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osa1 / lexgen

A fully-featured lexer generator, implemented as a proc macro
MIT License
63 stars 7 forks source link

match until/til? #56

Closed hh9527 closed 1 year ago

hh9527 commented 1 year ago

for example, how to lex rust like raw string: r###"..."###


rule Init {
  'r' '#'* '"' => |lexer| {
    *lexer.state() = lexer.match_().len() - 1; // set the number of end mark “#...
    lexer.switch_and_return(LexerRule::RawText, Token::RawTextStart)
  },
}

rule RawText {
  // here, I dont know how to constraint to number of '#'
  _* '"' '#'* => |lexer| {
    len n = *lexer.state();
    let cont = lexer.match_();
    let body = &cont[..cont.len() - n];
    lexer.switch_and_return(LexerRule::Init, Token::RawTextCont(body, n));
  },
}