1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/layout/generic/nsQueryFrame.h Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,96 @@
1.4 +/* This Source Code Form is subject to the terms of the Mozilla Public
1.5 + * License, v. 2.0. If a copy of the MPL was not distributed with this
1.6 + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
1.7 +
1.8 +#ifndef nsQueryFrame_h
1.9 +#define nsQueryFrame_h
1.10 +
1.11 +#include "nscore.h"
1.12 +#include "mozilla/Assertions.h"
1.13 +#include "mozilla/TypeTraits.h"
1.14 +
1.15 +// NOTE: the long lines in this file are intentional to make compiler error
1.16 +// messages more readable.
1.17 +
1.18 +#define NS_DECL_QUERYFRAME_TARGET(classname) \
1.19 + static const nsQueryFrame::FrameIID kFrameIID = nsQueryFrame::classname##_id; \
1.20 + typedef classname Has_NS_DECL_QUERYFRAME_TARGET;
1.21 +
1.22 +#define NS_DECL_QUERYFRAME \
1.23 + virtual void* QueryFrame(FrameIID id);
1.24 +
1.25 +#define NS_QUERYFRAME_HEAD(class) \
1.26 + void* class::QueryFrame(FrameIID id) { switch (id) {
1.27 +
1.28 +#define NS_QUERYFRAME_ENTRY(class) \
1.29 + case class::kFrameIID: { \
1.30 + static_assert(mozilla::IsSame<class, class::Has_NS_DECL_QUERYFRAME_TARGET>::value, \
1.31 + #class " must declare itself as a queryframe target"); \
1.32 + return static_cast<class*>(this); \
1.33 + }
1.34 +
1.35 +#define NS_QUERYFRAME_ENTRY_CONDITIONAL(class, condition) \
1.36 + case class::kFrameIID: \
1.37 + if (condition) { \
1.38 + static_assert(mozilla::IsSame<class, class::Has_NS_DECL_QUERYFRAME_TARGET>::value, \
1.39 + #class " must declare itself as a queryframe target"); \
1.40 + return static_cast<class*>(this); \
1.41 + } \
1.42 + break;
1.43 +
1.44 +#define NS_QUERYFRAME_TAIL_INHERITING(class) \
1.45 + default: break; \
1.46 + } \
1.47 + return class::QueryFrame(id); \
1.48 +}
1.49 +
1.50 +#define NS_QUERYFRAME_TAIL_INHERITANCE_ROOT \
1.51 + default: break; \
1.52 + } \
1.53 + MOZ_ASSERT(id != GetFrameId(), \
1.54 + "A frame failed to QueryFrame to its *own type*. " \
1.55 + "It may be missing NS_DECL_QUERYFRAME, or a " \
1.56 + "NS_QUERYFRAME_ENTRY() line with its own type name"); \
1.57 + return nullptr; \
1.58 +}
1.59 +
1.60 +class nsQueryFrame
1.61 +{
1.62 +public:
1.63 + enum FrameIID {
1.64 +#define FRAME_ID(classname) classname##_id,
1.65 +#include "nsFrameIdList.h"
1.66 +#undef FRAME_ID
1.67 +
1.68 + // The PresArena implementation uses this bit to distinguish objects
1.69 + // allocated by size from objects allocated by type ID (that is, frames
1.70 + // using AllocateByFrameID, and other objects using AllocateByObjectID).
1.71 + // It should not collide with any frame ID (above) or Object ID (in
1.72 + // nsPresArena.h). It is not 0x80000000 to avoid the question of
1.73 + // whether enumeration constants are signed.
1.74 + NON_FRAME_MARKER = 0x20000000
1.75 + };
1.76 +
1.77 + virtual void* QueryFrame(FrameIID id) = 0;
1.78 +};
1.79 +
1.80 +class do_QueryFrame
1.81 +{
1.82 +public:
1.83 + do_QueryFrame(nsQueryFrame *s) : mRawPtr(s) { }
1.84 +
1.85 + template<class Dest>
1.86 + operator Dest*() {
1.87 + static_assert(mozilla::IsSame<Dest, typename Dest::Has_NS_DECL_QUERYFRAME_TARGET>::value,
1.88 + "Dest must declare itself as a queryframe target");
1.89 + if (!mRawPtr)
1.90 + return nullptr;
1.91 +
1.92 + return reinterpret_cast<Dest*>(mRawPtr->QueryFrame(Dest::kFrameIID));
1.93 + }
1.94 +
1.95 +private:
1.96 + nsQueryFrame *mRawPtr;
1.97 +};
1.98 +
1.99 +#endif // nsQueryFrame_h
