v8/test/mjsunit/es6/generators-iteration.js

// Copyright 2013 the V8 project authors. All rights reserved.
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// modification, are permitted provided that the following conditions are
// met:
//
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// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

// Flags: --expose-gc

// Test generator iteration.

var GeneratorFunction = (function*(){yield 1;}).__proto__.constructor;

function assertIteratorResult(value, done, result) {
  assertEquals({ value: value, done: done}, result);
}

function assertIteratorIsClosed(iter) {
  assertIteratorResult(undefined, true, iter.next());
  assertDoesNotThrow(function() { iter.next(); });
}

function assertThrownIteratorIsClosed(iter) {
  assertIteratorIsClosed(iter);
}

function TestGeneratorResultPrototype() {
  function* g() { yield 1; }
  var iter = g();
  var result = iter.next();

  assertSame(Object.prototype, Object.getPrototypeOf(result));
  property_names = Object.getOwnPropertyNames(result);
  property_names.sort();
  assertEquals(["done", "value"], property_names);
  assertIteratorResult(1, false, result);
}
TestGeneratorResultPrototype()

function TestGenerator(g, expected_values_for_next,
                       send_val, expected_values_for_send) {
  function testNext(thunk) {
    var iter = thunk();
    for (var i = 0; i < expected_values_for_next.length; i++) {
      var v1 = expected_values_for_next[i];
      var v2 = i == expected_values_for_next.length - 1;
      // var v3 = iter.next();
      assertIteratorResult(v1, v2, iter.next());
    }
    assertIteratorIsClosed(iter);
  }
  function testSend(thunk) {
    var iter = thunk();
    for (var i = 0; i < expected_values_for_send.length; i++) {
      assertIteratorResult(expected_values_for_send[i],
                           i == expected_values_for_send.length - 1,
                           iter.next(send_val));
    }
    assertIteratorIsClosed(iter);
  }
  function testThrow(thunk) {
    for (var i = 0; i < expected_values_for_next.length; i++) {
      var iter = thunk();
      for (var j = 0; j < i; j++) {
        assertIteratorResult(expected_values_for_next[j],
                             j == expected_values_for_next.length - 1,
                             iter.next());
      }
      function Sentinel() {}
      assertThrows(function () { iter.throw(new Sentinel); }, Sentinel);
      assertThrownIteratorIsClosed(iter);
    }
  }

  testNext(g);
  testSend(g);
  testThrow(g);

  testNext(function*() { return yield* g(); });
  testSend(function*() { return yield* g(); });
  testThrow(function*() { return yield* g(); });

  if (g instanceof GeneratorFunction) {
    testNext(g);
    testSend(g);
    testThrow(g);
  }
}

TestGenerator(function* g1() { },
              [undefined],
              "foo",
              [undefined]);

TestGenerator(function* g2() { yield 1; },
              [1, undefined],
              "foo",
              [1, undefined]);

TestGenerator(function* g3() { yield 1; yield 2; },
              [1, 2, undefined],
              "foo",
              [1, 2, undefined]);

TestGenerator(function* g4() { yield 1; yield 2; return 3; },
              [1, 2, 3],
              "foo",
              [1, 2, 3]);

TestGenerator(function* g5() { return 1; },
              [1],
             "foo",
              [1]);

TestGenerator(function* g6() { var x = yield 1; return x; },
              [1, undefined],
              "foo",
              [1, "foo"]);

TestGenerator(function* g7() { var x = yield 1; yield 2; return x; },
              [1, 2, undefined],
              "foo",
              [1, 2, "foo"]);

TestGenerator(function* g8() { for (var x = 0; x < 4; x++) { yield x; } },
              [0, 1, 2, 3, undefined],
              "foo",
              [0, 1, 2, 3, undefined]);

// Generator with arguments.
TestGenerator(
    function g9() {
      return (function*(a, b, c, d) {
        yield a; yield b; yield c; yield d;
      })("fee", "fi", "fo", "fum");
    },
    ["fee", "fi", "fo", "fum", undefined],
    "foo",
    ["fee", "fi", "fo", "fum", undefined]);

