time-to-botec

Benchmark sampling in different programming languages
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polyfill.js (4090B)

      1 /**
      2 * @license Apache-2.0
      3 *
      4 * Copyright (c) 2018 The Stdlib Authors.
      5 *
      6 * Licensed under the Apache License, Version 2.0 (the "License");
      7 * you may not use this file except in compliance with the License.
      8 * You may obtain a copy of the License at
      9 *
     10 *    http://www.apache.org/licenses/LICENSE-2.0
     11 *
     12 * Unless required by applicable law or agreed to in writing, software
     13 * distributed under the License is distributed on an "AS IS" BASIS,
     14 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     15 * See the License for the specific language governing permissions and
     16 * limitations under the License.
     17 */
     18 
     19 'use strict';
     20 
     21 // MODULES //
     22 
     23 var isArrayBuffer = require( '@stdlib/assert/is-arraybuffer' );
     24 var isNonNegativeInteger = require( '@stdlib/assert/is-nonnegative-integer' ).isPrimitive;
     25 var Buffer = require( './../../ctor' );
     26 var Uint8Array = require( '@stdlib/array/uint8' );
     27 var fromArray = require( './../../from-array' );
     28 var version = require( './node_version.js' );
     29 
     30 
     31 // MAIN //
     32 
     33 /**
     34 * Allocates a buffer from an `ArrayBuffer`.
     35 *
     36 * ## Notes
     37 *
     38 * The behavior of this function varies across Node.js versions due to changes in the underlying Node.js APIs:
     39 *
     40 * -   `<3.0.0`: the function copies ArrayBuffer bytes to a new Buffer instance.
     41 * -   `>=3.0.0`: if provided a byte offset, the function copies `ArrayBuffer` bytes to a new `Buffer` instance; otherwise, the function returns a view of an `ArrayBuffer` without copying the underlying memory.
     42 * -   `<6.0.0`: if provided an empty ArrayBuffer, the function returns an empty Buffer which is **not** an ArrayBuffer view.
     43 *
     44 *
     45 * @param {ArrayBuffer} buf - ArrayBuffer instance
     46 * @param {NonNegativeInteger} [byteOffset=0] - index specifying the location of the first buffer byte
     47 * @param {NonNegativeInteger} [length=buf.byteLength] - number of buffer bytes
     48 * @throws {TypeError} first argument must be an ArrayBuffer
     49 * @throws {TypeError} second argument must be a nonnegative integer
     50 * @throws {RangeError} second argument must not exceed number of bytes in input ArrayBuffer
     51 * @throws {TypeError} last argument must be a nonnegative integer
     52 * @throws {RangeError} last argument must not exceed number of bytes in input ArrayBuffer
     53 * @returns {Buffer} new `Buffer` instance
     54 *
     55 * @example
     56 * var ArrayBuffer = require( '@stdlib/array/buffer' );
     57 * var ab = new ArrayBuffer( 10 );
     58 *
     59 * var buf = fromArrayBuffer( ab );
     60 * // returns <Buffer>
     61 *
     62 * @example
     63 * var ArrayBuffer = require( '@stdlib/array/buffer' );
     64 * var ab = new ArrayBuffer( 10 );
     65 *
     66 * var buf = fromArrayBuffer( ab, 2, 4 );
     67 * // returns <Buffer>
     68 */
     69 function fromArrayBuffer( buf, byteOffset, length ) {
     70 	var len;
     71 	if ( !isArrayBuffer( buf ) ) {
     72 		throw new TypeError( 'invalid argument. First argument must be an ArrayBuffer. Value: `' + buf + '`' );
     73 	}
     74 	if ( arguments.length > 1 ) {
     75 		if ( !isNonNegativeInteger( byteOffset ) ) {
     76 			throw new TypeError( 'invalid argument. Second argument must be a nonnegative integer. Value: `' + byteOffset + '`.' );
     77 		}
     78 		if ( byteOffset > buf.byteLength ) {
     79 			throw new RangeError( 'invalid argument. Second argument must not exceed the number of bytes in the input ArrayBuffer. Value: `' + byteOffset + '`.' );
     80 		}
     81 		if ( arguments.length > 2 ) {
     82 			if ( !isNonNegativeInteger( length ) ) {
     83 				throw new TypeError( 'invalid argument. Last argument must be a nonnegative integer. Value: `' + length + '`.' );
     84 			}
     85 			if ( length > buf.byteLength ) {
     86 				throw new RangeError( 'invalid argument. Last argument must not exceed the number of bytes in the input ArrayBuffer. Value: `' + length + '`.' );
     87 			}
     88 			len = length;
     89 		} else {
     90 			len = buf.byteLength - byteOffset;
     91 		}
     92 		return fromArray( new Uint8Array( buf, byteOffset, len ) );
     93 	}
     94 	if ( version < 3 ) {
     95 		return fromArray( new Uint8Array( buf ) );
     96 	}
     97 	// Address Node <= v5.x where providing an empty ArrayBuffer throws an error:
     98 	if ( buf.byteLength === 0 ) {
     99 		return new Buffer( [] ); // eslint-disable-line no-buffer-constructor
    100 	}
    101 	return new Buffer( buf ); // eslint-disable-line no-buffer-constructor
    102 }
    103 
    104 
    105 // EXPORTS //
    106 
    107 module.exports = fromArrayBuffer;