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MIT License
Copyright (c) Meta Platforms, Inc. and affiliates.
Copyright Contributors to the Jest project.
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.

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# jest-diff
Display differences clearly so people can review changes confidently.
The `diff` named export serializes JavaScript **values**, compares them line-by-line, and returns a string which includes comparison lines.
Two named exports compare **strings** character-by-character:
- `diffStringsUnified` returns a string.
- `diffStringsRaw` returns an array of `Diff` objects.
Three named exports compare **arrays of strings** line-by-line:
- `diffLinesUnified` and `diffLinesUnified2` return a string.
- `diffLinesRaw` returns an array of `Diff` objects.
## Installation
To add this package as a dependency of a project, run either of the following commands:
- `npm install jest-diff`
- `yarn add jest-diff`
## Usage of `diff()`
Given JavaScript **values**, `diff(a, b, options?)` does the following:
1. **serialize** the values as strings using the `pretty-format` package
2. **compare** the strings line-by-line using the `diff-sequences` package
3. **format** the changed or common lines using the `chalk` package
To use this function, write either of the following:
- `const {diff} = require('jest-diff');` in CommonJS modules
- `import {diff} from 'jest-diff';` in ECMAScript modules
### Example of `diff()`
```js
const a = ['delete', 'common', 'changed from'];
const b = ['common', 'changed to', 'insert'];
const difference = diff(a, b);
```
The returned **string** consists of:
- annotation lines: describe the two change indicators with labels, and a blank line
- comparison lines: similar to “unified” view on GitHub, but `Expected` lines are green, `Received` lines are red, and common lines are dim (by default, see Options)
```diff
- Expected
+ Received
Array [
- "delete",
"common",
- "changed from",
+ "changed to",
+ "insert",
]
```
### Edge cases of `diff()`
Here are edge cases for the return value:
- `' Comparing two different types of values. …'` if the arguments have **different types** according to the `jest-get-type` package (instances of different classes have the same `'object'` type)
- `'Compared values have no visual difference.'` if the arguments have either **referential identity** according to `Object.is` method or **same serialization** according to the `pretty-format` package
- `null` if either argument is a so-called **asymmetric matcher** in Jasmine or Jest
## Usage of diffStringsUnified
Given **strings**, `diffStringsUnified(a, b, options?)` does the following:
1. **compare** the strings character-by-character using the `diff-sequences` package
2. **clean up** small (often coincidental) common substrings, also known as chaff
3. **format** the changed or common lines using the `chalk` package
Although the function is mainly for **multiline** strings, it compares any strings.
Write either of the following:
- `const {diffStringsUnified} = require('jest-diff');` in CommonJS modules
- `import {diffStringsUnified} from 'jest-diff';` in ECMAScript modules
### Example of diffStringsUnified
```js
const a = 'common\nchanged from';
const b = 'common\nchanged to';
const difference = diffStringsUnified(a, b);
```
The returned **string** consists of:
- annotation lines: describe the two change indicators with labels, and a blank line
- comparison lines: similar to “unified” view on GitHub, and **changed substrings** have **inverse** foreground and background colors (that is, `from` has white-on-green and `to` has white-on-red, which the following example does not show)
```diff
- Expected
+ Received
common
- changed from
+ changed to
```
### Performance of diffStringsUnified
To get the benefit of **changed substrings** within the comparison lines, a character-by-character comparison has a higher computational cost (in time and space) than a line-by-line comparison.
If the input strings can have **arbitrary length**, we recommend that the calling code set a limit, beyond which splits the strings, and then calls `diffLinesUnified` instead. For example, Jest falls back to line-by-line comparison if either string has length greater than 20K characters.
## Usage of diffLinesUnified
Given **arrays of strings**, `diffLinesUnified(aLines, bLines, options?)` does the following:
1. **compare** the arrays line-by-line using the `diff-sequences` package
2. **format** the changed or common lines using the `chalk` package
You might call this function when strings have been split into lines and you do not need to see changed substrings within lines.
### Example of diffLinesUnified
```js
const aLines = ['delete', 'common', 'changed from'];
const bLines = ['common', 'changed to', 'insert'];
const difference = diffLinesUnified(aLines, bLines);
```
```diff
- Expected
+ Received
- delete
common
- changed from
+ changed to
+ insert
```
### Edge cases of diffLinesUnified or diffStringsUnified
Here are edge cases for arguments and return values:
- both `a` and `b` are empty strings: no comparison lines
- only `a` is empty string: all comparison lines have `bColor` and `bIndicator` (see Options)
- only `b` is empty string: all comparison lines have `aColor` and `aIndicator` (see Options)
- `a` and `b` are equal non-empty strings: all comparison lines have `commonColor` and `commonIndicator` (see Options)
## Usage of diffLinesUnified2
Given two **pairs** of arrays of strings, `diffLinesUnified2(aLinesDisplay, bLinesDisplay, aLinesCompare, bLinesCompare, options?)` does the following:
1. **compare** the pair of `Compare` arrays line-by-line using the `diff-sequences` package
2. **format** the corresponding lines in the pair of `Display` arrays using the `chalk` package
Jest calls this function to consider lines as common instead of changed if the only difference is indentation.
You might call this function for case insensitive or Unicode equivalence comparison of lines.
### Example of diffLinesUnified2
```js
import {format} from 'pretty-format';
const a = {
text: 'Ignore indentation in serialized object',
time: '2019-09-19T12:34:56.000Z',
type: 'CREATE_ITEM',
};
const b = {
payload: {
text: 'Ignore indentation in serialized object',
time: '2019-09-19T12:34:56.000Z',
},
type: 'CREATE_ITEM',
};
const difference = diffLinesUnified2(
// serialize with indentation to display lines
format(a).split('\n'),
format(b).split('\n'),
// serialize without indentation to compare lines
format(a, {indent: 0}).split('\n'),
format(b, {indent: 0}).split('\n'),
);
```
The `text` and `time` properties are common, because their only difference is indentation:
```diff
- Expected
+ Received
Object {
+ payload: Object {
text: 'Ignore indentation in serialized object',
time: '2019-09-19T12:34:56.000Z',
+ },
type: 'CREATE_ITEM',
}
```
The preceding example illustrates why (at least for indentation) it seems more intuitive that the function returns the common line from the `bLinesDisplay` array instead of from the `aLinesDisplay` array.
## Usage of diffStringsRaw
Given **strings** and a boolean option, `diffStringsRaw(a, b, cleanup)` does the following:
1. **compare** the strings character-by-character using the `diff-sequences` package
2. optionally **clean up** small (often coincidental) common substrings, also known as chaff
Because `diffStringsRaw` returns the difference as **data** instead of a string, you can format it as your application requires (for example, enclosed in HTML markup for browser instead of escape sequences for console).
The returned **array** describes substrings as instances of the `Diff` class, which calling code can access like array tuples:
The value at index `0` is one of the following:
| value | named export | description |
| ----: | :------------ | :-------------------- |
| `0` | `DIFF_EQUAL` | in `a` and in `b` |
| `-1` | `DIFF_DELETE` | in `a` but not in `b` |
| `1` | `DIFF_INSERT` | in `b` but not in `a` |
The value at index `1` is a substring of `a` or `b` or both.
### Example of diffStringsRaw with cleanup
```js
const diffs = diffStringsRaw('changed from', 'changed to', true);
```
| `i` | `diffs[i][0]` | `diffs[i][1]` |
| --: | ------------: | :------------ |
| `0` | `0` | `'changed '` |
| `1` | `-1` | `'from'` |
| `2` | `1` | `'to'` |
### Example of diffStringsRaw without cleanup
```js
const diffs = diffStringsRaw('changed from', 'changed to', false);
```
| `i` | `diffs[i][0]` | `diffs[i][1]` |
| --: | ------------: | :------------ |
| `0` | `0` | `'changed '` |
| `1` | `-1` | `'fr'` |
| `2` | `1` | `'t'` |
| `3` | `0` | `'o'` |
| `4` | `-1` | `'m'` |
### Advanced import for diffStringsRaw
Here are all the named imports that you might need for the `diffStringsRaw` function:
- `const {DIFF_DELETE, DIFF_EQUAL, DIFF_INSERT, Diff, diffStringsRaw} = require('jest-diff');` in CommonJS modules
- `import {DIFF_DELETE, DIFF_EQUAL, DIFF_INSERT, Diff, diffStringsRaw} from 'jest-diff';` in ECMAScript modules
To write a **formatting** function, you might need the named constants (and `Diff` in TypeScript annotations).