// Too few arguments.
TestGenerator(
    function g10() {
      return (function*(a, b, c, d) {
        yield a; yield b; yield c; yield d;
      })("fee", "fi");
    },
    ["fee", "fi", undefined, undefined, undefined],
    "foo",
    ["fee", "fi", undefined, undefined, undefined]);

// Too many arguments.
TestGenerator(
    function g11() {
      return (function*(a, b, c, d) {
        yield a; yield b; yield c; yield d;
      })("fee", "fi", "fo", "fum", "I smell the blood of an Englishman");
    },
    ["fee", "fi", "fo", "fum", undefined],
    "foo",
    ["fee", "fi", "fo", "fum", undefined]);

// The arguments object.
TestGenerator(
    function g12() {
      return (function*(a, b, c, d) {
        for (var i = 0; i < arguments.length; i++) {
          yield arguments[i];
        }
      })("fee", "fi", "fo", "fum", "I smell the blood of an Englishman");
    },
    ["fee", "fi", "fo", "fum", "I smell the blood of an Englishman",
     undefined],
    "foo",
    ["fee", "fi", "fo", "fum", "I smell the blood of an Englishman",
     undefined]);

// Access to captured free variables.
TestGenerator(
    function g13() {
      return (function(a, b, c, d) {
        return (function*() {
          yield a; yield b; yield c; yield d;
        })();
      })("fee", "fi", "fo", "fum");
    },
    ["fee", "fi", "fo", "fum", undefined],
    "foo",
    ["fee", "fi", "fo", "fum", undefined]);

// Abusing the arguments object.
TestGenerator(
    function g14() {
      return (function*(a, b, c, d) {
        arguments[0] = "Be he live";
        arguments[1] = "or be he dead";
        arguments[2] = "I'll grind his bones";
        arguments[3] = "to make my bread";
        yield a; yield b; yield c; yield d;
      })("fee", "fi", "fo", "fum");
    },
    ["Be he live", "or be he dead", "I'll grind his bones", "to make my bread",
     undefined],
    "foo",
    ["Be he live", "or be he dead", "I'll grind his bones", "to make my bread",
     undefined]);

// Abusing the arguments object: strict mode.
TestGenerator(
    function g15() {
      return (function*(a, b, c, d) {
        "use strict";
        arguments[0] = "Be he live";
        arguments[1] = "or be he dead";
        arguments[2] = "I'll grind his bones";
        arguments[3] = "to make my bread";
        yield a; yield b; yield c; yield d;
      })("fee", "fi", "fo", "fum");
    },
    ["fee", "fi", "fo", "fum", undefined],
    "foo",
    ["fee", "fi", "fo", "fum", undefined]);

// GC.
TestGenerator(function* g16() { yield "baz"; gc(); yield "qux"; },
              ["baz", "qux", undefined],
              "foo",
              ["baz", "qux", undefined]);

// Receivers.
TestGenerator(
    function g17() {
      function* g() { yield this.x; yield this.y; }
      var o = { start: g, x: 1, y: 2 };
      return o.start();
    },
    [1, 2, undefined],
    "foo",
    [1, 2, undefined]);

TestGenerator(
    function* g19() {
      var x = 1;
      yield x;
      with({x:2}) { yield x; }
      yield x;
    },
    [1, 2, 1, undefined],
    "foo",
    [1, 2, 1, undefined]);

TestGenerator(
    function* g20() { yield (1 + (yield 2) + 3); },
    [2, NaN, undefined],
    "foo",
    [2, "1foo3", undefined]);

TestGenerator(
    function* g21() { return (1 + (yield 2) + 3); },
    [2, NaN],
    "foo",
    [2, "1foo3"]);

TestGenerator(
    function* g22() { yield (1 + (yield 2) + 3); yield (4 + (yield 5) + 6); },
    [2, NaN, 5, NaN, undefined],
    "foo",
    [2, "1foo3", 5, "4foo6", undefined]);

TestGenerator(
    function* g23() {
      return (yield (1 + (yield 2) + 3)) + (yield (4 + (yield 5) + 6));
    },
    [2, NaN, 5, NaN, NaN],
    "foo",
    [2, "1foo3", 5, "4foo6", "foofoo"]);

