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feat: add string/base/last
PR-URL: #2145 Closed: #854 Reviewed-by: Philipp Burckhardt <[email protected]>
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‎lib/node_modules/@stdlib/string/last/README.md

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<!--
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@license Apache-2.0
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Copyright (c) 2024 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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# last
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> Return the last character(s) of a string.
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<section class="usage">
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## Usage
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```javascript
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var last = require( '@stdlib/string/last' );
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```
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#### last( str\[, n]\[, options] )
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Returns the last character(s) of a string.
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```javascript
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var out = last( 'last man standing' );
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// returns 'g'
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out = last( 'Hidden Treasures' );
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// returns 's'
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```
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The function supports the following options:
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- **mode**: type of characters to return. Must be one of the following:
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- `'grapheme'`: grapheme clusters. Appropriate for strings containing visual characters which can span multiple Unicode code points (e.g., emoji).
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- `'code_point'`: Unicode code points. Appropriate for strings containing visual characters which are comprised of more than one Unicode code unit (e.g., ideographic symbols and punctuation and mathematical alphanumerics).
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- `'code_unit'`: UTF-16 code units. Appropriate for strings containing visual characters drawn from the basic multilingual plane (BMP) (e.g., common characters, such as those from the Latin, Greek, and Cyrillic alphabets).
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Default: `'grapheme'`.
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By default, the function returns the last character. To return the last `n` characters, provide a second argument specifying the number of characters to return.
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```javascript
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var out = last( 'foo bar', 3 );
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// returns 'bar'
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out = last( 'foo bar', 10 );
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// returns 'foo bar'
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```
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</section>
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<!-- /.usage -->
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<!-- Package usage notes. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->
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<section class="notes">
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## Notes
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- By default, the function assumes the general case in which an input string may contain an arbitrary number of grapheme clusters. This assumption comes with a performance cost. Accordingly, if an input string is known to only contain visual characters of a particular type (e.g., only alphanumeric), one can achieve better performance by specifying the appropriate `mode` option.
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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" -->
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```javascript
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var last = require( '@stdlib/string/last' );
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var str = last( 'last man standing' );
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// returns 'g'
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str = last( 'presidential election' );
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// returns 'n'
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str = last( 'javaScript' );
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// returns 't'
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str = last( 'Hidden Treasures' );
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// returns 's'
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str = last( 'The Last of the Mohicans', 8 );
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// returns 'Mohicans'
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str = last( '🐶🐮🐷🐰🐸', 2 );
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// returns '🐰🐸'
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str = last( '🐶🐮🐷🐰🐸', 10 );
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// returns '🐶🐮🐷🐰🐸'
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```
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</section>
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<!-- /.examples -->
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* * *
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<section class="cli">
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## CLI
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<section class="usage">
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### Usage
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```text
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Usage: last [options] [<string>]
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Options:
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-h, --help Print this message.
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-V, --version Print the package version.
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--n num Number of characters to return. Default: 1.
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--split sep Delimiter for stdin data. Default: '/\\r?\\n/'.
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--mode mode Type of character to return. Default: 'grapheme'.
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```
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</section>
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<!-- /.usage -->
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<!-- CLI usage notes. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->
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<section class="notes">
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### Notes
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- If the split separator is a [regular expression][mdn-regexp], ensure that the `split` option is either properly escaped or enclosed in quotes.
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```bash
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# Not escaped...
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$ echo -n $'beep\nboop' | last --split /\r?\n/
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# Escaped...
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$ echo -n $'beep\nboop' | last --split /\\r?\\n/
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```
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- The implementation ignores trailing delimiters.
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</section>
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<!-- /.notes -->
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<section class="examples">
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### Examples
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```bash
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$ last beep
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p
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```
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To use as a [standard stream][standard-streams],
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```bash
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$ echo -n 'beep\nboop' | last --n=2
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ep
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op
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```
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By default, when used as a [standard stream][standard-streams], the implementation assumes newline-delimited data. To specify an alternative delimiter, set the `split` option.
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```bash
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$ echo -n 'beep\tboop' | last --split '\t'
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p
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p
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```
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</section>
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<!-- /.examples -->
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</section>
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<!-- /.cli -->
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<!-- Section for related `stdlib` packages. Do not manually edit this section, as it is automatically populated. -->
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<section class="related">
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* * *
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</section>
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<!-- /.related -->
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<!-- Section for all links. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->
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<section class="links">
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[standard-streams]: https://en.wikipedia.org/wiki/Standard_streams
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[mdn-regexp]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Regular_Expressions
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<!-- <related-links> -->
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<!-- </related-links> -->
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</section>
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<!-- /.links -->

‎lib/node_modules/@stdlib/string/last/benchmark/benchmark.js

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/**
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* @license Apache-2.0
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*
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* Copyright (c) 2024 The Stdlib Authors.
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*
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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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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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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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'use strict';
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// MODULES //
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var bench = require( '@stdlib/bench' );
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var isString = require( '@stdlib/assert/is-string' ).isPrimitive;
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var pkg = require( './../package.json' ).name;
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var last = require( './../lib' );
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// MAIN //
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bench( pkg, function benchmark( b ) {
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var values;
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var out;
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var i;
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values = [
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'beep boop',
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'foo bar',
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'xyz abc'
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];
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b.tic();
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for ( i = 0; i < b.iterations; i++ ) {
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out = last( values[ i%values.length ] );
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if ( typeof out !== 'string' ) {
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b.fail( 'should return a string' );
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}
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}
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b.toc();
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if ( !isString( out ) ) {
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b.fail( 'should return a string' );
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}
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b.pass( 'benchmark finished' );
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b.end();
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});
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bench( pkg+':mode=grapheme', function benchmark( b ) {
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var values;
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var opts;
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var out;
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var i;
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values = [
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'beep boop',
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'foo bar',
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'xyz abc'
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];
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opts = {
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'mode': 'grapheme'
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};
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b.tic();
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for ( i = 0; i < b.iterations; i++ ) {
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out = last( values[ i%values.length ], opts );
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if ( typeof out !== 'string' ) {
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b.fail( 'should return a string' );
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}
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}
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b.toc();
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if ( !isString( out ) ) {
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b.fail( 'should return a string' );
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}
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b.pass( 'benchmark finished' );
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b.end();
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});
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bench( pkg+':mode=code_point', function benchmark( b ) {
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var values;
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var opts;
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var out;
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var i;
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values = [
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'beep boop',
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'foo bar',
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'xyz abc'
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];
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opts = {
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'mode': 'code_point'
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};
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b.tic();
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for ( i = 0; i < b.iterations; i++ ) {
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out = last( values[ i%values.length ], opts );
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if ( typeof out !== 'string' ) {
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b.fail( 'should return a string' );
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}
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}
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b.toc();
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if ( !isString( out ) ) {
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b.fail( 'should return a string' );
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}
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b.pass( 'benchmark finished' );
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b.end();
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});
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bench( pkg+':mode=code_unit', function benchmark( b ) {
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var values;
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var opts;
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var out;
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var i;
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values = [
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'beep boop',
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'foo bar',
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'xyz abc'
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];
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opts = {
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'mode': 'code_unit'
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};
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b.tic();
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for ( i = 0; i < b.iterations; i++ ) {
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out = last( values[ i%values.length ], opts );
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if ( typeof out !== 'string' ) {
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b.fail( 'should return a string' );
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}
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}
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b.toc();
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if ( !isString( out ) ) {
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b.fail( 'should return a string' );
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}
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b.pass( 'benchmark finished' );
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b.end();
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});

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