137 lines
2.5 KiB
Markdown
137 lines
2.5 KiB
Markdown
<!--
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@license Apache-2.0
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Copyright (c) 2020 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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# hasUTF16SurrogatePairAt
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> Test if a position in a string marks the start of a [UTF-16][utf-16] surrogate pair.
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<section class="usage">
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## Usage
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```javascript
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var hasUTF16SurrogatePairAt = require( '@stdlib/assert/has-utf16-surrogate-pair-at' );
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```
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#### hasUTF16SurrogatePairAt( string, position )
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Tests if a `position` (in [UTF-16][utf-16] code units) in a `string` marks the start of a [UTF-16][utf-16] surrogate pair.
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```javascript
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var bool = hasUTF16SurrogatePairAt( '🌷', 0 );
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// returns true
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bool = hasUTF16SurrogatePairAt( '🌷', 1 );
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// returns false
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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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- Note that `position` does **not** refer to a visual character position, but to an index in the ordered sequence of [UTF-16][utf-16] code units.
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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 hasUTF16SurrogatePairAt = require( '@stdlib/assert/has-utf16-surrogate-pair-at' );
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var bool = hasUTF16SurrogatePairAt( '🌷', 0 );
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// returns true
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bool = hasUTF16SurrogatePairAt( '🌷', 1 );
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// returns false
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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: has-utf16-surrogate-pair-at [options] [<string>] --pos=<index>
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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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--pos index Position in string.
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```
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</section>
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<!-- /.usage -->
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<section class="examples">
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### Examples
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```bash
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$ has-utf16-surrogate-pair-at --pos=0 🌷
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true
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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 '🌷' | has-utf16-surrogate-pair-at --pos=1
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false
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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 class="links">
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[utf-16]: https://en.wikipedia.org/wiki/UTF-16
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[standard-streams]: https://en.wikipedia.org/wiki/Standard_streams
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</section>
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<!-- /.links -->
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