delegating-yield-2.js

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// Test yield* with iter.throw and monkeypatching.

function* g1() { return (yield 1); }

function* g2() { try { yield 1; } catch (e) { yield e; } }

function* delegate(iter) { return yield* iter; }

var GeneratorObjectPrototype = Object.getPrototypeOf(g1).prototype;

var GeneratorObjectPrototype_throw = GeneratorObjectPrototype.throw;

// An uncaught delegated throw.

var inner = g1();

var outer = delegate(inner);

assertIteratorNext(outer, 1);

assertThrowsValue(function () { outer.throw(42) }, 42);

assertThrowsValue(function () { outer.throw(42) }, 42);

// A caught delegated throw.

inner = g2();

outer = delegate(inner);

assertIteratorNext(outer, 1);

assertIteratorResult(outer.throw(42), 42, false);

assertThrowsValue(function () { outer.throw(42) }, 42);

assertThrowsValue(function () { outer.throw(42) }, 42);

// What would be an uncaught delegated throw, but with a monkeypatched iterator.

inner = g1();

outer = delegate(inner);

assertIteratorNext(outer, 1);

inner.throw = function(e) { return { value: e*2 }; };

assertEq(84, outer.throw(42).value);

assertIteratorDone(outer, undefined);

// Monkeypatching inner.next.

inner = g1();

outer = delegate(inner);

inner.next = function() { return { value: 13, done: true } };

assertIteratorDone(outer, 13);

// What would be a caught delegated throw, but with a monkeypunched prototype.

inner = g2();

outer = delegate(inner);

assertIteratorNext(outer, 1);

delete GeneratorObjectPrototype.throw;

var outer_throw_42 = GeneratorObjectPrototype_throw.bind(outer, 42);

// yield* protocol violation: no 'throw' method

assertThrowsInstanceOf(outer_throw_42, TypeError);

// Now done, so just throws.

assertThrowsValue(outer_throw_42, 42);

// Monkeypunch a different throw handler.

inner = g2();

outer = delegate(inner);

outer_throw_42 = GeneratorObjectPrototype_throw.bind(outer, 42);

assertIteratorNext(outer, 1);

GeneratorObjectPrototype.throw = function(e) { return { value: e*2 }; }

assertEq(84, outer_throw_42().value);

assertEq(84, outer_throw_42().value);

// This continues indefinitely.

assertEq(84, outer_throw_42().value);

assertIteratorDone(outer, undefined);

// The same, but restoring the original pre-monkey throw.

inner = g2();

outer = delegate(inner);

outer_throw_42 = GeneratorObjectPrototype_throw.bind(outer, 42);

assertIteratorNext(outer, 1);

assertEq(84, outer_throw_42().value);

assertEq(84, outer_throw_42().value);

GeneratorObjectPrototype.throw = GeneratorObjectPrototype_throw;

assertIteratorResult(outer_throw_42(), 42, false);

assertIteratorDone(outer, undefined);

if (typeof reportCompare == "function")

    reportCompare(true, true);