177 lines
4.5 KiB
Markdown
177 lines
4.5 KiB
Markdown
<!--
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@license Apache-2.0
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Copyright (c) 2018 The Stdlib Authors.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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-->
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# White Space
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> [Regular expression][regexp] to match a [white space][whitespace] character.
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<section class="usage">
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## Usage
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```javascript
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var reWhitespace = require( '@stdlib/regexp/whitespace' );
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```
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#### reWhitespace( \[options] )
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Returns a [regular expression][regexp] to match a [white space][whitespace] character.
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```javascript
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var RE_WHITESPACE = reWhitespace();
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var bool = RE_WHITESPACE.test( '\n' );
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// returns true
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bool = RE_WHITESPACE.test( ' ' );
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// returns true
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```
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The function accepts an `options` object with optional properties:
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- **flags**: `string` specifying regular expression [flags][mdn-regexp-flags]. Default: `''`.
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- **capture**: `boolean` indicating whether to create a capture group for the match. Default: `false`.
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By default, the function returns a regular expression which does not have any flags specified. To specify [flags][mdn-regexp-flags], set the `flags` option with a list of flags (which may be in any order).
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```javascript
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var RE_WHITESPACE = reWhitespace({
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'flags': 'gm'
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});
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var str = 'Hello World!';
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var bool = RE_WHITESPACE.test( str );
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// returns true
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bool = RE_WHITESPACE.test( str );
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// returns false
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```
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By default, the function returns a regular expression which does not capture the part of a string matching the regular expression. To capture matches, set the `capture` option.
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```javascript
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var RE_WHITESPACE = reWhitespace({
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'capture': true
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});
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var str = 'Hello World!';
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var arr = str.split( RE_WHITESPACE );
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// returns [ 'Hello', ' ', 'World!' ]
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```
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#### reWhitespace.REGEXP
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[Regular expression][regexp] to match a [white space][whitespace] character.
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```javascript
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var bool = reWhitespace.REGEXP.test( '\n' );
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// returns true
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bool = reWhitespace.REGEXP.test( '\\n' );
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// returns false
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```
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#### reWhitespace.REGEXP_CAPTURE
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[Regular expression][regexp] to capture characters matching a [white space][whitespace] character.
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```javascript
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var replace = require( '@stdlib/string/replace' );
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var str = 'Duplicate capture';
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var out = replace( str, reWhitespace.REGEXP_CAPTURE, '$1$1' );
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// returns 'Duplicate capture'
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```
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</section>
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<!-- /.usage -->
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<section class="notes">
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## Notes
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- Matches the `25` characters defined as white space ("WSpace=Y","WS") characters in the Unicode `9.0` character database.
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- Matches one related white space character without the Unicode character property "WSpace=Y" (zero width non-breaking space which was deprecated as of Unicode 3.2).
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- The `REGEXP` regular expression is defined as
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```text
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/[\u0009\u000A\u000B\u000C\u000D\u0020\u0085\u00A0\u1680\u2000\u2001\u2002\u2003\u2004\u2005\u2006\u2007\u2008\u2009\u200A\u2028\u2029\u202F\u205F\u3000\uFEFF]/
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```
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- The `REGEXP_CAPTURE` regular expression is defined as
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```text
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/([\u0009\u000A\u000B\u000C\u000D\u0020\u0085\u00A0\u1680\u2000\u2001\u2002\u2003\u2004\u2005\u2006\u2007\u2008\u2009\u200A\u2028\u2029\u202F\u205F\u3000\uFEFF])/
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```
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</section>
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<!-- /.notes -->
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<section class="examples">
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## Examples
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<!-- eslint no-undef: "error", stdlib/doctest: "off" -->
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```javascript
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var reWhitespace = require( '@stdlib/regexp/whitespace' );
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var RE_WHITESPACE = reWhitespace();
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var bool = RE_WHITESPACE.test( 'beep boop' );
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// returns true
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bool = RE_WHITESPACE.test( '\n' );
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// returns true
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bool = RE_WHITESPACE.test( '\r' );
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// returns true
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bool = RE_WHITESPACE.test( '\t' );
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// returns true
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bool = RE_WHITESPACE.test( 'beep' );
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// returns false
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var str = 'This is\na newline\r\ndelimited string.';
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var arr = str.split( RE_WHITESPACE );
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// returns [ 'This', 'is', 'a', 'newline', '', 'delimited', 'string.' ]
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```
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</section>
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<!-- /.examples -->
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<section class="links">
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[regexp]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Regular_Expressions
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[whitespace]: https://en.wikipedia.org/wiki/Whitespace_character
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[mdn-regexp-flags]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Regular_Expressions#advanced_searching_with_flags_2
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</section>
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<!-- /.links -->
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