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33 lines
1.4 KiB
33 lines
1.4 KiB
var $ = require('../internals/export'); |
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var anObject = require('../internals/an-object'); |
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var numberIsFinite = require('../internals/number-is-finite'); |
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var createIteratorConstructor = require('../internals/create-iterator-constructor'); |
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var InternalStateModule = require('../internals/internal-state'); |
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var SEEDED_RANDOM = 'Seeded Random'; |
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var SEEDED_RANDOM_GENERATOR = SEEDED_RANDOM + ' Generator'; |
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var setInternalState = InternalStateModule.set; |
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var getInternalState = InternalStateModule.getterFor(SEEDED_RANDOM_GENERATOR); |
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var SEED_TYPE_ERROR = 'Math.seededPRNG() argument should have a "seed" field with a finite value.'; |
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var $SeededRandomGenerator = createIteratorConstructor(function SeededRandomGenerator(seed) { |
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setInternalState(this, { |
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type: SEEDED_RANDOM_GENERATOR, |
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seed: seed % 2147483647 |
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}); |
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}, SEEDED_RANDOM, function next() { |
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var state = getInternalState(this); |
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var seed = state.seed = (state.seed * 1103515245 + 12345) % 2147483647; |
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return { value: (seed & 1073741823) / 1073741823, done: false }; |
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}); |
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// `Math.seededPRNG` method |
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// https://github.com/tc39/proposal-seeded-random |
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// based on https://github.com/tc39/proposal-seeded-random/blob/78b8258835b57fc2100d076151ab506bc3202ae6/demo.html |
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$({ target: 'Math', stat: true, forced: true }, { |
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seededPRNG: function seededPRNG(it) { |
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var seed = anObject(it).seed; |
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if (!numberIsFinite(seed)) throw TypeError(SEED_TYPE_ERROR); |
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return new $SeededRandomGenerator(seed); |
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} |
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});
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