v8/test/mjsunit/harmony/generators.js

// Copyright 2016 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

// Flags: --allow-natives-syntax


function MaybeOptimizeOrDeoptimize(f) {
  %PrepareFunctionForOptimization(f);
  let x = Math.random();  // --random-seed makes this deterministic
  if (x <= 0.33) {
    %OptimizeFunctionOnNextCall(f);
  } else if (x <= 0.66) {
    %DeoptimizeFunction(f);
  }
}

function Next(generator, ...args) {
  MaybeOptimizeOrDeoptimize(%GeneratorGetFunction(generator));
  return generator.next(...args);
}

function Return(generator, ...args) {
  MaybeOptimizeOrDeoptimize(%GeneratorGetFunction(generator));
  return generator.return(...args);
}

function Throw(generator, ...args) {
  MaybeOptimizeOrDeoptimize(%GeneratorGetFunction(generator));
  return generator.throw(...args);
}


{ // yield in try-catch

  let g = function*() {
    try {yield 1} catch (error) {assertEquals("caught", error)}
  };

  assertThrowsEquals(() => Throw(g(), "not caught"), "not caught");

  {
    let x = g();
    assertEquals({value: 1, done: false}, Next(x));
    assertEquals({value: undefined, done: true}, Throw(x, "caught"));
  }

  {
    let x = g();
    assertEquals({value: 1, done: false}, Next(x));
    assertEquals({value: undefined, done: true}, Next(x));
    assertThrowsEquals(() => Throw(x, "not caught"), "not caught");
  }
}


{ // return that doesn't close
  let g = function*() { try {return 42} finally {yield 43} };

  {
    let x = g();
    assertEquals({value: 43, done: false}, Next(x));
    assertEquals({value: 42, done: true}, Next(x));
  }
}


{ // return that doesn't close
  let x;
  let g = function*() { try {return 42} finally {Throw(x, 666)} };

  {
    x = g();
    assertThrows(() => Next(x), TypeError);  // still executing
  }
}


{ // yield in try-finally, finally clause performs return

  let g = function*() { try {yield 42} finally {return 13} };

  { // "return" closes at suspendedStart
    let x = g();
    assertEquals({value: 666, done: true}, Return(x, 666));
    assertEquals({value: undefined, done: true}, Next(x, 42));
    assertThrowsEquals(() => Throw(x, 43), 43);
    assertEquals({value: 42, done: true}, Return(x, 42));
  }

  { // "throw" closes at suspendedStart
    let x = g();
    assertThrowsEquals(() => Throw(x, 666), 666);
    assertEquals({value: undefined, done: true}, Next(x, 42));
    assertEquals({value: 43, done: true}, Return(x, 43));
    assertThrowsEquals(() => Throw(x, 44), 44);
  }

  { // "next" closes at suspendedYield
    let x = g();
    assertEquals({value: 42, done: false}, Next(x));
    assertEquals({value: 13, done: true}, Next(x, 666));
    assertEquals({value: undefined, done: true}, Next(x, 666));
    assertThrowsEquals(() => Throw(x, 666), 666);
  }

  { // "return" closes at suspendedYield
    let x = g();
    assertEquals({value: 42, done: false}, Next(x));
    assertEquals({value: 13, done: true}, Return(x, 666));
    assertEquals({value: undefined, done: true}, Next(x, 666));
    assertEquals({value: 666, done: true}, Return(x, 666));
  }

  { // "throw" closes at suspendedYield
    let x = g();
    assertEquals({value: 42, done: false}, Next(x));
    assertEquals({value: 13, done: true}, Throw(x, 666));
    assertThrowsEquals(() => Throw(x, 666), 666);
    assertEquals({value: undefined, done: true}, Next(x, 666));
  }
}


{ // yield in try-finally, finally clause doesn't perform return

  let g = function*() { try {yield 42} finally {13} };

  { // "return" closes at suspendedStart
    let x = g();
    assertEquals({value: 666, done: true}, Return(x, 666));
    assertEquals({value: undefined, done: true}, Next(x, 42));
    assertThrowsEquals(() => Throw(x, 43), 43);
    assertEquals({value: 42, done: true}, Return(x, 42));
  }

  { // "throw" closes at suspendedStart
    let x = g();
    assertThrowsEquals(() => Throw(x, 666), 666);
    assertEquals({value: undefined, done: true}, Next(x, 42));
    assertEquals({value: 43, done: true}, Return(x, 43));
    assertThrowsEquals(() => Throw(x, 44), 44);
  }

  { // "next" closes at suspendedYield
    let x = g();
    assertEquals({value: 42, done: false}, Next(x));
    assertEquals({value: undefined, done: true}, Next(x, 666));
    assertEquals({value: undefined, done: true}, Next(x, 666));
    assertThrowsEquals(() => Throw(x, 666), 666);
    assertEquals({value: 42, done: true}, Return(x, 42));
  }

