| // We want to be able to build this crate with a stable compiler, so no |
| // `#![feature]` attributes should be added. |
| |
| mod cursor; |
| pub mod unescape; |
| |
| use crate::cursor::{Cursor, EOF_CHAR}; |
| |
| pub struct Token { |
| pub kind: TokenKind, |
| pub len: usize, |
| } |
| |
| #[derive(Clone, Copy, Debug, PartialEq, Eq, PartialOrd, Ord)] |
| pub enum TokenKind { |
| LineComment, |
| BlockComment { terminated: bool }, |
| Whitespace, |
| Ident, |
| RawIdent, |
| Literal { kind: LiteralKind, suffix_start: usize }, |
| Lifetime { starts_with_number: bool }, |
| Semi, |
| Comma, |
| Dot, |
| OpenParen, |
| CloseParen, |
| OpenBrace, |
| CloseBrace, |
| OpenBracket, |
| CloseBracket, |
| At, |
| Pound, |
| Tilde, |
| Question, |
| Colon, |
| Dollar, |
| Eq, |
| Not, |
| Lt, |
| Gt, |
| Minus, |
| And, |
| Or, |
| Plus, |
| Star, |
| Slash, |
| Caret, |
| Percent, |
| Unknown, |
| } |
| use self::TokenKind::*; |
| |
| #[derive(Clone, Copy, Debug, PartialEq, Eq, PartialOrd, Ord)] |
| pub enum LiteralKind { |
| Int { base: Base, empty_int: bool }, |
| Float { base: Base, empty_exponent: bool }, |
| Char { terminated: bool }, |
| Byte { terminated: bool }, |
| Str { terminated: bool }, |
| ByteStr { terminated: bool }, |
| RawStr { n_hashes: usize, started: bool, terminated: bool }, |
| RawByteStr { n_hashes: usize, started: bool, terminated: bool }, |
| } |
| use self::LiteralKind::*; |
| |
| #[derive(Clone, Copy, Debug, PartialEq, Eq, PartialOrd, Ord)] |
| pub enum Base { |
| Binary, |
| Octal, |
| Hexadecimal, |
| Decimal, |
| } |
| |
| impl Token { |
| fn new(kind: TokenKind, len: usize) -> Token { |
| Token { kind, len } |
| } |
| } |
| |
| pub fn strip_shebang(input: &str) -> Option<usize> { |
| debug_assert!(!input.is_empty()); |
| if !input.starts_with("#!") || input.starts_with("#![") { |
| return None; |
| } |
| Some(input.find('\n').unwrap_or(input.len())) |
| } |
| |
| pub fn first_token(input: &str) -> Token { |
| debug_assert!(!input.is_empty()); |
| Cursor::new(input).advance_token() |
| } |
| |
| pub fn tokenize(mut input: &str) -> impl Iterator<Item = Token> + '_ { |
| std::iter::from_fn(move || { |
| if input.is_empty() { |
| return None; |
| } |
| let token = first_token(input); |
| input = &input[token.len..]; |
| Some(token) |
| }) |
| } |
| |
| // See [UAX #31](http://unicode.org/reports/tr31) for definitions of these |
| // classes. |
| |
| /// True if `c` is considered a whitespace according to Rust language definition. |
| pub fn is_whitespace(c: char) -> bool { |
| // This is Pattern_White_Space. |
| // |
| // Note that this set is stable (ie, it doesn't change with different |
| // Unicode versions), so it's ok to just hard-code the values. |
| |
| match c { |
| // Usual ASCII suspects |
| | '\u{0009}' // \t |
| | '\u{000A}' // \n |
| | '\u{000B}' // vertical tab |
| | '\u{000C}' // form feed |
| | '\u{000D}' // \r |
| | '\u{0020}' // space |
| |
| // NEXT LINE from latin1 |
| | '\u{0085}' |
| |
| // Bidi markers |
| | '\u{200E}' // LEFT-TO-RIGHT MARK |
| | '\u{200F}' // RIGHT-TO-LEFT MARK |
| |
| // Dedicated whitespace characters from Unicode |
| | '\u{2028}' // LINE SEPARATOR |
| | '\u{2029}' // PARAGRAPH SEPARATOR |
| => true, |
| _ => false, |
| } |
| } |
| |
| /// True if `c` is valid as a first character of an identifier. |
