58 lines
1.7 KiB
C++
58 lines
1.7 KiB
C++
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
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* vim: set ts=8 sts=4 et sw=4 tw=99:
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* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#ifndef vm_ShapedObject_h
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#define vm_ShapedObject_h
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#include "jsobj.h"
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namespace js {
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/*
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* Shaped objects extend the base implementation of an object with a shape
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* field. Subclasses of ShapedObject ascribe meaning to this field.
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*
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* ShapedObject is only created as the base class of some other class. It's
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* never created as a most-derived class.
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*/
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class ShapedObject : public JSObject
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{
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protected:
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// Property layout description and other state.
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GCPtrShape shape_;
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public:
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// Set the shape of an object. This pointer is valid for native objects and
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// some non-native objects. After creating an object, the objects for which
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// the shape pointer is invalid need to overwrite this pointer before a GC
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// can occur.
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void initShape(Shape* shape) {
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this->shape_.init(shape);
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}
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void setShape(Shape* shape) {
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this->shape_ = shape;
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}
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Shape* shape() const { return this->shape_; }
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void traceShape(JSTracer* trc) {
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TraceEdge(trc, &shape_, "shape");
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}
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static size_t offsetOfShape() { return offsetof(ShapedObject, shape_); }
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private:
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static void staticAsserts() {
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static_assert(offsetof(ShapedObject, shape_) == offsetof(shadow::Object, shape),
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"shadow shape must match actual shape");
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}
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};
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} // namespace js
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#endif /* vm_ShapedObject_h */
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