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47 lines
1.6 KiB
47 lines
1.6 KiB
1 week ago
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'use strict';
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var $TypeError = require('es-errors/type');
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var CreateIteratorResultObject = require('./CreateIteratorResultObject');
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var IsCallable = require('./IsCallable');
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var SLOT = require('internal-slot');
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var isObject = require('es-object-atoms/isObject');
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// https://262.ecma-international.org/16.0/#sec-generatorstart
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module.exports = function GeneratorStart(generator, closure) {
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SLOT.assert(generator, '[[GeneratorState]]');
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SLOT.assert(generator, '[[GeneratorContext]]');
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SLOT.assert(generator, '[[GeneratorBrand]]');
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SLOT.assert(generator, '[[Sentinel]]'); // our userland slot
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SLOT.assert(generator, '[[CloseIfAbrupt]]'); // our second userland slot
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if (!IsCallable(closure) || closure.length !== 0) {
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throw new $TypeError('`closure` must be a function that takes no arguments');
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}
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var sentinel = SLOT.get(closure, '[[Sentinel]]');
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if (!isObject(sentinel)) {
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throw new $TypeError('`closure.[[Sentinel]]` must be an object');
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}
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SLOT.set(generator, '[[GeneratorContext]]', function () { // steps 2-5
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try {
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var result = closure();
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if (result === sentinel) {
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SLOT.set(generator, '[[GeneratorState]]', 'COMPLETED');
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SLOT.set(generator, '[[GeneratorContext]]', null);
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return CreateIteratorResultObject(void undefined, true);
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}
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SLOT.set(generator, '[[GeneratorState]]', 'SUSPENDED-YIELD');
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return CreateIteratorResultObject(result, false);
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} catch (e) {
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SLOT.set(generator, '[[GeneratorState]]', 'COMPLETED');
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SLOT.set(generator, '[[GeneratorContext]]', null);
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throw e;
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}
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});
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SLOT.set(generator, '[[GeneratorState]]', 'SUSPENDED-START'); // step 6
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};
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