Add support for getting Unicode code point from string at specified position

lib/node_modules/@stdlib/string/code-point-at/README.md

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+<!--
+
+@license Apache-2.0
+
+Copyright (c) 2020 The Stdlib Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+   http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+
+-->
+
+# codePointAt
+
+> Return a Unicode [code point][code-point] from a string at a specified position.
+
+<!-- Section to include introductory text. Make sure to keep an empty line after the intro `section` element and another before the `/section` close. -->
+
+<section class="intro">
+
+</section>
+
+<!-- /.intro -->
+
+<!-- Package usage documentation. -->
+
+<section class="usage">
+
+## Usage
+
+```javascript
+var codePointAt = require( '@stdlib/string/code-point-at' );
+```
+
+#### codePointAt( string, position\[, backward] )
+
+Returns a Unicode [code point][code-point] from a string at a specified position.
+
+```javascript
+var out = codePointAt( 'last man standing', 4 );
+// returns 32
+```
+
+The function supports providing a `boolean` argument for performing backward iteration for low surrogates.
+
+```javascript
+var out = codePointAt( '🌷', 1, true );
+// returns 127799
+```
+
+</section>
+
+<!-- /.usage -->
+
+<!-- Package usage notes. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->
+
+<section class="notes">
+
+## Notes
+
+This function differs from [`String.codePointAt`][mdn-string-codepointat] in the following ways:
+
+-   The function supports providing a `boolean` argument for performing backward iteration for low surrogates. [`String.codePointAt`][mdn-string-codepointat] simply returns the low surrogate value if no [UTF-16][utf-16] surrogate pair begins at the specified position. If invoked with `backward` set to `true`, this function will return the code point after aggregating with the preceding high surrogate, if the specified position does not mark the start of a surrogate pair.
+
+</section>
+
+<!-- /.notes -->
+
+<!-- Package usage examples. -->
+
+<section class="examples">
+
+## Examples
+
+<!-- eslint no-undef: "error" -->
+
+```javascript
+var codePointAt = require( '@stdlib/string/code-point-at' );
+
+console.log( codePointAt( 'last man standing', 4 ) );
+// => 32
+
+console.log( codePointAt( 'presidential election', 8, true ) );
+// => 116
+
+console.log( codePointAt( 'अनुच्छेद', 2 ) );
+// => 2369
+
+console.log( codePointAt( '🌷', 1, true ) );
+// => 127799
+```
+
+</section>
+
+<!-- /.examples -->
+
+<!-- Section for describing a command-line interface. -->
+
+* * *
+
+<section class="cli">
+
+## CLI
+
+<!-- CLI usage documentation. -->
+
+<section class="usage">
+
+### Usage
+
+```text
+Usage: code-point-at [options] [<string>] --pos=<index>
+
+Options:
+
+  -h,    --help                Print this message.
+  -V,    --version             Print the package version.
+  -b,    --backward            Backward iteration for low surrogates.
+         --pos index           Position in string.
+```
+
+</section>
+
+<!-- /.usage -->
+
+<!-- CLI usage notes. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->
+
+<section class="notes">
+
+</section>
+
+<!-- /.notes -->
+
+<!-- CLI usage examples. -->
+
+<section class="examples">
+
+### Examples
+
+```bash
+$ code-point-at --pos=2 अनुच्छेद
+2369
+```
+
+To use as a [standard stream][standard-streams],
+
+```bash
+$ echo -n 'अनुच्छेद' | code-point-at --pos=2
+2369
+```
+
+</section>
+
+<!-- /.examples -->
+
+</section>
+
+<!-- /.cli -->
+
+<!-- Section to include cited references. If references are included, add a horizontal rule *before* the section. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->
+
+<section class="references">
+
+</section>
+
+<!-- /.references -->
+
+<!-- Section for all links. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->
+
+<section class="links">
+
+[code-point]: https://en.wikipedia.org/wiki/Code_point
+
+[standard-streams]: https://en.wikipedia.org/wiki/Standard_streams
+
+[mdn-string-codepointat]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/codePointAt
+
+[utf-16]: https://en.wikipedia.org/wiki/UTF-16
+
+</section>
+
+<!-- /.links -->

