28 lines
799 B
JavaScript
28 lines
799 B
JavaScript
'use strict';
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var $ = require('../internals/export');
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var aWeakMap = require('../internals/a-weak-map');
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var WeakMapHelpers = require('../internals/weak-map-helpers');
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var get = WeakMapHelpers.get;
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var has = WeakMapHelpers.has;
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var set = WeakMapHelpers.set;
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// `WeakMap.prototype.emplace` method
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// https://github.com/tc39/proposal-upsert
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$({ target: 'WeakMap', proto: true, real: true, forced: true }, {
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emplace: function emplace(key, handler) {
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var map = aWeakMap(this);
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var value, inserted;
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if (has(map, key)) {
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value = get(map, key);
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if ('update' in handler) {
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value = handler.update(value, key, map);
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set(map, key, value);
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} return value;
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}
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inserted = handler.insert(key, map);
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set(map, key, inserted);
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return inserted;
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}
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});
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