {
+            e1
+        })
+    }
+}
+
+impl Operator {
+    pub fn presedence(&self) -> u32 {
+        match self {
+            Operator::Assign => 0,
+            Operator::LessThan => 1,
+            Operator::GreaterThan => 1,
+            Operator::Add => 2,
+            Operator::Sub => 3,
+            Operator::Mul => 4,
+            Operator::Div => 5,
+            Operator::Access => 6,
+        }
+    }
+    pub fn str(&self) -> &str {
+        match self {
+            Self::Add => "+",
+            Self::Sub => "-",
+            Self::Mul => "*",
+            Self::Div => "/",
+            Self::LessThan => "<",
+            Self::GreaterThan => ">",
+            Self::Access => ".",
+            Self::Assign => "=",
+        }
+    }
+    pub fn from_token(token: &Token) -> Option<Self> {
+        let Token::Symbol(symbol) = token else {
+            return None;
+        };
+        Some(match symbol {
+            Symbol::OpenAngle => Operator::LessThan,
+            Symbol::CloseAngle => Operator::GreaterThan,
+            Symbol::Plus => Operator::Add,
+            Symbol::Minus => Operator::Sub,
+            Symbol::Asterisk => Operator::Mul,
+            Symbol::Slash => Operator::Div,
+            Symbol::Dot => Operator::Access,
+            Symbol::Equals => Operator::Assign,
+            _ => {
+                return None;
+            }
+        })
+    }
+    pub fn pad(&self) -> bool {
+        match self {
+            Self::Add => true,
+            Self::Sub => true,
+            Self::Mul => true,
+            Self::Div => true,
+            Self::LessThan => true,
+            Self::GreaterThan => true,
+            Self::Access => false,
+            Self::Assign => true,
+        }
+    }
+}
+
+impl Debug for Expr {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            Expr::Lit(c) => c.fmt(f)?,
+            Expr::Ident(n) => f.write_str(n)?,
+            Expr::Block(b) => b.fmt(f)?,
+            Expr::BinaryOp(op, e1, e2) => {
+                write!(f, "({:?}", *e1)?;
+                if op.pad() {
+                    write!(f, " {} ", op.str())?;
+                } else {
+                    write!(f, "{}", op.str())?;
+                }
+                write!(f, "{:?})", *e2)?;
+            }
+            Expr::Call(n, args) => {
+                n.fmt(f)?;
+                f.write_char('(')?;
+                if let Some(a) = args.first() {
+                    a.fmt(f)?;
+                }
+                for arg in args.iter().skip(1) {
+                    f.write_str(", ")?;
+                    arg.fmt(f)?;
+                }
+                f.write_char(')')?;
+            }
+            Expr::Group(inner) => inner.fmt(f)?,
+        }
+        Ok(())
+    }
+}

src/parser/v1/mod.rs

@@ -0,0 +1,46 @@
+use std::io::{stdout, BufRead, BufReader};
+
+mod body;
+mod cursor;
+mod error;
+mod expr;
+mod module;
+mod node;
+mod token;
+mod val;
+
+pub use body::*;
+pub use cursor::*;
+pub use error::*;
+pub use expr::*;
+pub use module::*;
+pub use node::*;
+pub use val::*;
+use token::*;
+
+pub fn parse_file(file: &str) {
+    let mut errors = ParserErrors::new();
+    let node = Node::<Module>::parse(&mut TokenCursor::from(file), &mut errors);
+    if let Ok(module) = node.as_ref() {
+        println!("{module:#?}");
+    };
+    let out = &mut stdout();
+    for err in errors.errs {
+        err.write_for(out, file).unwrap();
+    }
+}
+
+pub fn run_stdin() {
+    for line in BufReader::new(std::io::stdin()).lines() {
+        let mut errors = ParserErrors::new();
+        let str = &line.expect("failed to read line");
+        let mut cursor = TokenCursor::from(&str[..]);
+        if let Ok(expr) = Node::<Statement>::parse(&mut cursor, &mut errors).as_ref() {
+            println!("{:?}", expr);
+        }
+        let out = &mut stdout();
+        for err in errors.errs {
+            err.write_for(out, str).unwrap();
+        }
+    }
+}

src/parser/v1/module.rs

@@ -0,0 +1,52 @@
+use std::fmt::Debug;
+
+use super::{token::*, Body, Node, Parsable, ParserError, ParserErrors, TokenCursor};
+
+#[derive(Debug)]
+pub struct Module {
+    functions: Vec<Node<Function>>,
+}
+
+#[derive(Clone)]
+pub struct Function {
+    pub name: String,
+    pub body: Node<Body>,
+}
+
+impl Parsable for Module {
+    fn parse(cursor: &mut TokenCursor, errors: &mut ParserErrors) -> Result<Self, ParserError> {
+        let mut functions = Vec::new();
+        loop {
+            let Some(next) = cursor.peek() else {
+                return Ok(Self { functions });
+            };
+            if next.is_keyword(Keyword::Fn) {
+                functions.push(Node::parse(cursor, errors));
+            } else {
+                return Err(ParserError::unexpected_token(next, "fn"));
+            }
+        }
+    }
+}
+
+impl Parsable for Function {
+    fn parse(cursor: &mut TokenCursor, errors: &mut ParserErrors) -> Result<Self, ParserError> {
+        cursor.expect_kw(Keyword::Fn)?;
+        let name = cursor.expect_ident()?;
+        cursor.expect_sym(Symbol::OpenParen)?;
+        cursor.expect_sym(Symbol::CloseParen)?;
+        let body = Node::parse(cursor, errors);
+        Ok(Self { name, body })
+    }
+}
+
+impl Debug for Function {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        f.write_str("fn ")?;
+        f.write_str(&self.name)?;
+        f.write_str("() ")?;
+        self.body.fmt(f)?;
+        Ok(())
+    }
+}
+