| pub fn is_id_start(c: char) -> bool { |
| // This is XID_Start OR '_' (which formally is not a XID_Start). |
| // We also add fast-path for ascii idents |
| ('a' <= c && c <= 'z') |
| || ('A' <= c && c <= 'Z') |
| || c == '_' |
| || (c > '\x7f' && unicode_xid::UnicodeXID::is_xid_start(c)) |
| } |
| |
| /// True if `c` is valid as a non-first character of an identifier. |
| pub fn is_id_continue(c: char) -> bool { |
| // This is exactly XID_Continue. |
| // We also add fast-path for ascii idents |
| ('a' <= c && c <= 'z') |
| || ('A' <= c && c <= 'Z') |
| || ('0' <= c && c <= '9') |
| || c == '_' |
| || (c > '\x7f' && unicode_xid::UnicodeXID::is_xid_continue(c)) |
| } |
| |
| |
| impl Cursor<'_> { |
| fn advance_token(&mut self) -> Token { |
| let first_char = self.bump().unwrap(); |
| let token_kind = match first_char { |
| '/' => match self.nth_char(0) { |
| '/' => self.line_comment(), |
| '*' => self.block_comment(), |
| _ => Slash, |
| }, |
| c if is_whitespace(c) => self.whitespace(), |
| 'r' => match (self.nth_char(0), self.nth_char(1)) { |
| ('#', c1) if is_id_start(c1) => self.raw_ident(), |
| ('#', _) | ('"', _) => { |
| let (n_hashes, started, terminated) = self.raw_double_quoted_string(); |
| let suffix_start = self.len_consumed(); |
| if terminated { |
| self.eat_literal_suffix(); |
| } |
| let kind = RawStr { n_hashes, started, terminated }; |
| Literal { kind, suffix_start } |
| } |
| _ => self.ident(), |
| }, |
| 'b' => match (self.nth_char(0), self.nth_char(1)) { |
| ('\'', _) => { |
| self.bump(); |
| let terminated = self.single_quoted_string(); |
| let suffix_start = self.len_consumed(); |
| if terminated { |
| self.eat_literal_suffix(); |
| } |
| let kind = Byte { terminated }; |
| Literal { kind, suffix_start } |
| } |
| ('"', _) => { |
| self.bump(); |
| let terminated = self.double_quoted_string(); |
| let suffix_start = self.len_consumed(); |
| if terminated { |
| self.eat_literal_suffix(); |
| } |
| let kind = ByteStr { terminated }; |
| Literal { kind, suffix_start } |
| } |
| ('r', '"') | ('r', '#') => { |
| self.bump(); |
| let (n_hashes, started, terminated) = self.raw_double_quoted_string(); |
| let suffix_start = self.len_consumed(); |
| if terminated { |
| self.eat_literal_suffix(); |
| } |
| let kind = RawByteStr { n_hashes, started, terminated }; |
| Literal { kind, suffix_start } |
| } |
| _ => self.ident(), |
| }, |
| c if is_id_start(c) => self.ident(), |
| c @ '0'..='9' => { |
| let literal_kind = self.number(c); |
| let suffix_start = self.len_consumed(); |
| self.eat_literal_suffix(); |
| TokenKind::Literal { kind: literal_kind, suffix_start } |
| } |
| ';' => Semi, |
| ',' => Comma, |
| '.' => Dot, |
| '(' => OpenParen, |
| ')' => CloseParen, |
| '{' => OpenBrace, |
| '}' => CloseBrace, |
| '[' => OpenBracket, |
| ']' => CloseBracket, |
| '@' => At, |
| '#' => Pound, |
| '~' => Tilde, |
| '?' => Question, |
| ':' => Colon, |
| '$' => Dollar, |
| '=' => Eq, |
| '!' => Not, |
| '<' => Lt, |
| '>' => Gt, |
| '-' => Minus, |
| '&' => And, |
| '|' => Or, |
| '+' => Plus, |
| '*' => Star, |
| '^' => Caret, |
| '%' => Percent, |
| '\'' => self.lifetime_or_char(), |
| '"' => { |
| let terminated = self.double_quoted_string(); |
| let suffix_start = self.len_consumed(); |
| if terminated { |
| self.eat_literal_suffix(); |
| } |
| let kind = Str { terminated }; |