If you write an application-specific **cleanup** algorithm, then you might need to call the `Diff` constructor:
```js
const diffCommon = new Diff(DIFF_EQUAL, 'changed ');
const diffDelete = new Diff(DIFF_DELETE, 'from');
const diffInsert = new Diff(DIFF_INSERT, 'to');
```
## Usage of diffLinesRaw
Given **arrays of strings**, `diffLinesRaw(aLines, bLines)` does the following:
- **compare** the arrays line-by-line using the `diff-sequences` package
Because `diffLinesRaw` returns the difference as **data** instead of a string, you can format it as your application requires.
### Example of diffLinesRaw
```js
const aLines = ['delete', 'common', 'changed from'];
const bLines = ['common', 'changed to', 'insert'];
const diffs = diffLinesRaw(aLines, bLines);
```
| `i` | `diffs[i][0]` | `diffs[i][1]` |
| --: | ------------: | :--------------- |
| `0` | `-1` | `'delete'` |
| `1` | `0` | `'common'` |
| `2` | `-1` | `'changed from'` |
| `3` | `1` | `'changed to'` |
| `4` | `1` | `'insert'` |
### Edge case of diffLinesRaw
If you call `string.split('\n')` for an empty string:
- the result is `['']` an array which contains an empty string
- instead of `[]` an empty array
Depending of your application, you might call `diffLinesRaw` with either array.
### Example of split method
```js
import {diffLinesRaw} from 'jest-diff';
const a = 'non-empty string';
const b = '';
const diffs = diffLinesRaw(a.split('\n'), b.split('\n'));
```
| `i` | `diffs[i][0]` | `diffs[i][1]` |
| --: | ------------: | :------------------- |
| `0` | `-1` | `'non-empty string'` |
| `1` | `1` | `''` |
Which you might format as follows:
```diff
- Expected - 1
+ Received + 1
- non-empty string
+
```
### Example of splitLines0 function
For edge case behavior like the `diffLinesUnified` function, you might define a `splitLines0` function, which given an empty string, returns `[]` an empty array:
```js
export const splitLines0 = string =>
string.length === 0 ? [] : string.split('\n');
```
```js
import {diffLinesRaw} from 'jest-diff';
const a = '';
const b = 'line 1\nline 2\nline 3';
const diffs = diffLinesRaw(a.split('\n'), b.split('\n'));
```
| `i` | `diffs[i][0]` | `diffs[i][1]` |
| --: | ------------: | :------------ |
| `0` | `1` | `'line 1'` |
| `1` | `1` | `'line 2'` |
| `2` | `1` | `'line 3'` |
Which you might format as follows:
```diff
- Expected - 0
+ Received + 3
+ line 1
+ line 2
+ line 3
```
In contrast to the `diffLinesRaw` function, the `diffLinesUnified` and `diffLinesUnified2` functions **automatically** convert array arguments computed by string `split` method, so callers do **not** need a `splitLine0` function.
## Options
The default options are for the report when an assertion fails from the `expect` package used by Jest.
For other applications, you can provide an options object as a third argument:
- `diff(a, b, options)`
- `diffStringsUnified(a, b, options)`
- `diffLinesUnified(aLines, bLines, options)`
- `diffLinesUnified2(aLinesDisplay, bLinesDisplay, aLinesCompare, bLinesCompare, options)`
### Properties of options object
| name | default |
| :-------------------------------- | :----------------- |
| `aAnnotation` | `'Expected'` |
| `aColor` | `chalk.green` |
| `aIndicator` | `'-'` |
| `bAnnotation` | `'Received'` |
| `bColor` | `chalk.red` |
| `bIndicator` | `'+'` |
| `changeColor` | `chalk.inverse` |
| `changeLineTrailingSpaceColor` | `string => string` |
| `commonColor` | `chalk.dim` |
| `commonIndicator` | `' '` |
| `commonLineTrailingSpaceColor` | `string => string` |
| `compareKeys` | `undefined` |
| `contextLines` | `5` |
| `emptyFirstOrLastLinePlaceholder` | `''` |
| `expand` | `true` |
| `includeChangeCounts` | `false` |
| `omitAnnotationLines` | `false` |
| `patchColor` | `chalk.yellow` |
For more information about the options, see the following examples.
### Example of options for labels
If the application is code modification, you might replace the labels:
```js
const options = {
aAnnotation: 'Original',
bAnnotation: 'Modified',
};
```
```diff
- Original
+ Modified
common
- changed from
+ changed to
```
The `jest-diff` package does not assume that the 2 labels have equal length.
### Example of options for colors of changed lines
For consistency with most diff tools, you might exchange the colors:
```ts
import chalk from 'chalk';
const options = {
aColor: chalk.red,
bColor: chalk.green,
};
```
### Example of option for color of changed substrings
Although the default inverse of foreground and background colors is hard to beat for changed substrings **within lines**, especially because it highlights spaces, if you want bold font weight on yellow background color:
```ts
import chalk from 'chalk';
const options = {
changeColor: chalk.bold.bgYellowBright,
};
```
### Example of option to format trailing spaces
Because `diff()` does not display substring differences within lines, formatting can help you see when lines differ by the presence or absence of trailing spaces found by `/\s+$/` regular expression.
- If change lines have a background color, then you can see trailing spaces.
- If common lines have default dim color, then you cannot see trailing spaces. You might want yellowish background color to see them.
```js
const options = {
aColor: chalk.rgb(128, 0, 128).bgRgb(255, 215, 255), // magenta
bColor: chalk.rgb(0, 95, 0).bgRgb(215, 255, 215), // green
commonLineTrailingSpaceColor: chalk.bgYellow,
};
```
The value of a Color option is a function, which given a string, returns a string.
If you want to replace trailing spaces with middle dot characters:
```js
const replaceSpacesWithMiddleDot = string => '·'.repeat(string.length);
const options = {
changeLineTrailingSpaceColor: replaceSpacesWithMiddleDot,
commonLineTrailingSpaceColor: replaceSpacesWithMiddleDot,
};
```
If you need the TypeScript type of a Color option:
```ts
import {DiffOptionsColor} from 'jest-diff';
```
### Example of options for no colors
To store the difference in a file without escape codes for colors, provide an identity function:
```js
const noColor = string => string;
const options = {
aColor: noColor,
bColor: noColor,
changeColor: noColor,
commonColor: noColor,
patchColor: noColor,
};
```
### Example of options for indicators
For consistency with the `diff` command, you might replace the indicators:
```js
const options = {
aIndicator: '<',
bIndicator: '>',
};
```
The `jest-diff` package assumes (but does not enforce) that the 3 indicators have equal length.
### Example of options to limit common lines
By default, the output includes all common lines.
To emphasize the changes, you might limit the number of common “context” lines:
```js
const options = {
contextLines: 1,
expand: false,
};
```
A patch mark like `@@ -12,7 +12,9 @@` accounts for omitted common lines.
### Example of option for color of patch marks
If you want patch marks to have the same dim color as common lines:
```ts
import chalk from 'chalk';
const options = {
expand: false,
patchColor: chalk.dim,
};
```
### Example of option to include change counts
To display the number of changed lines at the right of annotation lines:
```js
const a = ['common', 'changed from'];
const b = ['common', 'changed to', 'insert'];
const options = {
includeChangeCounts: true,
};
const difference = diff(a, b, options);
```
```diff
- Expected - 1
+ Received + 2
Array [
"common",
- "changed from",
+ "changed to",
+ "insert",
]
```
### Example of option to omit annotation lines
To display only the comparison lines:
```js
const a = 'common\nchanged from';
const b = 'common\nchanged to';
const options = {
omitAnnotationLines: true,
};
const difference = diffStringsUnified(a, b, options);
```
```diff
common
- changed from
+ changed to
```
### Example of option for empty first or last lines
If the **first** or **last** comparison line is **empty**, because the content is empty and the indicator is a space, you might not notice it.
