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merge: rewrite bottom half of trivial_merge() for non-copyable types

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The input values of trivial_merge() will be changed to Iterator<Item = T>
where T: Eq + Hash. It could be <Item = &'a T>, but it doesn't have to be.
This commit is contained in:
Yuya Nishihara 2023-11-05 10:40:55 +09:00
parent d8a7822c38
commit 01523ba4f3
1 changed files with 22 additions and 24 deletions
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46
lib/src/merge.rs
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@ -72,31 +72,29 @@ where
// Collect non-zero value. Values with a count of 0 means that they have
// cancelled out.
let counts = counts
.into_iter()
.filter(|&(_, count)| count != 0)
.collect_vec();
match counts[..] {
[(value, 1)] => {
// If there is a single value with a count of 1 left, then that is the result.
Some(value)
counts.retain(|_, count| *count != 0);
if counts.len() == 1 {
// If there is a single value with a count of 1 left, then that is the result.
let (value, count) = counts.into_iter().next().unwrap();
assert_eq!(count, 1);
Some(value)
} else if counts.len() == 2 {
// All sides made the same change.
// This matches what Git and Mercurial do (in the 3-way case at least), but not
// what Darcs and Pijul do. It means that repeated 3-way merging of multiple
// trees may give different results depending on the order of merging.
// TODO: Consider removing this special case, making the algorithm more strict,
// and maybe add a more lenient version that is used when the user explicitly
// asks for conflict resolution.
let ((value1, count1), (value2, count2)) = counts.into_iter().next_tuple().unwrap();
assert_eq!(count1 + count2, 1);
if count1 > 0 {
Some(value1)
} else {
Some(value2)
}
[(value1, count1), (value2, count2)] => {
// All sides made the same change.
// This matches what Git and Mercurial do (in the 3-way case at least), but not
// what Darcs and Pijul do. It means that repeated 3-way merging of multiple
// trees may give different results depending on the order of merging.
// TODO: Consider removing this special case, making the algorithm more strict,
// and maybe add a more lenient version that is used when the user explicitly
// asks for conflict resolution.
assert_eq!(count1 + count2, 1);
if count1 > 0 {
Some(value1)
} else {
Some(value2)
}
}
_ => None,
} else {
None
}
}