54 lines
1.5 KiB
JavaScript
54 lines
1.5 KiB
JavaScript
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var META = require('./_uid')('meta');
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var isObject = require('./_is-object');
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var has = require('./_has');
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var setDesc = require('./_object-dp').f;
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var id = 0;
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var isExtensible = Object.isExtensible || function () {
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return true;
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};
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var FREEZE = !require('./_fails')(function () {
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return isExtensible(Object.preventExtensions({}));
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});
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var setMeta = function (it) {
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setDesc(it, META, { value: {
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i: 'O' + ++id, // object ID
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w: {} // weak collections IDs
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} });
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};
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var fastKey = function (it, create) {
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// return primitive with prefix
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if (!isObject(it)) return typeof it == 'symbol' ? it : (typeof it == 'string' ? 'S' : 'P') + it;
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if (!has(it, META)) {
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// can't set metadata to uncaught frozen object
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if (!isExtensible(it)) return 'F';
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// not necessary to add metadata
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if (!create) return 'E';
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// add missing metadata
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setMeta(it);
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// return object ID
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} return it[META].i;
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};
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var getWeak = function (it, create) {
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if (!has(it, META)) {
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// can't set metadata to uncaught frozen object
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if (!isExtensible(it)) return true;
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// not necessary to add metadata
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if (!create) return false;
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// add missing metadata
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setMeta(it);
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// return hash weak collections IDs
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} return it[META].w;
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};
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// add metadata on freeze-family methods calling
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var onFreeze = function (it) {
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if (FREEZE && meta.NEED && isExtensible(it) && !has(it, META)) setMeta(it);
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return it;
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};
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var meta = module.exports = {
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KEY: META,
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NEED: false,
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fastKey: fastKey,
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getWeak: getWeak,
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onFreeze: onFreeze
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};
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