tor-browser

AsyncIteration.js (14743B)

---

/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */

function AsyncIteratorIdentity() {
 return this;
}

function AsyncGeneratorNext(val) {
 assert(
   IsAsyncGeneratorObject(this),
   "ThisArgument must be a generator object for async generators"
 );
 return resumeGenerator(this, val, "next");
}

function AsyncGeneratorThrow(val) {
 assert(
   IsAsyncGeneratorObject(this),
   "ThisArgument must be a generator object for async generators"
 );
 return resumeGenerator(this, val, "throw");
}

function AsyncGeneratorReturn(val) {
 assert(
   IsAsyncGeneratorObject(this),
   "ThisArgument must be a generator object for async generators"
 );
 return resumeGenerator(this, val, "return");
}

/* ECMA262 7.4.7 AsyncIteratorClose */
async function AsyncIteratorClose(iteratorRecord, value) {
 // Step 3.
 var iterator = iteratorRecord.iterator;
 // Step 4.
 var returnMethod = iterator.return;
 // Step 5.
 if (!IsNullOrUndefined(returnMethod)) {
   var result = await callContentFunction(returnMethod, iterator);
   // Step 8.
   if (!IsObject(result)) {
     ThrowTypeError(JSMSG_OBJECT_REQUIRED, DecompileArg(0, result));
   }
 }
 // Step 5b & 9.
 return value;
}

/* Iterator Helpers proposal 1.1.1 */
function GetIteratorDirect(obj) {
 // Step 1.
 if (!IsObject(obj)) {
   ThrowTypeError(JSMSG_OBJECT_REQUIRED, DecompileArg(0, obj));
 }

 // Step 2.
 var nextMethod = obj.next;
 // Step 3.
 if (!IsCallable(nextMethod)) {
   ThrowTypeError(JSMSG_NOT_FUNCTION, DecompileArg(0, nextMethod));
 }

 // Steps 4-5.
 return {
   iterator: obj,
   nextMethod,
   done: false,
 };
}

/* Iterator Helpers proposal 1.1.1 */
function GetAsyncIteratorDirectWrapper(obj) {
 // Step 1.
 if (!IsObject(obj)) {
   ThrowTypeError(JSMSG_OBJECT_REQUIRED, obj);
 }

 // Step 2.
 var nextMethod = obj.next;
 // Step 3.
 if (!IsCallable(nextMethod)) {
   ThrowTypeError(JSMSG_NOT_FUNCTION, nextMethod);
 }

 // Steps 4-5.
 return {
   // Use a named function expression instead of a method definition, so
   // we don't create an inferred name for this function at runtime.
   [GetBuiltinSymbol("asyncIterator")]: function AsyncIteratorMethod() {
     return this;
   },
   next(value) {
     return callContentFunction(nextMethod, obj, value);
   },
   async return(value) {
     var returnMethod = obj.return;
     if (!IsNullOrUndefined(returnMethod)) {
       return callContentFunction(returnMethod, obj, value);
     }
     return { done: true, value };
   },
 };
}

/* AsyncIteratorHelper object prototype methods. */
function AsyncIteratorHelperNext(value) {
 var O = this;
 if (!IsObject(O) || (O = GuardToAsyncIteratorHelper(O)) === null) {
   return callFunction(
     CallAsyncIteratorHelperMethodIfWrapped,
     this,
     value,
     "AsyncIteratorHelperNext"
   );
 }
 var generator = UnsafeGetReservedSlot(
   O,
   ASYNC_ITERATOR_HELPER_GENERATOR_SLOT
 );
 return callFunction(IntrinsicAsyncGeneratorNext, generator, value);
}

function AsyncIteratorHelperReturn(value) {
 var O = this;
 if (!IsObject(O) || (O = GuardToAsyncIteratorHelper(O)) === null) {
   return callFunction(
     CallAsyncIteratorHelperMethodIfWrapped,
     this,
     value,
     "AsyncIteratorHelperReturn"
   );
 }
 var generator = UnsafeGetReservedSlot(
   O,
   ASYNC_ITERATOR_HELPER_GENERATOR_SLOT
 );
 return callFunction(IntrinsicAsyncGeneratorReturn, generator, value);
}

function AsyncIteratorHelperThrow(value) {
 var O = this;
 if (!IsObject(O) || (O = GuardToAsyncIteratorHelper(O)) === null) {
   return callFunction(
     CallAsyncIteratorHelperMethodIfWrapped,
     this,
     value,
     "AsyncIteratorHelperThrow"
   );
 }
 var generator = UnsafeGetReservedSlot(
   O,
   ASYNC_ITERATOR_HELPER_GENERATOR_SLOT
 );
 return callFunction(IntrinsicAsyncGeneratorThrow, generator, value);
}

// AsyncIterator lazy Iterator Helper methods
// Iterator Helpers proposal 2.1.6.2-2.1.6.7
//
// The AsyncIterator lazy methods are structured closely to how the Iterator
// lazy methods are. See builtin/Iterator.js for the reasoning.

