diff options
| -rw-r--r-- | users/tazjin/rlox/src/scanner.rs | 16 |
1 files changed, 16 insertions, 0 deletions
diff --git a/users/tazjin/rlox/src/scanner.rs b/users/tazjin/rlox/src/scanner.rs index 78a019592ca4..659f280de72b 100644 --- a/users/tazjin/rlox/src/scanner.rs +++ b/users/tazjin/rlox/src/scanner.rs @@ -90,6 +90,7 @@ impl<'a> Scanner<'a> { fn scan_token(&mut self) { match self.advance() { + // simple single-character tokens '(' => self.add_token(TokenKind::LeftParen), ')' => self.add_token(TokenKind::RightParen), '{' => self.add_token(TokenKind::LeftBrace), @@ -101,6 +102,12 @@ impl<'a> Scanner<'a> { ';' => self.add_token(TokenKind::Semicolon), '*' => self.add_token(TokenKind::Star), + // possible multi-character tokens + '!' => self.add_if_next('=', TokenKind::BangEqual, TokenKind::Bang), + '=' => self.add_if_next('=', TokenKind::EqualEqual, TokenKind::Equal), + '<' => self.add_if_next('=', TokenKind::LessEqual, TokenKind::Less), + '>' => self.add_if_next('=', TokenKind::GreaterEqual, TokenKind::Greater), + unexpected => self.errors.push(Error { line: self.line, kind: ErrorKind::UnexpectedChar(unexpected), @@ -108,6 +115,15 @@ impl<'a> Scanner<'a> { }; } + fn add_if_next(&mut self, expected:char, then: TokenKind, or: TokenKind) { + if self.is_at_end() || self.source[self.current] != expected { + self.add_token(or); + } else { + self.current += 1; + self.add_token(then); + } + } + fn scan_tokens(mut self) -> Vec<Token<'a>> { while !self.is_at_end() { self.start = self.current; |