bc-envelope-pattern 0.14.0

Pattern matcher for Gordian Envelope
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23

use super::super::{Token, meta};
use crate::{Error, Pattern, Result};

pub(crate) fn parse_subject(
    lexer: &mut logos::Lexer<Token>,
) -> Result<Pattern> {
    let mut lookahead = lexer.clone();
    match lookahead.next() {
        Some(Ok(Token::ParenOpen)) => {
            lexer.next();
            let pattern = meta::parse_or(lexer)?;
            match lexer.next() {
                Some(Ok(Token::ParenClose)) => Ok(Pattern::subject(pattern)),
                Some(Ok(t)) => {
                    Err(Error::UnexpectedToken(Box::new(t), lexer.span()))
                }
                Some(Err(e)) => Err(e),
                None => Err(Error::ExpectedCloseParen(lexer.span())),
            }
        }
        _ => Ok(Pattern::any_subject()),
    }
}