Line data    Source code

       1             : /* This Source Code Form is subject to the terms of the Mozilla Public
       2             :  * License, v. 2.0. If a copy of the MPL was not distributed with this
       3             :  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
       4             : 
       5             : #ifndef nsQueryFrame_h
       6             : #define nsQueryFrame_h
       7             : 
       8             : #include "nscore.h"
       9             : #include "mozilla/Assertions.h"
      10             : #include "mozilla/TypeTraits.h"
      11             : 
      12             : // NOTE: the long lines in this file are intentional to make compiler error
      13             : // messages more readable.
      14             : 
      15             : #define NS_DECL_QUERYFRAME_TARGET(classname)                    \
      16             :   static const nsQueryFrame::FrameIID kFrameIID = nsQueryFrame::classname##_id; \
      17             :   typedef classname Has_NS_DECL_QUERYFRAME_TARGET;
      18             : 
      19             : #define NS_DECL_QUERYFRAME                                      \
      20             :   void* QueryFrame(FrameIID id) override;
      21             : 
      22             : #define NS_QUERYFRAME_HEAD(class)                               \
      23             :   void* class::QueryFrame(FrameIID id) { switch (id) {
      24             : 
      25             : #define NS_QUERYFRAME_ENTRY(class)                              \
      26             :   case class::kFrameIID: {                                      \
      27             :     static_assert(mozilla::IsSame<class, class::Has_NS_DECL_QUERYFRAME_TARGET>::value, \
      28             :                   #class " must declare itself as a queryframe target"); \
      29             :     return static_cast<class*>(this);                           \
      30             :   }
      31             : 
      32             : #define NS_QUERYFRAME_ENTRY_CONDITIONAL(class, condition)       \
      33             :   case class::kFrameIID:                                        \
      34             :   if (condition) {                                              \
      35             :     static_assert(mozilla::IsSame<class, class::Has_NS_DECL_QUERYFRAME_TARGET>::value, \
      36             :                   #class " must declare itself as a queryframe target"); \
      37             :     return static_cast<class*>(this);                           \
      38             :   }                                                             \
      39             :   break;
      40             : 
      41             : #define NS_QUERYFRAME_TAIL_INHERITING(class)                    \
      42             :   default: break;                                               \
      43             :   }                                                             \
      44             :   return class::QueryFrame(id);                                 \
      45             : }
      46             : 
      47             : #define NS_QUERYFRAME_TAIL_INHERITANCE_ROOT                     \
      48             :   default: break;                                               \
      49             :   }                                                             \
      50             :   MOZ_ASSERT(id != GetFrameId(),                                \
      51             :     "A frame failed to QueryFrame to its *own type*. "          \
      52             :     "It may be missing NS_DECL_QUERYFRAME, or a "               \
      53             :     "NS_QUERYFRAME_ENTRY() line with its own type name");       \
      54             :   return nullptr;                                               \
      55             : }
      56             : 
      57         866 : class nsQueryFrame
      58             : {
      59             : public:
      60             :   enum FrameIID {
      61             : #define FRAME_ID(classname, ...) classname##_id,
      62             : #define ABSTRACT_FRAME_ID(classname) classname##_id,
      63             : #include "nsFrameIdList.h"
      64             : #undef FRAME_ID
      65             : #undef ABSTRACT_FRAME_ID
      66             : 
      67             :     // This marker allows mozilla::ArenaObjectID to "extend" this enum
      68             :     // with additional sequential values for use in nsPresArena and
      69             :     // nsIPresShell::{Allocate,Free}ByObjectId
      70             :     NON_FRAME_MARKER
      71             :   };
      72             : 
      73             :   // A strict subset of FrameIID above for frame classes that we instantiate.
      74             :   enum class ClassID : uint8_t {
      75             : #define FRAME_ID(classname, ...) classname##_id,
      76             : #define ABSTRACT_FRAME_ID(classname)
      77             : #include "nsFrameIdList.h"
      78             : #undef FRAME_ID
      79             : #undef ABSTRACT_FRAME_ID
      80             :   };
      81             : 
      82             :   virtual void* QueryFrame(FrameIID id) = 0;
      83             : };
      84             : 
      85             : class do_QueryFrame
      86             : {
      87             : public:
      88       11569 :   explicit do_QueryFrame(nsQueryFrame *s) : mRawPtr(s) { }
      89             : 
      90             :   // The return and argument types here are arbitrarily selected so no
      91             :   // corresponding member function exists.
      92             :   typedef void (do_QueryFrame::* MatchNullptr)(double, float);
      93             :   // Implicit constructor for nullptr, trick borrowed from already_AddRefed.
      94           0 :   MOZ_IMPLICIT do_QueryFrame(MatchNullptr aRawPtr) : mRawPtr(nullptr) {}
      95             : 
      96             :   template<class Dest>
      97       11569 :   operator Dest*() {
      98             :     static_assert(mozilla::IsSame<Dest, typename Dest::Has_NS_DECL_QUERYFRAME_TARGET>::value,
      99             :                   "Dest must declare itself as a queryframe target");
     100       11569 :     if (!mRawPtr)
     101         624 :       return nullptr;
     102             : 
     103       10945 :     return reinterpret_cast<Dest*>(mRawPtr->QueryFrame(Dest::kFrameIID));
     104             :   }
     105             : 
     106             : private:
     107             :   nsQueryFrame *mRawPtr;
     108             : };
     109             : 
     110             : #endif // nsQueryFrame_h