src/parser/v1/node.rs

@@ -0,0 +1,98 @@
+use std::{
+    fmt::Debug,
+    ops::{Deref, DerefMut},
+};
+
+use super::{FileSpan, ParserError, ParserErrors, TokenCursor};
+
+#[derive(Clone)]
+pub struct Node<T> {
+    pub inner: Result<T, ()>,
+    pub span: FileSpan,
+}
+
+pub trait Parsable: Sized {
+    fn parse(cursor: &mut TokenCursor, errors: &mut ParserErrors) -> Result<Self, ParserError>;
+}
+
+pub trait MaybeParsable: Sized {
+    fn maybe_parse(
+        cursor: &mut TokenCursor,
+        errors: &mut ParserErrors,
+    ) -> Result<Option<Self>, ParserError>;
+}
+
+impl<T: Parsable> Node<T> {
+    pub fn parse(cursor: &mut TokenCursor, errors: &mut ParserErrors) -> Self {
+        let start = cursor.next_pos();
+        let inner = T::parse(cursor, errors).map_err(|e| errors.add(e));
+        let end = cursor.prev_end();
+        Self {
+            inner,
+            span: start.to(end),
+        }
+    }
+}
+
+impl<T: MaybeParsable> Node<T> {
+    pub fn maybe_parse(cursor: &mut TokenCursor, errors: &mut ParserErrors) -> Option<Self> {
+        let start = cursor.next_pos();
+        let inner = match T::maybe_parse(cursor, errors) {
+            Ok(v) => Ok(v?),
+            Err(e) => {
+                errors.add(e);
+                Err(())
+            }
+        };
+        let end = cursor.prev_end();
+        Some(Self {
+            inner,
+            span: start.to(end),
+        })
+    }
+}
+
+impl<T> Node<T> {
+    pub fn new(inner: T, span: FileSpan) -> Self {
+        Self {
+            inner: Ok(inner),
+            span,
+        }
+    }
+    pub fn bx(self) -> Node<Box<T>> {
+        Node {
+            inner: self.inner.map(|v| Box::new(v)),
+            span: self.span,
+        }
+    }
+}
+
+impl<T> Node<Box<T>> {
+    pub fn unbx(self) -> Node<T> {
+        Node {
+            inner: self.inner.map(|v| *v),
+            span: self.span,
+        }
+    }
+}
+impl<T> Deref for Node<T> {
+    type Target = Result<T, ()>;
+    fn deref(&self) -> &Self::Target {
+        &self.inner
+    }
+}
+
+impl<T> DerefMut for Node<T> {
+    fn deref_mut(&mut self) -> &mut Self::Target {
+        &mut self.inner
+    }
+}
+
+impl<T: Debug> Debug for Node<T> {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match &self.inner {
+            Ok(v) => v.fmt(f),
+            Err(_) => f.write_str("{error}"),
+        }
+    }
+}

src/parser/v1/token/cursor.rs

@@ -0,0 +1,77 @@
+use std::{iter::Peekable, str::Chars};
+
+use super::super::ParserError;
+use super::FilePos;
+
+pub struct CharCursor<'a> {
+    chars: Peekable<Chars<'a>>,
+    next_pos: FilePos,
+    prev_pos: FilePos,
+}
+
+impl CharCursor<'_> {
+    pub fn next(&mut self) -> Option<char> {
+        let res = self.peek()?;
+        self.advance();
+        Some(res)
+    }
+    pub fn expect(&mut self, c: char) -> Result<(), ParserError> {
+        let next = self.expect_next()?;
+        if next == c {
+            Ok(())
+        } else {
+            Err(ParserError::at(
+                self.prev_pos,
+                format!("unexpected char '{next}'; expected '{c}'"),
+            ))
+        }
+    }
+    pub fn skip_whitespace(&mut self) {
+        while self.peek().is_some_and(|c| c.is_whitespace()) {
+            self.advance();
+        }
+    }
+    pub fn peek(&mut self) -> Option<char> {
+        self.chars.peek().copied()
+    }
+    pub fn advance(&mut self) {
+        let Some(next) = self.chars.next() else {
+            return;
+        };
+        self.prev_pos = self.next_pos;
+        if next == '\n' {
+            self.next_pos.col = 0;
+            self.next_pos.line += 1;
+        } else {
+            self.next_pos.col += 1;
+        }
+    }
+    pub fn advance_if(&mut self, c: char) -> bool {
+        if let Some(c2) = self.peek() {
+            if c2 == c {
+                self.advance();
+                return true;
+            }
+        }
+        false
+    }
+    pub fn expect_next(&mut self) -> Result<char, ParserError> {
+        self.next().ok_or(ParserError::unexpected_end())
+    }
+    pub fn next_pos(&self) -> FilePos {
+        self.next_pos
+    }
+    pub fn prev_pos(&self) -> FilePos {
+        self.prev_pos
+    }
+}
+
+impl<'a> From<&'a str> for CharCursor<'a> {
+    fn from(value: &'a str) -> Self {
+        Self {
+            chars: value.chars().peekable(),
+            next_pos: FilePos::start(),
+            prev_pos: FilePos::start(),
+        }
+    }
+}