// Rewind a try context with and without operands on the stack.
TestGenerator(
    function* g24() {
      try {
        return (yield (1 + (yield 2) + 3)) + (yield (4 + (yield 5) + 6));
      } catch (e) {
        throw e;
      }
    },
    [2, NaN, 5, NaN, NaN],
    "foo",
    [2, "1foo3", 5, "4foo6", "foofoo"]);

// Yielding in a catch context, with and without operands on the stack.
TestGenerator(
    function* g25() {
      try {
        throw (yield (1 + (yield 2) + 3))
      } catch (e) {
        if (typeof e == 'object') throw e;
        return e + (yield (4 + (yield 5) + 6));
      }
    },
    [2, NaN, 5, NaN, NaN],
    "foo",
    [2, "1foo3", 5, "4foo6", "foofoo"]);

// Yield with no arguments yields undefined.
TestGenerator(
    function* g26() { return yield yield },
    [undefined, undefined, undefined],
    "foo",
    [undefined, "foo", "foo"]);

// A newline causes the parser to stop looking for an argument to yield.
TestGenerator(
    function* g27() {
      yield
      3
      return
    },
    [undefined, undefined],
    "foo",
    [undefined, undefined]);

// TODO(wingo): We should use TestGenerator for these, except that
// currently yield* will unconditionally propagate a throw() to the
// delegate iterator, which fails for these iterators that don't have
// throw().  See http://code.google.com/p/v8/issues/detail?id=3484.
(function() {
    function* g28() {
      yield* [1, 2, 3];
    }
    var iter = g28();
    assertIteratorResult(1, false, iter.next());
    assertIteratorResult(2, false, iter.next());
    assertIteratorResult(3, false, iter.next());
    assertIteratorResult(undefined, true, iter.next());
})();

(function() {
    function* g29() {
      yield* "abc";
    }
    var iter = g29();
    assertIteratorResult("a", false, iter.next());
    assertIteratorResult("b", false, iter.next());
    assertIteratorResult("c", false, iter.next());
    assertIteratorResult(undefined, true, iter.next());
})();

// Generator function instances.
TestGenerator(GeneratorFunction(),
              [undefined],
              "foo",
              [undefined]);

TestGenerator(new GeneratorFunction(),
              [undefined],
              "foo",
              [undefined]);

TestGenerator(GeneratorFunction('yield 1;'),
              [1, undefined],
              "foo",
              [1, undefined]);

TestGenerator(
    function() { return GeneratorFunction('x', 'y', 'yield x + y;')(1, 2) },
    [3, undefined],
    "foo",
    [3, undefined]);

// Access to this with formal arguments.
TestGenerator(
    function () {
      return ({ x: 42, g: function* (a) { yield this.x } }).g(0);
    },
    [42, undefined],
    "foo",
    [42, undefined]);

// Test that yield* validates iterator results.
function TestDelegatingYield(junk) {
  var iterator = {next: () => junk};
  var iterable = {[Symbol.iterator]: () => iterator};
  function* g() { return yield* iterable };
  assertThrows(() => g().next(), TypeError);
}
TestDelegatingYield();
TestDelegatingYield(null);
TestDelegatingYield(42);
TestDelegatingYield(true);

function TestTryCatch(instantiate) {
  function* g() { yield 1; try { yield 2; } catch (e) { yield e; } yield 3; }
  function Sentinel() {}

  function Test1(iter) {
    assertIteratorResult(1, false, iter.next());
    assertIteratorResult(2, false, iter.next());
    assertIteratorResult(3, false, iter.next());
    assertIteratorIsClosed(iter);
  }
  Test1(instantiate(g));

  function Test2(iter) {
    assertThrows(function() { iter.throw(new Sentinel); }, Sentinel);
    assertThrownIteratorIsClosed(iter);
  }
  Test2(instantiate(g));

  function Test3(iter) {
    assertIteratorResult(1, false, iter.next());
    assertThrows(function() { iter.throw(new Sentinel); }, Sentinel);
    assertThrownIteratorIsClosed(iter);
  }
  Test3(instantiate(g));

