{ "manifest": { "name": "diff-sequences", "version": "27.5.1", "repository": { "type": "git", "url": "https://github.com/facebook/jest.git", "directory": "packages/diff-sequences" }, "license": "MIT", "description": "Compare items in two sequences to find a longest common subsequence", "keywords": [ "fast", "linear", "space", "callback", "diff" ], "engines": { "node": "^10.13.0 || ^12.13.0 || ^14.15.0 || >=15.0.0" }, "main": "./build/index.js", "types": "./build/index.d.ts", "exports": { ".": { "types": "./build/index.d.ts", "default": "./build/index.js" }, "./package.json": "./package.json" }, "scripts": { "perf": "node --expose-gc perf/index.js" }, "devDependencies": { "benchmark": "^2.1.4", "diff": "^5.0.0", "fast-check": "^2.0.0" }, "publishConfig": { "access": "public" }, "gitHead": "67c1aa20c5fec31366d733e901fee2b981cb1850", "_registry": "npm", "_loc": "/homez.1033/heliovt/.cache/yarn/v6/npm-diff-sequences-27.5.1-eaecc0d327fd68c8d9672a1e64ab8dccb2ef5327-integrity/node_modules/diff-sequences/package.json", "readmeFilename": "README.md", "readme": "# diff-sequences\n\nCompare items in two sequences to find a **longest common subsequence**.\n\nThe items not in common are the items to delete or insert in a **shortest edit script**.\n\nTo maximize flexibility and minimize memory, you write **callback** functions as configuration:\n\n**Input** function `isCommon(aIndex, bIndex)` compares items at indexes in the sequences and returns a truthy/falsey value. This package might call your function more than once for some pairs of indexes.\n\n- Because your function encapsulates **comparison**, this package can compare items according to `===` operator, `Object.is` method, or other criterion.\n- Because your function encapsulates **sequences**, this package can find differences in arrays, strings, or other data.\n\n**Output** function `foundSubsequence(nCommon, aCommon, bCommon)` receives the number of adjacent items and starting indexes of each common subsequence. If sequences do not have common items, then this package does not call your function.\n\nIf N is the sum of lengths of sequences and L is length of a longest common subsequence, then D = N – 2L is the number of **differences** in the corresponding shortest edit script.\n\n[_An O(ND) Difference Algorithm and Its Variations_](http://xmailserver.org/diff2.pdf) by Eugene W. Myers is fast when sequences have **few** differences.\n\nThis package implements the **linear space** variation with optimizations so it is fast even when sequences have **many** differences.\n\n## Usage\n\nTo add this package as a dependency of a project, do either of the following:\n\n- `npm install diff-sequences`\n- `yarn add diff-sequences`\n\nTo use `diff` as the name of the default export from this package, do either of the following:\n\n- `var diff = require('diff-sequences').default; // CommonJS modules`\n- `import diff from 'diff-sequences'; // ECMAScript modules`\n\nCall `diff` with the **lengths** of sequences and your **callback** functions:\n\n```js\nconst a = ['a', 'b', 'c', 'a', 'b', 'b', 'a'];\nconst b = ['c', 'b', 'a', 'b', 'a', 'c'];\n\nfunction isCommon(aIndex, bIndex) {\n return a[aIndex] === b[bIndex];\n}\nfunction foundSubsequence(nCommon, aCommon, bCommon) {\n // see examples\n}\n\ndiff(a.length, b.length, isCommon, foundSubsequence);\n```\n\n## Example of longest common subsequence\n\nSome sequences (for example, `a` and `b` in the example of usage) have more than one longest common subsequence.