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+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ * vim: set ts=8 sts=2 et sw=2 tw=80:
+ * 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/. */
+
+#ifndef vm_BoundFunctionObject_h
+#define vm_BoundFunctionObject_h
+
+#include "jstypes.h"
+
+#include "gc/Policy.h"
+#include "vm/ArrayObject.h"
+#include "vm/JSObject.h"
+
+namespace js {
+
+// Implementation of Bound Function Exotic Objects.
+// ES2023 10.4.1
+// https://tc39.es/ecma262/#sec-bound-function-exotic-objects
+class BoundFunctionObject : public NativeObject {
+ public:
+ static const JSClass class_;
+
+ // FlagsSlot uses the low bit for the is-constructor flag and the other bits
+ // for the number of arguments.
+ static constexpr size_t IsConstructorFlag = 0b1;
+ static constexpr size_t NumBoundArgsShift = 1;
+
+ // The maximum number of bound arguments that can be stored inline in
+ // BoundArg*Slot.
+ static constexpr size_t MaxInlineBoundArgs = 3;
+
+ private:
+ enum {
+ // The [[BoundTargetFunction]] (a callable object).
+ TargetSlot,
+
+ // The number of arguments + the is-constructor flag, stored as Int32Value.
+ FlagsSlot,
+
+ // The [[BoundThis]] Value.
+ BoundThisSlot,
+
+ // The [[BoundArguments]]. If numBoundArgs exceeds MaxInlineBoundArgs,
+ // BoundArg0Slot will contain an array object that stores the values and the
+ // other two slots will be unused.
+ BoundArg0Slot,
+ BoundArg1Slot,
+ BoundArg2Slot,
+
+ // Initial slots for the `length` and `name` own data properties. Note that
+ // these properties are configurable, so these slots can be mutated when the
+ // object is exposed to JS.
+ LengthSlot,
+ NameSlot,
+
+ SlotCount
+ };
+
+ // The AllocKind should match SlotCount. See assertion in functionBindImpl.
+ static constexpr gc::AllocKind allocKind = gc::AllocKind::OBJECT8_BACKGROUND;
+
+ void initFlags(size_t numBoundArgs, bool isConstructor) {
+ int32_t val = (numBoundArgs << NumBoundArgsShift) | isConstructor;
+ initReservedSlot(FlagsSlot, Int32Value(val));
+ }
+
+ public:
+ size_t numBoundArgs() const {
+ int32_t v = getReservedSlot(FlagsSlot).toInt32();
+ MOZ_ASSERT(v >= 0);
+ return v >> NumBoundArgsShift;
+ }
+ bool isConstructor() const {
+ int32_t v = getReservedSlot(FlagsSlot).toInt32();
+ return v & IsConstructorFlag;
+ }
+
+ Value getTargetVal() const { return getReservedSlot(TargetSlot); }
+ JSObject* getTarget() const { return &getTargetVal().toObject(); }
+
+ Value getBoundThis() const { return getReservedSlot(BoundThisSlot); }
+
+ Value getInlineBoundArg(size_t i) const {
+ MOZ_ASSERT(i < numBoundArgs());
+ MOZ_ASSERT(numBoundArgs() <= MaxInlineBoundArgs);
+ return getReservedSlot(BoundArg0Slot + i);
+ }
+ ArrayObject* getBoundArgsArray() const {
+ MOZ_ASSERT(numBoundArgs() > MaxInlineBoundArgs);
+ return &getReservedSlot(BoundArg0Slot).toObject().as<ArrayObject>();
+ }
+ Value getBoundArg(size_t i) const {
+ MOZ_ASSERT(i < numBoundArgs());
+ if (numBoundArgs() <= MaxInlineBoundArgs) {
+ return getInlineBoundArg(i);
+ }
+ return getBoundArgsArray()->getDenseElement(i);
+ }
+
+ void initLength(double len) {
+ MOZ_ASSERT(getReservedSlot(LengthSlot).isUndefined());
+ initReservedSlot(LengthSlot, NumberValue(len));
+ }
+ void initName(JSAtom* name) {
+ MOZ_ASSERT(getReservedSlot(NameSlot).isUndefined());
+ initReservedSlot(NameSlot, StringValue(name));
+ }
+
+ // Get the `length` and `name` property values when the object has the
+ // original shape. See comment for LengthSlot and NameSlot.
+ Value getLengthForInitialShape() const { return getReservedSlot(LengthSlot); }
+ Value getNameForInitialShape() const { return getReservedSlot(NameSlot); }
+
+ // The [[Call]] and [[Construct]] hooks.
+ static bool call(JSContext* cx, unsigned argc, Value* vp);
+ static bool construct(JSContext* cx, unsigned argc, Value* vp);
+
+ // The JSFunToStringOp implementation for Function.prototype.toString.
+ static JSString* funToString(JSContext* cx, Handle<JSObject*> obj,
+ bool isToSource);
+
+ // Implementation of Function.prototype.bind.
+ static bool functionBind(JSContext* cx, unsigned argc, Value* vp);
+
+ static SharedShape* assignInitialShape(JSContext* cx,
+ Handle<BoundFunctionObject*> obj);
+
+ static BoundFunctionObject* functionBindImpl(
+ JSContext* cx, Handle<JSObject*> target, Value* args, uint32_t argc,
+ Handle<BoundFunctionObject*> maybeBound);
+
+ static BoundFunctionObject* createWithTemplate(
+ JSContext* cx, Handle<BoundFunctionObject*> templateObj);
+ static BoundFunctionObject* functionBindSpecializedBaseline(
+ JSContext* cx, Handle<JSObject*> target, Value* args, uint32_t argc,
+ Handle<BoundFunctionObject*> templateObj);
+
+ static BoundFunctionObject* createTemplateObject(JSContext* cx);
+
+ bool initTemplateSlotsForSpecializedBind(JSContext* cx, uint32_t numBoundArgs,
+ bool targetIsConstructor,
+ uint32_t targetLength,
+ JSAtom* targetName);
+
+ static constexpr size_t offsetOfTargetSlot() {
+ return getFixedSlotOffset(TargetSlot);
+ }
+ static constexpr size_t offsetOfFlagsSlot() {
+ return getFixedSlotOffset(FlagsSlot);
+ }
+ static constexpr size_t offsetOfBoundThisSlot() {
+ return getFixedSlotOffset(BoundThisSlot);
+ }
+ static constexpr size_t offsetOfFirstInlineBoundArg() {
+ return getFixedSlotOffset(BoundArg0Slot);
+ }
+ static constexpr size_t offsetOfLengthSlot() {
+ return getFixedSlotOffset(LengthSlot);
+ }
+ static constexpr size_t offsetOfNameSlot() {
+ return getFixedSlotOffset(NameSlot);
+ }
+
+ static constexpr size_t targetSlot() { return TargetSlot; }
+ static constexpr size_t boundThisSlot() { return BoundThisSlot; }
+ static constexpr size_t firstInlineBoundArgSlot() { return BoundArg0Slot; }
+};
+
+}; // namespace js
+
+#endif /* vm_BoundFunctionObject_h */