  function Test4(iter) {
    assertIteratorResult(1, false, iter.next());
    assertIteratorResult(2, false, iter.next());
    var exn = new Sentinel;
    assertIteratorResult(exn, false, iter.throw(exn));
    assertIteratorResult(3, false, iter.next());
    assertIteratorIsClosed(iter);
  }
  Test4(instantiate(g));

  function Test5(iter) {
    assertIteratorResult(1, false, iter.next());
    assertIteratorResult(2, false, iter.next());
    var exn = new Sentinel;
    assertIteratorResult(exn, false, iter.throw(exn));
    assertIteratorResult(3, false, iter.next());
    assertThrows(function() { iter.throw(new Sentinel); }, Sentinel);
    assertThrownIteratorIsClosed(iter);
  }
  Test5(instantiate(g));

  function Test6(iter) {
    assertIteratorResult(1, false, iter.next());
    assertIteratorResult(2, false, iter.next());
    var exn = new Sentinel;
    assertIteratorResult(exn, false, iter.throw(exn));
    assertThrows(function() { iter.throw(new Sentinel); }, Sentinel);
    assertThrownIteratorIsClosed(iter);
  }
  Test6(instantiate(g));

  function Test7(iter) {
    assertIteratorResult(1, false, iter.next());
    assertIteratorResult(2, false, iter.next());
    assertIteratorResult(3, false, iter.next());
    assertIteratorIsClosed(iter);
  }
  Test7(instantiate(g));
}
TestTryCatch(function (g) { return g(); });
TestTryCatch(function* (g) { return yield* g(); });

function TestTryFinally(instantiate) {
  function* g() { yield 1; try { yield 2; } finally { yield 3; } yield 4; }
  function Sentinel() {}
  function Sentinel2() {}

  function Test1(iter) {
    assertIteratorResult(1, false, iter.next());
    assertIteratorResult(2, false, iter.next());
    assertIteratorResult(3, false, iter.next());
    assertIteratorResult(4, false, iter.next());
    assertIteratorIsClosed(iter);
  }
  Test1(instantiate(g));

  function Test2(iter) {
    assertThrows(function() { iter.throw(new Sentinel); }, Sentinel);
    assertThrownIteratorIsClosed(iter);
  }
  Test2(instantiate(g));

  function Test3(iter) {
    assertIteratorResult(1, false, iter.next());
    assertThrows(function() { iter.throw(new Sentinel); }, Sentinel);
    assertThrownIteratorIsClosed(iter);
  }
  Test3(instantiate(g));

  function Test4(iter) {
    assertIteratorResult(1, false, iter.next());
    assertIteratorResult(2, false, iter.next());
    assertIteratorResult(3, false, iter.throw(new Sentinel));
    assertThrows(function() { iter.next(); }, Sentinel);
    assertThrownIteratorIsClosed(iter);
  }
  Test4(instantiate(g));

  function Test5(iter) {
    assertIteratorResult(1, false, iter.next());
    assertIteratorResult(2, false, iter.next());
    assertIteratorResult(3, false, iter.throw(new Sentinel));
    assertThrows(function() { iter.throw(new Sentinel2); }, Sentinel2);
    assertThrownIteratorIsClosed(iter);
  }
  Test5(instantiate(g));

  function Test6(iter) {
    assertIteratorResult(1, false, iter.next());
    assertIteratorResult(2, false, iter.next());
    assertIteratorResult(3, false, iter.next());
    assertThrows(function() { iter.throw(new Sentinel); }, Sentinel);
    assertThrownIteratorIsClosed(iter);
  }
  Test6(instantiate(g));

  function Test7(iter) {
    assertIteratorResult(1, false, iter.next());
    assertIteratorResult(2, false, iter.next());
    assertIteratorResult(3, false, iter.next());
    assertIteratorResult(4, false, iter.next());
    assertThrows(function() { iter.throw(new Sentinel); }, Sentinel);
    assertThrownIteratorIsClosed(iter);
  }
  Test7(instantiate(g));

  function Test8(iter) {
    assertIteratorResult(1, false, iter.next());
    assertIteratorResult(2, false, iter.next());
    assertIteratorResult(3, false, iter.next());
    assertIteratorResult(4, false, iter.next());
    assertIteratorIsClosed(iter);
  }
  Test8(instantiate(g));
}
TestTryFinally(function (g) { return g(); });
TestTryFinally(function* (g) { return yield* g(); });