src/parser/v1/token/file.rs

@@ -0,0 +1,80 @@
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub struct FilePos {
+    pub line: usize,
+    pub col: usize,
+}
+
+#[derive(Debug, Clone, Copy)]
+pub struct FileSpan {
+    pub start: FilePos,
+    pub end: FilePos,
+}
+
+impl FilePos {
+    pub fn start() -> Self {
+        Self { line: 0, col: 0 }
+    }
+}
+
+impl FilePos {
+    pub fn to(self, end: FilePos) -> FileSpan {
+        FileSpan { start: self, end }
+    }
+    pub fn char_span(self) -> FileSpan {
+        FileSpan::at(self)
+    }
+}
+
+const BEFORE: usize = 1;
+const AFTER: usize = 0;
+
+impl FileSpan {
+    pub fn at(pos: FilePos) -> Self {
+        Self {
+            start: pos,
+            end: pos,
+        }
+    }
+    pub fn write_for(&self, writer: &mut impl std::io::Write, file: &str) -> std::io::Result<()> {
+        let start = self.start.line.saturating_sub(BEFORE);
+        let num_before = self.start.line - start;
+        let mut lines = file.lines().skip(start);
+        let width = format!("{}", self.end.line + AFTER).len();
+        let same_line = self.start.line == self.end.line;
+        for i in 0..num_before {
+            writeln!(writer, "{:>width$} | {}", start + i, lines.next().unwrap())?;
+        }
+        let line = lines.next().unwrap();
+        writeln!(writer, "{:>width$} | {}", self.start.line, line)?;
+        let len = if same_line {
+            self.end.col - self.start.col + 1
+        } else {
+            line.len() - self.start.col
+        };
+        writeln!(
+            writer,
+            "{} | {}",
+            " ".repeat(width),
+            " ".repeat(self.start.col) + &"^".repeat(len)
+        )?;
+        if !same_line {
+            for _ in 0..self.end.line - self.start.line - 1 {
+                lines.next();
+            }
+            let line = lines.next().unwrap();
+            writeln!(writer, "{:>width$} | {}", self.end.line, line)?;
+            writeln!(
+                writer,
+                "{} | {}",
+                " ".repeat(width),
+                "^".repeat(self.end.col + 1)
+            )?;
+        }
+        // for i in 0..AFTER {
+        //     if let Some(next) = lines.next() {
+        //         writeln!(writer, "{:>width$} | {}", self.end.line + i + 1, next)?;
+        //     }
+        // }
+        Ok(())
+    }
+}

src/parser/v1/token/keyword.rs

@@ -0,0 +1,27 @@
+#[derive(Debug, PartialEq, Eq, Clone, Copy)]
+pub enum Keyword {
+    Fn,
+    Let,
+    If,
+    Return,
+}
+
+impl Keyword {
+    pub fn from_string(str: &str) -> Option<Self> {
+        Some(match str {
+            "fn" => Self::Fn,
+            "let" => Self::Let,
+            "if" => Self::If,
+            "return" => Self::Return,
+            _ => return None,
+        })
+    }
+    pub const fn str(&self) -> &str {
+        match self {
+            Keyword::Fn => "fn",
+            Keyword::Let => "let",
+            Keyword::If => "if",
+            Keyword::Return => "return",
+        }
+    }
+}

src/parser/v1/token/mod.rs

@@ -0,0 +1,90 @@
+mod cursor;
+mod file;
+mod keyword;
+mod symbol;
+
+use std::ops::Deref;
+
+pub use cursor::*;
+pub use file::*;
+pub use keyword::*;
+pub use symbol::*;
+
+#[derive(Debug, PartialEq, Eq, Clone)]
+pub enum Token {
+    Symbol(Symbol),
+    Ident(String),
+    Keyword(Keyword),
+}
+
+#[derive(Debug, Clone)]
+pub struct TokenInstance {
+    pub token: Token,
+    pub span: FileSpan,
+}
+
+impl TokenInstance {
+    pub fn parse(cursor: &mut CharCursor) -> Option<TokenInstance> {
+        cursor.skip_whitespace();
+        cursor.peek()?;
+        let start = cursor.next_pos();
+        if let Some(s) = Symbol::parse(cursor) {
+            if s == Symbol::DoubleSlash {
+                while cursor.next() != Some('\n') {}
+                return Self::parse(cursor);
+            }
+            let end = cursor.prev_pos();
+            return Some(Self {
+                token: Token::Symbol(s),
+                span: FileSpan { start, end },
+            });
+        }
+        let mut word = String::new();
+        while let Some(c) = cursor.peek() {
+            if c.is_whitespace() || Symbol::from_char(c).is_some() {
+                break;
+            }
+            word.push(c);
+            cursor.advance();
+        }
+        let end = cursor.prev_pos();
+        let token = if let Some(keyword) = Keyword::from_string(&word) {
+            Token::Keyword(keyword)
+        } else {
+            Token::Ident(word)
+        };
+        Some(Self {
+            token,
+            span: FileSpan { start, end },
+        })
+    }
+}
+
+impl Token {
+    pub fn is_symbol(&self, symbol: Symbol) -> bool {
+        match self {
+            Token::Symbol(s) => *s == symbol,
+            _ => false,
+        }
+    }
+    pub fn is_symbol_and(&self, f: impl Fn(Symbol) -> bool) -> bool {
+        match self {
+            Token::Symbol(s) => f(*s),
+            _ => false,
+        }
+    }
+    pub fn is_keyword(&self, kw: Keyword) -> bool {
+        match self {
+            Token::Keyword(k) => *k == kw,
+            _ => false,
+        }
+    }
+}
+
+impl Deref for TokenInstance {
+    type Target = Token;
+
+    fn deref(&self) -> &Self::Target {
+        &self.token
+    }
+}

