GeneratorStart.jsā¢1.62 kB
'use strict';
var $TypeError = require('es-errors/type');
var CreateIteratorResultObject = require('./CreateIteratorResultObject');
var IsCallable = require('./IsCallable');
var SLOT = require('internal-slot');
var isObject = require('es-object-atoms/isObject');
// https://262.ecma-international.org/16.0/#sec-generatorstart
module.exports = function GeneratorStart(generator, closure) {
SLOT.assert(generator, '[[GeneratorState]]');
SLOT.assert(generator, '[[GeneratorContext]]');
SLOT.assert(generator, '[[GeneratorBrand]]');
SLOT.assert(generator, '[[Sentinel]]'); // our userland slot
SLOT.assert(generator, '[[CloseIfAbrupt]]'); // our second userland slot
if (!IsCallable(closure) || closure.length !== 0) {
throw new $TypeError('`closure` must be a function that takes no arguments');
}
var sentinel = SLOT.get(closure, '[[Sentinel]]');
if (!isObject(sentinel)) {
throw new $TypeError('`closure.[[Sentinel]]` must be an object');
}
SLOT.set(generator, '[[GeneratorContext]]', function () { // steps 2-5
try {
var result = closure();
if (result === sentinel) {
SLOT.set(generator, '[[GeneratorState]]', 'COMPLETED');
SLOT.set(generator, '[[GeneratorContext]]', null);
return CreateIteratorResultObject(void undefined, true);
}
SLOT.set(generator, '[[GeneratorState]]', 'SUSPENDED-YIELD');
return CreateIteratorResultObject(result, false);
} catch (e) {
SLOT.set(generator, '[[GeneratorState]]', 'COMPLETED');
SLOT.set(generator, '[[GeneratorContext]]', null);
throw e;
}
});
SLOT.set(generator, '[[GeneratorState]]', 'SUSPENDED-START'); // step 6
};