The replacement option is a string whose default value is `''` empty string.
Because Jest trims the report when a matcher fails, it deletes an empty last line.
Therefore, Jest uses as placeholder the downwards arrow with corner leftwards:
```js
const options = {
emptyFirstOrLastLinePlaceholder: '↵', // U+21B5
};
```
If a content line is empty, then the corresponding comparison line is automatically trimmed to remove the margin space (represented as a middle dot below) for the default indicators:
| Indicator | untrimmed | trimmed |
| ----------------: | :-------- | :------ |
| `aIndicator` | `'-·'` | `'-'` |
| `bIndicator` | `'+·'` | `'+'` |
| `commonIndicator` | `' ·'` | `''` |
### Example of option for sorting object keys
When two objects are compared their keys are printed in alphabetical order by default. If this was not the original order of the keys the diff becomes harder to read as the keys are not in their original position.
Use `compareKeys` to pass a function which will be used when sorting the object keys.
```js
const a = {c: 'c', b: 'b1', a: 'a'};
const b = {c: 'c', b: 'b2', a: 'a'};
const options = {
// The keys will be in their original order
compareKeys: () => 0,
};
const difference = diff(a, b, options);
```
```diff
- Expected
+ Received
Object {
"c": "c",
- "b": "b1",
+ "b": "b2",
"a": "a",
}
```
Depending on the implementation of `compareKeys` any sort order can be used.
```js
const a = {c: 'c', b: 'b1', a: 'a'};
const b = {c: 'c', b: 'b2', a: 'a'};
const options = {
// The keys will be in reverse order
compareKeys: (a, b) => (a > b ? -1 : 1),
};
const difference = diff(a, b, options);
```
```diff
- Expected
+ Received
Object {
"a": "a",
- "b": "b1",
+ "b": "b2",
"c": "c",
}
```

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/**
* Copyright (c) Meta Platforms, Inc. and affiliates.
*
* This source code is licensed under the MIT license found in the
* LICENSE file in the root directory of this source tree.
*/
import {CompareKeys} from 'pretty-format';
/**
* Class representing one diff tuple.
* Attempts to look like a two-element array (which is what this used to be).
* @param {number} op Operation, one of: DIFF_DELETE, DIFF_INSERT, DIFF_EQUAL.
* @param {string} text Text to be deleted, inserted, or retained.
* @constructor
*/
export declare class Diff {
0: number;
1: string;
constructor(op: number, text: string);
}
export declare function diff(
a: any,
b: any,
options?: DiffOptions,
): string | null;
/**
* The data structure representing a diff is an array of tuples:
* [[DIFF_DELETE, 'Hello'], [DIFF_INSERT, 'Goodbye'], [DIFF_EQUAL, ' world.']]
* which means: delete 'Hello', add 'Goodbye' and keep ' world.'
*/
export declare var DIFF_DELETE: number;
export declare var DIFF_EQUAL: number;
export declare var DIFF_INSERT: number;
export declare const diffLinesRaw: (
aLines: Array<string>,
bLines: Array<string>,
) => Array<Diff>;
export declare const diffLinesUnified: (
aLines: Array<string>,
bLines: Array<string>,
options?: DiffOptions,
) => string;
export declare const diffLinesUnified2: (
aLinesDisplay: Array<string>,
bLinesDisplay: Array<string>,
aLinesCompare: Array<string>,
bLinesCompare: Array<string>,
options?: DiffOptions,
) => string;
export declare type DiffOptions = {
aAnnotation?: string;
aColor?: DiffOptionsColor;
aIndicator?: string;
bAnnotation?: string;
bColor?: DiffOptionsColor;
bIndicator?: string;
changeColor?: DiffOptionsColor;
changeLineTrailingSpaceColor?: DiffOptionsColor;
commonColor?: DiffOptionsColor;
commonIndicator?: string;
commonLineTrailingSpaceColor?: DiffOptionsColor;
contextLines?: number;
emptyFirstOrLastLinePlaceholder?: string;
expand?: boolean;
includeChangeCounts?: boolean;
omitAnnotationLines?: boolean;
patchColor?: DiffOptionsColor;
compareKeys?: CompareKeys;
};
export declare type DiffOptionsColor = (arg: string) => string;
export declare const diffStringsRaw: (
a: string,
b: string,
cleanup: boolean,
) => Array<Diff>;
export declare const diffStringsUnified: (
a: string,
b: string,
options?: DiffOptions,
) => string;

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import cjsModule from './index.js';
export const DIFF_DELETE = cjsModule.DIFF_DELETE;
export const DIFF_EQUAL = cjsModule.DIFF_EQUAL;
export const DIFF_INSERT = cjsModule.DIFF_INSERT;
export const Diff = cjsModule.Diff;
export const diff = cjsModule.diff;
export const diffLinesRaw = cjsModule.diffLinesRaw;
export const diffLinesUnified = cjsModule.diffLinesUnified;
export const diffLinesUnified2 = cjsModule.diffLinesUnified2;
export const diffStringsRaw = cjsModule.diffStringsRaw;
export const diffStringsUnified = cjsModule.diffStringsUnified;

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MIT License
Copyright (c) Meta Platforms, Inc. and affiliates.
Copyright Contributors to the Jest project.
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.

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# diff-sequences
Compare items in two sequences to find a **longest common subsequence**.
The items not in common are the items to delete or insert in a **shortest edit script**.
To maximize flexibility and minimize memory, you write **callback** functions as configuration:
**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.
- Because your function encapsulates **comparison**, this package can compare items according to `===` operator, `Object.is` method, or other criterion.
- Because your function encapsulates **sequences**, this package can find differences in arrays, strings, or other data.
**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.
If 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.
[_An O(ND) Difference Algorithm and Its Variations_](http://xmailserver.org/diff2.pdf) by Eugene W. Myers is fast when sequences have **few** differences.
This package implements the **linear space** variation with optimizations so it is fast even when sequences have **many** differences.
## Usage
To add this package as a dependency of a project, do either of the following:
- `npm install diff-sequences`
- `yarn add diff-sequences`
To use `diff` as the name of the default export from this package, do either of the following:
- `var diff = require('@jest/diff-sequences').default; // CommonJS modules`
- `import diff from '@jest/diff-sequences'; // ECMAScript modules`
Call `diff` with the **lengths** of sequences and your **callback** functions:
```js
const a = ['a', 'b', 'c', 'a', 'b', 'b', 'a'];
const b = ['c', 'b', 'a', 'b', 'a', 'c'];
function isCommon(aIndex, bIndex) {
return a[aIndex] === b[bIndex];
}
function foundSubsequence(nCommon, aCommon, bCommon) {
// see examples
}
diff(a.length, b.length, isCommon, foundSubsequence);
```
## Example of longest common subsequence
Some sequences (for example, `a` and `b` in the example of usage) have more than one longest common subsequence.
This package finds the following common items:
| comparisons of common items | values | output arguments |
| :------------------------------- | :--------- | --------------------------: |
| `a[2] === b[0]` | `'c'` | `foundSubsequence(1, 2, 0)` |
| `a[4] === b[1]` | `'b'` | `foundSubsequence(1, 4, 1)` |
| `a[5] === b[3] && a[6] === b[4]` | `'b', 'a'` | `foundSubsequence(2, 5, 3)` |
The “edit graph” analogy in the Myers paper shows the following common items:
| comparisons of common items | values |
| :------------------------------- | :--------- |
| `a[2] === b[0]` | `'c'` |
| `a[3] === b[2] && a[4] === b[3]` | `'a', 'b'` |
| `a[6] === b[4]` | `'a'` |
Various 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.