  { // "return" closes at suspendedYield
    let x = g();
    assertEquals({value: 42, done: false}, Next(x));
    assertEquals({value: 666, done: true}, Return(x, 666));
    assertEquals({value: undefined, done: true}, Next(x, 666));
    assertThrowsEquals(() => Throw(x, 44), 44);
    assertEquals({value: 42, done: true}, Return(x, 42));
  }

  { // "throw" closes at suspendedYield
    let x = g();
    assertEquals({value: 42, done: false}, Next(x));
    assertThrowsEquals(() => Throw(x, 666), 666);
    assertEquals({value: undefined, done: true}, Next(x, 666));
    assertThrowsEquals(() => Throw(x, 666), 666);
    assertEquals({value: 42, done: true}, Return(x, 42));
  }
}


{ // yield in try-finally, finally clause yields and performs return

  let g = function*() { try {yield 42} finally {yield 43; return 13} };

  {
    let x = g();
    assertEquals({value: 42, done: false}, Next(x));
    assertEquals({value: 43, done: false}, Return(x, 666));
    assertEquals({value: 13, done: true}, Next(x));
    assertEquals({value: 666, done: true}, Return(x, 666));
  }

  {
    let x = g();
    assertEquals({value: 666, done: true}, Return(x, 666));
    assertEquals({value: undefined, done: true}, Next(x));
    assertEquals({value: 666, done: true}, Return(x, 666));
  }
}


{ // yield in try-finally, finally clause yields and doesn't perform return

  let g = function*() { try {yield 42} finally {yield 43; 13} };

  {
    let x = g();
    assertEquals({value: 42, done: false}, Next(x));
    assertEquals({value: 43, done: false}, Return(x, 666));
    assertEquals({value: 666, done: true}, Next(x));
    assertEquals({value: 5, done: true}, Return(x, 5));
  }

  {
    let x = g();
    assertEquals({value: 666, done: true}, Return(x, 666));
    assertEquals({value: undefined, done: true}, Next(x));
    assertEquals({value: 666, done: true}, Return(x, 666));
  }
}


{ // yield*, finally clause performs return

  let h = function*() { try {yield 42} finally {yield 43; return 13} };
  let g = function*() { yield 1; yield yield* h(); };

  {
    let x = g();
    assertEquals({value: 1, done: false}, Next(x));
    assertEquals({value: 42, done: false}, Next(x));
    assertEquals({value: 43, done: false}, Next(x, 666));
    assertEquals({value: 13, done: false}, Next(x));
    assertEquals({value: undefined, done: true}, Next(x));
  }

  {
    let x = g();
    assertEquals({value: 1, done: false}, Next(x));
    assertEquals({value: 42, done: false}, Next(x));
    assertEquals({value: 43, done: false}, Return(x, 666));
    assertEquals({value: 13, done: false}, Next(x));
    assertEquals({value: undefined, done: true}, Next(x));
  }

  {
    let x = g();
    assertEquals({value: 1, done: false}, Next(x));
    assertEquals({value: 42, done: false}, Next(x));
    assertEquals({value: 43, done: false}, Throw(x, 666));
    assertEquals({value: 13, done: false}, Next(x));
    assertEquals({value: undefined, done: true}, Next(x));
  }
}


{ // yield*, finally clause does not perform return

  let h = function*() { try {yield 42} finally {yield 43; 13} };
  let g = function*() { yield 1; yield yield* h(); };

  {
    let x = g();
    assertEquals({value: 1, done: false}, Next(x));
    assertEquals({value: 42, done: false}, Next(x));
    assertEquals({value: 43, done: false}, Next(x, 666));
    assertEquals({value: undefined, done: false}, Next(x));
    assertEquals({value: undefined, done: true}, Next(x));
  }

  {
    let x = g();
    assertEquals({value: 1, done: false}, Next(x));
    assertEquals({value: 42, done: false}, Next(x));
    assertEquals({value: 43, done: false}, Return(x, 44));
    assertEquals({value: 44, done: false}, Next(x));
    assertEquals({value: undefined, done: true}, Next(x));
  }

  {
    let x = g();
    assertEquals({value: 1, done: false}, Next(x));
    assertEquals({value: 42, done: false}, Next(x));
    assertEquals({value: 43, done: false}, Throw(x, 666));
    assertThrowsEquals(() => Next(x), 666);
  }
}


{ // yield*, .return argument is final result

  function* inner() {
    yield 2;
  }

  function* g() {
    yield 1;
    return yield* inner();
  }

  {
    let x = g();
    assertEquals({value: 1, done: false}, Next(x));
    assertEquals({value: 2, done: false}, Next(x));
    assertEquals({value: 42, done: true}, Return(x, 42));
  }
}


// More or less random tests from here on.


