source: frontend/node_modules/es-abstract/2025/GeneratorStart.js

'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
};