## Example of callback functions to count common items
```js
// Return length of longest common subsequence according to === operator.
function countCommonItems(a, b) {
let n = 0;
function isCommon(aIndex, bIndex) {
return a[aIndex] === b[bIndex];
}
function foundSubsequence(nCommon) {
n += nCommon;
}
diff(a.length, b.length, isCommon, foundSubsequence);
return n;
}
const commonLength = countCommonItems(
['a', 'b', 'c', 'a', 'b', 'b', 'a'],
['c', 'b', 'a', 'b', 'a', 'c'],
);
```
| category of items | expression | value |
| :----------------- | ------------------------: | ----: |
| in common | `commonLength` | `4` |
| to delete from `a` | `a.length - commonLength` | `3` |
| to insert from `b` | `b.length - commonLength` | `2` |
If the length difference `b.length - a.length` is:
- negative: its absolute value is the minimum number of items to **delete** from `a`
- positive: it is the minimum number of items to **insert** from `b`
- zero: there is an **equal** number of items to delete from `a` and insert from `b`
- non-zero: there is an equal number of **additional** items to delete from `a` and insert from `b`
In this example, `6 - 7` is:
- negative: `1` is the minimum number of items to **delete** from `a`
- non-zero: `2` is the number of **additional** items to delete from `a` and insert from `b`
## Example of callback functions to find common items
```js
// Return array of items in longest common subsequence according to Object.is method.
const findCommonItems = (a, b) => {
const array = [];
diff(
a.length,
b.length,
(aIndex, bIndex) => Object.is(a[aIndex], b[bIndex]),
(nCommon, aCommon) => {
for (; nCommon !== 0; nCommon -= 1, aCommon += 1) {
array.push(a[aCommon]);
}
},
);
return array;
};
const commonItems = findCommonItems(
['a', 'b', 'c', 'a', 'b', 'b', 'a'],
['c', 'b', 'a', 'b', 'a', 'c'],
);
```
| `i` | `commonItems[i]` | `aIndex` |
| --: | :--------------- | -------: |
| `0` | `'c'` | `2` |
| `1` | `'b'` | `4` |
| `2` | `'b'` | `5` |
| `3` | `'a'` | `6` |
## Example of callback functions to diff index intervals
Instead of slicing array-like objects, you can adjust indexes in your callback functions.
```js
// Diff index intervals that are half open [start, end) like array slice method.
const diffIndexIntervals = (a, aStart, aEnd, b, bStart, bEnd) => {
// Validate: 0 <= aStart and aStart <= aEnd and aEnd <= a.length
// Validate: 0 <= bStart and bStart <= bEnd and bEnd <= b.length
diff(
aEnd - aStart,
bEnd - bStart,
(aIndex, bIndex) => Object.is(a[aStart + aIndex], b[bStart + bIndex]),
(nCommon, aCommon, bCommon) => {
// aStart + aCommon, bStart + bCommon
},
);
// After the last common subsequence, do any remaining work.
};
```
## Example of callback functions to emulate diff command
Linux or Unix has a `diff` command to compare files line by line. Its output is a **shortest edit script**:
- **c**hange adjacent lines from the first file to lines from the second file
- **d**elete lines from the first file
- **a**ppend or insert lines from the second file
```js
// Given zero-based half-open range [start, end) of array indexes,
// return one-based closed range [start + 1, end] as string.
const getRange = (start, end) =>
start + 1 === end ? `${start + 1}` : `${start + 1},${end}`;
// Given index intervals of lines to delete or insert, or both, or neither,
// push formatted diff lines onto array.
const pushDelIns = (aLines, aIndex, aEnd, bLines, bIndex, bEnd, array) => {
const deleteLines = aIndex !== aEnd;
const insertLines = bIndex !== bEnd;
const changeLines = deleteLines && insertLines;
if (changeLines) {
array.push(`${getRange(aIndex, aEnd)}c${getRange(bIndex, bEnd)}`);
} else if (deleteLines) {
array.push(`${getRange(aIndex, aEnd)}d${String(bIndex)}`);
} else if (insertLines) {
array.push(`${String(aIndex)}a${getRange(bIndex, bEnd)}`);
} else {
return;
}
for (; aIndex !== aEnd; aIndex += 1) {
array.push(`< ${aLines[aIndex]}`); // delete is less than
}
if (changeLines) {
array.push('---');
}
for (; bIndex !== bEnd; bIndex += 1) {
array.push(`> ${bLines[bIndex]}`); // insert is greater than
}
};
// Given content of two files, return emulated output of diff utility.
const findShortestEditScript = (a, b) => {
const aLines = a.split('\n');
const bLines = b.split('\n');
const aLength = aLines.length;
const bLength = bLines.length;
const isCommon = (aIndex, bIndex) => aLines[aIndex] === bLines[bIndex];
let aIndex = 0;
let bIndex = 0;
const array = [];
const foundSubsequence = (nCommon, aCommon, bCommon) => {
pushDelIns(aLines, aIndex, aCommon, bLines, bIndex, bCommon, array);
aIndex = aCommon + nCommon; // number of lines compared in a
bIndex = bCommon + nCommon; // number of lines compared in b
};
diff(aLength, bLength, isCommon, foundSubsequence);
// After the last common subsequence, push remaining change lines.
pushDelIns(aLines, aIndex, aLength, bLines, bIndex, bLength, array);
return array.length === 0 ? '' : `${array.join('\n')}\n`;
};
```
## Example of callback functions to format diff lines
Here is simplified code to format **changed and unchanged lines** in expected and received values after a test fails in Jest:
```js
// Format diff with minus or plus for change lines and space for common lines.
const formatDiffLines = (a, b) => {
// Jest depends on pretty-format package to serialize objects as strings.
// Unindented for comparison to avoid distracting differences:
const aLinesUn = format(a, {indent: 0 /*, other options*/}).split('\n');
const bLinesUn = format(b, {indent: 0 /*, other options*/}).split('\n');
// Indented to display changed and unchanged lines:
const aLinesIn = format(a, {indent: 2 /*, other options*/}).split('\n');
const bLinesIn = format(b, {indent: 2 /*, other options*/}).split('\n');
const aLength = aLinesIn.length; // Validate: aLinesUn.length === aLength
const bLength = bLinesIn.length; // Validate: bLinesUn.length === bLength
const isCommon = (aIndex, bIndex) => aLinesUn[aIndex] === bLinesUn[bIndex];
// Only because the GitHub Flavored Markdown doc collapses adjacent spaces,
// this example code and the following table represent spaces as middle dots.
let aIndex = 0;
let bIndex = 0;
const array = [];
const foundSubsequence = (nCommon, aCommon, bCommon) => {
for (; aIndex !== aCommon; aIndex += 1) {
array.push(`-·${aLinesIn[aIndex]}`); // delete is minus
}
for (; bIndex !== bCommon; bIndex += 1) {
array.push(`+·${bLinesIn[bIndex]}`); // insert is plus
}
for (; nCommon !== 0; nCommon -= 1, aIndex += 1, bIndex += 1) {
// For common lines, received indentation seems more intuitive.
array.push(`··${bLinesIn[bIndex]}`); // common is space
}
};
diff(aLength, bLength, isCommon, foundSubsequence);
// After the last common subsequence, push remaining change lines.
for (; aIndex !== aLength; aIndex += 1) {
array.push(`-·${aLinesIn[aIndex]}`);
}
for (; bIndex !== bLength; bIndex += 1) {
array.push(`+·${bLinesIn[bIndex]}`);
}
return array;
};
const expected = {
searching: '',
sorting: {
ascending: true,
fieldKey: 'what',
},
};
const received = {
searching: '',
sorting: [
{
descending: false,
fieldKey: 'what',
},
],
};
const diffLines = formatDiffLines(expected, received);
```
If 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.
| `i` | `diffLines[i]` | `aIndex` | `bIndex` |
| ---: | :--------------------------------- | -------: | -------: |
| `0` | `'··Object {'` | `0` | `0` |
| `1` | `'····"searching": "",'` | `1` | `1` |
| `2` | `'-···"sorting": Object {'` | `2` | |
| `3` | `'-·····"ascending": true,'` | `3` | |
| `4` | `'+·····"sorting": Array ['` | | `2` |
| `5` | `'+·······Object {'` | | `3` |
| `6` | `'+·········"descending": false,'` | | `4` |
| `7` | `'··········"fieldKey": "what",'` | `4` | `5` |
| `8` | `'········},'` | `5` | `6` |
| `9` | `'+·····],'` | | `7` |
| `10` | `'··}'` | `6` | `8` |
## Example of callback functions to find diff items
Here is simplified code to find changed and unchanged substrings **within adjacent changed lines** in expected and received values after a test fails in Jest:
```js
// Return diff items for strings (compatible with diff-match-patch package).
