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Added deadlines to all algorithms (#18)

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This adds a deadline to all algorithms which lets one bail in a fixed amount of
time to avoid pathological cases.
This commit is contained in:
Armin Ronacher 2021-02-20 10:12:06 +01:00 • committed by GitHub
parent 99386e8106
commit 74e2805a95
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GPG key ID: 4AEE18F83AFDEB23
11 changed files with 412 additions and 57 deletions
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50
src/algorithms/mod.rs
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@ -39,6 +39,7 @@ mod replace;
use std::hash::Hash;
use std::ops::{Index, Range};
use std::time::Instant;
pub use capture::Capture;
pub use hook::{DiffHook, NoFinishHook};
@ -62,6 +63,34 @@ pub fn diff<Old, New, D>(
new: &New,
new_range: Range<usize>,
) -> Result<(), D::Error>
where
Old: Index<usize> + ?Sized,
New: Index<usize> + ?Sized,
D: DiffHook,
Old::Output: Hash + Eq + Ord,
New::Output: PartialEq<Old::Output> + Hash + Eq + Ord,
{
diff_deadline(alg, d, old, old_range, new, new_range, None)
}
/// Creates a diff between old and new with the given algorithm with deadline.
///
/// Diffs `old`, between indices `old_range` and `new` between indices `new_range`.
///
/// This diff is done with an optional deadline that defines the maximal
/// execution time permitted before it bails and falls back to an approximation.
/// Note that not all algorithms behave well if they reach the deadline (LCS
/// for instance produces a very simplistic diff when the deadline is reached
/// in all cases).
pub fn diff_deadline<Old, New, D>(
alg: Algorithm,
d: &mut D,
old: &Old,
old_range: Range<usize>,
new: &New,
new_range: Range<usize>,
deadline: Option<Instant>,
) -> Result<(), D::Error>
where
Old: Index<usize> + ?Sized,
New: Index<usize> + ?Sized,
@ -70,9 +99,9 @@ where
New::Output: PartialEq<Old::Output> + Hash + Eq + Ord,
{
match alg {
Algorithm::Myers => myers::diff(d, old, old_range, new, new_range),
Algorithm::Patience => patience::diff(d, old, old_range, new, new_range),
Algorithm::Lcs => lcs::diff(d, old, old_range, new, new_range),
Algorithm::Myers => myers::diff_deadline(d, old, old_range, new, new_range, deadline),
Algorithm::Patience => patience::diff_deadline(d, old, old_range, new, new_range, deadline),
Algorithm::Lcs => lcs::diff_deadline(d, old, old_range, new, new_range, deadline),
}
}
@ -84,3 +113,18 @@ where
{
diff(alg, d, old, 0..old.len(), new, 0..new.len())
}
/// Shortcut for diffing slices with a specific algorithm.
pub fn diff_slices_deadline<D, T>(
alg: Algorithm,
d: &mut D,
old: &[T],
new: &[T],
deadline: Option<Instant>,
) -> Result<(), D::Error>
where
D: DiffHook,
T: Eq + Hash + Ord,
{
diff_deadline(alg, d, old, 0..old.len(), new, 0..new.len(), deadline)
}