\n\nThis package finds the following common items:\n\n| comparisons of common items | values | output arguments |\n| :------------------------------- | :--------- | --------------------------: |\n| `a[2] === b[0]` | `'c'` | `foundSubsequence(1, 2, 0)` |\n| `a[4] === b[1]` | `'b'` | `foundSubsequence(1, 4, 1)` |\n| `a[5] === b[3] && a[6] === b[4]` | `'b', 'a'` | `foundSubsequence(2, 5, 3)` |\n\nThe “edit graph” analogy in the Myers paper shows the following common items:\n\n| comparisons of common items | values |\n| :------------------------------- | :--------- |\n| `a[2] === b[0]` | `'c'` |\n| `a[3] === b[2] && a[4] === b[3]` | `'a', 'b'` |\n| `a[6] === b[4]` | `'a'` |\n\nVarious packages which implement the Myers algorithm will **always agree** on the **length** of a longest common subsequence, but might **sometimes disagree** on which **items** are in it.\n\n## Example of callback functions to count common items\n\n```js\n// Return length of longest common subsequence according to === operator.\nfunction countCommonItems(a, b) {\n let n = 0;\n function isCommon(aIndex, bIndex) {\n return a[aIndex] === b[bIndex];\n }\n function foundSubsequence(nCommon) {\n n += nCommon;\n }\n\n diff(a.length, b.length, isCommon, foundSubsequence);\n\n return n;\n}\n\nconst commonLength = countCommonItems(\n ['a', 'b', 'c', 'a', 'b', 'b', 'a'],\n ['c', 'b', 'a', 'b', 'a', 'c'],\n);\n```\n\n| category of items | expression | value |\n| :----------------- | ------------------------: | ----: |\n| in common | `commonLength` | `4` |\n| to delete from `a` | `a.length - commonLength` | `3` |\n| to insert from `b` | `b.length - commonLength` | `2` |\n\nIf the length difference `b.length - a.length` is:\n\n- negative: its absolute value is the minimum number of items to **delete** from `a`\n- positive: it is the minimum number of items to **insert** from `b`\n- zero: there is an **equal** number of items to delete from `a` and insert from `b`\n- non-zero: there is an equal number of **additional** items to delete from `a` and insert from `b`\n\nIn this example, `6 - 7` is:\n\n- negative: `1` is the minimum number of items to **delete** from `a`\n- non-zero: `2` is the number of **additional** items to delete from `a` and insert from `b`\n\n## Example of callback functions to find common items\n\n```js\n// Return array of items in longest common subsequence according to Object.is method.\nconst findCommonItems = (a, b) => {\n const array = [];\n diff(\n a.length,\n b.length,\n (aIndex, bIndex) => Object.is(a[aIndex], b[bIndex]),\n (nCommon, aCommon) => {\n for (; nCommon !== 0; nCommon -= 1, aCommon += 1) {\n array.push(a[aCommon]);\n }\n },\n );\n return array;\n};\n\nconst commonItems = findCommonItems(\n ['a', 'b', 'c', 'a', 'b', 'b', 'a'],\n ['c', 'b', 'a', 'b', 'a', 'c'],\n);\n```\n\n| `i` | `commonItems[i]` | `aIndex` |\n| --: | :--------------- | -------: |\n| `0` | `'c'` | `2` |\n| `1` | `'b'` | `4` |\n| `2` | `'b'` | `5` |\n| `3` | `'a'` | `6` |\n\n## Example of callback functions to diff index intervals\n\nInstead of slicing array-like objects, you can adjust indexes in your callback functions.\n\n```js\n// Diff index intervals that are half open [start, end) like array slice method.\nconst diffIndexIntervals = (a, aStart, aEnd, b, bStart, bEnd) => {\n // Validate: 0 <= aStart and aStart <= aEnd and aEnd <= a.length\n // Validate: 0 <= bStart and bStart <= bEnd and bEnd <= b.length\n\n diff(\n aEnd - aStart,\n bEnd - bStart,\n (aIndex, bIndex) => Object.is(a[aStart + aIndex], b[bStart + bIndex]),\n (nCommon, aCommon, bCommon) => {\n // aStart + aCommon, bStart + bCommon\n },\n );\n\n // After the last common subsequence, do any remaining work.