@sanity/diff-match-patch
v3.1.1
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Robust diff, match and patch algorithms to perform operations required for synchronizing plain text
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@sanity/diff-match-patch
A TypeScript fork of the JavaScript version of google/diff-match-patch, that includes a few long-standing pull requests, fixing certain bugs and with an API more familiar to the JavaScript ecosystem.
Installing
npm install --save @sanity/diff-match-patch
What is diff-match-patch?
The Diff Match and Patch libraries offer robust algorithms to perform the operations required for synchronizing plain text.
- Diff:
- Compare two blocks of plain text and efficiently return a list of differences.
- Diff Demo
- Match:
- Given a search string, find its best fuzzy match in a block of plain text. Weighted for both accuracy and location.
- Match Demo
- Patch:
- Apply a list of patches onto plain text. Use best-effort to apply patch even when the underlying text doesn't match.
- Patch Demo
Originally built in 2006 to power Google Docs, this library is now available in C++, C#, Dart, Java, JavaScript, Lua, Objective C, and Python.
API
Creating and applying patches
import {makePatches, applyPatches, stringifyPatches, parsePatches} from '@sanity/diff-match-patch'
// Make array of diffs in internal array format, eg tuples of `[DiffType, string]`
const patches = makePatches('from this', 'to this')
// Make unidiff-formatted (string) patch
const patch = stringifyPatches(patches)
// Apply the patch (array representation)
const [newValue] = applyPatches(patches, 'from this')
// Apply the patch (unidiff-formatted)
const [alsoNewValue] = applyPatches(parsePatch(patch), 'from this')
Creating diffs
import {makeDiff} from '@sanity/diff-match-patch'
// Make an array of diff tuples, eg `[DiffType, string]`
const diff = makeDiff('from this', 'to this')
Matching text
import {match} from '@sanity/diff-match-patch'
// Find position in text for the given pattern, at the approximate location given
const position = match('some text to match against', 'match', 9)
Applying patches
import {applyPatches} from '@sanity/diff-match-patch'
const [newValue, results] = applyPatches(patch, 'source text')
const matches = results.filter((matched) => matched === true).length
const misses = results.length - matches
console.log('Patch applied with %d matches and %d misses', matches, misses)
console.log('New value: %s', newValue)
Migrating from diff-match-patch
The original library that this is a fork of has a different API, meaning this fork is not a drop-in replacement. Here's a breakdown of the most common operations and their API differences:
Creating diffs
-import {diff_match_patch as DiffMatchPatch} from 'diff-match-patch'
-const dmp = new DiffMatchPatch()
-const diffs = dmp.diff_main('from this', 'to this')
-dmp.diff_cleanupSemantic(diffs)
+import {makeDiff, cleanupSemantic} from '@sanity/diff-match-patch'
+const diffs = cleanupSemantic(makeDiff('from this', 'to this'))
Make patches
-import {diff_match_patch as DiffMatchPatch} from 'diff-match-patch'
-const dmp = new DiffMatchPatch()
-const rawPatch = dmp.patch_make('from this', 'to this')
-const patch = rawPatch.map(p => p.toString()).join('')
+import {makePatches, stringifyPatches} from '@sanity/diff-match-patch'
+const patch = stringifyPatches(makePatches('from this', 'to this'))
Apply patches
-import {diff_match_patch as DiffMatchPatch} from 'diff-match-patch'
-const dmp = new DiffMatchPatch()
-const patch = dmp.patch_fromText('some-text-patch')
-const [newValue] = dmp.patch_apply(patch, 'source text')
+import {applyPatches, parsePatch} from '@sanity/diff-match-patch'
+const [newValue] = applyPatches(parsePatch('some-text-patch'), 'source text')
Algorithms
This library implements Myer's diff algorithm which is generally considered to be the best general-purpose diff. A layer of pre-diff speedups and post-diff cleanups surround the diff algorithm, improving both performance and output quality.
This library also implements a Bitap matching algorithm at the heart of a flexible matching and patching strategy.
Significant changes in fork
This fork has a few modifications to the original:
- Written in TypeScript, and shipped with CommonJS and ES module builds
- API has changed - individual methods are exposed as importable functions instead of being attached to a
DiffMatchPatch
prototype. Enables better tree-shaking. - Includes a fix for surrogate pair handling
- Includes a fix for indicies calculated using UCS-2 instead of UTF-8
- Uses modern tooling for code compilation and testing
License
Apache-2.0 Copyright 2018 The diff-match-patch Authors https://github.com/google/diff-match-patch