oni_comb_parser/combinator/
sep_by_fold.rs

1use crate::fail::{Fail, PResult};
2use crate::input::Input;
3use crate::parser::Parser;
4
5pub struct SepByFold0<P, S, B, F> {
6  pub(crate) parser: P,
7  pub(crate) sep: S,
8  pub(crate) init: B,
9  pub(crate) f: F,
10}
11
12impl<I, P, S, B, F, Acc> Parser<I> for SepByFold0<P, S, B, F>
13where
14  I: Input,
15  P: Parser<I>,
16  S: Parser<I, Error = P::Error>,
17  B: FnMut() -> Acc,
18  F: FnMut(Acc, P::Output) -> Acc,
19{
20  type Error = P::Error;
21  type Output = Acc;
22
23  #[inline(always)]
24  fn parse_next(&mut self, input: &mut I) -> PResult<Self::Output, Self::Error> {
25    let mut acc = (self.init)();
26
27    // 最初の要素
28    let cp = input.checkpoint();
29    match self.parser.parse_next(input) {
30      Ok(v) => acc = (self.f)(acc, v),
31      Err(Fail::Backtrack(_)) => {
32        input.reset(cp);
33        return Ok(acc);
34      }
35      Err(e) => return Err(e),
36    }
37
38    // sep + 要素 の繰り返し
39    loop {
40      let cp = input.checkpoint();
41      match self.sep.parse_next(input) {
42        Ok(_) => {}
43        Err(Fail::Backtrack(_)) => {
44          input.reset(cp);
45          break;
46        }
47        Err(e) => return Err(e),
48      }
49      match self.parser.parse_next(input) {
50        Ok(v) => acc = (self.f)(acc, v),
51        Err(Fail::Backtrack(_)) => {
52          input.reset(cp);
53          break;
54        }
55        Err(e) => return Err(e),
56      }
57    }
58
59    Ok(acc)
60  }
61}
62
63pub struct SepByFold1<P, S, B, F> {
64  pub(crate) parser: P,
65  pub(crate) sep: S,
66  pub(crate) init: B,
67  pub(crate) f: F,
68}
69
70impl<I, P, S, B, F, Acc> Parser<I> for SepByFold1<P, S, B, F>
71where
72  I: Input,
73  P: Parser<I>,
74  S: Parser<I, Error = P::Error>,
75  B: FnMut() -> Acc,
76  F: FnMut(Acc, P::Output) -> Acc,
77{
78  type Error = P::Error;
79  type Output = Acc;
80
81  #[inline(always)]
82  fn parse_next(&mut self, input: &mut I) -> PResult<Self::Output, Self::Error> {
83    // 最初の要素は必須
84    let first = self.parser.parse_next(input)?;
85    let mut acc = (self.f)((self.init)(), first);
86
87    // sep + 要素 の繰り返し
88    loop {
89      let cp = input.checkpoint();
90      match self.sep.parse_next(input) {
91        Ok(_) => {}
92        Err(Fail::Backtrack(_)) => {
93          input.reset(cp);
94          break;
95        }
96        Err(e) => return Err(e),
97      }
98      match self.parser.parse_next(input) {
99        Ok(v) => acc = (self.f)(acc, v),
100        Err(Fail::Backtrack(_)) => {
101          input.reset(cp);
102          break;
103        }
104        Err(e) => return Err(e),
105      }
106    }
107
108    Ok(acc)
109  }
110}
oni_comb_parser/combinator/sep_by_fold.rs

oni_comb_parser/combinator/
sep_by_fold.rs
