hir_ty/diagnostics/match_check/
pat_util.rs

1//! Pattern utilities.
2//!
3//! Originates from `rustc_hir::pat_util`
4
5use std::iter::Enumerate;
6
7pub(crate) struct EnumerateAndAdjust<I> {
8    enumerate: Enumerate<I>,
9    gap_pos: usize,
10    gap_len: usize,
11}
12
13impl<I> Iterator for EnumerateAndAdjust<I>
14where
15    I: Iterator,
16{
17    type Item = (usize, <I as Iterator>::Item);
18
19    fn next(&mut self) -> Option<(usize, <I as Iterator>::Item)> {
20        self.enumerate
21            .next()
22            .map(|(i, elem)| (if i < self.gap_pos { i } else { i + self.gap_len }, elem))
23    }
24
25    fn size_hint(&self) -> (usize, Option<usize>) {
26        self.enumerate.size_hint()
27    }
28}
29
30pub(crate) trait EnumerateAndAdjustIterator {
31    fn enumerate_and_adjust(
32        self,
33        expected_len: usize,
34        gap_pos: Option<usize>,
35    ) -> EnumerateAndAdjust<Self>
36    where
37        Self: Sized;
38}
39
40impl<T: ExactSizeIterator> EnumerateAndAdjustIterator for T {
41    fn enumerate_and_adjust(
42        self,
43        expected_len: usize,
44        gap_pos: Option<usize>,
45    ) -> EnumerateAndAdjust<Self>
46    where
47        Self: Sized,
48    {
49        let actual_len = self.len();
50        EnumerateAndAdjust {
51            enumerate: self.enumerate(),
52            gap_pos: gap_pos.unwrap_or(expected_len),
53            gap_len: expected_len - actual_len,
54        }
55    }
56}
hir_ty/diagnostics/match_check/pat_util.rs

hir_ty/diagnostics/match_check/
pat_util.rs
