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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.)

# Installation

Via npm:

npm install regenerate

Via Bower:

bower install regenerate

Via Component:

component install mathiasbynens/regenerate

In a browser:

<script src="regenerate.js"></script>

In Node.js, io.js, and RingoJS ≥ v0.8.0:

var regenerate = require('regenerate');

In Narwhal and RingoJS ≤ v0.7.0:

var regenerate = require('regenerate').regenerate;

In Rhino:

load('regenerate.js');

Using an AMD loader like RequireJS:

require(
{
'paths': {
'regenerate': 'path/to/regenerate'
}
},
['regenerate'],
function(regenerate) {
console.log(regenerate);
}
);

# API

## <tt>regenerate(value1, value2, value3, ...)</tt>

The main Regenerate function. Calling this function creates a new set that gets a chainable API.

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.

regenerate(0x1D306, 'A', '©', 0x2603).toString();
// → '[A\\xA9\\u2603]|\\uD834\\uDF06'
var items = [0x1D306, 'A', '©', 0x2603];
regenerate(items).toString();
// → '[A\\xA9\\u2603]|\\uD834\\uDF06'

## <tt>regenerate.prototype.add(value1, value2, value3, ...)</tt>

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.

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.

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:

regenerate(0x1D306, 'A', '©', 0x2603).toString();
// → '[A\\xA9\\u2603]|\\uD834\\uDF06'

## <tt>regenerate.prototype.remove(value1, value2, value3, ...)</tt>

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.

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.

var set = regenerate('☃');
regenerate(0x1D306, 'A', '©', 0x2603).remove(set).toString();
// → '[A\\xA9]|\\uD834\\uDF06'

## <tt>regenerate.prototype.addRange(start, end)</tt>

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.

regenerate(0x1D306).addRange(0x00, 0xFF).toString(16);
// → '[\\0-\\xFF]|\\uD834\\uDF06'
regenerate().addRange('A', 'z').toString();
// → '[A-z]'

## <tt>regenerate.prototype.removeRange(start, end)</tt>

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.

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]'

## <tt>regenerate.prototype.intersection(codePoints)</tt>

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.

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.

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]'

## <tt>regenerate.prototype.contains(value)</tt>

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.

var set = regenerate().addRange(0x00, 0xFF);
set.contains('A');
// → true
set.contains(0x1D306);
// → false

## <tt>regenerate.prototype.clone()</tt>

Returns a clone of the current code point set. Any actions performed on the clone won’t mutate the original set.

var setA = regenerate(0x1D306);
var setB = setA.clone().add(0x1F4A9);
setA.toArray();
// → [0x1D306]
setB.toArray();
// → [0x1D306, 0x1F4A9]

## <tt>regenerate.prototype.toString(options)</tt>

Returns a string representing (part of) a regular expression that matches all the symbols mapped to the code points within the set.

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.

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, which aren't yet widely supported. Regenerate’s output makes a best-effort approach but there can be false negatives in this regard.

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 enabled.

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 to be added to the regular expression.

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.

## <tt>regenerate.prototype.valueOf()</tt> or <tt>regenerate.prototype.toArray()</tt>

Returns a sorted array of unique code points in the set.

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]

## <tt>regenerate.version</tt>

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. Here’s an example where Punycode.js is used to convert a string into an array of code points, that is then passed on to Regenerate:

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` which uses the string’s iterator to split the given string into an array of strings that each contain a single symbol. `regenerate()` accepts both strings and code points, remember?

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

Mathias Bynens

# License

Regenerate is available under the MIT license.