Skip to content

[rustc_data_structures] Use partition_point to find slice range end. #114231

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
bors merged 2 commits into from
Jan 18, 2024
Merged

[rustc_data_structures] Use partition_point to find slice range end. #114231

Changes from 1 commit
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
9ced089
[rustc_data_structures] Use partition_point to find binary_search_sl…
ttsugriy Jul 30, 2023
97bc528
Remove invariant comments
ttsugriy Nov 5, 2023
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
29 changes: 8 additions & 21 deletions compiler/rustc_data_structures/src/binary_search_util/mod.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -14,31 +14,18 @@ where
let start = data.partition_point(|x| key_fn(x) < *key);
// At this point `start` either points at the first entry with equal or
// greater key or is equal to `size` in case all elements have smaller keys
// Invariant: start == size || key_fn(&data[start]) >= *key
if start == size || key_fn(&data[start]) != *key {
return &[];
};
// Invariant: start < size && key_fn(&data[start]) == *key

// Now search forward to find the *last* one.
let mut end = start;
let mut previous = start;
let mut step = 1;
loop {
end = end.saturating_add(step).min(size);
if end == size || key_fn(&data[end]) != *key {
break;
}
previous = end;
step *= 2;
}
step = end - previous;
while step > 1 {
let half = step / 2;
let mid = end - half;
if key_fn(&data[mid]) != *key {
end = mid;
}
step -= half;
}
// Find the first entry with key > `key`. Skip `start` entries since
// key_fn(&data[start]) == *key
// Invariant: offset == size || key_fn(&data[offset]) >= *key
let offset = start + 1;
let end = data[offset..].partition_point(|x| key_fn(x) <= *key) + offset;
// Invariant: end == size || key_fn(&data[end]) > *key

&data[start..end]
}