michael@0: /* This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this
michael@0:  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: 
michael@0: #ifndef nsQueryFrame_h
michael@0: #define nsQueryFrame_h
michael@0: 
michael@0: #include "nscore.h"
michael@0: #include "mozilla/Assertions.h"
michael@0: #include "mozilla/TypeTraits.h"
michael@0: 
michael@0: // NOTE: the long lines in this file are intentional to make compiler error
michael@0: // messages more readable.
michael@0: 
michael@0: #define NS_DECL_QUERYFRAME_TARGET(classname)                    \
michael@0:   static const nsQueryFrame::FrameIID kFrameIID = nsQueryFrame::classname##_id; \
michael@0:   typedef classname Has_NS_DECL_QUERYFRAME_TARGET;
michael@0: 
michael@0: #define NS_DECL_QUERYFRAME                                      \
michael@0:   virtual void* QueryFrame(FrameIID id);
michael@0: 
michael@0: #define NS_QUERYFRAME_HEAD(class)                               \
michael@0:   void* class::QueryFrame(FrameIID id) { switch (id) {
michael@0: 
michael@0: #define NS_QUERYFRAME_ENTRY(class)                              \
michael@0:   case class::kFrameIID: {                                      \
michael@0:     static_assert(mozilla::IsSame<class, class::Has_NS_DECL_QUERYFRAME_TARGET>::value, \
michael@0:                   #class " must declare itself as a queryframe target"); \
michael@0:     return static_cast<class*>(this);                           \
michael@0:   }
michael@0: 
michael@0: #define NS_QUERYFRAME_ENTRY_CONDITIONAL(class, condition)       \
michael@0:   case class::kFrameIID:                                        \
michael@0:   if (condition) {                                              \
michael@0:     static_assert(mozilla::IsSame<class, class::Has_NS_DECL_QUERYFRAME_TARGET>::value, \
michael@0:                   #class " must declare itself as a queryframe target"); \
michael@0:     return static_cast<class*>(this);                           \
michael@0:   }                                                             \
michael@0:   break;
michael@0: 
michael@0: #define NS_QUERYFRAME_TAIL_INHERITING(class)                    \
michael@0:   default: break;                                               \
michael@0:   }                                                             \
michael@0:   return class::QueryFrame(id);                                 \
michael@0: }
michael@0: 
michael@0: #define NS_QUERYFRAME_TAIL_INHERITANCE_ROOT                     \
michael@0:   default: break;                                               \
michael@0:   }                                                             \
michael@0:   MOZ_ASSERT(id != GetFrameId(),                                \
michael@0:     "A frame failed to QueryFrame to its *own type*. "          \
michael@0:     "It may be missing NS_DECL_QUERYFRAME, or a "               \
michael@0:     "NS_QUERYFRAME_ENTRY() line with its own type name");       \
michael@0:   return nullptr;                                               \
michael@0: }
michael@0: 
michael@0: class nsQueryFrame
michael@0: {
michael@0: public:
michael@0:   enum FrameIID {
michael@0: #define FRAME_ID(classname) classname##_id,
michael@0: #include "nsFrameIdList.h"
michael@0: #undef FRAME_ID
michael@0: 
michael@0:     // The PresArena implementation uses this bit to distinguish objects
michael@0:     // allocated by size from objects allocated by type ID (that is, frames
michael@0:     // using AllocateByFrameID, and other objects using AllocateByObjectID).
michael@0:     // It should not collide with any frame ID (above) or Object ID (in
michael@0:     // nsPresArena.h).  It is not 0x80000000 to avoid the question of
michael@0:     // whether enumeration constants are signed.
michael@0:     NON_FRAME_MARKER = 0x20000000
michael@0:   };
michael@0: 
michael@0:   virtual void* QueryFrame(FrameIID id) = 0;
michael@0: };
michael@0: 
michael@0: class do_QueryFrame
michael@0: {
michael@0: public:
michael@0:   do_QueryFrame(nsQueryFrame *s) : mRawPtr(s) { }
michael@0: 
michael@0:   template<class Dest>
michael@0:   operator Dest*() {
michael@0:     static_assert(mozilla::IsSame<Dest, typename Dest::Has_NS_DECL_QUERYFRAME_TARGET>::value,
michael@0:                   "Dest must declare itself as a queryframe target");
michael@0:     if (!mRawPtr)
michael@0:       return nullptr;
michael@0: 
michael@0:     return reinterpret_cast<Dest*>(mRawPtr->QueryFrame(Dest::kFrameIID));
michael@0:   }
michael@0: 
michael@0: private:
michael@0:   nsQueryFrame *mRawPtr;
michael@0: };
michael@0: 
michael@0: #endif // nsQueryFrame_h