src/parser/v1/token/symbol.rs

@@ -0,0 +1,125 @@
+use std::fmt::Debug;
+
+use super::CharCursor;
+
+#[derive(PartialEq, Eq, Clone, Copy)]
+pub enum Symbol {
+    Semicolon,
+    Colon,
+    DoubleColon,
+    Equals,
+    DoubleEquals,
+    Arrow,
+    DoubleArrow,
+    Plus,
+    Minus,
+    Asterisk,
+    Slash,
+    DoubleSlash,
+    Dot,
+    OpenParen,
+    CloseParen,
+    OpenCurly,
+    CloseCurly,
+    OpenSquare,
+    CloseSquare,
+    OpenAngle,
+    CloseAngle,
+    SingleQuote,
+    DoubleQuote,
+    Bang,
+}
+
+impl Symbol {
+    pub fn parse(cursor: &mut CharCursor) -> Option<Self> {
+        Self::from_char(cursor.peek()?).map(|mut s| {
+            cursor.advance();
+            s.finish(cursor);
+            s
+        })
+    }
+    pub fn from_char(c: char) -> Option<Self> {
+        Some(match c {
+            '(' => Self::OpenParen,
+            ')' => Self::CloseParen,
+            '[' => Self::OpenSquare,
+            ']' => Self::CloseSquare,
+            '{' => Self::OpenCurly,
+            '}' => Self::CloseCurly,
+            '<' => Self::OpenAngle,
+            '>' => Self::CloseAngle,
+            ';' => Self::Semicolon,
+            ':' => Self::Colon,
+            '+' => Self::Plus,
+            '-' => Self::Minus,
+            '*' => Self::Asterisk,
+            '/' => Self::Slash,
+            '=' => Self::Equals,
+            '.' => Self::Dot,
+            '\'' => Self::SingleQuote,
+            '"' => Self::DoubleQuote,
+            '!' => Self::Bang,
+            _ => return None,
+        })
+    }
+    pub fn finish(&mut self, cursor: &mut CharCursor) {
+        let Some(next) = cursor.peek() else {
+            return;
+        };
+        *self = match self {
+            Self::Colon => match next {
+                ':' => Self::DoubleColon,
+                _ => return,
+            },
+            Self::Minus => match next {
+                '>' => Self::Arrow,
+                _ => return,
+            },
+            Self::Equals => match next {
+                '=' => Self::DoubleEquals,
+                '>' => Self::DoubleArrow,
+                _ => return,
+            }
+            Self::Slash => match next {
+                '/' => Self::DoubleSlash,
+                _ => return,
+            }
+            _ => return,
+        };
+        cursor.advance();
+    }
+    pub fn str(&self) -> &str {
+        match self {
+            Self::Semicolon => ";",
+            Self::Colon => ":",
+            Self::DoubleColon => "::",
+            Self::Equals => "=",
+            Self::DoubleEquals => "==",
+            Self::Arrow => "->",
+            Self::DoubleArrow => "=>",
+            Self::Plus => "+",
+            Self::Minus => "-",
+            Self::Asterisk => "*",
+            Self::Slash => "/",
+            Self::DoubleSlash => "//",
+            Self::Dot => ".",
+            Self::OpenParen => "(",
+            Self::CloseParen => ")",
+            Self::OpenCurly => "{",
+            Self::CloseCurly => "}",
+            Self::OpenSquare => "[",
+            Self::CloseSquare => "]",
+            Self::OpenAngle => "<",
+            Self::CloseAngle => ">",
+            Self::SingleQuote => "'",
+            Self::DoubleQuote => "\"",
+            Self::Bang => "!",
+        }
+    }
+}
+
+impl Debug for Symbol {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(f, "'{}'", self.str())
+    }
+}

