Implement an easy way to get the matched char in a wildcard rule #10

osa1 · 2021-06-19T12:36:36Z

Currently getting the matched character in a wildcard is quite verbose (and probably also inefficient):

_ => |mut lexer| {
    let char = lexer.match_().chars().next_back().unwrap();
    ...
}

One easy fix would be to add a char method to lexer that returns the last matched character.

Alternatively with #9 we could allow <char:_> => ... syntax.

The text was updated successfully, but these errors were encountered:

osa1 · 2021-10-26T01:38:38Z

Another example:

let whitespace =
    ['\t' '\n' '\u{B}' '\u{C}' '\r' ' ' '\u{85}' '\u{200E}' '\u{200F}' '\u{2028}' '\u{2029}'];

rule DecInt {
    ($dec_digit | '_')* $int_suffix?,

    $ => |lexer| {
        let match_ = lexer.match_();
        lexer.return_(Token::Lit(Lit::Int(match_)))
    },

    $whitespace => |lexer| {
        let match_ = lexer.match_();
        // TODO: Rust whitespace characters 1, 2, or 3 bytes long
        lexer.return_(Token::Lit(Lit::Int(&match_[..match_.len() - match_.chars().last().unwrap().len_utf8()])))
    },
}

In the last rule we want to exclude the trailing whitespace. We can't just drop the last byte as the allowed whitespace characters can be 1, 2, or 3 bytes long. If we could bind the whitespace character we could do match_[..match.len() - whitespace_clar.len_utf8()].

osa1 added the feature New feature or request label Jun 19, 2021

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Implement an easy way to get the matched char in a wildcard rule #10

Implement an easy way to get the matched char in a wildcard rule #10

osa1 commented Jun 19, 2021

osa1 commented Oct 26, 2021 •

edited

Implement an easy way to get the matched char in a wildcard rule #10

Implement an easy way to get the matched char in a wildcard rule #10

Comments

osa1 commented Jun 19, 2021

osa1 commented Oct 26, 2021 • edited

osa1 commented Oct 26, 2021 •

edited