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Brady Blair
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feat: add codemod for iterate-iterator
refactor: use [Symbol.iterator]
1 parent 574e0c2 commit 37a9feb

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7 files changed

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‎codemods/iterate-iterator/index.js‎

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import jscodeshift from 'jscodeshift';
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import { removeImport } from '../shared.js';
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/**
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* @typedef {import('../../types.js').Codemod} Codemod
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* @typedef {import('../../types.js').CodemodOptions} CodemodOptions
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*/
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/**
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* @param {CodemodOptions} [options]
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* @returns {Codemod}
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*/
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export default function (options) {
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return {
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name: 'iterate-iterator',
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transform: ({ file }) => {
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const j = jscodeshift;
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const root = j(file.source);
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let isDirty = false;
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const { identifier } = removeImport('iterate-iterator', root, j);
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if (identifier) {
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const callExpressions = root.find(j.CallExpression, {
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callee: { type: 'Identifier', name: identifier },
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});
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for (const path of callExpressions.paths()) {
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const args = path.node.arguments;
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if (args.length === 1) {
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// Case: Converting an iterator to an array
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const [iterable] = args;
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const iterableArg =
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iterable.type === 'SpreadElement' ? iterable.argument : iterable;
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const wrappedIterable = j.objectExpression([
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j.property(
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'init',
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j.memberExpression(
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j.identifier('Symbol'),
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j.identifier('iterator'),
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),
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j.arrowFunctionExpression([], iterableArg),
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),
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]);
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if (
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wrappedIterable.properties[0].type !== 'SpreadProperty' &&
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wrappedIterable.properties[0].type !== 'SpreadElement'
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) {
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wrappedIterable.properties[0].computed = true;
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}
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const arrayFromExpression = j.callExpression(
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j.memberExpression(j.identifier('Array'), j.identifier('from')),
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[wrappedIterable],
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);
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j(path).replaceWith(arrayFromExpression);
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isDirty = true;
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} else if (args.length === 2) {
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// Case: Using a callback function
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const [iterable, callback] = args;
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const iterableArg =
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iterable.type === 'SpreadElement' ? iterable.argument : iterable;
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if (
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callback.type !== 'Identifier' &&
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callback.type !== 'FunctionExpression' &&
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callback.type !== 'ArrowFunctionExpression'
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) {
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continue;
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}
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const wrappedIterable = j.objectExpression([
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j.property(
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'init',
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j.memberExpression(
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j.identifier('Symbol'),
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j.identifier('iterator'),
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),
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j.arrowFunctionExpression([], iterableArg),
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),
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]);
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if (
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wrappedIterable.properties[0].type !== 'SpreadProperty' &&
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wrappedIterable.properties[0].type !== 'SpreadElement'
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) {
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wrappedIterable.properties[0].computed = true;
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}
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const forOfStatement = j.forOfStatement(
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j.variableDeclaration('const', [
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j.variableDeclarator(j.identifier('i')),
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]),
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wrappedIterable,
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j.blockStatement([
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j.expressionStatement(
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j.callExpression(
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callback.type === 'Identifier'
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? callback
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: j.parenthesizedExpression(callback),
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[j.identifier('i')],
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),
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),
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]),
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);
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j(path).replaceWith(forOfStatement);
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isDirty = true;
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}
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}
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}
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return isDirty ? root.toSource(options) : file.source;
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},
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};
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}

