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103 lines
3.9 KiB
C++
103 lines
3.9 KiB
C++
/* 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 nsQueryFrame_h
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#define nsQueryFrame_h
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#include "nscore.h"
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#include "mozilla/Assertions.h"
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#include "mozilla/TypeTraits.h"
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// NOTE: the long lines in this file are intentional to make compiler error
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// messages more readable.
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#define NS_DECL_QUERYFRAME_TARGET(classname) \
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static const nsQueryFrame::FrameIID kFrameIID = nsQueryFrame::classname##_id; \
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typedef classname Has_NS_DECL_QUERYFRAME_TARGET;
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#define NS_DECL_QUERYFRAME \
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virtual void* QueryFrame(FrameIID id);
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#define NS_QUERYFRAME_HEAD(class) \
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void* class::QueryFrame(FrameIID id) { switch (id) {
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#define NS_QUERYFRAME_ENTRY(class) \
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case class::kFrameIID: { \
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static_assert(mozilla::IsSame<class, class::Has_NS_DECL_QUERYFRAME_TARGET>::value, \
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#class " must declare itself as a queryframe target"); \
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return static_cast<class*>(this); \
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}
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#define NS_QUERYFRAME_ENTRY_CONDITIONAL(class, condition) \
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case class::kFrameIID: \
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if (condition) { \
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static_assert(mozilla::IsSame<class, class::Has_NS_DECL_QUERYFRAME_TARGET>::value, \
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#class " must declare itself as a queryframe target"); \
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return static_cast<class*>(this); \
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} \
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break;
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#define NS_QUERYFRAME_TAIL_INHERITING(class) \
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default: break; \
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} \
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return class::QueryFrame(id); \
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}
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#define NS_QUERYFRAME_TAIL_INHERITANCE_ROOT \
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default: break; \
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} \
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MOZ_ASSERT(id != GetFrameId(), \
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"A frame failed to QueryFrame to its *own type*. " \
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"It may be missing NS_DECL_QUERYFRAME, or a " \
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"NS_QUERYFRAME_ENTRY() line with its own type name"); \
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return nullptr; \
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}
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class nsQueryFrame
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{
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public:
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enum FrameIID {
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#define FRAME_ID(classname) classname##_id,
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#include "nsFrameIdList.h"
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#undef FRAME_ID
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// The PresArena implementation uses this bit to distinguish objects
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// allocated by size from objects allocated by type ID (that is, frames
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// using AllocateByFrameID, and other objects using AllocateByObjectID).
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// It should not collide with any frame ID (above) or Object ID (in
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// nsPresArena.h). It is not 0x80000000 to avoid the question of
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// whether enumeration constants are signed.
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NON_FRAME_MARKER = 0x20000000
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};
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virtual void* QueryFrame(FrameIID id) = 0;
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};
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class do_QueryFrame
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{
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public:
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explicit do_QueryFrame(nsQueryFrame *s) : mRawPtr(s) { }
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// The return and argument types here are arbitrarily selected so no
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// corresponding member function exists.
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typedef void (do_QueryFrame::* MatchNullptr)(double, float);
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// Implicit constructor for nullptr, trick borrowed from already_AddRefed.
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MOZ_IMPLICIT do_QueryFrame(MatchNullptr aRawPtr) : mRawPtr(nullptr) {}
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template<class Dest>
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operator Dest*() {
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static_assert(mozilla::IsSame<Dest, typename Dest::Has_NS_DECL_QUERYFRAME_TARGET>::value,
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"Dest must declare itself as a queryframe target");
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if (!mRawPtr)
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return nullptr;
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return reinterpret_cast<Dest*>(mRawPtr->QueryFrame(Dest::kFrameIID));
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}
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private:
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nsQueryFrame *mRawPtr;
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};
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#endif // nsQueryFrame_h
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