34 lines
1.4 KiB
JavaScript
34 lines
1.4 KiB
JavaScript
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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