\n};\n```\n\n## Example of callback functions to emulate diff command\n\nLinux or Unix has a `diff` command to compare files line by line. Its output is a **shortest edit script**:\n\n- **c**hange adjacent lines from the first file to lines from the second file\n- **d**elete lines from the first file\n- **a**ppend or insert lines from the second file\n\n```js\n// Given zero-based half-open range [start, end) of array indexes,\n// return one-based closed range [start + 1, end] as string.\nconst getRange = (start, end) =>\n start + 1 === end ? `${start + 1}` : `${start + 1},${end}`;\n\n// Given index intervals of lines to delete or insert, or both, or neither,\n// push formatted diff lines onto array.\nconst pushDelIns = (aLines, aIndex, aEnd, bLines, bIndex, bEnd, array) => {\n const deleteLines = aIndex !== aEnd;\n const insertLines = bIndex !== bEnd;\n const changeLines = deleteLines && insertLines;\n if (changeLines) {\n array.push(getRange(aIndex, aEnd) + 'c' + getRange(bIndex, bEnd));\n } else if (deleteLines) {\n array.push(getRange(aIndex, aEnd) + 'd' + String(bIndex));\n } else if (insertLines) {\n array.push(String(aIndex) + 'a' + getRange(bIndex, bEnd));\n } else {\n return;\n }\n\n for (; aIndex !== aEnd; aIndex += 1) {\n array.push('< ' + aLines[aIndex]); // delete is less than\n }\n\n if (changeLines) {\n array.push('---');\n }\n\n for (; bIndex !== bEnd; bIndex += 1) {\n array.push('> ' + bLines[bIndex]); // insert is greater than\n }\n};\n\n// Given content of two files, return emulated output of diff utility.\nconst findShortestEditScript = (a, b) => {\n const aLines = a.split('\\n');\n const bLines = b.split('\\n');\n const aLength = aLines.length;\n const bLength = bLines.length;\n\n const isCommon = (aIndex, bIndex) => aLines[aIndex] === bLines[bIndex];\n\n let aIndex = 0;\n let bIndex = 0;\n const array = [];\n const foundSubsequence = (nCommon, aCommon, bCommon) => {\n pushDelIns(aLines, aIndex, aCommon, bLines, bIndex, bCommon, array);\n aIndex = aCommon + nCommon; // number of lines compared in a\n bIndex = bCommon + nCommon; // number of lines compared in b\n };\n\n diff(aLength, bLength, isCommon, foundSubsequence);\n\n // After the last common subsequence, push remaining change lines.\n pushDelIns(aLines, aIndex, aLength, bLines, bIndex, bLength, array);\n\n return array.length === 0 ? '' : array.join('\\n') + '\\n';\n};\n```\n\n## Example of callback functions to format diff lines\n\nHere is simplified code to format **changed and unchanged lines** in expected and received values after a test fails in Jest:\n\n```js\n// Format diff with minus or plus for change lines and space for common lines.\nconst formatDiffLines = (a, b) => {\n // Jest depends on pretty-format package to serialize objects as strings.\n // Unindented for comparison to avoid distracting differences:\n const aLinesUn = format(a, {indent: 0 /*, other options*/}).split('\\n');\n const bLinesUn = format(b, {indent: 0 /*, other options*/}).split('\\n');\n // Indented to display changed and unchanged lines:\n const aLinesIn = format(a, {indent: 2 /*, other options*/}).split('\\n');\n const bLinesIn = format(b, {indent: 2 /*, other options*/}).split('\\n');\n\n const aLength = aLinesIn.length; // Validate: aLinesUn.length === aLength\n const bLength = bLinesIn.length; // Validate: bLinesUn.length === bLength\n\n const isCommon = (aIndex, bIndex) => aLinesUn[aIndex] === bLinesUn[bIndex];\n\n // Only because the GitHub Flavored Markdown doc collapses adjacent spaces,\n // this example code and the following table represent spaces as middle dots.