Introduce Myers algorithm in linear space #112

lppedd · 2024-05-16T12:22:19Z

This PR requires #111 to be merged first.
I will then rebase.

codecov · 2024-05-16T12:27:59Z

Codecov Report

Attention: Patch coverage is 94.21769% with 17 lines in your changes missing coverage. Please review.

Project coverage is 86.07%. Comparing base (875f4ce) to head (37933be).

Files	Patch %	Lines
...github/petertrr/diffutils/text/DiffRowGenerator.kt	93.61%	3 Missing and 6 partials ⚠️
...futils/algorithm/myers/MyersDiffWithLinearSpace.kt	92.78%	1 Missing and 6 partials ⚠️
...hub/petertrr/diffutils/algorithm/myers/PathNode.kt	80.00%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##               main     #112      +/-   ##
============================================
+ Coverage     84.26%   86.07%   +1.80%     
- Complexity      151      221      +70     
============================================
  Files            22       30       +8     
  Lines           534      632      +98     
  Branches         89      117      +28     
============================================
+ Hits            450      544      +94     
- Misses           57       59       +2     
- Partials         27       29       +2

Flag	Coverage Δ
unittests	`86.07% <94.21%> (+1.80%)`	⬆️

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Required to correctly host the new code.

This fixes a long-standing bug, where we did not copy the list, but merely return of view of it.

This replaces the untyped lambda.

testPerformanceProblemsIssue124 showed a 30s vs 7s runtime. Moving to fields instead of getters drastically improved performance down to 10s. Still, not optimal.

lppedd · 2024-05-20T10:27:53Z

src/commonMain/kotlin/io/github/petertrr/diffutils/text/DiffRowGenerator.kt

+        val origList = inlineDiffSplitter.split(joinedOrig)
+        val revList = inlineDiffSplitter.split(joinedRev)
+
+        // Copying of `origList` and `revList` is needed because otherwise `wrapInTag` results in ConcurrentModificationException


@petertrr I don't understand why this would throw a ConcurrentModificationException

I'm not sure TBH; this part was copied from the original library.

@petertrr no problem, I can remove it, it's not needed as we aren't operating on the lists concurrently.

lppedd · 2024-05-20T10:29:40Z

I'm done with this one. The refactor: clean up DiffRowGenerator commit has a bit of changes but they're mostly to remove "untyped" lambdas.

This PR is a breaking API change for DiffRowGenerator.

lppedd · 2024-05-20T11:40:26Z

.gitignore

+.DS_Store
+.kotlin/


Kotlin 2.0 introduces a new folder to store metadata.

lppedd · 2024-05-20T11:40:55Z

README.md


+- fuzzy patches


Will port in another PR.

petertrr

Hey, sorry for disappearing. Your PR generally LGTM, I have just a couple of questions. Also, what's the breaking change in the DiffRowGenerator? Is it a new constructor parameter, or did I overlook something else?

petertrr · 2024-05-19T18:25:00Z

src/commonMain/kotlin/io/github/petertrr/diffutils/algorithm/Change.kt

@@ -19,11 +19,12 @@
 package io.github.petertrr.diffutils.algorithm

 import io.github.petertrr.diffutils.patch.DeltaType
+import kotlin.jvm.JvmField

 public data class Change(


I wonder if making the class @JvmRecord instead would have similar effect

@petertrr we are targeting Java 8, so it wouldn't make any difference unfortunately.
But anyway, with records the only difference is method naming, e.g. getX() > x(), so you'd still not expose fields directly.

petertrr · 2024-06-04T20:29:49Z

src/commonMain/kotlin/io/github/petertrr/diffutils/algorithm/myers/MyersDiffWithLinearSpace.kt

+
+            while (i < end1 || j < end2) {
+                if (i < end1 && j < end2 && equalizer.test(data.source[i], data.target[j])) {
+                    // script.append(new KeepCommand<>(left.charAt(i)));


What's the plan for the commented code?

@petertrr I'll get rid of them!

petertrr · 2024-06-04T20:32:18Z

src/commonMain/kotlin/io/github/petertrr/diffutils/text/DiffRowGenerator.kt

+        val origList = inlineDiffSplitter.split(joinedOrig)
+        val revList = inlineDiffSplitter.split(joinedRev)
+
+        // Copying of `origList` and `revList` is needed because otherwise `wrapInTag` results in ConcurrentModificationException


I'm not sure TBH; this part was copied from the original library.

lppedd · 2024-06-04T21:01:16Z

what's the breaking change in the DiffRowGenerator

It's just the constructor, we introduced new interfaces so I'm not sure it would work straight away.
Edit: well, the new interfaces are not only there, so I'd say this is a general breaking change, but, guess it's ok!

petertrr

LGTM, thanks for a nice improvement!

lppedd · 2024-06-11T21:27:50Z

@petertrr np. I have another PR with a small cleanup and then it would be cool to do a release imo!

lppedd · 2024-06-11T21:32:18Z

Ah I see you already released ahaha, well no problem, will be for another minor release.

lppedd marked this pull request as ready for review May 17, 2024 09:40

lppedd added 12 commits May 20, 2024 00:01

chore: disable unnecessary Detekt rules

53153e2

Required to correctly host the new code.

fix: replace subList with slice

034774e

This fixes a long-standing bug, where we did not copy the list, but merely return of view of it.

refactor: introduce the DiffEqualizer interface

b07b979

This replaces the untyped lambda.

refactor: rename Chunk.verify to Chunk.verifyChunk

cbb1f4f

refactor: align delta's string representation with java-diff

3a87497

feat: introduce MyersDiffWithLinearSpace

df9a059

feat: allow skipping delta decompression

ef11cb1

perf: mitigate *embarrassing* performance difference with java-diff

69e32f6

testPerformanceProblemsIssue124 showed a 30s vs 7s runtime. Moving to fields instead of getters drastically improved performance down to 10s. Still, not optimal.

chore: refresh yarn.lock

241a30d

refactor: clean up DiffRowGenerator

84029fd

build: prepare for Kotlin 2.0

743edaa

docs: update readme

f3d1caf

lppedd force-pushed the refactor/myers-linear-space branch from 45d28ee to f3d1caf Compare May 20, 2024 10:24

lppedd commented May 20, 2024

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.gitignore

.DS_Store

.kotlin/

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Kotlin 2.0 introduces a new folder to store metadata.

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lppedd commented May 20, 2024

View reviewed changes

README.md

- fuzzy patches

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Will port in another PR.

petertrr reviewed Jun 4, 2024

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lppedd added 2 commits June 5, 2024 10:00

refactor: remove commented out lines

0121c61

refactor: remove unnecessary list copying

37933be

lppedd requested a review from petertrr June 5, 2024 08:11

petertrr approved these changes Jun 11, 2024

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petertrr merged commit edfab24 into petertrr:main Jun 11, 2024
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Introduce Myers algorithm in linear space #112

Introduce Myers algorithm in linear space #112

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Introduce Myers algorithm in linear space #112

Introduce Myers algorithm in linear space #112

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