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# Regenerate [![Build status](https://travis-ci.org/mathiasbynens/regenerate.svg?branch=master)](https://travis-ci.org/mathiasbynens/regenerate) [![Code coverage status](https://img.shields.io/codecov/c/github/mathiasbynens/regenerate.svg)](https://codecov.io/gh/mathiasbynens/regenerate)
_Regenerate_ is a Unicode-aware regex generator for JavaScript. It allows you to easily generate ES5-compatible regular expressions based on a given set of Unicode symbols or code points. (This is trickier than you might think, because of [how JavaScript deals with astral symbols](https://mathiasbynens.be/notes/javascript-unicode).)
## Installation
Via [npm](https://npmjs.org/):
```bash npm install regenerate ```
Via [Bower](http://bower.io/):
```bash bower install regenerate ```
In a browser:
```html <script src="regenerate.js"></script> ```
In [Node.js](https://nodejs.org/), [io.js](https://iojs.org/), and [RingoJS ≥ v0.8.0](http://ringojs.org/):
```js var regenerate = require('regenerate'); ```
In [Narwhal](http://narwhaljs.org/) and [RingoJS ≤ v0.7.0](http://ringojs.org/):
```js var regenerate = require('regenerate').regenerate; ```
In [Rhino](http://www.mozilla.org/rhino/):
```js load('regenerate.js'); ```
Using an AMD loader like [RequireJS](http://requirejs.org/):
```js require( { 'paths': { 'regenerate': 'path/to/regenerate' } }, ['regenerate'], function(regenerate) { console.log(regenerate); } ); ```
## API
### `regenerate(value1, value2, value3, ...)`
The main Regenerate function. Calling this function creates a new set that gets a chainable API.
```js var set = regenerate() .addRange(0x60, 0x69) // add U+0060 to U+0069 .remove(0x62, 0x64) // remove U+0062 and U+0064 .add(0x1D306); // add U+1D306 set.valueOf(); // → [0x60, 0x61, 0x63, 0x65, 0x66, 0x67, 0x68, 0x69, 0x1D306] set.toString(); // → '[`ace-i]|\\uD834\\uDF06' set.toRegExp(); // → /[`ace-i]|\uD834\uDF06/ ```
Any arguments passed to `regenerate()` will be added to the set right away. Both code points (numbers) and symbols (strings consisting of a single Unicode symbol) are accepted, as well as arrays containing values of these types.
```js regenerate(0x1D306, 'A', '©', 0x2603).toString(); // → '[A\\xA9\\u2603]|\\uD834\\uDF06'
var items = [0x1D306, 'A', '©', 0x2603]; regenerate(items).toString(); // → '[A\\xA9\\u2603]|\\uD834\\uDF06' ```
### `regenerate.prototype.add(value1, value2, value3, ...)`
Any arguments passed to `add()` are added to the set. Both code points (numbers) and symbols (strings consisting of a single Unicode symbol) are accepted, as well as arrays containing values of these types.
```js regenerate().add(0x1D306, 'A', '©', 0x2603).toString(); // → '[A\\xA9\\u2603]|\\uD834\\uDF06'
var items = [0x1D306, 'A', '©', 0x2603]; regenerate().add(items).toString(); // → '[A\\xA9\\u2603]|\\uD834\\uDF06' ```
It’s also possible to pass in a Regenerate instance. Doing so adds all code points in that instance to the current set.
```js var set = regenerate(0x1D306, 'A'); regenerate().add('©', 0x2603).add(set).toString(); // → '[A\\xA9\\u2603]|\\uD834\\uDF06' ```
Note that the initial call to `regenerate()` acts like `add()`. This allows you to create a new Regenerate instance and add some code points to it in one go:
```js regenerate(0x1D306, 'A', '©', 0x2603).toString(); // → '[A\\xA9\\u2603]|\\uD834\\uDF06' ```
### `regenerate.prototype.remove(value1, value2, value3, ...)`
Any arguments passed to `remove()` are removed from the set. Both code points (numbers) and symbols (strings consisting of a single Unicode symbol) are accepted, as well as arrays containing values of these types.
```js regenerate(0x1D306, 'A', '©', 0x2603).remove('☃').toString(); // → '[A\\xA9]|\\uD834\\uDF06' ```
It’s also possible to pass in a Regenerate instance. Doing so removes all code points in that instance from the current set.
```js var set = regenerate('☃'); regenerate(0x1D306, 'A', '©', 0x2603).remove(set).toString(); // → '[A\\xA9]|\\uD834\\uDF06' ```
### `regenerate.prototype.addRange(start, end)`
Adds a range of code points from `start` to `end` (inclusive) to the set. Both code points (numbers) and symbols (strings consisting of a single Unicode symbol) are accepted.
