| 62 | self.span.start, self.span.end |
| 63 | ) |
| 64 | } |
| 65 | } |
| 66 | |
| 67 | impl std::error::Error for LexError {} |
| 68 | |
| 69 | impl LexError { |
| 70 | fn new(kind: LexErrorKind, start: usize, end: usize) -> Self { |
| 71 | Self { |
| 72 | kind, |
| 73 | span: Span { start, end }, |
| 74 | } |
| 75 | } |
| 76 | } |
| 77 | |
| 78 | pub struct Lexer<'a> { |
| 79 | src: &'a str, |
| 80 | pos: usize, |
| 81 | } |
| 82 | |
| 83 | impl<'a> Lexer<'a> { |
| 84 | pub fn new(src: &'a str) -> Self { |
| 85 | Self { src, pos: 0 } |
| 86 | } |
| 87 | |
| 88 | fn peek(&self) -> Option<char> { |
| 89 | self.src[self.pos..].chars().next() |
| 90 | } |
| 91 | |
| 92 | fn bump(&mut self) -> Option<char> { |
| 93 | let c = self.peek()?; |
| 94 | self.pos += c.len_utf8(); |
| 95 | Some(c) |
| 96 | } |
| 97 | |
| 98 | fn skip_ws(&mut self) { |
| 99 | while matches!(self.peek(), Some(c) if c.is_whitespace()) { |
| 100 | self.bump(); |
| 101 | } |
| 102 | } |
| 103 | |
| 104 | fn skip_until_newline(&mut self) { |
| 105 | while let Some(c) = self.peek() { |
| 106 | if c == '\n' || c == '\r' { |
| 107 | break; |
| 108 | } |
| 109 | self.bump(); |
| 110 | } |
| 111 | } |
| 112 | |
| 113 | pub fn next_token(&mut self) -> Token<'a> { |
| 114 | loop { |
| 115 | self.skip_ws(); |
| 116 | match (self.peek(), self.src[self.pos..].chars().nth(1)) { |
| 117 | (Some('#'), _) => { |
| 118 | self.bump(); |
| 119 | self.skip_until_newline(); |
| 120 | } |
| 121 | (Some('/'), Some('/')) => { |