55 lines
1.6 KiB
JavaScript
55 lines
1.6 KiB
JavaScript
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'use strict';
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var GetIntrinsic = require('get-intrinsic');
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var $ArrayPrototype = GetIntrinsic('%Array.prototype%');
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var $RangeError = GetIntrinsic('%RangeError%');
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var $SyntaxError = GetIntrinsic('%SyntaxError%');
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var $TypeError = GetIntrinsic('%TypeError%');
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var isInteger = require('../helpers/isInteger');
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var hasProto = require('has-proto')();
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var MAX_ARRAY_LENGTH = Math.pow(2, 32) - 1;
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var $setProto = GetIntrinsic('%Object.setPrototypeOf%', true) || (
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hasProto
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? function (O, proto) {
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O.__proto__ = proto; // eslint-disable-line no-proto, no-param-reassign
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return O;
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}
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: null
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);
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// https://262.ecma-international.org/6.0/#sec-arraycreate
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module.exports = function ArrayCreate(length) {
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if (!isInteger(length) || length < 0) {
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throw new $TypeError('Assertion failed: `length` must be an integer Number >= 0');
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}
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if (length > MAX_ARRAY_LENGTH) {
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throw new $RangeError('length is greater than (2**32 - 1)');
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}
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var proto = arguments.length > 1 ? arguments[1] : $ArrayPrototype;
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var A = []; // steps 5 - 7, and 9
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if (proto !== $ArrayPrototype) { // step 8
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if (!$setProto) {
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throw new $SyntaxError('ArrayCreate: a `proto` argument that is not `Array.prototype` is not supported in an environment that does not support setting the [[Prototype]]');
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}
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$setProto(A, proto);
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}
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if (length !== 0) { // bypasses the need for step 2
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A.length = length;
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}
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/* step 10, the above as a shortcut for the below
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OrdinaryDefineOwnProperty(A, 'length', {
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'[[Configurable]]': false,
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'[[Enumerable]]': false,
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'[[Value]]': length,
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'[[Writable]]': true
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});
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*/
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return A;
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};
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