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Bug 907744 - Implement iterator result boxing in ES6 generators. r=jorendorff

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This patchset causes the bytecode emitter to yield boxed return values
in ES6 generators, of the form { value: foo, done: bool }.

If the generator function does not end in a return, the compiler inserts
the equivalent of a "return { value: undefined, done:true }" statement
at the end.

When an ES6 generator finishes, it does so with {done:true} instead of
throwing a StopIteration.

This patch also ports lib/asserts.js to "default version" JS, and ports
ecma_6/Generators to use it.
This commit is contained in:
Andy Wingo
2013-09-04 13:20:48 -04:00
parent 3775bdc13e
commit f8074904e6
11 changed files with 1084 additions and 333 deletions
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268
js/src/jsiter.cpp
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@@ -999,24 +999,6 @@ js::ValueToIterator(JSContext *cx, unsigned flags, MutableHandleValue vp)
return GetIterator(cx, obj, flags, vp);
}
bool
IsStarGeneratorObject(HandleValue v)
{
return v.isObject() && v.toObject().is<StarGeneratorObject>();
}
bool
IsLegacyGeneratorObject(HandleValue v)
{
return v.isObject() && v.toObject().is<LegacyGeneratorObject>();
}
bool
IsGeneratorObject(HandleValue v)
{
return IsLegacyGeneratorObject(v) || IsStarGeneratorObject(v);
}
bool
js::CloseIterator(JSContext *cx, HandleObject obj)
{
@@ -1339,26 +1321,15 @@ Class StopIterationObject::class_ = {
/*** Generators **********************************************************************************/
static JSGenerator*
GetGenerator(JSObject *obj)
{
if (obj->is<LegacyGeneratorObject>())
return obj->as<LegacyGeneratorObject>().getGenerator();
JS_ASSERT(obj->is<StarGeneratorObject>());
return obj->as<StarGeneratorObject>().getGenerator();
}
template<typename T>
static void
generator_finalize(FreeOp *fop, JSObject *obj)
FinalizeGenerator(FreeOp *fop, JSObject *obj)
{
JSGenerator *gen = GetGenerator(obj);
if (!gen)
return;
/*
* gen is open when a script has not called its close method while
* explicitly manipulating it.
*/
JS_ASSERT(obj->is<T>());
JSGenerator *gen = obj->as<T>().getGenerator();
JS_ASSERT(gen);
// gen is open when a script has not called its close method while
// explicitly manipulating it.
JS_ASSERT(gen->state == JSGEN_NEWBORN ||
gen->state == JSGEN_CLOSED ||
gen->state == JSGEN_OPEN);
@@ -1404,8 +1375,8 @@ GeneratorWriteBarrierPost(JSContext *cx, JSGenerator *gen)
* stack or closed. Barriers when copying onto the stack or closing preserve
* gc invariants.