lib/node_modules/@stdlib/string/code-point-at/benchmark/benchmark.js

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+/**
+* @license Apache-2.0
+*
+* Copyright (c) 2020 The Stdlib Authors.
+*
+* Licensed under the Apache License, Version 2.0 (the "License");
+* you may not use this file except in compliance with the License.
+* You may obtain a copy of the License at
+*
+*    http://www.apache.org/licenses/LICENSE-2.0
+*
+* Unless required by applicable law or agreed to in writing, software
+* distributed under the License is distributed on an "AS IS" BASIS,
+* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+* See the License for the specific language governing permissions and
+* limitations under the License.
+*/
+
+'use strict';
+
+// MODULES //
+
+var bench = require( '@stdlib/bench' );
+var randu = require( '@stdlib/random/base/randu' );
+var floor = require( '@stdlib/math/base/special/floor' );
+var fromCodePoint = require( '@stdlib/string/from-code-point' );
+var isNonNegativeInteger = require( '@stdlib/assert/is-nonnegative-integer' ).isPrimitive;
+var UNICODE_MAX = require( '@stdlib/constants/string/unicode-max' );
+var pkg = require( './../package.json' ).name;
+var codePointAt = require( './../lib' );
+
+
+// VARIABLES //
+
+var opts = {
+	'skip': ( typeof String.prototype.codePointAt !== 'function' )
+};
+
+
+// MAIN //
+
+bench( pkg, function benchmark( b ) {
+	var out;
+	var x;
+	var i;
+
+	b.tic();
+	for ( i = 0; i < b.iterations; i++ ) {
+		x = floor( randu() * UNICODE_MAX );
+		out = codePointAt( fromCodePoint( x ), 0 );
+		if ( typeof out !== 'number' ) {
+			b.fail( 'should return a number' );
+		}
+	}
+	b.toc();
+	if ( !isNonNegativeInteger( out ) ) {
+		b.fail( 'should return a nonnegative integer' );
+	}
+	b.pass( 'benchmark finished' );
+	b.end();
+});
+
+bench( pkg+'::built-in', opts, function benchmark( b ) {
+	var out;
+	var x;
+	var i;
+
+	b.tic();
+	for ( i = 0; i < b.iterations; i++ ) {
+		x = floor( randu() * UNICODE_MAX );
+		out = String.prototype.codePointAt.call( fromCodePoint( x ), 0 );
+		if ( typeof out !== 'number' ) {
+			b.fail( 'should return a number' );
+		}
+	}
+	b.toc();
+	if ( !isNonNegativeInteger( out ) ) {
+		b.fail( 'should return a nonnegative integer' );
+	}
+	b.pass( 'benchmark finished' );
+	b.end();
+});

lib/node_modules/@stdlib/string/code-point-at/bin/cli

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+#!/usr/bin/env node
+
+/**
+* @license Apache-2.0
+*
+* Copyright (c) 2020 The Stdlib Authors.
+*
+* Licensed under the Apache License, Version 2.0 (the "License");
+* you may not use this file except in compliance with the License.
+* You may obtain a copy of the License at
+*
+*    http://www.apache.org/licenses/LICENSE-2.0
+*
+* Unless required by applicable law or agreed to in writing, software
+* distributed under the License is distributed on an "AS IS" BASIS,
+* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+* See the License for the specific language governing permissions and
+* limitations under the License.
+*/
+
+'use strict';
+
+// MODULES //
+
+var resolve = require( 'path' ).resolve;
+var readFileSync = require( '@stdlib/fs/read-file' ).sync;
+var CLI = require( '@stdlib/tools/cli' );
+var stdin = require( '@stdlib/process/read-stdin' );
+var codePointAt = require( './../lib' );
+
+
+// MAIN //
+
+/**
+* Main execution sequence.
+*
+* @private
+* @returns {void}
+*/
+function main() {
+	var flags;
+	var args;
+	var cli;
+	var pos;
+
+	// Create a command-line interface:
+	cli = new CLI({
+		'pkg': require( './../package.json' ),
+		'options': require( './../etc/cli_opts.json' ),
+		'help': readFileSync( resolve( __dirname, '..', 'docs', 'usage.txt' ), {
+			'encoding': 'utf8'
+		})
+	});
+
+	// Get any provided command-line options:
+	flags = cli.flags();
+	if ( flags.help || flags.version ) {
+		return;
+	}
+	pos = parseInt( flags.pos, 10 );
+
+	// Get any provided command-line arguments:
+	args = cli.args();
+
+	// Check if we are receiving data from `stdin`...
+	if ( process.stdin.isTTY ) {
+		return console.log( codePointAt( args[ 0 ], pos, flags.backward ) ); // eslint-disable-line no-console
+	}
+	return stdin( onRead );
+
+	/**
+	* Callback invoked upon reading from `stdin`.
+	*
+	* @private
+	* @param {(Error|null)} error - error object
+	* @param {Buffer} data - data
+	* @returns {void}
+	*/
+	function onRead( error, data ) {
+		if ( error ) {
+			return cli.error( error );
+		}
+		console.log( codePointAt( data.toString(), pos, flags.backward ) ); // eslint-disable-line no-console
+	}
+}
+
+main();

lib/node_modules/@stdlib/string/code-point-at/docs/repl.txt

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+
+{{alias}}( str, idx[, backward] )
+    Returns a Unicode code point from a string at a specified position.
+
+    Parameters
+    ----------
+    str: string
+        Input string.
+
+    idx: integer
+        Position.
+
+    backward: boolean (optional)
+        Backward iteration for low surrogates.
+
+    Returns
+    -------
+    out: integer
+        Unicode code point.
+
+    Examples
+    --------
+    > var out = {{alias}}( 'last man standing', 4 )
+    32
+    > out = {{alias}}( 'presidential election', 8, true )
+    116
+    > out = {{alias}}( 'अनुच्छेद', 2 )
+    2369
+    > out = {{alias}}( '🌷', 1, true )
+    127799
+
+    See Also
+    --------