‎test/fixtures/iterate-iterator/case-1/after.js‎

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import assert from 'assert';
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assert.deepEqual(Array.from({
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[Symbol.iterator]: () => 'a 💩'[Symbol.iterator]()
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}), ['a', ' ', '💩']);
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assert.deepEqual(Array.from({
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[Symbol.iterator]: () => [1, 2][Symbol.iterator]()
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}), [1, 2]);
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assert.deepEqual(Array.from({
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[Symbol.iterator]: () => new Set([1, 2]).values()
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}), [1, 2]);
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assert.deepEqual(Array.from({
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[Symbol.iterator]: () => new Map([[1, 2], [3, 4]]).entries()
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}), [[1, 2], [3, 4]]);
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const foo = {
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count: 0,
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next() {
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if (this.count < 5) {
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this.count++;
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return { done: false, value: 42 };
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} else {
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return { done: true };
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}
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}
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};
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assert.deepStrictEqual(Array.from({
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[Symbol.iterator]: () => foo
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}), [42, 42, 42, 42, 42]);
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function assertWithCallback(iterable, expected) {
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const values = [];
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const callback = function (x) { values.push(x); };
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for (const i of {
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[Symbol.iterator]: () => iterable
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}) {
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callback(i);
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};
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assert.deepEqual(values, expected);
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}
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assertWithCallback('a 💩'[Symbol.iterator](), ['a', ' ', '💩']);
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assertWithCallback([1, 2][Symbol.iterator](), [1, 2]);
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assertWithCallback(new Set([1, 2]).values(), [1, 2]);
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assertWithCallback(new Map([[1, 2], [3, 4]]).entries(), [[1, 2], [3, 4]]);
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for (const i of {
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[Symbol.iterator]: () => [1, 2][Symbol.iterator]()
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}) {
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(function (x) { console.log(x); })(i);
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};
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for (const i of {
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[Symbol.iterator]: () => [1, 2][Symbol.iterator]()
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}) {
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(x => console.log(x))(i);
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};

‎test/fixtures/iterate-iterator/case-1/before.js‎

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import iterateIterator from 'iterate-iterator';
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import assert from 'assert';
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assert.deepEqual(iterateIterator('a 💩'[Symbol.iterator]()), ['a', ' ', '💩']);
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assert.deepEqual(iterateIterator([1, 2][Symbol.iterator]()), [1, 2]);
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assert.deepEqual(iterateIterator(new Set([1, 2]).values()), [1, 2]);
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assert.deepEqual(iterateIterator(new Map([[1, 2], [3, 4]]).entries()), [[1, 2], [3, 4]]);
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const foo = {
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count: 0,
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next() {
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if (this.count < 5) {
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this.count++;
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return { done: false, value: 42 };
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} else {
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return { done: true };
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}
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}
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};
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assert.deepStrictEqual(iterateIterator(foo), [42, 42, 42, 42, 42]);
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function assertWithCallback(iterable, expected) {
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const values = [];
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const callback = function (x) { values.push(x); };
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iterateIterator(iterable, callback);
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assert.deepEqual(values, expected);
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}
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assertWithCallback('a 💩'[Symbol.iterator](), ['a', ' ', '💩']);
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assertWithCallback([1, 2][Symbol.iterator](), [1, 2]);
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assertWithCallback(new Set([1, 2]).values(), [1, 2]);
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assertWithCallback(new Map([[1, 2], [3, 4]]).entries(), [[1, 2], [3, 4]]);
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iterateIterator([1, 2][Symbol.iterator](), function (x) { console.log(x); });
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iterateIterator([1, 2][Symbol.iterator](), x => console.log(x));

‎test/fixtures/iterate-iterator/case-1/result.js‎

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import assert from 'assert';
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assert.deepEqual(Array.from({
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[Symbol.iterator]: () => 'a 💩'[Symbol.iterator]()
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}), ['a', ' ', '💩']);
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assert.deepEqual(Array.from({
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[Symbol.iterator]: () => [1, 2][Symbol.iterator]()
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}), [1, 2]);
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assert.deepEqual(Array.from({
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[Symbol.iterator]: () => new Set([1, 2]).values()
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}), [1, 2]);
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assert.deepEqual(Array.from({
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[Symbol.iterator]: () => new Map([[1, 2], [3, 4]]).entries()
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}), [[1, 2], [3, 4]]);
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const foo = {
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count: 0,
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next() {
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if (this.count < 5) {
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this.count++;
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return { done: false, value: 42 };
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} else {
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return { done: true };
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}
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}
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};
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assert.deepStrictEqual(Array.from({
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[Symbol.iterator]: () => foo
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}), [42, 42, 42, 42, 42]);
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function assertWithCallback(iterable, expected) {
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const values = [];
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const callback = function (x) { values.push(x); };
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for (const i of {
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[Symbol.iterator]: () => iterable
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}) {
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callback(i);
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};
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assert.deepEqual(values, expected);
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}
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assertWithCallback('a 💩'[Symbol.iterator](), ['a', ' ', '💩']);
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assertWithCallback([1, 2][Symbol.iterator](), [1, 2]);
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assertWithCallback(new Set([1, 2]).values(), [1, 2]);
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assertWithCallback(new Map([[1, 2], [3, 4]]).entries(), [[1, 2], [3, 4]]);
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for (const i of {
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[Symbol.iterator]: () => [1, 2][Symbol.iterator]()
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}) {
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(function (x) { console.log(x); })(i);
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};
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for (const i of {
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[Symbol.iterator]: () => [1, 2][Symbol.iterator]()
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}) {
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(x => console.log(x))(i);
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};