src/parser/v1/val.rs

@@ -0,0 +1,111 @@
+use super::{CharCursor, MaybeParsable, ParserError, ParserErrors, Symbol, Token, TokenCursor};
+use std::fmt::Debug;
+
+#[derive(Clone, PartialEq, Eq)]
+pub enum Literal {
+    String(String),
+    Char(char),
+    Number(Number),
+    Unit,
+}
+
+#[derive(Clone, PartialEq, Eq)]
+pub struct Number {
+    pub whole: String,
+    pub decimal: Option<String>,
+    pub ty: Option<String>,
+}
+
+impl MaybeParsable for Literal {
+    fn maybe_parse(cursor: &mut TokenCursor, _: &mut ParserErrors) -> Result<Option<Self>, ParserError> {
+        let inst = cursor.expect_peek()?;
+        let mut res = match &inst.token {
+            Token::Symbol(Symbol::SingleQuote) => {
+                let chars = cursor.chars();
+                let c = chars.expect_next()?;
+                chars.expect('\'')?;
+                Self::Char(c)
+            }
+            Token::Symbol(Symbol::DoubleQuote) => Self::String(string_from(cursor.chars())?),
+            Token::Ident(text) => {
+                let first = text.chars().next().unwrap();
+                if first.is_ascii_digit() {
+                    Self::Number(Number {
+                        whole: text.to_string(),
+                        decimal: None,
+                        ty: None,
+                    })
+                } else {
+                    return Ok(None);
+                }
+            }
+            _ => return Ok(None),
+        };
+        cursor.next();
+        if let Some(next) = cursor.peek() {
+            if let Self::Number(num) = &mut res {
+                if let Token::Symbol(Symbol::Dot) = next.token {
+                    let chars = cursor.chars();
+                    if let Some(c) = chars.peek() {
+                        if c.is_ascii_digit() {
+                            cursor.next();
+                            let decimal = cursor.expect_ident()?;
+                            num.decimal = Some(decimal);
+                        }
+                    }
+                }
+            }
+        }
+        Ok(Some(res))
+    }
+}
+pub fn string_from(cursor: &mut CharCursor) -> Result<String, ParserError> {
+    let mut str = String::new();
+    loop {
+        let c = cursor.expect_next()?;
+        if c == '"' {
+            return Ok(str);
+        }
+        str.push(match c {
+            '\\' => {
+                let next = cursor.expect_next()?;
+                match next {
+                    '"' => '"',
+                    '\'' => '\'',
+                    't' => '\t',
+                    'n' => '\n',
+                    '0' => '\0',
+                    _ => {
+                        todo!();
+                    }
+                }
+            }
+            _ => c,
+        })
+    }
+}
+
+impl Debug for Literal {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            Self::String(str) => str.fmt(f),
+            Self::Char(c) => c.fmt(f),
+            Self::Number(n) => n.fmt(f),
+            Self::Unit => f.write_str("()"),
+        }
+    }
+}
+
+impl Debug for Number {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(f, "{}", self.whole)?;
+        if let Some(d) = &self.decimal {
+            write!(f, ".{}", d)?;
+        }
+        if let Some(ty) = &self.ty {
+            write!(f, "T{}", ty)?;
+        }
+        Ok(())
+    }
+}
+

src/parser/v2/body.rs

@@ -0,0 +1,120 @@
+use std::collections::HashSet;
+use std::fmt::{Debug, Write};
+use std::sync::LazyLock;
+
+use crate::util::Padder;
+
+use super::util::WHITESPACE_SET;
+use super::CharCursor;
+use super::Expr;
+use super::ParserError;
+
+static NAME_END: LazyLock<HashSet<char>> = LazyLock::new(|| {
+    let mut set = WHITESPACE_SET.clone();
+    set.extend(&['(']);
+    set
+});
+
+pub struct Body {
+    statements: Vec<Statement>,
+}
+
+pub enum Statement {
+    Let(String, Expr),
+    Return(Expr),
+    Expr(Expr),
+}
+
+impl Body {
+    pub fn parse(cursor: &mut CharCursor) -> Result<Self, ParserError> {
+        cursor.skip_whitespace();
+        let mut statements = Vec::new();
+        cursor.expect_char('{')?;
+        loop {
+            cursor.skip_whitespace();
+            let next = cursor.expect_peek()?;
+            if next == '}' {
+                cursor.next();
+                return Ok(Self { statements });
+            }
+            statements.push(Statement::parse(cursor)?);
+        }
+    }
+}
+
+impl Statement {
+    pub fn parse(cursor: &mut CharCursor) -> Result<Self, ParserError> {
+        cursor.skip_whitespace();
+        Ok(if cursor.advance_if_str("let", &WHITESPACE_SET) {
+            cursor.skip_whitespace();
+            let name = cursor.until(&NAME_END);
+            if name.is_empty() {
+                return Err(ParserError::at(
+                    cursor.pos(),
+                    "Expected variable name".to_string(),
+                ));
+            }
+            cursor.skip_whitespace();
+            cursor.expect_char('=')?;
+            let expr = Expr::parse(cursor)?;
+            cursor.skip_whitespace();
+            cursor.expect_char(';')?;
+            Self::Let(name, expr)
+        } else if cursor.advance_if_str("return", &WHITESPACE_SET) {
+            let expr = Expr::parse(cursor)?;
+            cursor.skip_whitespace();
+            cursor.expect_char(';')?;
+            Self::Return(expr)
+        } else {
+            let expr = Expr::parse(cursor)?;
+            match cursor.expect_peek()? {
+                ';' => {
+                    cursor.next();
+                    Self::Expr(expr)
+                }
+                '}' => Self::Return(expr),
+                _ => {
+                    cursor.next();
+                    return Err(ParserError::at(
+                        cursor.prev_pos(),
+                        "unexpected end of statement; expected a ';' or '}'".to_string(),
+                    ));
+                }
+            }
+        })
+    }
+}
+
+impl Debug for Statement {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            Statement::Let(n, e) => {
+                write!(f, "let {n} = {e:?};")?;
+            }
+            Statement::Return(e) => {
+                write!(f, "return {e:?};")?;
+            }
+            Statement::Expr(e) => {
+                write!(f, "{e:?};")?;
+            }
+        }
+        Ok(())
+    }
+}
+
+impl Debug for Body {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        if self.statements.first().is_some() {
+            write!(f, "{{\n    ")?;
+            let mut padder = Padder::new(f);
+            for s in &self.statements {
+                // they don't expose wrap_buf :grief:
+                writeln!(padder, "{s:?}")?;
+            }
+            write!(f, "}}")?;
+        } else {
+            write!(f, "{{}}")?;
+        }
+        Ok(())
+    }
+}