\n let aIndex = 0;\n let bIndex = 0;\n const array = [];\n const foundSubsequence = (nCommon, aCommon, bCommon) => {\n for (; aIndex !== aCommon; aIndex += 1) {\n array.push('-·' + aLinesIn[aIndex]); // delete is minus\n }\n for (; bIndex !== bCommon; bIndex += 1) {\n array.push('+·' + bLinesIn[bIndex]); // insert is plus\n }\n for (; nCommon !== 0; nCommon -= 1, aIndex += 1, bIndex += 1) {\n // For common lines, received indentation seems more intuitive.\n array.push('··' + bLinesIn[bIndex]); // common is space\n }\n };\n\n diff(aLength, bLength, isCommon, foundSubsequence);\n\n // After the last common subsequence, push remaining change lines.\n for (; aIndex !== aLength; aIndex += 1) {\n array.push('-·' + aLinesIn[aIndex]);\n }\n for (; bIndex !== bLength; bIndex += 1) {\n array.push('+·' + bLinesIn[bIndex]);\n }\n\n return array;\n};\n\nconst expected = {\n searching: '',\n sorting: {\n ascending: true,\n fieldKey: 'what',\n },\n};\nconst received = {\n searching: '',\n sorting: [\n {\n descending: false,\n fieldKey: 'what',\n },\n ],\n};\n\nconst diffLines = formatDiffLines(expected, received);\n```\n\nIf N is the sum of lengths of sequences and L is length of a longest common subsequence, then N – L is length of an array of diff lines. In this example, N is 7 + 9, L is 5, and N – L is 11.\n\n| `i` | `diffLines[i]` | `aIndex` | `bIndex` |\n| ---: | :--------------------------------- | -------: | -------: |\n| `0` | `'··Object {'` | `0` | `0` |\n| `1` | `'····\"searching\": \"\",'` | `1` | `1` |\n| `2` | `'-···\"sorting\": Object {'` | `2` | |\n| `3` | `'-·····\"ascending\": true,'` | `3` | |\n| `4` | `'+·····\"sorting\": Array ['` | | `2` |\n| `5` | `'+·······Object {'` | | `3` |\n| `6` | `'+·········\"descending\": false,'` | | `4` |\n| `7` | `'··········\"fieldKey\": \"what\",'` | `4` | `5` |\n| `8` | `'········},'` | `5` | `6` |\n| `9` | `'+·····],'` | | `7` |\n| `10` | `'··}'` | `6` | `8` |\n\n## Example of callback functions to find diff items\n\nHere is simplified code to find changed and unchanged substrings **within adjacent changed lines** in expected and received values after a test fails in Jest:\n\n```js\n// Return diff items for strings (compatible with diff-match-patch package).\nconst findDiffItems = (a, b) => {\n const isCommon = (aIndex, bIndex) => a[aIndex] === b[bIndex];\n\n let aIndex = 0;\n let bIndex = 0;\n const array = [];\n const foundSubsequence = (nCommon, aCommon, bCommon) => {\n if (aIndex !== aCommon) {\n array.push([-1, a.slice(aIndex, aCommon)]); // delete is -1\n }\n if (bIndex !== bCommon) {\n array.push([1, b.slice(bIndex, bCommon)]); // insert is 1\n }\n\n aIndex = aCommon + nCommon; // number of characters compared in a\n bIndex = bCommon + nCommon; // number of characters compared in b\n array.push([0, a.slice(aCommon, aIndex)]); // common is 0\n };\n\n diff(a.length, b.length, isCommon, foundSubsequence);\n\n // After the last common subsequence, push remaining change items.\n if (aIndex !== a.length) {\n array.push([-1, a.slice(aIndex)]);\n }\n if (bIndex !