*/
bool
js::GeneratorHasMarkableFrame(JSGenerator *gen)
static bool
GeneratorHasMarkableFrame(JSGenerator *gen)
{
return gen->state == JSGEN_NEWBORN || gen->state == JSGEN_OPEN;
}
@@ -1432,6 +1403,17 @@ SetGeneratorClosed(JSContext *cx, JSGenerator *gen)
#endif
}
template<typename T>
static void
TraceGenerator(JSTracer *trc, JSObject *obj)
{
JS_ASSERT(obj->is<T>());
JSGenerator *gen = obj->as<T>().getGenerator();
JS_ASSERT(gen);
if (GeneratorHasMarkableFrame(gen))
MarkGeneratorFrame(trc, gen);
}
GeneratorState::GeneratorState(JSContext *cx, JSGenerator *gen, JSGeneratorState futureState)
: RunState(cx, Generator, gen->fp->script()),
cx_(cx),
@@ -1472,17 +1454,6 @@ GeneratorState::pushInterpreterFrame(JSContext *cx, FrameGuard *)
return gen_->fp;
}
static void
generator_trace(JSTracer *trc, JSObject *obj)
{
JSGenerator *gen = GetGenerator(obj);
if (!gen)
return;
if (GeneratorHasMarkableFrame(gen))
MarkGeneratorFrame(trc, gen);
}
Class LegacyGeneratorObject::class_ = {
"Generator",
JSCLASS_HAS_PRIVATE | JSCLASS_IMPLEMENTS_BARRIERS,
@@ -1493,12 +1464,12 @@ Class LegacyGeneratorObject::class_ = {
JS_EnumerateStub,
JS_ResolveStub,
JS_ConvertStub,
generator_finalize,
FinalizeGenerator<LegacyGeneratorObject>,
NULL, /* checkAccess */
NULL, /* call */
NULL, /* hasInstance */
NULL, /* construct */
generator_trace,
TraceGenerator<LegacyGeneratorObject>,
{
NULL, /* outerObject */
NULL, /* innerObject */
@@ -1516,12 +1487,12 @@ Class StarGeneratorObject::class_ = {
JS_EnumerateStub,
JS_ResolveStub,
JS_ConvertStub,
generator_finalize,
FinalizeGenerator<StarGeneratorObject>,
NULL, /* checkAccess */
NULL, /* call */
NULL, /* hasInstance */
NULL, /* construct */
generator_trace,
TraceGenerator<StarGeneratorObject>,
{
NULL, /* outerObject */
NULL, /* innerObject */
@@ -1626,8 +1597,11 @@ typedef enum JSGeneratorOp {
*/
static bool
SendToGenerator(JSContext *cx, JSGeneratorOp op, HandleObject obj,
JSGenerator *gen, HandleValue arg)
JSGenerator *gen, HandleValue arg, GeneratorKind generatorKind,
MutableHandleValue rval)
{
JS_ASSERT(generatorKind == LegacyGenerator || generatorKind == StarGenerator);
if (gen->state == JSGEN_RUNNING || gen->state == JSGEN_CLOSING) {
JS_ReportErrorNumber(cx, js_GetErrorMessage, NULL, JSMSG_NESTING_GENERATOR);
return false;
@@ -1658,6 +1632,7 @@ SendToGenerator(JSContext *cx, JSGeneratorOp op, HandleObject obj,
default:
JS_ASSERT(op == JSGENOP_CLOSE);
JS_ASSERT(generatorKind == LegacyGenerator);
cx->setPendingException(MagicValue(JS_GENERATOR_CLOSING));
futureState = JSGEN_CLOSING;
break;
@@ -1681,45 +1656,72 @@ SendToGenerator(JSContext *cx, JSGeneratorOp op, HandleObject obj,
gen->fp->clearYielding();
gen->state = JSGEN_OPEN;
GeneratorWriteBarrierPost(cx, gen);
rval.set(gen->fp->returnValue());
return ok;
}
gen->fp->clearReturnValue();
SetGeneratorClosed(cx, gen);
if (ok) {
/* Returned, explicitly or by falling off the end. */
if (op == JSGENOP_CLOSE)
return true;
return js_ThrowStopIteration(cx);
if (generatorKind == StarGenerator) {
// Star generators return a {value:FOO, done:true} object.
rval.set(gen->fp->returnValue());
} else {
JS_ASSERT(generatorKind == LegacyGenerator);
// Otherwise we discard the return value and throw a StopIteration
// if needed.
rval.setUndefined();
if (op != JSGENOP_CLOSE)
ok = js_ThrowStopIteration(cx);
}
}
/*
* An error, silent termination by operation callback or an exception.
* Propagate the condition to the caller.