src/parser/v2/cursor.rs

@@ -0,0 +1,135 @@
+use std::{collections::HashSet, iter::Peekable, str::Chars};
+
+use super::{error::ParserError, util::WHITESPACE_SET};
+
+#[derive(Debug, Clone, Copy)]
+pub struct FilePos {
+    pub line: usize,
+    pub col: usize,
+}
+
+#[derive(Debug, Clone, Copy)]
+pub struct FileRegion {
+    pub start: FilePos,
+    pub end: FilePos,
+}
+
+pub struct CharCursor<'a> {
+    chars: Peekable<Chars<'a>>,
+    pos: FilePos,
+    prev_pos: FilePos,
+}
+
+impl CharCursor<'_> {
+    pub fn until(&mut self, set: &HashSet<char>) -> String {
+        let mut str = String::new();
+        loop {
+            let Some(next) = self.peek() else {
+                return str;
+            };
+            if set.contains(&next) {
+                return str;
+            }
+            str.push(next);
+            self.advance();
+        }
+    }
+    pub fn skip_whitespace(&mut self) {
+        while self.peek().is_some_and(|c| c.is_whitespace()) {
+            self.advance();
+        }
+        let mut copy = self.chars.clone();
+        if let Some('/') = copy.next() {
+            if let Some('/') = copy.next() {
+                self.advance();
+                self.advance();
+                while self.next() != Some('\n') {}
+                self.skip_whitespace();
+            }
+        }
+    }
+    pub fn next(&mut self) -> Option<char> {
+        let res = self.peek()?;
+        self.advance();
+        Some(res)
+    }
+    pub fn peek(&mut self) -> Option<char> {
+        self.chars.peek().copied()
+    }
+    pub fn advance(&mut self) {
+        self.prev_pos = self.pos;
+        if self.peek().is_some_and(|c| c == '\n') {
+            self.pos.col = 0;
+            self.pos.line += 1;
+        } else {
+            self.pos.col += 1;
+        }
+        self.chars.next();
+    }
+    pub fn advance_if(&mut self, c: char) -> bool {
+        if let Some(c2) = self.peek() {
+            if c2 == c {
+                self.advance();
+                return true;
+            }
+        }
+        false
+    }
+    pub fn advance_if_str(&mut self, exp: &str, end: &HashSet<char>) -> bool {
+        let mut new = self.chars.clone();
+        for e in exp.chars() {
+            let Some(c) = new.next() else {
+                return false;
+            };
+            if e != c {
+                return false;
+            }
+        }
+        if new.peek().is_some_and(|c| !end.contains(c)) {
+            return false;
+        }
+        for _ in 0..exp.len() {
+            self.advance();
+        }
+        true
+    }
+    pub fn expect_char(&mut self, c: char) -> Result<(), ParserError> {
+        let next = self.expect_next()?;
+        if next == c {
+            Ok(())
+        } else {
+            Err(ParserError::at(
+                self.prev_pos,
+                format!("unexpected char '{next}'; expected '{c}'"),
+            ))
+        }
+    }
+    pub fn expect_next(&mut self) -> Result<char, ParserError> {
+        self.next().ok_or(ParserError::unexpected_end())
+    }
+    pub fn expect_peek(&mut self) -> Result<char, ParserError> {
+        self.peek().ok_or(ParserError::unexpected_end())
+    }
+    pub fn pos(&self) -> FilePos {
+        self.pos
+    }
+    pub fn prev_pos(&self) -> FilePos {
+        self.prev_pos
+    }
+}
+
+impl<'a> From<&'a str> for CharCursor<'a> {
+    fn from(value: &'a str) -> Self {
+        Self {
+            chars: value.chars().peekable(),
+            pos: FilePos::start(),
+            prev_pos: FilePos::start(),
+        }
+    }
+}
+
+impl FilePos {
+    pub fn start() -> Self {
+        Self { line: 0, col: 0 }
+    }
+}

src/parser/v2/error.rs

@@ -0,0 +1,60 @@
+use super::{FilePos, FileRegion};
+
+#[derive(Debug)]
+pub struct ParserError {
+    pub msg: String,
+    pub regions: Vec<FileRegion>,
+}
+
+impl ParserError {
+    pub fn from_msg(msg: String) -> Self {
+        Self {
+            msg,
+            regions: Vec::new(),
+        }
+    }
+    pub fn at(pos: FilePos, msg: String) -> Self {
+        Self {
+            msg,
+            regions: vec![FileRegion {
+                start: pos,
+                end: pos,
+            }],
+        }
+    }
+    pub fn unexpected_end() -> Self {
+        Self::from_msg("Unexpected end of input".to_string())
+    }
+}
+
+const BEFORE: usize = 1;
+const AFTER: usize = 1;
+
+pub fn print_error(err: ParserError, file: &str) {
+    let after = if err.regions.is_empty() {""} else {":"};
+    println!("error: {}{}", err.msg, after);
+    for reg in err.regions {
+        print_region(file, reg);
+    }
+}
+
+pub fn print_region(file: &str, reg: FileRegion) {
+    let start = reg.start.line.saturating_sub(BEFORE);
+    let num_before = reg.start.line - start;
+    let mut lines = file.lines().skip(start);
+    let len = reg.end.col - reg.start.col + 1;
+    let width = format!("{}", reg.end.line + AFTER).len();
+    for i in 0..num_before + 1 {
+        println!("{:>width$} | {}", start + i, lines.next().unwrap());
+    }
+    println!(
+        "{} | {}",
+        " ".repeat(width),
+        " ".repeat(reg.start.col) + &"^".repeat(len)
+    );
+    for i in 0..AFTER {
+        if let Some(next) = lines.next() {
+            println!("{:>width$} | {}", reg.end.line + i + 1, next);
+        }
+    }
+}