```js regenerate(0x1D306).addRange(0x00, 0xFF).toString(16); // → '[\\0-\\xFF]|\\uD834\\uDF06'
regenerate().addRange('A', 'z').toString(); // → '[A-z]' ```
### `regenerate.prototype.removeRange(start, end)`
Removes a range of code points from `start` to `end` (inclusive) from the set. Both code points (numbers) and symbols (strings consisting of a single Unicode symbol) are accepted.
```js regenerate() .addRange(0x000000, 0x10FFFF) // add all Unicode code points .removeRange('A', 'z') // remove all symbols from `A` to `z` .toString(); // → '[\\0-@\\{-\\uD7FF\\uE000-\\uFFFF]|[\\uD800-\\uDBFF][\\uDC00-\\uDFFF]|[\\uD800-\\uDBFF](?![\\uDC00-\\uDFFF])|(?:[^\\uD800-\\uDBFF]|^)[\\uDC00-\\uDFFF]'
regenerate() .addRange(0x000000, 0x10FFFF) // add all Unicode code points .removeRange(0x0041, 0x007A) // remove all code points from U+0041 to U+007A .toString(); // → '[\\0-@\\{-\\uD7FF\\uE000-\\uFFFF]|[\\uD800-\\uDBFF][\\uDC00-\\uDFFF]|[\\uD800-\\uDBFF](?![\\uDC00-\\uDFFF])|(?:[^\\uD800-\\uDBFF]|^)[\\uDC00-\\uDFFF]' ```
### `regenerate.prototype.intersection(codePoints)`
Removes any code points from the set that are not present in both the set and the given `codePoints` array. `codePoints` must be an array of numeric code point values, i.e. numbers.
```js regenerate() .addRange(0x00, 0xFF) // add extended ASCII code points .intersection([0x61, 0x69]) // remove all code points from the set except for these .toString(); // → '[ai]' ```
Instead of the `codePoints` array, it’s also possible to pass in a Regenerate instance.
```js var whitelist = regenerate(0x61, 0x69);
regenerate() .addRange(0x00, 0xFF) // add extended ASCII code points .intersection(whitelist) // remove all code points from the set except for those in the `whitelist` set .toString(); // → '[ai]' ```
### `regenerate.prototype.contains(value)`
Returns `true` if the given value is part of the set, and `false` otherwise. Both code points (numbers) and symbols (strings consisting of a single Unicode symbol) are accepted.
```js var set = regenerate().addRange(0x00, 0xFF); set.contains('A'); // → true set.contains(0x1D306); // → false ```
### `regenerate.prototype.clone()`
Returns a clone of the current code point set. Any actions performed on the clone won’t mutate the original set.
```js var setA = regenerate(0x1D306); var setB = setA.clone().add(0x1F4A9); setA.toArray(); // → [0x1D306] setB.toArray(); // → [0x1D306, 0x1F4A9] ```
### `regenerate.prototype.toString(options)`
Returns a string representing (part of) a regular expression that matches all the symbols mapped to the code points within the set.
```js regenerate(0x1D306, 0x1F4A9).toString(); // → '\\uD834\\uDF06|\\uD83D\\uDCA9' ```
If the `bmpOnly` property of the optional `options` object is set to `true`, the output matches surrogates individually, regardless of whether they’re lone surrogates or just part of a surrogate pair. This simplifies the output, but it can only be used in case you’re certain the strings it will be used on don’t contain any astral symbols.
```js var highSurrogates = regenerate().addRange(0xD800, 0xDBFF); highSurrogates.toString(); // → '[\\uD800-\\uDBFF](?![\\uDC00-\\uDFFF])' highSurrogates.toString({ 'bmpOnly': true }); // → '[\\uD800-\\uDBFF]'
var lowSurrogates = regenerate().addRange(0xDC00, 0xDFFF); lowSurrogates.toString(); // → '(?:[^\\uD800-\\uDBFF]|^)[\\uDC00-\\uDFFF]' lowSurrogates.toString({ 'bmpOnly': true }); // → '[\\uDC00-\\uDFFF]' ```
Note that lone low surrogates cannot be matched accurately using regular expressions in JavaScript without the use of [lookbehind assertions](https://mathiasbynens.be/notes/es-regexp-proposals#lookbehinds), which aren't yet widely supported. Regenerate’s output makes a best-effort approach but [there can be false negatives in this regard](https://github.com/mathiasbynens/regenerate/issues/28#issuecomment-72224808).