/* Iterator Helpers proposal 2.1.6.2 Prelude */
function AsyncIteratorMap(mapper) {
 // Step 1.
 var iterated = GetIteratorDirect(this);

 // Step 2.
 if (!IsCallable(mapper)) {
   ThrowTypeError(JSMSG_NOT_FUNCTION, DecompileArg(0, mapper));
 }

 var iteratorHelper = NewAsyncIteratorHelper();
 var generator = AsyncIteratorMapGenerator(iterated, mapper);
 callFunction(IntrinsicAsyncGeneratorNext, generator);
 UnsafeSetReservedSlot(
   iteratorHelper,
   ASYNC_ITERATOR_HELPER_GENERATOR_SLOT,
   generator
 );
 return iteratorHelper;
}

/* Iterator Helpers proposal 2.1.6.2 Body */
async function* AsyncIteratorMapGenerator(iterated, mapper) {
 // Step 1.
 var lastValue;
 // Step 2.
 var needClose = true;
 try {
   yield;
   needClose = false;

   for (
     var next = await IteratorNext(iterated, lastValue);
     !next.done;
     next = await IteratorNext(iterated, lastValue)
   ) {
     // Step c.
     var value = next.value;

     // Steps d-i.
     needClose = true;
     lastValue = yield callContentFunction(mapper, undefined, value);
     needClose = false;
   }
 } finally {
   if (needClose) {
     AsyncIteratorClose(iterated);
   }
 }
}

/* Iterator Helpers proposal 2.1.6.3 Prelude */
function AsyncIteratorFilter(filterer) {
 // Step 1.
 var iterated = GetIteratorDirect(this);

 // Step 2.
 if (!IsCallable(filterer)) {
   ThrowTypeError(JSMSG_NOT_FUNCTION, DecompileArg(0, filterer));
 }

 var iteratorHelper = NewAsyncIteratorHelper();
 var generator = AsyncIteratorFilterGenerator(iterated, filterer);
 callFunction(IntrinsicAsyncGeneratorNext, generator);
 UnsafeSetReservedSlot(
   iteratorHelper,
   ASYNC_ITERATOR_HELPER_GENERATOR_SLOT,
   generator
 );
 return iteratorHelper;
}

/* Iterator Helpers proposal 2.1.6.3 Body */
async function* AsyncIteratorFilterGenerator(iterated, filterer) {
 // Step 1.
 var lastValue;
 // Step 2.
 var needClose = true;
 try {
   yield;
   needClose = false;

   for (
     var next = await IteratorNext(iterated, lastValue);
     !next.done;
     next = await IteratorNext(iterated, lastValue)
   ) {
     // Step c.
     var value = next.value;

     // Steps d-h.
     needClose = true;
     if (await callContentFunction(filterer, undefined, value)) {
       lastValue = yield value;
     }
     needClose = false;
   }
 } finally {
   if (needClose) {
     AsyncIteratorClose(iterated);
   }
 }
}

/* Iterator Helpers proposal 2.1.6.4 Prelude */
function AsyncIteratorTake(limit) {
 // Step 1.
 var iterated = GetIteratorDirect(this);

 // Step 2.
 var remaining = ToInteger(limit);
 // Step 3.
 if (remaining < 0) {
   ThrowRangeError(JSMSG_NEGATIVE_LIMIT);
 }

 var iteratorHelper = NewAsyncIteratorHelper();
 var generator = AsyncIteratorTakeGenerator(iterated, remaining);
 callFunction(IntrinsicAsyncGeneratorNext, generator);
 UnsafeSetReservedSlot(
   iteratorHelper,
   ASYNC_ITERATOR_HELPER_GENERATOR_SLOT,
   generator
 );
 return iteratorHelper;
}