const findDiffItems = (a, b) => {
const isCommon = (aIndex, bIndex) => a[aIndex] === b[bIndex];
let aIndex = 0;
let bIndex = 0;
const array = [];
const foundSubsequence = (nCommon, aCommon, bCommon) => {
if (aIndex !== aCommon) {
array.push([-1, a.slice(aIndex, aCommon)]); // delete is -1
}
if (bIndex !== bCommon) {
array.push([1, b.slice(bIndex, bCommon)]); // insert is 1
}
aIndex = aCommon + nCommon; // number of characters compared in a
bIndex = bCommon + nCommon; // number of characters compared in b
array.push([0, a.slice(aCommon, aIndex)]); // common is 0
};
diff(a.length, b.length, isCommon, foundSubsequence);
// After the last common subsequence, push remaining change items.
if (aIndex !== a.length) {
array.push([-1, a.slice(aIndex)]);
}
if (bIndex !== b.length) {
array.push([1, b.slice(bIndex)]);
}
return array;
};
const expectedDeleted = ['"sorting": Object {', '"ascending": true,'].join(
'\n',
);
const receivedInserted = [
'"sorting": Array [',
'Object {',
'"descending": false,',
].join('\n');
const diffItems = findDiffItems(expectedDeleted, receivedInserted);
```
| `i` | `diffItems[i][0]` | `diffItems[i][1]` |
| --: | ----------------: | :---------------- |
| `0` | `0` | `'"sorting": '` |
| `1` | `1` | `'Array [\n'` |
| `2` | `0` | `'Object {\n"'` |
| `3` | `-1` | `'a'` |
| `4` | `1` | `'de'` |
| `5` | `0` | `'scending": '` |
| `6` | `-1` | `'tru'` |
| `7` | `1` | `'fals'` |
| `8` | `0` | `'e,'` |
The 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`.
| category of diff item | `[0]` | `[1]` lengths | subtotal |
| :-------------------- | ----: | -----------------: | -------: |
| in common | `0` | `11 + 10 + 11 + 2` | `0` |
| to delete from `a` | `1` | `1 + 3` | `-4` |
| to insert from `b` | `1` | `8 + 2 + 4` | `14` |
Instead 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:
| `i` | `diffItems[i][0]` | `diffItems[i][1]` |
| --: | ----------------: | :---------------- |
| `6` | `-1` | `'true'` |
| `7` | `1` | `'false'` |
| `8` | `0` | `','` |
For 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.

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@@ -0,0 +1,37 @@
/**
* Copyright (c) Meta Platforms, Inc. and affiliates.
*
* This source code is licensed under the MIT license found in the
* LICENSE file in the root directory of this source tree.
*/
export declare type Callbacks = {
foundSubsequence: FoundSubsequence;
isCommon: IsCommon;
};
declare function diffSequence(
aLength: number,
bLength: number,
isCommon: IsCommon,
foundSubsequence: FoundSubsequence,
): void;
export default diffSequence;
declare type FoundSubsequence = (
nCommon: number, // caller can assume: 0 < nCommon
aCommon: number, // caller can assume: 0 <= aCommon && aCommon < aLength
bCommon: number,
) => void;
/**
* Copyright (c) Meta Platforms, Inc. and affiliates.
*
* This source code is licensed under the MIT license found in the
* LICENSE file in the root directory of this source tree.
*
*/
declare type IsCommon = (
aIndex: number, // caller can assume: 0 <= aIndex && aIndex < aLength
bIndex: number,
) => boolean;

View File

@@ -0,0 +1,637 @@
/*!
* /**
* * Copyright (c) Meta Platforms, Inc. and affiliates.
* *
* * This source code is licensed under the MIT license found in the
* * LICENSE file in the root directory of this source tree.
* * /
*/
/******/ (() => { // webpackBootstrap
/******/ "use strict";
var __webpack_exports__ = {};
// This entry needs to be wrapped in an IIFE because it uses a non-standard name for the exports (exports).
(() => {
var exports = __webpack_exports__;
Object.defineProperty(exports, "__esModule", ({
value: true
}));
exports["default"] = diffSequence;
/**
* Copyright (c) Meta Platforms, Inc. and affiliates.
*
* This source code is licensed under the MIT license found in the
* LICENSE file in the root directory of this source tree.
*
*/
// This diff-sequences package implements the linear space variation in
// An O(ND) Difference Algorithm and Its Variations by Eugene W. Myers
// Relationship in notation between Myers paper and this package:
// A is a
// N is aLength, aEnd - aStart, and so on
// x is aIndex, aFirst, aLast, and so on
// B is b
// M is bLength, bEnd - bStart, and so on
// y is bIndex, bFirst, bLast, and so on
// Δ = N - M is negative of baDeltaLength = bLength - aLength
// D is d
// k is kF
// k + Δ is kF = kR - baDeltaLength
// V is aIndexesF or aIndexesR (see comment below about Indexes type)
// index intervals [1, N] and [1, M] are [0, aLength) and [0, bLength)
// starting point in forward direction (0, 0) is (-1, -1)
// starting point in reverse direction (N + 1, M + 1) is (aLength, bLength)
// The “edit graph” for sequences a and b corresponds to items:
// in a on the horizontal axis
// in b on the vertical axis
//
// Given a-coordinate of a point in a diagonal, you can compute b-coordinate.
//
// Forward diagonals kF:
// zero diagonal intersects top left corner
// positive diagonals intersect top edge
// negative diagonals intersect left edge
//
// Reverse diagonals kR:
// zero diagonal intersects bottom right corner
// positive diagonals intersect right edge
// negative diagonals intersect bottom edge
// The graph contains a directed acyclic graph of edges:
// horizontal: delete an item from a
// vertical: insert an item from b
// diagonal: common item in a and b
//
// The algorithm solves dual problems in the graph analogy:
// Find longest common subsequence: path with maximum number of diagonal edges
// Find shortest edit script: path with minimum number of non-diagonal edges
// Input callback function compares items at indexes in the sequences.
// Output callback function receives the number of adjacent items
// and starting indexes of each common subsequence.
// Either original functions or wrapped to swap indexes if graph is transposed.
// Indexes in sequence a of last point of forward or reverse paths in graph.
// Myers algorithm indexes by diagonal k which for negative is bad deopt in V8.
// This package indexes by iF and iR which are greater than or equal to zero.
// and also updates the index arrays in place to cut memory in half.
// kF = 2 * iF - d
// kR = d - 2 * iR
// Division of index intervals in sequences a and b at the middle change.
// Invariant: intervals do not have common items at the start or end.
const pkg = '@jest/diff-sequences'; // for error messages
const NOT_YET_SET = 0; // small int instead of undefined to avoid deopt in V8
// Return the number of common items that follow in forward direction.
// The length of what Myers paper calls a “snake” in a forward path.
const countCommonItemsF = (aIndex, aEnd, bIndex, bEnd, isCommon) => {
let nCommon = 0;
while (aIndex < aEnd && bIndex < bEnd && isCommon(aIndex, bIndex)) {
aIndex += 1;
bIndex += 1;
nCommon += 1;
}
return nCommon;
};
// Return the number of common items that precede in reverse direction.
