serde-tcod-config-parser 0.1.1

A best-effort implementation of the now deprecated libtcod config file parser functionality from libtcod
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use logos::internal::LexerInternal;
use logos::{Lexer, Logos, Source};

#[derive(Debug, PartialEq, Clone, Copy, Logos)]
pub(crate) enum Token {
    #[end]
    EndOfProgram,

    #[regex = "\"[^\"]*\""]
    Text,

    #[regex = "'(\\\\x[0-9a-fA-F]+|\\\\[0-7]+|\\\\(n|t|r|\\\\|\"|')|.)'"]
    Char,

    #[regex = "(-|\\+)?([0-9]*\\.[0-9]+|[0-9]+\\.[0-9]*)((E|e)(-|\\+)?[0-9]+)?"]
    Float,

    #[regex = "-?0(x|X)[0-9a-fA-F]+"]
    Hex,

    #[regex = "-?[0-9]+"]
    Integer,

    #[regex = "[a-zA-Z][a-zA-Z0-9_]*"]
    Identifier,

    #[regex = "#[0-9a-fA-F][0-9a-fA-F][0-9a-fA-F][0-9a-fA-F][0-9a-fA-F][0-9a-fA-F]"]
    Color,

    #[token = "{"]
    BraceOpen,

    #[token = "}"]
    BraceClose,

    #[token = "="]
    Assign,

    #[token = ","]
    Comma,

    #[token = "["]
    BracketOpen,

    #[token = "]"]
    BracketClose,

    #[regex = "//[^\n]*"]
    #[token = "/*"]
    #[callback = "ignore_comments"]
    #[error]
    Unexpected,
    UnclosedMultilineComment,
}

fn ignore_comments<'source, Src: Source<'source>>(lex: &mut Lexer<Token, Src>) {
    use logos::Slice;

    if lex.slice().as_bytes() == b"/*" {
        let mut level = 1;
        loop {
            match lex.read() {
                None => return lex.token = Token::UnclosedMultilineComment,
                Some(b'*') => {
                    if lex.read_at(1) == Some(b'/') {
                        lex.bump(2);
                        level -= 1;
                        if level == 0 {
                            break;
                        }
                    } else {
                        lex.bump(1);
                    }
                }
                Some(b'/') => {
                    if lex.read_at(1) == Some(b'*') {
                        lex.bump(2);
                        level += 1;
                    } else {
                        lex.bump(1);
                    }
                }
                _ => lex.bump(1),
            }
        }
    }

    lex.advance();
}

#[cfg(test)]
mod tests {
    use super::Token;
    use logos::Logos;

    #[test]
    fn char_hex() {
        let sut = Token::lexer("'\\x9F' ");

        assert_eq!(sut.token, Token::Char);
        assert_eq!(sut.slice(), "'\\x9F'");
    }

    #[test]
    fn char_oct() {
        let sut = Token::lexer("'\\200' ");

        assert_eq!(sut.token, Token::Char);
        assert_eq!(sut.slice(), "'\\200'");
    }

    #[test]
    fn char_special() {
        let mut sut = Token::lexer("'\\n' '\\t' '\\r' '\\\\' '\\\"' '\\''");

        assert_eq!(sut.token, Token::Char);
        assert_eq!(sut.slice(), "'\\n'");

        sut.advance();

        assert_eq!(sut.token, Token::Char);
        assert_eq!(sut.slice(), "'\\t'");

        sut.advance();

        assert_eq!(sut.token, Token::Char);
        assert_eq!(sut.slice(), "'\\r'");

        sut.advance();

        assert_eq!(sut.token, Token::Char);
        assert_eq!(sut.slice(), "'\\\\'");

        sut.advance();

        assert_eq!(sut.token, Token::Char);
        assert_eq!(sut.slice(), "'\\\"'");

        sut.advance();

        assert_eq!(sut.token, Token::Char);
        assert_eq!(sut.slice(), "'\\''");

        sut.advance();
    }
}