/* Iterator Helpers proposal 2.1.6.4 Body */
async function* AsyncIteratorTakeGenerator(iterated, remaining) {
 // Step 1.
 var lastValue;
 // Step 2.
 var needClose = true;
 try {
   yield;
   needClose = false;

   for (; remaining > 0; remaining--) {
     var next = await IteratorNext(iterated, lastValue);
     if (next.done) {
       return undefined;
     }

     var value = next.value;

     needClose = true;
     lastValue = yield value;
     needClose = false;
   }
 } finally {
   if (needClose) {
     AsyncIteratorClose(iterated, undefined);
   }
 }

 return AsyncIteratorClose(iterated, undefined);
}

/* Iterator Helpers proposal 2.1.6.5 Prelude */
function AsyncIteratorDrop(limit) {
 // Step 1.
 var iterated = GetIteratorDirect(this);

 // Step 2.
 var remaining = ToInteger(limit);
 // Step 3.
 if (remaining < 0) {
   ThrowRangeError(JSMSG_NEGATIVE_LIMIT);
 }

 var iteratorHelper = NewAsyncIteratorHelper();
 var generator = AsyncIteratorDropGenerator(iterated, remaining);
 callFunction(IntrinsicAsyncGeneratorNext, generator);
 UnsafeSetReservedSlot(
   iteratorHelper,
   ASYNC_ITERATOR_HELPER_GENERATOR_SLOT,
   generator
 );
 return iteratorHelper;
}

/* Iterator Helpers proposal 2.1.6.5 Body */
async function* AsyncIteratorDropGenerator(iterated, remaining) {
 var needClose = true;
 try {
   yield;
   needClose = false;

   // Step 1.
   for (; remaining > 0; remaining--) {
     var next = await IteratorNext(iterated);
     if (next.done) {
       return;
     }
   }

   // Step 2.
   var lastValue;
   // Step 3.
   for (
     var next = await IteratorNext(iterated, lastValue);
     !next.done;
     next = await IteratorNext(iterated, lastValue)
   ) {
     // Steps c-d.
     var value = next.value;

     needClose = true;
     lastValue = yield value;
     needClose = false;
   }
 } finally {
   if (needClose) {
     AsyncIteratorClose(iterated);
   }
 }
}

/* Iterator Helpers proposal 2.1.6.6 Prelude */
function AsyncIteratorAsIndexedPairs() {
 // Step 1.
 var iterated = GetIteratorDirect(this);

 var iteratorHelper = NewAsyncIteratorHelper();
 var generator = AsyncIteratorAsIndexedPairsGenerator(iterated);
 callFunction(IntrinsicAsyncGeneratorNext, generator);
 UnsafeSetReservedSlot(
   iteratorHelper,
   ASYNC_ITERATOR_HELPER_GENERATOR_SLOT,
   generator
 );
 return iteratorHelper;
}

/* Iterator Helpers proposal 2.1.6.6 Body */
async function* AsyncIteratorAsIndexedPairsGenerator(iterated) {
 var needClose = true;
 try {
   yield;
   needClose = false;

   // Step 2.
   var lastValue;
   // Step 3.
   for (
     var next = await IteratorNext(iterated, lastValue), index = 0;
     !next.done;
     next = await IteratorNext(iterated, lastValue), index++
   ) {
     // Steps c-g.
     var value = next.value;

     needClose = true;
     lastValue = yield [index, value];
     needClose = false;
   }
 } finally {
   if (needClose) {
     AsyncIteratorClose(iterated);
   }
 }
}

/* Iterator Helpers proposal 2.1.6.7 Prelude */
function AsyncIteratorFlatMap(mapper) {
 // Step 1.
 var iterated = GetIteratorDirect(this);

 // Step 2.
 if (!IsCallable(mapper)) {
   ThrowTypeError(JSMSG_NOT_FUNCTION, DecompileArg(0, mapper));
 }

 var iteratorHelper = NewAsyncIteratorHelper();
 var generator = AsyncIteratorFlatMapGenerator(iterated, mapper);
 callFunction(IntrinsicAsyncGeneratorNext, generator);
 UnsafeSetReservedSlot(
   iteratorHelper,
   ASYNC_ITERATOR_HELPER_GENERATOR_SLOT,
   generator
 );
 return iteratorHelper;
}

/* Iterator Helpers proposal 2.1.6.7 Body */
async function* AsyncIteratorFlatMapGenerator(iterated, mapper) {
 var needClose = true;
 try {
   yield;
   needClose = false;