// The length of what Myers paper calls a “snake” in a reverse path.
const countCommonItemsR = (aStart, aIndex, bStart, bIndex, isCommon) => {
let nCommon = 0;
while (aStart <= aIndex && bStart <= bIndex && isCommon(aIndex, bIndex)) {
aIndex -= 1;
bIndex -= 1;
nCommon += 1;
}
return nCommon;
};
// A simple function to extend forward paths from (d - 1) to d changes
// when forward and reverse paths cannot yet overlap.
const extendPathsF = (d, aEnd, bEnd, bF, isCommon, aIndexesF, iMaxF // return the value because optimization might decrease it
) => {
// Unroll the first iteration.
let iF = 0;
let kF = -d; // kF = 2 * iF - d
let aFirst = aIndexesF[iF]; // in first iteration always insert
let aIndexPrev1 = aFirst; // prev value of [iF - 1] in next iteration
aIndexesF[iF] += countCommonItemsF(aFirst + 1, aEnd, bF + aFirst - kF + 1, bEnd, isCommon);
// Optimization: skip diagonals in which paths cannot ever overlap.
const nF = Math.min(d, iMaxF);
// The diagonals kF are odd when d is odd and even when d is even.
for (iF += 1, kF += 2; iF <= nF; iF += 1, kF += 2) {
// To get first point of path segment, move one change in forward direction
// from last point of previous path segment in an adjacent diagonal.
// In last possible iteration when iF === d and kF === d always delete.
if (iF !== d && aIndexPrev1 < aIndexesF[iF]) {
aFirst = aIndexesF[iF]; // vertical to insert from b
} else {
aFirst = aIndexPrev1 + 1; // horizontal to delete from a
if (aEnd <= aFirst) {
// Optimization: delete moved past right of graph.
return iF - 1;
}
}
// To get last point of path segment, move along diagonal of common items.
aIndexPrev1 = aIndexesF[iF];
aIndexesF[iF] = aFirst + countCommonItemsF(aFirst + 1, aEnd, bF + aFirst - kF + 1, bEnd, isCommon);
}
return iMaxF;
};
// A simple function to extend reverse paths from (d - 1) to d changes
// when reverse and forward paths cannot yet overlap.
const extendPathsR = (d, aStart, bStart, bR, isCommon, aIndexesR, iMaxR // return the value because optimization might decrease it
) => {
// Unroll the first iteration.
let iR = 0;
let kR = d; // kR = d - 2 * iR
let aFirst = aIndexesR[iR]; // in first iteration always insert
let aIndexPrev1 = aFirst; // prev value of [iR - 1] in next iteration
aIndexesR[iR] -= countCommonItemsR(aStart, aFirst - 1, bStart, bR + aFirst - kR - 1, isCommon);
// Optimization: skip diagonals in which paths cannot ever overlap.
const nR = Math.min(d, iMaxR);
// The diagonals kR are odd when d is odd and even when d is even.
for (iR += 1, kR -= 2; iR <= nR; iR += 1, kR -= 2) {
// To get first point of path segment, move one change in reverse direction
// from last point of previous path segment in an adjacent diagonal.
// In last possible iteration when iR === d and kR === -d always delete.
if (iR !== d && aIndexesR[iR] < aIndexPrev1) {
aFirst = aIndexesR[iR]; // vertical to insert from b
} else {
aFirst = aIndexPrev1 - 1; // horizontal to delete from a
if (aFirst < aStart) {
// Optimization: delete moved past left of graph.
return iR - 1;
}
}
// To get last point of path segment, move along diagonal of common items.
aIndexPrev1 = aIndexesR[iR];
aIndexesR[iR] = aFirst - countCommonItemsR(aStart, aFirst - 1, bStart, bR + aFirst - kR - 1, isCommon);
}
return iMaxR;
};
// A complete function to extend forward paths from (d - 1) to d changes.
// Return true if a path overlaps reverse path of (d - 1) changes in its diagonal.
const extendOverlappablePathsF = (d, aStart, aEnd, bStart, bEnd, isCommon, aIndexesF, iMaxF, aIndexesR, iMaxR, division // update prop values if return true
) => {
const bF = bStart - aStart; // bIndex = bF + aIndex - kF
const aLength = aEnd - aStart;
const bLength = bEnd - bStart;
const baDeltaLength = bLength - aLength; // kF = kR - baDeltaLength
// Range of diagonals in which forward and reverse paths might overlap.
const kMinOverlapF = -baDeltaLength - (d - 1); // -(d - 1) <= kR
const kMaxOverlapF = -baDeltaLength + (d - 1); // kR <= (d - 1)
let aIndexPrev1 = NOT_YET_SET; // prev value of [iF - 1] in next iteration
// Optimization: skip diagonals in which paths cannot ever overlap.
const nF = Math.min(d, iMaxF);
// The diagonals kF = 2 * iF - d are odd when d is odd and even when d is even.
for (let iF = 0, kF = -d; iF <= nF; iF += 1, kF += 2) {
// To get first point of path segment, move one change in forward direction
// from last point of previous path segment in an adjacent diagonal.
// In first iteration when iF === 0 and kF === -d always insert.
// In last possible iteration when iF === d and kF === d always delete.
const insert = iF === 0 || iF !== d && aIndexPrev1 < aIndexesF[iF];
const aLastPrev = insert ? aIndexesF[iF] : aIndexPrev1;
const aFirst = insert ? aLastPrev // vertical to insert from b
: aLastPrev + 1; // horizontal to delete from a
// To get last point of path segment, move along diagonal of common items.
const bFirst = bF + aFirst - kF;
const nCommonF = countCommonItemsF(aFirst + 1, aEnd, bFirst + 1, bEnd, isCommon);
const aLast = aFirst + nCommonF;
aIndexPrev1 = aIndexesF[iF];
aIndexesF[iF] = aLast;
if (kMinOverlapF <= kF && kF <= kMaxOverlapF) {
// Solve for iR of reverse path with (d - 1) changes in diagonal kF:
// kR = kF + baDeltaLength
// kR = (d - 1) - 2 * iR
const iR = (d - 1 - (kF + baDeltaLength)) / 2;
// If this forward path overlaps the reverse path in this diagonal,
// then this is the middle change of the index intervals.
if (iR <= iMaxR && aIndexesR[iR] - 1 <= aLast) {
// Unlike the Myers algorithm which finds only the middle “snake”
// this package can find two common subsequences per division.
// Last point of previous path segment is on an adjacent diagonal.
const bLastPrev = bF + aLastPrev - (insert ? kF + 1 : kF - 1);
// Because of invariant that intervals preceding the middle change
// cannot have common items at the end,
// move in reverse direction along a diagonal of common items.
const nCommonR = countCommonItemsR(aStart, aLastPrev, bStart, bLastPrev, isCommon);
const aIndexPrevFirst = aLastPrev - nCommonR;
const bIndexPrevFirst = bLastPrev - nCommonR;
const aEndPreceding = aIndexPrevFirst + 1;
const bEndPreceding = bIndexPrevFirst + 1;
division.nChangePreceding = d - 1;
if (d - 1 === aEndPreceding + bEndPreceding - aStart - bStart) {
// Optimization: number of preceding changes in forward direction
// is equal to number of items in preceding interval,
// therefore it cannot contain any common items.
division.aEndPreceding = aStart;
division.bEndPreceding = bStart;
} else {
division.aEndPreceding = aEndPreceding;
division.bEndPreceding = bEndPreceding;
}
division.nCommonPreceding = nCommonR;
if (nCommonR !== 0) {
division.aCommonPreceding = aEndPreceding;
division.bCommonPreceding = bEndPreceding;
}
division.nCommonFollowing = nCommonF;
if (nCommonF !== 0) {
division.aCommonFollowing = aFirst + 1;
division.bCommonFollowing = bFirst + 1;
}
const aStartFollowing = aLast + 1;
const bStartFollowing = bFirst + nCommonF + 1;
division.nChangeFollowing = d - 1;
if (d - 1 === aEnd + bEnd - aStartFollowing - bStartFollowing) {
// Optimization: number of changes in reverse direction
// is equal to number of items in following interval,
// therefore it cannot contain any common items.
division.aStartFollowing = aEnd;
division.bStartFollowing = bEnd;
} else {
division.aStartFollowing = aStartFollowing;
division.bStartFollowing = bStartFollowing;
}
return true;
}
}
}
return false;
};
// A complete function to extend reverse paths from (d - 1) to d changes.