| Literal { kind, suffix_start } |
| } |
| _ => Unknown, |
| }; |
| Token::new(token_kind, self.len_consumed()) |
| } |
| |
| fn line_comment(&mut self) -> TokenKind { |
| debug_assert!(self.prev() == '/' && self.nth_char(0) == '/'); |
| self.bump(); |
| loop { |
| match self.nth_char(0) { |
| '\n' => break, |
| EOF_CHAR if self.is_eof() => break, |
| _ => { |
| self.bump(); |
| } |
| } |
| } |
| LineComment |
| } |
| |
| fn block_comment(&mut self) -> TokenKind { |
| debug_assert!(self.prev() == '/' && self.nth_char(0) == '*'); |
| self.bump(); |
| let mut depth = 1usize; |
| while let Some(c) = self.bump() { |
| match c { |
| '/' if self.nth_char(0) == '*' => { |
| self.bump(); |
| depth += 1; |
| } |
| '*' if self.nth_char(0) == '/' => { |
| self.bump(); |
| depth -= 1; |
| if depth == 0 { |
| break; |
| } |
| } |
| _ => (), |
| } |
| } |
| |
| BlockComment { terminated: depth == 0 } |
| } |
| |
| fn whitespace(&mut self) -> TokenKind { |
| debug_assert!(is_whitespace(self.prev())); |
| while is_whitespace(self.nth_char(0)) { |
| self.bump(); |
| } |
| Whitespace |
| } |
| |
| fn raw_ident(&mut self) -> TokenKind { |
| debug_assert!( |
| self.prev() == 'r' |
| && self.nth_char(0) == '#' |
| && is_id_start(self.nth_char(1)) |
| ); |
| self.bump(); |
| self.bump(); |
| while is_id_continue(self.nth_char(0)) { |
| self.bump(); |
| } |
| RawIdent |
| } |
| |
| fn ident(&mut self) -> TokenKind { |
| debug_assert!(is_id_start(self.prev())); |
| while is_id_continue(self.nth_char(0)) { |
| self.bump(); |
| } |
| Ident |
| } |
| |
| fn number(&mut self, first_digit: char) -> LiteralKind { |
| debug_assert!('0' <= self.prev() && self.prev() <= '9'); |
| let mut base = Base::Decimal; |
| if first_digit == '0' { |
| let has_digits = match self.nth_char(0) { |
| 'b' => { |
| base = Base::Binary; |
| self.bump(); |
| self.eat_decimal_digits() |
| } |
| 'o' => { |
| base = Base::Octal; |
| self.bump(); |
| self.eat_decimal_digits() |
| } |
| 'x' => { |
| base = Base::Hexadecimal; |
| self.bump(); |
| self.eat_hexadecimal_digits() |
| } |
| '0'..='9' | '_' | '.' | 'e' | 'E' => { |
| self.eat_decimal_digits(); |
| true |
| } |
| // just a 0 |
| _ => return Int { base, empty_int: false }, |
| }; |
| if !has_digits { |
| return Int { base, empty_int: true }; |
| } |
| } else { |
| self.eat_decimal_digits(); |
| }; |
| |
| match self.nth_char(0) { |
| // Don't be greedy if this is actually an |
| // integer literal followed by field/method access or a range pattern |
| // (`0..2` and `12.foo()`) |
| '.' if self.nth_char(1) != '.' |
| && !is_id_start(self.nth_char(1)) => |
| { |
| // might have stuff after the ., and if it does, it needs to start |
| // with a number |
| self.bump(); |
| let mut empty_exponent = false; |
| if self.nth_char(0).is_digit(10) { |
| self.eat_decimal_digits(); |
| match self.nth_char(0) { |
| 'e' | 'E' => { |
| self.bump(); |
| empty_exponent = self.float_exponent().is_err() |
| } |
| _ => (), |
| } |
| } |
| Float { base, empty_exponent } |
| } |
| 'e' | 'E' => { |
| self.bump(); |
| let empty_exponent = self.float_exponent().is_err(); |
| Float { base, empty_exponent } |
| } |
| _ => Int { base, empty_int: false }, |
| } |
| } |
| |
| fn lifetime_or_char(&mut self) -> TokenKind { |
| debug_assert!(self.prev() == '\''); |
| let mut starts_with_number = false; |