function TestNestedTry(instantiate) {
  function* g() {
    try {
      yield 1;
      try { yield 2; } catch (e) { yield e; }
      yield 3;
    } finally {
      yield 4;
    }
    yield 5;
  }
  function Sentinel() {}
  function Sentinel2() {}

  function Test1(iter) {
    assertIteratorResult(1, false, iter.next());
    assertIteratorResult(2, false, iter.next());
    assertIteratorResult(3, false, iter.next());
    assertIteratorResult(4, false, iter.next());
    assertIteratorResult(5, false, iter.next());
    assertIteratorIsClosed(iter);
  }
  Test1(instantiate(g));

  function Test2(iter) {
    assertThrows(function() { iter.throw(new Sentinel); }, Sentinel);
    assertThrownIteratorIsClosed(iter);
  }
  Test2(instantiate(g));

  function Test3(iter) {
    assertIteratorResult(1, false, iter.next());
    assertIteratorResult(4, false, iter.throw(new Sentinel));
    assertThrows(function() { iter.next(); }, Sentinel);
    assertThrownIteratorIsClosed(iter);
  }
  Test3(instantiate(g));

  function Test4(iter) {
    assertIteratorResult(1, false, iter.next());
    assertIteratorResult(4, false, iter.throw(new Sentinel));
    assertThrows(function() { iter.throw(new Sentinel2); }, Sentinel2);
    assertThrownIteratorIsClosed(iter);
  }
  Test4(instantiate(g));

  function Test5(iter) {
    assertIteratorResult(1, false, iter.next());
    assertIteratorResult(2, false, iter.next());
    var exn = new Sentinel;
    assertIteratorResult(exn, false, iter.throw(exn));
    assertIteratorResult(3, false, iter.next());
    assertIteratorResult(4, false, iter.next());
    assertIteratorResult(5, false, iter.next());
    assertIteratorIsClosed(iter);
  }
  Test5(instantiate(g));

  function Test6(iter) {
    assertIteratorResult(1, false, iter.next());
    assertIteratorResult(2, false, iter.next());
    var exn = new Sentinel;
    assertIteratorResult(exn, false, iter.throw(exn));
    assertIteratorResult(4, false, iter.throw(new Sentinel2));
    assertThrows(function() { iter.next(); }, Sentinel2);
    assertThrownIteratorIsClosed(iter);
  }
  Test6(instantiate(g));

  function Test7(iter) {
    assertIteratorResult(1, false, iter.next());
    assertIteratorResult(2, false, iter.next());
    var exn = new Sentinel;
    assertIteratorResult(exn, false, iter.throw(exn));
    assertIteratorResult(3, false, iter.next());
    assertIteratorResult(4, false, iter.throw(new Sentinel2));
    assertThrows(function() { iter.next(); }, Sentinel2);
    assertThrownIteratorIsClosed(iter);
  }
  Test7(instantiate(g));

  // That's probably enough.
}
TestNestedTry(function (g) { return g(); });
TestNestedTry(function* (g) { return yield* g(); });

function TestRecursion() {
  function TestNextRecursion() {
    function* g() { yield iter.next(); }
    var iter = g();
    return iter.next();
  }
  function TestSendRecursion() {
    function* g() { yield iter.next(42); }
    var iter = g();
    return iter.next();
  }
  function TestThrowRecursion() {
    function* g() { yield iter.throw(1); }
    var iter = g();
    return iter.next();
  }
  assertThrows(TestNextRecursion, Error);
  assertThrows(TestSendRecursion, Error);
  assertThrows(TestThrowRecursion, Error);
}
TestRecursion();


// Test yield* on non-iterable objects.
function* g(junk) { return yield* junk }
var non_iterables = [
  42,
  {[Symbol.iterator]: 42},
  {[Symbol.iterator]: () => 42},
  {[Symbol.iterator]: () => ({next: 42})},
];
for (let junk of non_iterables) {
  assertThrows(() => g(junk).next(), TypeError);
}