// Return true if a path overlaps forward path of d changes in its diagonal.
const extendOverlappablePathsR = (d, aStart, aEnd, bStart, bEnd, isCommon, aIndexesF, iMaxF, aIndexesR, iMaxR, division // update prop values if return true
) => {
const bR = bEnd - aEnd; // bIndex = bR + aIndex - kR
const aLength = aEnd - aStart;
const bLength = bEnd - bStart;
const baDeltaLength = bLength - aLength; // kR = kF + baDeltaLength
// Range of diagonals in which forward and reverse paths might overlap.
const kMinOverlapR = baDeltaLength - d; // -d <= kF
const kMaxOverlapR = baDeltaLength + d; // kF <= d
let aIndexPrev1 = NOT_YET_SET; // prev value of [iR - 1] in next iteration
// Optimization: skip diagonals in which paths cannot ever overlap.
const nR = Math.min(d, iMaxR);
// The diagonals kR = d - 2 * iR are odd when d is odd and even when d is even.
for (let iR = 0, kR = d; iR <= nR; iR += 1, kR -= 2) {
// To get first point of path segment, move one change in reverse direction
// from last point of previous path segment in an adjacent diagonal.
// In first iteration when iR === 0 and kR === d always insert.
// In last possible iteration when iR === d and kR === -d always delete.
const insert = iR === 0 || iR !== d && aIndexesR[iR] < aIndexPrev1;
const aLastPrev = insert ? aIndexesR[iR] : aIndexPrev1;
const aFirst = insert ? aLastPrev // vertical to insert from b
: aLastPrev - 1; // horizontal to delete from a
// To get last point of path segment, move along diagonal of common items.
const bFirst = bR + aFirst - kR;
const nCommonR = countCommonItemsR(aStart, aFirst - 1, bStart, bFirst - 1, isCommon);
const aLast = aFirst - nCommonR;
aIndexPrev1 = aIndexesR[iR];
aIndexesR[iR] = aLast;
if (kMinOverlapR <= kR && kR <= kMaxOverlapR) {
// Solve for iF of forward path with d changes in diagonal kR:
// kF = kR - baDeltaLength
// kF = 2 * iF - d
const iF = (d + (kR - baDeltaLength)) / 2;
// If this reverse path overlaps the forward path in this diagonal,
// then this is a middle change of the index intervals.
if (iF <= iMaxF && aLast - 1 <= aIndexesF[iF]) {
const bLast = bFirst - nCommonR;
division.nChangePreceding = d;
if (d === aLast + bLast - aStart - bStart) {
// Optimization: number of changes in reverse direction
// is equal to number of items in preceding interval,
// therefore it cannot contain any common items.
division.aEndPreceding = aStart;
division.bEndPreceding = bStart;
} else {
division.aEndPreceding = aLast;
division.bEndPreceding = bLast;
}
division.nCommonPreceding = nCommonR;
if (nCommonR !== 0) {
// The last point of reverse path segment is start of common subsequence.
division.aCommonPreceding = aLast;
division.bCommonPreceding = bLast;
}
division.nChangeFollowing = d - 1;
if (d === 1) {
// There is no previous path segment.
division.nCommonFollowing = 0;
division.aStartFollowing = aEnd;
division.bStartFollowing = bEnd;
} else {
// Unlike the Myers algorithm which finds only the middle “snake”
// this package can find two common subsequences per division.
// Last point of previous path segment is on an adjacent diagonal.
const bLastPrev = bR + aLastPrev - (insert ? kR - 1 : kR + 1);
// Because of invariant that intervals following the middle change
// cannot have common items at the start,
// move in forward direction along a diagonal of common items.
const nCommonF = countCommonItemsF(aLastPrev, aEnd, bLastPrev, bEnd, isCommon);
division.nCommonFollowing = nCommonF;
if (nCommonF !== 0) {
// The last point of reverse path segment is start of common subsequence.
division.aCommonFollowing = aLastPrev;
division.bCommonFollowing = bLastPrev;
}
const aStartFollowing = aLastPrev + nCommonF; // aFirstPrev
const bStartFollowing = bLastPrev + nCommonF; // bFirstPrev
if (d - 1 === aEnd + bEnd - aStartFollowing - bStartFollowing) {
// Optimization: number of changes in forward direction
// is equal to number of items in following interval,
// therefore it cannot contain any common items.
division.aStartFollowing = aEnd;
division.bStartFollowing = bEnd;
} else {
division.aStartFollowing = aStartFollowing;
division.bStartFollowing = bStartFollowing;
}
}
return true;
}
}
}
return false;
};
// Given index intervals and input function to compare items at indexes,
// divide at the middle change.
//
// DO NOT CALL if start === end, because interval cannot contain common items
// and because this function will throw the “no overlap” error.
const divide = (nChange, aStart, aEnd, bStart, bEnd, isCommon, aIndexesF, aIndexesR, division // output
) => {
const bF = bStart - aStart; // bIndex = bF + aIndex - kF
const bR = bEnd - aEnd; // bIndex = bR + aIndex - kR
const aLength = aEnd - aStart;
const bLength = bEnd - bStart;
// Because graph has square or portrait orientation,
// length difference is minimum number of items to insert from b.
// Corresponding forward and reverse diagonals in graph
// depend on length difference of the sequences:
// kF = kR - baDeltaLength
// kR = kF + baDeltaLength
const baDeltaLength = bLength - aLength;
// Optimization: max diagonal in graph intersects corner of shorter side.
let iMaxF = aLength;
let iMaxR = aLength;
// Initialize no changes yet in forward or reverse direction:
aIndexesF[0] = aStart - 1; // at open start of interval, outside closed start
aIndexesR[0] = aEnd; // at open end of interval
if (baDeltaLength % 2 === 0) {
// The number of changes in paths is 2 * d if length difference is even.
const dMin = (nChange || baDeltaLength) / 2;
const dMax = (aLength + bLength) / 2;
for (let d = 1; d <= dMax; d += 1) {
iMaxF = extendPathsF(d, aEnd, bEnd, bF, isCommon, aIndexesF, iMaxF);
if (d < dMin) {
iMaxR = extendPathsR(d, aStart, bStart, bR, isCommon, aIndexesR, iMaxR);
} else if (
// If a reverse path overlaps a forward path in the same diagonal,
// return a division of the index intervals at the middle change.
extendOverlappablePathsR(d, aStart, aEnd, bStart, bEnd, isCommon, aIndexesF, iMaxF, aIndexesR, iMaxR, division)) {
return;
}
}
} else {
// The number of changes in paths is 2 * d - 1 if length difference is odd.
const dMin = ((nChange || baDeltaLength) + 1) / 2;
const dMax = (aLength + bLength + 1) / 2;
// Unroll first half iteration so loop extends the relevant pairs of paths.
// Because of invariant that intervals have no common items at start or end,
// and limitation not to call divide with empty intervals,
// therefore it cannot be called if a forward path with one change
// would overlap a reverse path with no changes, even if dMin === 1.
let d = 1;
iMaxF = extendPathsF(d, aEnd, bEnd, bF, isCommon, aIndexesF, iMaxF);
for (d += 1; d <= dMax; d += 1) {
iMaxR = extendPathsR(d - 1, aStart, bStart, bR, isCommon, aIndexesR, iMaxR);
if (d < dMin) {
iMaxF = extendPathsF(d, aEnd, bEnd, bF, isCommon, aIndexesF, iMaxF);
} else if (
// If a forward path overlaps a reverse path in the same diagonal,
// return a division of the index intervals at the middle change.
extendOverlappablePathsF(d, aStart, aEnd, bStart, bEnd, isCommon, aIndexesF, iMaxF, aIndexesR, iMaxR, division)) {
return;
}
}
}
/* istanbul ignore next */
throw new Error(`${pkg}: no overlap aStart=${aStart} aEnd=${aEnd} bStart=${bStart} bEnd=${bEnd}`);
};
// Given index intervals and input function to compare items at indexes,
// return by output function the number of adjacent items and starting indexes
// of each common subsequence. Divide and conquer with only linear space.
//
// The index intervals are half open [start, end) like array slice method.
