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