If the `hasUnicodeFlag` property of the optional `options` object is set to `true`, the output makes use of Unicode code point escapes (`\u{…}`) where applicable. This simplifies the output at the cost of compatibility and portability, since it means the output can only be used as a pattern in a regular expression with [the ES6 `u` flag](https://mathiasbynens.be/notes/es6-unicode-regex) enabled.
```js var set = regenerate().addRange(0x0, 0x10FFFF);
set.toString(); // → '[\\0-\\uD7FF\\uE000-\\uFFFF]|[\\uD800-\\uDBFF][\\uDC00-\\uDFFF]|[\\uD800-\\uDBFF](?![\\uDC00-\\uDFFF])|(?:[^\\uD800-\\uDBFF]|^)[\\uDC00-\\uDFFF]''
set.toString({ 'hasUnicodeFlag': true }); // → '[\\0-\\u{10FFFF}]' ```
### `regenerate.prototype.toRegExp(flags = '')`
Returns a regular expression that matches all the symbols mapped to the code points within the set. Optionally, you can pass [flags](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/RegExp#Parameters) to be added to the regular expression.
```js var regex = regenerate(0x1D306, 0x1F4A9).toRegExp(); // → /\uD834\uDF06|\uD83D\uDCA9/ regex.test('𝌆'); // → true regex.test('A'); // → false
// With flags: var regex = regenerate(0x1D306, 0x1F4A9).toRegExp('g'); // → /\uD834\uDF06|\uD83D\uDCA9/g ```
**Note:** This probably shouldn’t be used. Regenerate is intended as a tool that is used as part of a build process, not at runtime.
### `regenerate.prototype.valueOf()` or `regenerate.prototype.toArray()`
Returns a sorted array of unique code points in the set.
```js regenerate(0x1D306) .addRange(0x60, 0x65) .add(0x59, 0x60) // note: 0x59 is added after 0x65, and 0x60 is a duplicate .valueOf(); // → [0x59, 0x60, 0x61, 0x62, 0x63, 0x64, 0x65, 0x1D306] ```
### `regenerate.version`
A string representing the semantic version number.
## Combine Regenerate with other libraries
Regenerate gets even better when combined with other libraries such as [Punycode.js](https://mths.be/punycode). Here’s an example where [Punycode.js](https://mths.be/punycode) is used to convert a string into an array of code points, that is then passed on to Regenerate:
```js var regenerate = require('regenerate'); var punycode = require('punycode');
var string = 'Lorem ipsum dolor sit amet.'; // Get an array of all code points used in the string: var codePoints = punycode.ucs2.decode(string);
// Generate a regular expression that matches any of the symbols used in the string: regenerate(codePoints).toString(); // → '[ \\.Ladeilmopr-u]' ```
In ES6 you can do something similar with [`Array.from`](https://mths.be/array-from) which uses [the string’s iterator](https://mathiasbynens.be/notes/javascript-unicode#iterating-over-symbols) to split the given string into an array of strings that each contain a single symbol. [`regenerate()`](#regenerateprototypeaddvalue1-value2-value3-) accepts both strings and code points, remember?
```js var regenerate = require('regenerate');
var string = 'Lorem ipsum dolor sit amet.'; // Get an array of all symbols used in the string: var symbols = Array.from(string);
// Generate a regular expression that matches any of the symbols used in the string: regenerate(symbols).toString(); // → '[ \\.Ladeilmopr-u]' ```
## Support
Regenerate supports at least Chrome 27+, Firefox 3+, Safari 4+, Opera 10+, IE 6+, Node.js v0.10.0+, io.js v1.0.0+, Narwhal 0.3.2+, RingoJS 0.8+, PhantomJS 1.9.0+, and Rhino 1.7RC4+.
## Unit tests & code coverage
After cloning this repository, run `npm install` to install the dependencies needed for Regenerate development and testing. You may want to install Istanbul _globally_ using `npm install istanbul -g`.
Once that’s done, you can run the unit tests in Node using `npm test` or `node tests/tests.js`. To run the tests in Rhino, Ringo, Narwhal, and web browsers as well, use `grunt test`.
To generate the code coverage report, use `grunt cover`.
## Author
| [![twitter/mathias](https://gravatar.com/avatar/24e08a9ea84deb17ae121074d0f17125?s=70)](https://twitter.com/mathias "Follow @mathias on Twitter") | |---| | [Mathias Bynens](https://mathiasbynens.be/) |
## License
Regenerate is available under the [MIT](https://mths.be/mit) license.
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