‎test/fixtures/iterate-iterator/case-2/after.js‎

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const assert = require('assert');
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assert.deepEqual(Array.from({
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[Symbol.iterator]: () => 'a 💩'[Symbol.iterator]()
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}), ['a', ' ', '💩']);
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assert.deepEqual(Array.from({
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[Symbol.iterator]: () => [1, 2][Symbol.iterator]()
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}), [1, 2]);
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assert.deepEqual(Array.from({
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[Symbol.iterator]: () => new Set([1, 2]).values()
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}), [1, 2]);
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assert.deepEqual(Array.from({
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[Symbol.iterator]: () => new Map([[1, 2], [3, 4]]).entries()
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}), [[1, 2], [3, 4]]);
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const foo = {
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count: 0,
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next() {
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if (this.count < 5) {
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this.count++;
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return { done: false, value: 42 };
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} else {
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return { done: true };
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}
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}
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};
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assert.deepStrictEqual(Array.from({
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[Symbol.iterator]: () => foo
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}), [42, 42, 42, 42, 42]);
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function assertWithCallback(iterable, expected) {
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const values = [];
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const callback = function (x) { values.push(x); };
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for (const i of {
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[Symbol.iterator]: () => iterable
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}) {
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callback(i);
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};
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assert.deepEqual(values, expected);
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}
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assertWithCallback('a 💩'[Symbol.iterator](), ['a', ' ', '💩']);
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assertWithCallback([1, 2][Symbol.iterator](), [1, 2]);
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assertWithCallback(new Set([1, 2]).values(), [1, 2]);
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assertWithCallback(new Map([[1, 2], [3, 4]]).entries(), [[1, 2], [3, 4]]);
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for (const i of {
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[Symbol.iterator]: () => [1, 2][Symbol.iterator]()
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}) {
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(function (x) { console.log(x); })(i);
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};
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for (const i of {
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[Symbol.iterator]: () => [1, 2][Symbol.iterator]()
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}) {
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(x => console.log(x))(i);
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};

‎test/fixtures/iterate-iterator/case-2/before.js‎

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const assert = require('assert');
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const iterate = require('iterate-iterator');
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assert.deepEqual(iterate('a 💩'[Symbol.iterator]()), ['a', ' ', '💩']);
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assert.deepEqual(iterate([1, 2][Symbol.iterator]()), [1, 2]);
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assert.deepEqual(iterate(new Set([1, 2]).values()), [1, 2]);
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assert.deepEqual(iterate(new Map([[1, 2], [3, 4]]).entries()), [[1, 2], [3, 4]]);
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const foo = {
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count: 0,
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next() {
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if (this.count < 5) {
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this.count++;
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return { done: false, value: 42 };
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} else {
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return { done: true };
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}
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}
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};
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assert.deepStrictEqual(iterate(foo), [42, 42, 42, 42, 42]);
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function assertWithCallback(iterable, expected) {
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const values = [];
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const callback = function (x) { values.push(x); };
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iterate(iterable, callback);
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assert.deepEqual(values, expected);
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}
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assertWithCallback('a 💩'[Symbol.iterator](), ['a', ' ', '💩']);
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assertWithCallback([1, 2][Symbol.iterator](), [1, 2]);
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assertWithCallback(new Set([1, 2]).values(), [1, 2]);
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assertWithCallback(new Map([[1, 2], [3, 4]]).entries(), [[1, 2], [3, 4]]);
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iterate([1, 2][Symbol.iterator](), function (x) { console.log(x); });
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iterate([1, 2][Symbol.iterator](), x => console.log(x));

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