== b.length) {\n array.push([1, b.slice(bIndex)]);\n }\n\n return array;\n};\n\nconst expectedDeleted = ['\"sorting\": Object {', '\"ascending\": true,'].join(\n '\\n',\n);\nconst receivedInserted = [\n '\"sorting\": Array [',\n 'Object {',\n '\"descending\": false,',\n].join('\\n');\n\nconst diffItems = findDiffItems(expectedDeleted, receivedInserted);\n```\n\n| `i` | `diffItems[i][0]` | `diffItems[i][1]` |\n| --: | ----------------: | :---------------- |\n| `0` | `0` | `'\"sorting\": '` |\n| `1` | `1` | `'Array [\\n'` |\n| `2` | `0` | `'Object {\\n\"'` |\n| `3` | `-1` | `'a'` |\n| `4` | `1` | `'de'` |\n| `5` | `0` | `'scending\": '` |\n| `6` | `-1` | `'tru'` |\n| `7` | `1` | `'fals'` |\n| `8` | `0` | `'e,'` |\n\nThe length difference `b.length - a.length` is equal to the sum of `diffItems[i][0]` values times `diffItems[i][1]` lengths. In this example, the difference `48 - 38` is equal to the sum `10`.\n\n| category of diff item | `[0]` | `[1]` lengths | subtotal |\n| :-------------------- | ----: | -----------------: | -------: |\n| in common | `0` | `11 + 10 + 11 + 2` | `0` |\n| to delete from `a` | `–1` | `1 + 3` | `-4` |\n| to insert from `b` | `1` | `8 + 2 + 4` | `14` |\n\nInstead of formatting the changed substrings with escape codes for colors in the `foundSubsequence` function to save memory, this example spends memory to **gain flexibility** before formatting, so a separate heuristic algorithm might modify the generic array of diff items to show changes more clearly:\n\n| `i` | `diffItems[i][0]` | `diffItems[i][1]` |\n| --: | ----------------: | :---------------- |\n| `6` | `-1` | `'true'` |\n| `7` | `1` | `'false'` |\n| `8` | `0` | `','` |\n\nFor expected and received strings of serialized data, the result of finding changed **lines**, and then finding changed **substrings** within adjacent changed lines (as in the preceding two examples) sometimes displays the changes in a more intuitive way than the result of finding changed substrings, and then splitting them into changed and unchanged lines.\n", "licenseText": "MIT License\n\nCopyright (c) Facebook, Inc. and its affiliates.\n\nPermission is hereby granted, free of charge, to any person obtaining a copy\nof this software and associated documentation files (the \"Software\"), to deal\nin the Software without restriction, including without limitation the rights\nto use, copy, modify, merge, publish, distribute, sublicense, and/or sell\ncopies of the Software, and to permit persons to whom the Software is\nfurnished to do so, subject to the following conditions:\n\nThe above copyright notice and this permission notice shall be included in all\ncopies or substantial portions of the Software.\n\nTHE SOFTWARE IS PROVIDED \"AS IS\", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR\nIMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,\nFITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE\nAUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER\nLIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,\nOUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE\nSOFTWARE.\n" }, "artifacts": [], "remote": { "resolved": "https://registry.yarnpkg.com/diff-sequences/-/diff-sequences-27.5.1.tgz#eaecc0d327fd68c8d9672a1e64ab8dccb2ef5327", "type": "tarball", "reference": "https://registry.yarnpkg.com/diff-sequences/-/diff-sequences-27.5.1.tgz", "hash": "eaecc0d327fd68c8d9672a1e64ab8dccb2ef5327", "integrity": "sha512-k1gCAXAsNgLwEL+Y8Wvl+M6oEFj5bgazfZULpS5CneoPPXRaCCW7dm+q21Ky2VEE5X+VeRDBVg1Pcvvsr4TtNQ==", "registry": "npm", "packageName": "diff-sequences", "cacheIntegrity": "sha512-k1gCAXAsNgLwEL+Y8Wvl+M6oEFj5bgazfZULpS5CneoPPXRaCCW7dm+q21Ky2VEE5X+VeRDBVg1Pcvvsr4TtNQ== sha1-6uzA0yf9aMjZZyoeZKuNzLLvUyc=" }, "registry": "npm", "hash": "eaecc0d327fd68c8d9672a1e64ab8dccb2ef5327" }