{
  function* foo() { }
  let g = foo();
  assertEquals({value: undefined, done: true}, Next(g));
  assertEquals({value: undefined, done: true}, Next(g));
}

{
  function* foo() { return new.target }
  let g = foo();
  assertEquals({value: undefined, done: true}, Next(g));
  assertEquals({value: undefined, done: true}, Next(g));
}

{
  function* foo() { throw 666; return 42}
  let g = foo();
  assertThrowsEquals(() => Next(g), 666);
  assertEquals({value: undefined, done: true}, Next(g));
}

{
  function* foo(a) { return a; }
  let g = foo(42);
  assertEquals({value: 42, done: true}, Next(g));
  assertEquals({value: undefined, done: true}, Next(g));
}

{
  function* foo(a) { a.iwashere = true; return a; }
  let x = {};
  let g = foo(x);
  assertEquals({value: {iwashere: true}, done: true}, Next(g));
  assertEquals({value: undefined, done: true}, Next(g));
}

{
  let a = 42;
  function* foo() { return a; }
  let g = foo();
  assertEquals({value: 42, done: true}, Next(g));
  assertEquals({value: undefined, done: true}, Next(g));
}

{
  let a = 40;
  function* foo(b) { return a + b; }
  let g = foo(2);
  assertEquals({value: 42, done: true}, Next(g));
  assertEquals({value: undefined, done: true}, Next(g));
}

{
  let a = 40;
  function* foo(b) { a--; b++; return a + b; }
  let g = foo(2);
  assertEquals({value: 42, done: true}, Next(g));
  assertEquals({value: undefined, done: true}, Next(g));
}

{
  let g;
  function* foo() { Next(g) }
  g = foo();
  assertThrows(() => Next(g), TypeError);
  assertEquals({value: undefined, done: true}, Next(g));
}

{
  function* foo() { yield 2; yield 3; yield 4 }
  g = foo();
  assertEquals({value: 2, done: false}, Next(g));
  assertEquals({value: 3, done: false}, Next(g));
  assertEquals({value: 4, done: false}, Next(g));
  assertEquals({value: undefined, done: true}, Next(g));
  assertEquals({value: undefined, done: true}, Next(g));
}


{
  function* foo() { yield 2; if (true) { yield 3 }; yield 4 }
  g = foo();
  assertEquals({value: 2, done: false}, Next(g));
  assertEquals({value: 3, done: false}, Next(g));
  assertEquals({value: 4, done: false}, Next(g));
  assertEquals({value: undefined, done: true}, Next(g));
  assertEquals({value: undefined, done: true}, Next(g));
}

{
  function* foo() { yield 2; if (true) { yield 3; yield 4 } }
  g = foo();
  assertEquals({value: 2, done: false}, Next(g));
  assertEquals({value: 3, done: false}, Next(g));
  assertEquals({value: 4, done: false}, Next(g));
  assertEquals({value: undefined, done: true}, Next(g));
  assertEquals({value: undefined, done: true}, Next(g));
}

{
  function* foo() { yield 2; if (false) { yield 3 }; yield 4 }
  g = foo();
  assertEquals({value: 2, done: false}, Next(g));
  assertEquals({value: 4, done: false}, Next(g));
  assertEquals({value: undefined, done: true}, Next(g));
  assertEquals({value: undefined, done: true}, Next(g));
}

{
  function* foo() { yield 2; while (true) { yield 3 }; yield 4 }
  g = foo();
  assertEquals({value: 2, done: false}, Next(g));
  assertEquals({value: 3, done: false}, Next(g));
  assertEquals({value: 3, done: false}, Next(g));
  assertEquals({value: 3, done: false}, Next(g));
  assertEquals({value: 3, done: false}, Next(g));
}

{
  function* foo() { yield 2; (yield 3) + 42; yield 4 }
  g = foo();
  assertEquals({value: 2, done: false}, Next(g));
  assertEquals({value: 3, done: false}, Next(g));
  assertEquals({value: 4, done: false}, Next(g));
}

{
  function* foo() { yield 2; return (yield 3) + 42; yield 4 }
  g = foo();
  assertEquals({value: 2, done: false}, Next(g));
  assertEquals({value: 3, done: false}, Next(g));
  assertEquals({value: 42, done: true}, Next(g, 0));
  assertEquals({value: undefined, done: true}, Next(g));
}

