48 lines
1.2 KiB
JavaScript
48 lines
1.2 KiB
JavaScript
'use strict';
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let idKey = exports.idKey = Symbol();
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let realmKey = exports.realmKey = Symbol();
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let resizeListKey = exports.resizeListKey = Symbol();
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exports.createList = createList;
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function createList(prototype, getterForLength, getterForIndex, setterForIndex) {
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var list = prototype ? Object.create(prototype) : {};
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var size = 0;
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Object.defineProperty(list, 'length', {get: getterForLength});
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list[resizeListKey] = function(length) {
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if (length == null) {
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length = this.length;
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}
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if (length == size) {
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return;
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}
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if (length > size) {
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let props = {};
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for (let i = size; i < length; i++) {
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props[i] = {
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get: getterForIndex(i),
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set: setterForIndex && setterForIndex(i),
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enumerable: true,
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configurable: true,
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};
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}
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Object.defineProperties(this, props);
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}
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else if (length < size) {
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for (let i = size - 1; i >= length; i--) {
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delete this[i];
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}
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}
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size = length;
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};
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return list;
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}
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