*/
return false;
}
static bool
CloseLegacyGenerator(JSContext *cx, HandleObject obj)
{
JS_ASSERT(obj->is<LegacyGeneratorObject>());
JSGenerator *gen = GetGenerator(obj);
if (gen->state == JSGEN_CLOSED)
return true;
return SendToGenerator(cx, JSGENOP_CLOSE, obj, gen, JS::UndefinedHandleValue);
SetGeneratorClosed(cx, gen);
return ok;
}
JS_ALWAYS_INLINE bool
generator_next_impl(JSContext *cx, CallArgs args)
star_generator_next(JSContext *cx, CallArgs args)
{
JS_ASSERT(IsGeneratorObject(args.thisv()));
RootedObject thisObj(cx, &args.thisv().toObject());
JSGenerator *gen = thisObj->as<StarGeneratorObject>().getGenerator();
if (gen->state == JSGEN_CLOSED) {
JS_ReportErrorNumber(cx, js_GetErrorMessage, NULL, JSMSG_GENERATOR_FINISHED);
return false;
}
if (gen->state == JSGEN_NEWBORN && args.hasDefined(0)) {
RootedValue val(cx, args[0]);
js_ReportValueError(cx, JSMSG_BAD_GENERATOR_SEND,
JSDVG_SEARCH_STACK, val, NullPtr());
return false;
}
return SendToGenerator(cx, JSGENOP_SEND, thisObj, gen, args.get(0), StarGenerator,
args.rval());
}
JS_ALWAYS_INLINE bool
star_generator_throw(JSContext *cx, CallArgs args)
{
RootedObject thisObj(cx, &args.thisv().toObject());
JSGenerator *gen = GetGenerator(thisObj);
JSGenerator *gen = thisObj->as<StarGeneratorObject>().getGenerator();
if (gen->state == JSGEN_CLOSED) {
JS_ReportErrorNumber(cx, js_GetErrorMessage, NULL, JSMSG_GENERATOR_FINISHED);
return false;
}
return SendToGenerator(cx, JSGENOP_THROW, thisObj, gen, args.get(0), StarGenerator,
args.rval());
}
JS_ALWAYS_INLINE bool
legacy_generator_next(JSContext *cx, CallArgs args)
{
RootedObject thisObj(cx, &args.thisv().toObject());
JSGenerator *gen = thisObj->as<LegacyGeneratorObject>().getGenerator();
if (gen->state == JSGEN_CLOSED)
return js_ThrowStopIteration(cx);
@@ -1730,96 +1732,94 @@ generator_next_impl(JSContext *cx, CallArgs args)
return false;
}
if (!SendToGenerator(cx, JSGENOP_SEND, thisObj, gen, args.get(0)))
return false;
args.rval().set(gen->fp->returnValue());
return true;
}
bool
generator_next(JSContext *cx, unsigned argc, Value *vp)
{
CallArgs args = CallArgsFromVp(argc, vp);
return CallNonGenericMethod<IsGeneratorObject, generator_next_impl>(cx, args);
return SendToGenerator(cx, JSGENOP_SEND, thisObj, gen, args.get(0), LegacyGenerator,
args.rval());
}
JS_ALWAYS_INLINE bool
generator_throw_impl(JSContext *cx, CallArgs args)
legacy_generator_throw(JSContext *cx, CallArgs args)
{
JS_ASSERT(IsGeneratorObject(args.thisv()));
RootedObject thisObj(cx, &args.thisv().toObject());
JSGenerator *gen = GetGenerator(thisObj);
JSGenerator *gen = thisObj->as<LegacyGeneratorObject>().getGenerator();
if (gen->state == JSGEN_CLOSED) {
cx->setPendingException(args.length() >= 1 ? args[0] : UndefinedValue());
return false;
}
if (!SendToGenerator(cx, JSGENOP_THROW, thisObj, gen, args.get(0)))
return false;
args.rval().set(gen->fp->returnValue());
return true;
return SendToGenerator(cx, JSGENOP_THROW, thisObj, gen, args.get(0), LegacyGenerator,
args.rval());
}
bool
generator_throw(JSContext *cx, unsigned argc, Value *vp)
static bool
CloseLegacyGenerator(JSContext *cx, HandleObject obj, MutableHandleValue rval)
{
