rOACCT/node_modules/regexpu-corebc5dca4d9e2bdrf-api-tracking
README.md
regexpu-core ![Build status](https://travis-ci.org/mathiasbynens/regexpu-core) ![Code coverage status](https://codecov.io/gh/mathiasbynens/regexpu-core)
_regexpu_ is a source code transpiler that enables the use of ES2015 Unicode regular expressions in JavaScript-of-today (ES5).
_regexpu-core_ contains _regexpu_’s core functionality, i.e. rewritePattern(pattern, flag), which enables rewriting regular expressions that make use of [the ES2015 u flag](https://mathiasbynens.be/notes/es6-unicode-regex) into equivalent ES5-compatible regular expression patterns.
Installation
To use _regexpu-core_ programmatically, install it as a dependency via npm:
bash npm install regexpu-core --save
Then, require it:
js const rewritePattern = require('regexpu-core');
API
This module exports a single function named rewritePattern.
rewritePattern(pattern, flags, options)
This function takes a string that represents a regular expression pattern as well as a string representing its flags, and returns an ES5-compatible version of the pattern.
js rewritePattern('foo.bar', 'u'); // → 'foo(?:[\\0-\\t\\x0B\\f\\x0E-\\u2027\\u202A-\\uD7FF\\uDC00-\\uFFFF]|[\\uD800-\\uDBFF][\\uDC00-\\uDFFF]|[\\uD800-\\uDBFF])bar' rewritePattern('[\\u{1D306}-\\u{1D308}a-z]', 'u'); // → '(?:[a-z]|\\uD834[\\uDF06-\\uDF08])' rewritePattern('[\\u{1D306}-\\u{1D308}a-z]', 'ui'); // → '(?:[a-z\\u017F\\u212A]|\\uD834[\\uDF06-\\uDF08])'
_regexpu-core_ can rewrite non-ES6 regular expressions too, which is useful to demonstrate how their behavior changes once the u and i flags are added:
js // In ES5, the dot operator only matches BMP symbols: rewritePattern('foo.bar'); // → 'foo(?:[\\0-\\t\\x0B\\f\\x0E-\\u2027\\u202A-\\uFFFF])bar' // But with the ES2015 `u` flag, it matches astral symbols too: rewritePattern('foo.bar', 'u'); // → 'foo(?:[\\0-\\t\\x0B\\f\\x0E-\\u2027\\u202A-\\uD7FF\\uDC00-\\uFFFF]|[\\uD800-\\uDBFF][\\uDC00-\\uDFFF]|[\\uD800-\\uDBFF])bar'
The optional options argument recognizes the following properties:
dotAllFlag (default: false)
Setting this option to true enables support for [the s (dotAll) flag](https://github.com/mathiasbynens/es-regexp-dotall-flag).
js rewritePattern('.'); // → '[\\0-\\t\\x0B\\f\\x0E-\\u2027\\u202A-\\uFFFF]' rewritePattern('.', '', { 'dotAllFlag': true }); // → '[\\0-\\t\\x0B\\f\\x0E-\\u2027\\u202A-\\uFFFF]' rewritePattern('.', 's', { 'dotAllFlag': true }); // → '[\\0-\\uFFFF]' rewritePattern('.', 'su', { 'dotAllFlag': true }); // → '(?:[\\0-\\uD7FF\\uE000-\\uFFFF]|[\\uD800-\\uDBFF][\\uDC00-\\uDFFF]|[\\uD800-\\uDBFF](?![\\uDC00-\\uDFFF])|(?:[^\\uD800-\\uDBFF]|^)[\\uDC00-\\uDFFF])'
unicodePropertyEscape (default: false)
Setting this option to true enables [support for Unicode property escapes](property-escapes.md):
js rewritePattern('\\p{Script_Extensions=Anatolian_Hieroglyphs}', 'u', { 'unicodePropertyEscape': true }); // → '(?:\\uD811[\\uDC00-\\uDE46])'
lookbehind (default: false)
Setting this option to true enables support for lookbehind assertions.
js rewritePattern('(?<=.)a', '', { 'lookbehind': true }); // → '(?<=[\\0-\\t\\x0B\\f\\x0E-\\u2027\\u202A-\\uFFFF])a'
namedGroup (default: false)
Setting this option to true enables support for named capture groups.
js rewritePattern('(?<name>.)\k<name>', '', { 'namedGroup': true }); // → '(.)\1'
onNamedGroup
This option is a function that gets called when a named capture group is found. It receives two parameters: the name of the group, and its index.
js rewritePattern('(?<name>.)\k<name>', '', { 'namedGroup': true, onNamedGroup(name, index) { console.log(name, index); // → 'name', 1 } });
useUnicodeFlag (default: false)
Setting this option to true enables the use of Unicode code point escapes of the form \u{…}. Note that in regular expressions, such escape sequences only work correctly when the ES2015 u flag is set. Enabling this setting often results in more compact output, although there are cases (such as \p{Lu}) where it actually _increases_ the output size.
js rewritePattern('\\p{Script_Extensions=Anatolian_Hieroglyphs}', 'u', { 'unicodePropertyEscape': true, 'useUnicodeFlag': true }); // → '[\\u{14400}-\\u{14646}]'
Author
![twitter/mathias](https://twitter.com/mathias "Follow @mathias on Twitter") |
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Mathias Bynens |
License
_regexpu-core_ is available under the MIT license.