   // Step 1.
   for (
     var next = await IteratorNext(iterated);
     !next.done;
     next = await IteratorNext(iterated)
   ) {
     // Step c.
     var value = next.value;

     needClose = true;
     // Step d.
     var mapped = await callContentFunction(mapper, undefined, value);
     // Steps f-k.
     for await (var innerValue of allowContentIter(mapped)) {
       yield innerValue;
     }
     needClose = false;
   }
 } finally {
   if (needClose) {
     AsyncIteratorClose(iterated);
   }
 }
}

/* Iterator Helpers proposal 2.1.6.8 */
async function AsyncIteratorReduce(reducer /*, initialValue*/) {
 // Step 1.
 var iterated = GetAsyncIteratorDirectWrapper(this);

 // Step 2.
 if (!IsCallable(reducer)) {
   ThrowTypeError(JSMSG_NOT_FUNCTION, DecompileArg(0, reducer));
 }

 // Step 3.
 var accumulator;
 if (ArgumentsLength() === 1) {
   // Step a.
   var next = await callContentFunction(iterated.next, iterated);
   if (!IsObject(next)) {
     ThrowTypeError(JSMSG_OBJECT_REQUIRED, DecompileArg(0, next));
   }
   // Step b.
   if (next.done) {
     ThrowTypeError(JSMSG_EMPTY_ITERATOR_REDUCE);
   }
   // Step c.
   accumulator = next.value;
 } else {
   // Step 4.
   accumulator = GetArgument(1);
 }

 // Step 5.
 for await (var value of allowContentIter(iterated)) {
   // Steps d-h.
   accumulator = await callContentFunction(
     reducer,
     undefined,
     accumulator,
     value
   );
 }
 // Step 5b.
 return accumulator;
}

/* Iterator Helpers proposal 2.1.6.9 */
async function AsyncIteratorToArray() {
 // Step 1.
 var iterated = { [GetBuiltinSymbol("asyncIterator")]: () => this };
 // Step 2.
 var items = [];
 var index = 0;
 // Step 3.
 for await (var value of allowContentIter(iterated)) {
   // Step d.
   DefineDataProperty(items, index++, value);
 }
 // Step 3b.
 return items;
}

/* Iterator Helpers proposal 2.1.6.10 */
async function AsyncIteratorForEach(fn) {
 // Step 1.
 var iterated = GetAsyncIteratorDirectWrapper(this);

 // Step 2.
 if (!IsCallable(fn)) {
   ThrowTypeError(JSMSG_NOT_FUNCTION, DecompileArg(0, fn));
 }

 // Step 3.
 for await (var value of allowContentIter(iterated)) {
   // Steps d-g.
   await callContentFunction(fn, undefined, value);
 }
}

/* Iterator Helpers proposal 2.1.6.11 */
async function AsyncIteratorSome(fn) {
 // Step 1.
 var iterated = GetAsyncIteratorDirectWrapper(this);

 // Step 2.
 if (!IsCallable(fn)) {
   ThrowTypeError(JSMSG_NOT_FUNCTION, DecompileArg(0, fn));
 }

 // Step 3.
 for await (var value of allowContentIter(iterated)) {
   // Steps d-h.
   if (await callContentFunction(fn, undefined, value)) {
     return true;
   }
 }
 // Step 3b.
 return false;
}

/* Iterator Helpers proposal 2.1.6.12 */
async function AsyncIteratorEvery(fn) {
 // Step 1.
 var iterated = GetAsyncIteratorDirectWrapper(this);

 // Step 2.
 if (!IsCallable(fn)) {
   ThrowTypeError(JSMSG_NOT_FUNCTION, DecompileArg(0, fn));
 }

 // Step 3.
 for await (var value of allowContentIter(iterated)) {
   // Steps d-h.
   if (!(await callContentFunction(fn, undefined, value))) {
     return false;
   }
 }
 // Step 3b.
 return true;
}

/* Iterator Helpers proposal 2.1.6.13 */
async function AsyncIteratorFind(fn) {
 // Step 1.
 var iterated = GetAsyncIteratorDirectWrapper(this);

 // Step 2.
 if (!IsCallable(fn)) {
   ThrowTypeError(JSMSG_NOT_FUNCTION, DecompileArg(0, fn));
 }

 // Step 3.
 for await (var value of allowContentIter(iterated)) {
   // Steps d-h.
   if (await callContentFunction(fn, undefined, value)) {
     return value;
   }
 }
}