| if (is_id_start(self.nth_char(0)) |
| || self.nth_char(0).is_digit(10) && { |
| starts_with_number = true; |
| true |
| }) |
| && self.nth_char(1) != '\'' |
| { |
| self.bump(); |
| while is_id_continue(self.nth_char(0)) { |
| self.bump(); |
| } |
| |
| return if self.nth_char(0) == '\'' { |
| self.bump(); |
| let kind = Char { terminated: true }; |
| Literal { kind, suffix_start: self.len_consumed() } |
| } else { |
| Lifetime { starts_with_number } |
| }; |
| } |
| let terminated = self.single_quoted_string(); |
| let suffix_start = self.len_consumed(); |
| if terminated { |
| self.eat_literal_suffix(); |
| } |
| let kind = Char { terminated }; |
| return Literal { kind, suffix_start }; |
| } |
| |
| fn single_quoted_string(&mut self) -> bool { |
| debug_assert!(self.prev() == '\''); |
| // parse `'''` as a single char literal |
| if self.nth_char(0) == '\'' && self.nth_char(1) == '\'' { |
| self.bump(); |
| } |
| let mut first = true; |
| loop { |
| match self.nth_char(0) { |
| '/' if !first => break, |
| '\n' if self.nth_char(1) != '\'' => break, |
| EOF_CHAR if self.is_eof() => break, |
| '\'' => { |
| self.bump(); |
| return true; |
| } |
| '\\' => { |
| self.bump(); |
| self.bump(); |
| } |
| _ => { |
| self.bump(); |
| } |
| } |
| first = false; |
| } |
| false |
| } |
| |
| fn double_quoted_string(&mut self) -> bool { |
| debug_assert!(self.prev() == '"'); |
| loop { |
| match self.nth_char(0) { |
| '"' => { |
| self.bump(); |
| return true; |
| } |
| EOF_CHAR if self.is_eof() => return false, |
| '\\' if self.nth_char(1) == '\\' || self.nth_char(1) == '"' => { |
| self.bump(); |
| } |
| _ => (), |
| } |
| self.bump(); |
| } |
| } |
| |
| fn raw_double_quoted_string(&mut self) -> (usize, bool, bool) { |
| debug_assert!(self.prev() == 'r'); |
| let n_hashes = { |
| let mut acc: usize = 0; |
| loop { |
| match self.bump() { |
| Some('#') => acc += 1, |
| Some('"') => break acc, |
| None | Some(_) => return (acc, false, false), |
| } |
| } |
| }; |
| |
| loop { |
| match self.bump() { |
| Some('"') => { |
| let mut acc = n_hashes; |
| while self.nth_char(0) == '#' && acc > 0 { |
| self.bump(); |
| acc -= 1; |
| } |
| if acc == 0 { |
| return (n_hashes, true, true); |
| } |
| } |
| Some(_) => (), |
| None => return (n_hashes, true, false), |
| } |
| } |
| } |
| |
| fn eat_decimal_digits(&mut self) -> bool { |
| let mut has_digits = false; |
| loop { |
| match self.nth_char(0) { |
| '_' => { |
| self.bump(); |
| } |
| '0'..='9' => { |
| has_digits = true; |
| self.bump(); |
| } |
| _ => break, |
| } |
| } |
| has_digits |
| } |
| |
| fn eat_hexadecimal_digits(&mut self) -> bool { |
| let mut has_digits = false; |
| loop { |
| match self.nth_char(0) { |
| '_' => { |
| self.bump(); |
| } |
| '0'..='9' | 'a'..='f' | 'A'..='F' => { |
| has_digits = true; |
| self.bump(); |
| } |
| _ => break, |
| } |
| } |
| has_digits |
| } |
| |
| fn float_exponent(&mut self) -> Result<(), ()> { |
| debug_assert!(self.prev() == 'e' || self.prev() == 'E'); |
| if self.nth_char(0) == '-' || self.nth_char(0) == '+' { |
| self.bump(); |
| } |
| if self.eat_decimal_digits() { Ok(()) } else { Err(()) } |
| } |
| |
| fn eat_literal_suffix(&mut self) { |
| if !is_id_start(self.nth_char(0)) { |
| return; |
| } |
| self.bump(); |
| |
| while is_id_continue(self.nth_char(0)) { |
| self.bump(); |
| } |
| } |
| } |