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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
* 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_ShapedObject_h
#define vm_ShapedObject_h
#include "jsobj.h"
namespace js {
/*
* Shaped objects extend the base implementation of an object with a shape
* field. Subclasses of ShapedObject ascribe meaning to this field.
*
* ShapedObject is only created as the base class of some other class. It's
* never created as a most-derived class.
*/
class ShapedObject : public JSObject
{
protected:
// Property layout description and other state.
GCPtrShape shape_;
public:
// Set the shape of an object. This pointer is valid for native objects and
// some non-native objects. After creating an object, the objects for which
// the shape pointer is invalid need to overwrite this pointer before a GC
// can occur.
void initShape(Shape* shape) {
this->shape_.init(shape);
}
void setShape(Shape* shape) {
this->shape_ = shape;
}
Shape* shape() const { return this->shape_; }
void traceShape(JSTracer* trc) {
TraceEdge(trc, &shape_, "shape");
}
static size_t offsetOfShape() { return offsetof(ShapedObject, shape_); }
private:
static void staticAsserts() {
static_assert(offsetof(ShapedObject, shape_) == offsetof(shadow::Object, shape),
"shadow shape must match actual shape");
}
};
} // namespace js
#endif /* vm_ShapedObject_h */
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