// DO NOT CALL if start === end, because interval cannot contain common items
// and because divide function will throw the “no overlap” error.
const findSubsequences = (nChange, aStart, aEnd, bStart, bEnd, transposed, callbacks, aIndexesF, aIndexesR, division // temporary memory, not input nor output
) => {
if (bEnd - bStart < aEnd - aStart) {
// Transpose graph so it has portrait instead of landscape orientation.
// Always compare shorter to longer sequence for consistency and optimization.
transposed = !transposed;
if (transposed && callbacks.length === 1) {
// Lazily wrap callback functions to swap args if graph is transposed.
const {
foundSubsequence,
isCommon
} = callbacks[0];
callbacks[1] = {
foundSubsequence: (nCommon, bCommon, aCommon) => {
foundSubsequence(nCommon, aCommon, bCommon);
},
isCommon: (bIndex, aIndex) => isCommon(aIndex, bIndex)
};
}
const tStart = aStart;
const tEnd = aEnd;
aStart = bStart;
aEnd = bEnd;
bStart = tStart;
bEnd = tEnd;
}
const {
foundSubsequence,
isCommon
} = callbacks[transposed ? 1 : 0];
// Divide the index intervals at the middle change.
divide(nChange, aStart, aEnd, bStart, bEnd, isCommon, aIndexesF, aIndexesR, division);
const {
nChangePreceding,
aEndPreceding,
bEndPreceding,
nCommonPreceding,
aCommonPreceding,
bCommonPreceding,
nCommonFollowing,
aCommonFollowing,
bCommonFollowing,
nChangeFollowing,
aStartFollowing,
bStartFollowing
} = division;
// Unless either index interval is empty, they might contain common items.
if (aStart < aEndPreceding && bStart < bEndPreceding) {
// Recursely find and return common subsequences preceding the division.
findSubsequences(nChangePreceding, aStart, aEndPreceding, bStart, bEndPreceding, transposed, callbacks, aIndexesF, aIndexesR, division);
}
// Return common subsequences that are adjacent to the middle change.
if (nCommonPreceding !== 0) {
foundSubsequence(nCommonPreceding, aCommonPreceding, bCommonPreceding);
}
if (nCommonFollowing !== 0) {
foundSubsequence(nCommonFollowing, aCommonFollowing, bCommonFollowing);
}
// Unless either index interval is empty, they might contain common items.
if (aStartFollowing < aEnd && bStartFollowing < bEnd) {
// Recursely find and return common subsequences following the division.
findSubsequences(nChangeFollowing, aStartFollowing, aEnd, bStartFollowing, bEnd, transposed, callbacks, aIndexesF, aIndexesR, division);
}
};
const validateLength = (name, arg) => {
if (typeof arg !== 'number') {
throw new TypeError(`${pkg}: ${name} typeof ${typeof arg} is not a number`);
}
if (!Number.isSafeInteger(arg)) {
throw new RangeError(`${pkg}: ${name} value ${arg} is not a safe integer`);
}
if (arg < 0) {
throw new RangeError(`${pkg}: ${name} value ${arg} is a negative integer`);
}
};
const validateCallback = (name, arg) => {
const type = typeof arg;
if (type !== 'function') {
throw new TypeError(`${pkg}: ${name} typeof ${type} is not a function`);
}
};
// Compare items in two sequences to find a longest common subsequence.
// Given lengths of sequences and input function to compare items at indexes,
// return by output function the number of adjacent items and starting indexes
// of each common subsequence.
function diffSequence(aLength, bLength, isCommon, foundSubsequence) {
validateLength('aLength', aLength);
validateLength('bLength', bLength);
validateCallback('isCommon', isCommon);
validateCallback('foundSubsequence', foundSubsequence);
// Count common items from the start in the forward direction.
const nCommonF = countCommonItemsF(0, aLength, 0, bLength, isCommon);
if (nCommonF !== 0) {
foundSubsequence(nCommonF, 0, 0);
}
// Unless both sequences consist of common items only,
// find common items in the half-trimmed index intervals.
if (aLength !== nCommonF || bLength !== nCommonF) {
// Invariant: intervals do not have common items at the start.
// The start of an index interval is closed like array slice method.
const aStart = nCommonF;
const bStart = nCommonF;
// Count common items from the end in the reverse direction.
const nCommonR = countCommonItemsR(aStart, aLength - 1, bStart, bLength - 1, isCommon);
// Invariant: intervals do not have common items at the end.
// The end of an index interval is open like array slice method.
const aEnd = aLength - nCommonR;
const bEnd = bLength - nCommonR;
// Unless one sequence consists of common items only,
// therefore the other trimmed index interval consists of changes only,
// find common items in the trimmed index intervals.
const nCommonFR = nCommonF + nCommonR;
if (aLength !== nCommonFR && bLength !== nCommonFR) {
const nChange = 0; // number of change items is not yet known
const transposed = false; // call the original unwrapped functions
const callbacks = [{
foundSubsequence,
isCommon
}];
// Indexes in sequence a of last points in furthest reaching paths
// from outside the start at top left in the forward direction:
const aIndexesF = [NOT_YET_SET];
// from the end at bottom right in the reverse direction:
const aIndexesR = [NOT_YET_SET];
// Initialize one object as output of all calls to divide function.
const division = {
aCommonFollowing: NOT_YET_SET,
aCommonPreceding: NOT_YET_SET,
aEndPreceding: NOT_YET_SET,
aStartFollowing: NOT_YET_SET,
bCommonFollowing: NOT_YET_SET,
bCommonPreceding: NOT_YET_SET,
bEndPreceding: NOT_YET_SET,
bStartFollowing: NOT_YET_SET,
nChangeFollowing: NOT_YET_SET,
nChangePreceding: NOT_YET_SET,
nCommonFollowing: NOT_YET_SET,
nCommonPreceding: NOT_YET_SET
};
// Find and return common subsequences in the trimmed index intervals.
findSubsequences(nChange, aStart, aEnd, bStart, bEnd, transposed, callbacks, aIndexesF, aIndexesR, division);
}
if (nCommonR !== 0) {
foundSubsequence(nCommonR, aEnd, bEnd);
}
}
}
})();
module.exports = __webpack_exports__;
/******/ })()
;

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import cjsModule from './index.js';
export default cjsModule.default;

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{
"name": "@jest/diff-sequences",
"version": "30.4.0",
"repository": {
"type": "git",
"url": "https://github.com/jestjs/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": "^18.14.0 || ^20.0.0 || ^22.0.0 || >=24.0.0"
},
"main": "./build/index.js",
"types": "./build/index.d.ts",
"exports": {
".": {
"types": "./build/index.d.ts",
"require": "./build/index.js",
"import": "./build/index.mjs",
"default": "./build/index.js"
},
"./package.json": "./package.json"
},
"devDependencies": {
"@fast-check/jest": "^2.1.1",
"benchmark": "^2.1.4",
"diff": "^9.0.0"
},
"publishConfig": {
"access": "public"
},
"gitHead": "5cbb21e0b3037edb42e503ec1a1ce80efad40c20"
}

37
node_modules/jest-diff/package.json generated vendored Normal file
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{
"name": "jest-diff",
"version": "30.4.1",
"repository": {
"type": "git",
"url": "https://github.com/jestjs/jest.git",
"directory": "packages/jest-diff"
},
"license": "MIT",
"main": "./build/index.js",
"types": "./build/index.d.ts",
"exports": {
".": {
"types": "./build/index.d.ts",
"require": "./build/index.js",
"import": "./build/index.mjs",
"default": "./build/index.js"
},
"./package.json": "./package.json"
},
"dependencies": {
"@jest/diff-sequences": "30.4.0",
"@jest/get-type": "30.1.0",
"chalk": "^4.1.2",
"pretty-format": "30.4.1"
},
"devDependencies": {
"@jest/test-utils": "30.4.1"
},
"engines": {
"node": "^18.14.0 || ^20.0.0 || ^22.0.0 || >=24.0.0"
},
"publishConfig": {
"access": "public"
},
"gitHead": "b3b4a09ed3005369dacc7466d1d2122797283785"
}