108 lines
4.0 KiB
JavaScript
108 lines
4.0 KiB
JavaScript
/**
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* @license Apache-2.0
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*
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* Copyright (c) 2018 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 isArrayBuffer = require( '@stdlib/assert/is-arraybuffer' );
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var isNonNegativeInteger = require( '@stdlib/assert/is-nonnegative-integer' ).isPrimitive;
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var Buffer = require( './../../ctor' );
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var Uint8Array = require( '@stdlib/array/uint8' );
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var fromArray = require( './../../from-array' );
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var version = require( './node_version.js' );
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// MAIN //
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/**
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* Allocates a buffer from an `ArrayBuffer`.
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*
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* ## Notes
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*
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* The behavior of this function varies across Node.js versions due to changes in the underlying Node.js APIs:
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*
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* - `<3.0.0`: the function copies ArrayBuffer bytes to a new Buffer instance.
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* - `>=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.
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* - `<6.0.0`: if provided an empty ArrayBuffer, the function returns an empty Buffer which is **not** an ArrayBuffer view.
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*
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*
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* @param {ArrayBuffer} buf - ArrayBuffer instance
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* @param {NonNegativeInteger} [byteOffset=0] - index specifying the location of the first buffer byte
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* @param {NonNegativeInteger} [length=buf.byteLength] - number of buffer bytes
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* @throws {TypeError} first argument must be an ArrayBuffer
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* @throws {TypeError} second argument must be a nonnegative integer
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* @throws {RangeError} second argument must not exceed number of bytes in input ArrayBuffer
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* @throws {TypeError} last argument must be a nonnegative integer
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* @throws {RangeError} last argument must not exceed number of bytes in input ArrayBuffer
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* @returns {Buffer} new `Buffer` instance
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*
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* @example
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* var ArrayBuffer = require( '@stdlib/array/buffer' );
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* var ab = new ArrayBuffer( 10 );
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*
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* var buf = fromArrayBuffer( ab );
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* // returns <Buffer>
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*
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* @example
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* var ArrayBuffer = require( '@stdlib/array/buffer' );
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* var ab = new ArrayBuffer( 10 );
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*
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* var buf = fromArrayBuffer( ab, 2, 4 );
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* // returns <Buffer>
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*/
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function fromArrayBuffer( buf, byteOffset, length ) {
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var len;
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if ( !isArrayBuffer( buf ) ) {
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throw new TypeError( 'invalid argument. First argument must be an ArrayBuffer. Value: `' + buf + '`' );
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}
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if ( arguments.length > 1 ) {
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if ( !isNonNegativeInteger( byteOffset ) ) {
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throw new TypeError( 'invalid argument. Second argument must be a nonnegative integer. Value: `' + byteOffset + '`.' );
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}
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if ( byteOffset > buf.byteLength ) {
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throw new RangeError( 'invalid argument. Second argument must not exceed the number of bytes in the input ArrayBuffer. Value: `' + byteOffset + '`.' );
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}
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if ( arguments.length > 2 ) {
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if ( !isNonNegativeInteger( length ) ) {
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throw new TypeError( 'invalid argument. Last argument must be a nonnegative integer. Value: `' + length + '`.' );
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}
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if ( length > buf.byteLength ) {
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throw new RangeError( 'invalid argument. Last argument must not exceed the number of bytes in the input ArrayBuffer. Value: `' + length + '`.' );
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}
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len = length;
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} else {
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len = buf.byteLength - byteOffset;
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}
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return fromArray( new Uint8Array( buf, byteOffset, len ) );
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}
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if ( version < 3 ) {
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return fromArray( new Uint8Array( buf ) );
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}
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// Address Node <= v5.x where providing an empty ArrayBuffer throws an error:
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if ( buf.byteLength === 0 ) {
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return new Buffer( [] ); // eslint-disable-line no-buffer-constructor
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}
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return new Buffer( buf ); // eslint-disable-line no-buffer-constructor
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}
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// EXPORTS //
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module.exports = fromArrayBuffer;
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