{
  let x = 42;
  function* foo() {
    yield x;
    for (let x in {a: 1, b: 2}) {
      let i = 2;
      yield x;
      yield i;
      do {
        yield i;
      } while (i-- > 0);
    }
    yield x;
    return 5;
  }
  g = foo();
  assertEquals({value: 42, done: false}, Next(g));
  assertEquals({value: 'a', done: false}, Next(g));
  assertEquals({value: 2, done: false}, Next(g));
  assertEquals({value: 2, done: false}, Next(g));
  assertEquals({value: 1, done: false}, Next(g));
  assertEquals({value: 0, done: false}, Next(g));
  assertEquals({value: 'b', done: false}, Next(g));
  assertEquals({value: 2, done: false}, Next(g));
  assertEquals({value: 2, done: false}, Next(g));
  assertEquals({value: 1, done: false}, Next(g));
  assertEquals({value: 0, done: false}, Next(g));
  assertEquals({value: 42, done: false}, Next(g));
  assertEquals({value: 5, done: true}, Next(g));
}

{
  let a = 3;
  function* foo() {
    let b = 4;
    yield 1;
    { let c = 5; yield 2; yield a; yield b; yield c; }
  }
  g = foo();
  assertEquals({value: 1, done: false}, Next(g));
  assertEquals({value: 2, done: false}, Next(g));
  assertEquals({value: 3, done: false}, Next(g));
  assertEquals({value: 4, done: false}, Next(g));
  assertEquals({value: 5, done: false}, Next(g));
  assertEquals({value: undefined, done: true}, Next(g));
}

{
  function* foo() {
    yield 42;
    yield 42;
    yield 42;
    yield 42;
    yield 42;
    yield 42;
    yield 42;
    yield 42;
    yield 42;
    yield 42;
    yield 42;
    yield 42;
    yield 42;
    yield 42;
    yield 42;
    yield 42;
    yield 42;
    yield 42;
    yield 42;
    yield 42;
    yield 42;
    yield 42;
    yield 42;
    yield 42;
    yield 42;
    yield 42;
    yield 42;
    yield 42;
    yield 42;
    yield 42;
    yield 42;
    yield 42;
    yield 42;
    yield 42;
    yield 42;
    yield 42;
    yield 42;
    yield 42;
    yield 42;
    yield 42;
    yield 42;
    yield 42;
    yield 42;
    yield 42;
    yield 42;
    yield 42;
    yield 42;
    yield 42;
    yield 42;
    yield 42;
    yield 42;
    yield 42;
    yield 42;
    yield 42;
    yield 42;
    yield 42;
    yield 42;
    yield 42;
    yield 42;
    yield 42;
    yield 42;
    yield 42;
    yield 42;
    yield 42;
    yield 42;
    yield 42;
    yield 42;
    yield 42;
    yield 42;
    yield 42;
    yield 42;
    yield 42;
    yield 42;
    yield 42;
    yield 42;
    yield 42;
    yield 42;
    yield 42;
    yield 42;
    yield 42;
    yield 42;
    yield 42;
    yield 42;
    yield 42;
    yield 42;
    yield 42;
    yield 42;
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    yield 42;
    yield 42;
    yield 42;
    yield 42;
    yield 42;
    yield 42;
    yield 42;
    yield 42;
    yield 42;
    yield 42;
    yield 42;
  }
  g = foo();
  for (let i = 0; i < 100; ++i) {
    assertEquals({value: 42, done: false}, i%25 === 0 ? Next(g) : g.next());
  }
  assertEquals({value: undefined, done: true}, Next(g));
}

{
  function* foo() {
    for (let i = 0; i < 3; ++i) {
      let j = 0
      yield i;
      do {
        yield (i + 10);
      } while (++j < 2);
    }
  }
  g = foo();
  assertEquals({value: 0, done: false}, Next(g));
  assertEquals({value: 10, done: false}, Next(g));
  assertEquals({value: 10, done: false}, Next(g));
  assertEquals({value: 1, done: false}, Next(g));
  assertEquals({value: 11, done: false}, Next(g));
  assertEquals({value: 11, done: false}, Next(g));
  assertEquals({value: 2, done: false}, Next(g));
  assertEquals({value: 12, done: false}, Next(g));
  assertEquals({value: 12, done: false}, Next(g));
  assertEquals({value: undefined, done: true}, Next(g));
}

{
  let foo = function*() {
    while (true) {
      if (true || false) yield 42;
      continue;
    }
  }
  g = foo();
  assertEquals({value: 42, done: false}, Next(g));
  assertEquals({value: 42, done: false}, Next(g));
  assertEquals({value: 42, done: false}, Next(g));
}

{
  let foo = function*() {
    yield* (function*() { yield 42; }());
    assertUnreachable();
  }
  g = foo();
  assertEquals({value: 42, done: false}, Next(g));
  assertEquals({value: 23, done: true}, Return(g, 23));
}

{
  let iterable = {
    [Symbol.iterator]() {
      return { next() { return {} } };
    }
  };
  let foo = function*() { yield* iterable };
  g = foo();
  g.next();
  assertThrows(() => Throw(g), TypeError);
}