src/parser/v2/expr.rs

@@ -0,0 +1,247 @@
+use super::{util::WHITESPACE_SET, Body, CharCursor, ParserError};
+use std::{collections::HashSet, fmt::Debug, sync::LazyLock};
+
+static SYMBOLS: LazyLock<HashSet<char>> = LazyLock::new(|| {
+    let mut set = HashSet::new();
+    for o in Operator::ALL {
+        for c in o.str().chars() {
+            set.insert(c);
+        }
+    }
+    set
+});
+
+static IDENT_END: LazyLock<HashSet<char>> = LazyLock::new(|| {
+    let mut set = WHITESPACE_SET.clone();
+    let symbols = &SYMBOLS;
+    set.extend(symbols.iter().chain(&[';', '(', ')']));
+    set
+});
+
+#[derive(Debug)]
+pub enum Val {
+    String(String),
+    Number(String),
+    Unit,
+}
+
+pub enum Expr {
+    Block(Body),
+    Val(Val),
+    Ident(String),
+    BinaryOp(Operator, Box<Expr>, Box<Expr>),
+    Call(Box<Expr>, Vec<Expr>),
+}
+
+#[derive(Debug, PartialEq, Eq)]
+pub enum Operator {
+    Add,
+    Sub,
+    Mul,
+    Div,
+    LessThan,
+    GreaterThan,
+    Offset,
+}
+
+impl Expr {
+    pub fn parse(cursor: &mut CharCursor) -> Result<Self, ParserError> {
+        cursor.skip_whitespace();
+        let Some(next) = cursor.peek() else {
+            return Ok(Self::Val(Val::Unit));
+        };
+        let mut e1 = match next {
+            '(' => {
+                cursor.advance();
+                let expr = Self::parse(cursor)?;
+                cursor.skip_whitespace();
+                cursor.expect_char(')')?;
+                expr
+            }
+            '{' => {
+                Self::Block(Body::parse(cursor)?)
+            }
+            _ => {
+                if let Some(val) = Val::parse_nonunit(cursor)? {
+                    Self::Val(val)
+                } else {
+                    let name = cursor.until(&IDENT_END);
+                    Self::Ident(name)
+                }
+            }
+        };
+        cursor.skip_whitespace();
+        let Some(mut next) = cursor.peek() else {
+            return Ok(e1);
+        };
+        while next == '(' {
+            cursor.advance();
+            let inner = Self::parse(cursor)?;
+            cursor.skip_whitespace();
+            cursor.expect_char(')')?;
+            e1 = Self::Call(Box::new(e1), vec![inner]);
+            let Some(next2) = cursor.peek() else {
+                return Ok(e1);
+            };
+            next = next2
+        }
+        if let Some(op) = Operator::parse(cursor) {
+            let e2 = Self::parse(cursor)?;
+            return Ok(if let Self::BinaryOp(op_next, e2, e3) = e2 {
+                if op.presedence() > op_next.presedence() {
+                    Self::BinaryOp(op_next, Box::new(Self::BinaryOp(op, Box::new(e1), e2)), e3)
+                } else {
+                    Self::BinaryOp(op, Box::new(e1), Box::new(Self::BinaryOp(op_next, e2, e3)))
+                }
+            } else {
+                Self::BinaryOp(op, Box::new(e1), Box::new(e2))
+            });
+        };
+        Ok(e1)
+    }
+}
+
+impl Val {
+    pub fn parse_nonunit(cursor: &mut CharCursor) -> Result<Option<Self>, ParserError> {
+        let Some(next) = cursor.peek() else {
+            return Ok(None);
+        };
+        Ok(Some(match next {
+            '"' => {
+                cursor.advance();
+                let mut str = String::new();
+                loop {
+                    let mut next = cursor.expect_next()?;
+                    if next == '"' {
+                        break;
+                    }
+                    if next == '\\' {
+                        next = match cursor.expect_next()? {
+                            '"' => '"',
+                            c => {
+                                return Err(ParserError::at(
+                                    cursor.pos(),
+                                    format!("unexpected escape char '{c}'"),
+                                ))
+                            }
+                        }
+                    }
+                    str.push(next);
+                }
+                Self::String(str)
+            }
+            '0' | '1' | '2' | '3' | '4' | '5' | '6' | '7' | '8' | '9' => {
+                let mut str = String::new();
+                loop {
+                    let Some(next) = cursor.peek() else {
+                        break;
+                    };
+                    match next {
+                        '0' | '1' | '2' | '3' | '4' | '5' | '6' | '7' | '8' | '9' => {
+                            str.push(next);
+                        }
+                        _ => break,
+                    }
+                    cursor.advance();
+                }
+                Self::Number(str)
+            }
+            _ => {
+                return Ok(None);
+            }
+        }))
+    }
+}
+
+impl Operator {
+    const ALL: [Self; 7] = [
+        Self::Add,
+        Self::Sub,
+        Self::Mul,
+        Self::Div,
+        Self::Offset,
+        Self::GreaterThan,
+        Self::LessThan,
+    ];
+    pub fn presedence(&self) -> u32 {
+        match self {
+            Operator::LessThan => 0,
+            Operator::GreaterThan => 0,
+            Operator::Add => 1,
+            Operator::Sub => 2,
+            Operator::Mul => 3,
+            Operator::Div => 4,
+            Operator::Offset => 5,
+        }
+    }
+    pub fn str(&self) -> &str {
+        match self {
+            Self::Add => "+",
+            Self::Sub => "-",
+            Self::Mul => "*",
+            Self::Div => "/",
+            Self::LessThan => "<",
+            Self::GreaterThan => ">",
+            Self::Offset => ".",
+        }
+    }
+    pub fn parse(cursor: &mut CharCursor) -> Option<Self> {
+        let res = match cursor.peek()? {
+            '+' => Operator::Add,
+            '-' => Operator::Sub,
+            '*' => Operator::Mul,
+            '/' => Operator::Div,
+            '.' => Operator::Offset,
+            _ => return None,
+        };
+        for _ in 0..res.str().len() {
+            cursor.advance();
+        }
+        Some(res)
+    }
+    pub fn pad(&self) -> bool {
+        match self {
+            Operator::Add => true,
+            Operator::Sub => true,
+            Operator::Mul => true,
+            Operator::Div => true,
+            Operator::LessThan => true,
+            Operator::GreaterThan => true,
+            Operator::Offset => false,
+        }
+    }
+}
+
+impl Debug for Expr {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            Expr::Block(b) => write!(f, "{:?}", b)?,
+            Expr::Ident(n) => f.write_str(n)?,
+            Expr::BinaryOp(op, e1, e2) => {
+                write!(f, "({:?}", *e1)?;
+                if op.pad() {
+                    write!(f, " {} ", op.str())?;
+                } else {
+                    write!(f, "{}", op.str())?;
+                }
+                write!(f, "{:?})", *e2)?;
+            }
+            Expr::Call(n, args) => {
+                n.fmt(f)?;
+                write!(f, "(")?;
+                if let Some(a) = args.first() {
+                    a.fmt(f)?;
+                }
+                for arg in args.iter().skip(1) {
+                    write!(f, ", ")?;
+                    arg.fmt(f)?;
+                }
+                write!(f, ")")?;
+            }
+            Expr::Val(v) => {
+                write!(f, "{:?}", v)?;
+            }
+        }
+        Ok(())
+    }
+}

