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oni_comb_parser/text/
satisfy.rs

1use crate::error::ParseError;
2use crate::fail::{Fail, PResult};
3use crate::input::Input;
4use crate::parser::Parser;
5use crate::str_input::StrInput;
6
7pub struct Satisfy<F>(F);
8
9pub fn satisfy<F: FnMut(char) -> bool>(f: F) -> Satisfy<F> {
10  Satisfy(f)
11}
12
13impl<'a, F> Parser<StrInput<'a>> for Satisfy<F>
14where
15  F: FnMut(char) -> bool,
16{
17  type Error = ParseError;
18  type Output = char;
19
20  #[inline]
21  fn parse_next(&mut self, input: &mut StrInput<'a>) -> PResult<char, ParseError> {
22    let pos = input.offset();
23    let remaining = input.as_str();
24    match remaining.chars().next() {
25      Some(c) if (self.0)(c) => {
26        input.advance(c.len_utf8());
27        Ok(c)
28      }
29      _ => Err(Fail::Backtrack(ParseError::expected_description(pos, "satisfy"))),
30    }
31  }
32}