CallArgs args = CallArgsFromVp(argc, vp);
return CallNonGenericMethod<IsGeneratorObject, generator_throw_impl>(cx, args);
}
JS_ASSERT(obj->is<LegacyGeneratorObject>());
JS_ALWAYS_INLINE bool
generator_close_impl(JSContext *cx, CallArgs args)
{
JS_ASSERT(IsLegacyGeneratorObject(args.thisv()));
JSGenerator *gen = obj->as<LegacyGeneratorObject>().getGenerator();
RootedObject thisObj(cx, &args.thisv().toObject());
JSGenerator *gen = GetGenerator(thisObj);
if (gen->state == JSGEN_CLOSED) {
args.rval().setUndefined();
rval.setUndefined();
return true;
}
if (gen->state == JSGEN_NEWBORN) {
SetGeneratorClosed(cx, gen);
args.rval().setUndefined();
rval.setUndefined();
return true;
}
if (!SendToGenerator(cx, JSGENOP_CLOSE, thisObj, gen, JS::UndefinedHandleValue))
return false;
args.rval().setUndefined();
return true;
return SendToGenerator(cx, JSGENOP_CLOSE, obj, gen, JS::UndefinedHandleValue, LegacyGenerator,
rval);
}
bool
generator_close(JSContext *cx, unsigned argc, Value *vp)
static bool
CloseLegacyGenerator(JSContext *cx, HandleObject obj)
{
RootedValue rval(cx);
return CloseLegacyGenerator(cx, obj, &rval);
}
JS_ALWAYS_INLINE bool
legacy_generator_close(JSContext *cx, CallArgs args)
{
RootedObject thisObj(cx, &args.thisv().toObject());
return CloseLegacyGenerator(cx, thisObj, args.rval());
}
template<typename T>
JS_ALWAYS_INLINE bool
IsObjectOfType(HandleValue v)
{
return v.isObject() && v.toObject().is<T>();
}
template<typename T, NativeImpl Impl>
static bool
NativeMethod(JSContext *cx, unsigned argc, Value *vp)
{
CallArgs args = CallArgsFromVp(argc, vp);
return CallNonGenericMethod<IsLegacyGeneratorObject, generator_close_impl>(cx, args);
return CallNonGenericMethod<IsObjectOfType<T>, Impl>(cx, args);
}
#define JSPROP_ROPERM (JSPROP_READONLY | JSPROP_PERMANENT)
#define JS_METHOD(name, T, impl, len, perms) JS_FN(name, (NativeMethod<T,impl>), len, perms)
static const JSFunctionSpec legacy_generator_methods[] = {
JS_FN("iterator", iterator_iterator, 0, 0),
JS_FN("next", generator_next, 1,JSPROP_ROPERM),
// Send is exactly the same as next.
JS_FN("send", generator_next, 1,JSPROP_ROPERM),
JS_FN("throw", generator_throw, 1,JSPROP_ROPERM),
JS_FN("close", generator_close, 0,JSPROP_ROPERM),
static const JSFunctionSpec star_generator_methods[] = {
JS_FN("iterator", iterator_iterator, 0, 0),
JS_METHOD("next", StarGeneratorObject, star_generator_next, 1, JSPROP_ROPERM),
JS_METHOD("throw", StarGeneratorObject, star_generator_throw, 1, JSPROP_ROPERM),
JS_FS_END
};
static const JSFunctionSpec star_generator_methods[] = {
JS_FN("iterator", iterator_iterator, 0, 0),
JS_FN("next", generator_next, 1,JSPROP_ROPERM),
JS_FN("throw", generator_throw, 1,JSPROP_ROPERM),
static const JSFunctionSpec legacy_generator_methods[] = {
JS_FN("iterator", iterator_iterator, 0, 0),
// "send" is an alias for "next".
JS_METHOD("next", LegacyGeneratorObject, legacy_generator_next, 1, JSPROP_ROPERM),
JS_METHOD("send", LegacyGeneratorObject, legacy_generator_next, 1, JSPROP_ROPERM),
JS_METHOD("throw", LegacyGeneratorObject, legacy_generator_throw, 1, JSPROP_ROPERM),
JS_METHOD("close", LegacyGeneratorObject, legacy_generator_close, 0, JSPROP_ROPERM),
JS_FS_END
};