src/parser/v2/mod.rs

@@ -0,0 +1,32 @@
+use std::io::{BufRead, BufReader};
+
+mod body;
+mod cursor;
+mod error;
+mod expr;
+mod module;
+mod util;
+
+pub use body::*;
+pub use cursor::*;
+pub use error::*;
+pub use expr::*;
+pub use module::*;
+
+pub fn parse_file(file: &str) {
+    match Module::parse(&mut CharCursor::from(file)) {
+        Err(err) => print_error(err, file),
+        Ok(module) => println!("{module:#?}"),
+    }
+}
+
+pub fn run_stdin() {
+    for line in BufReader::new(std::io::stdin()).lines() {
+        let str = &line.expect("failed to read line");
+        let mut cursor = CharCursor::from(&str[..]);
+        match Statement::parse(&mut cursor) {
+            Ok(expr) => println!("{:?}", expr),
+            Err(err) => print_error(err, str),
+        }
+    }
+}

src/parser/v2/module.rs

@@ -0,0 +1,59 @@
+use std::{collections::HashSet, fmt::Debug, sync::LazyLock};
+use super::{util::WHITESPACE_SET, Body, CharCursor, ParserError};
+
+#[derive(Debug)]
+pub struct Module {
+    functions: Vec<Function>,
+}
+
+pub struct Function {
+    pub name: String,
+    pub body: Body,
+}
+
+static NAME_END: LazyLock<HashSet<char>> = LazyLock::new(|| {
+    let mut set = WHITESPACE_SET.clone();
+    set.extend(&['(']);
+    set
+});
+
+impl Module {
+    pub fn parse(cursor: &mut CharCursor) -> Result<Self, ParserError> {
+        let mut functions = Vec::new();
+        loop {
+            let next = cursor.until(&WHITESPACE_SET);
+            if next.is_empty() {
+                return Ok(Self { functions });
+            }
+            if next == "fn" {
+                functions.push(Function::parse(cursor)?);
+            } else {
+                return Err(ParserError::at(cursor.pos(), "expected fn".to_string()));
+            }
+        }
+    }
+}
+
+impl Function {
+    pub fn parse(cursor: &mut CharCursor) -> Result<Self, ParserError> {
+        cursor.skip_whitespace();
+        let name = cursor.until(&NAME_END);
+        if name.is_empty() {
+            return Err(ParserError::at(cursor.pos(), "expected function name".to_string()));
+        }
+        cursor.expect_char('(')?;
+        cursor.expect_char(')')?;
+        let body = Body::parse(cursor)?;
+        Ok(Self { name, body })
+    }
+}
+
+impl Debug for Function {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        f.write_str("fn ")?;
+        f.write_str(&self.name)?;
+        f.write_str("() ")?;
+        self.body.fmt(f)?;
+        Ok(())
+    }
+}

src/parser/v2/util.rs

@@ -0,0 +1,10 @@
+use std::{collections::HashSet, sync::LazyLock};
+
+pub const WHITESPACE: [char; 25] = [
+    '\u{0009}', '\u{000A}', '\u{000B}', '\u{000C}', '\u{000D}', '\u{0020}', '\u{0085}', '\u{00A0}',
+    '\u{1680}', '\u{2000}', '\u{2001}', '\u{2002}', '\u{2003}', '\u{2004}', '\u{2005}', '\u{2006}',
+    '\u{2007}', '\u{2008}', '\u{2009}', '\u{200A}', '\u{2028}', '\u{2029}', '\u{202F}', '\u{205F}',
+    '\u{3000}',
+];
+
+pub static WHITESPACE_SET: LazyLock<HashSet<char>> = LazyLock::new(|| HashSet::from_iter(WHITESPACE));