gecko/mfbt/Types.h

135 lines
4.1 KiB
C

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* 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/. */
/* mfbt foundational types and macros. */
#ifndef mozilla_Types_h
#define mozilla_Types_h
/*
* This header must be valid C and C++, includable by code embedding either
* SpiderMonkey or Gecko.
*/
/* Expose all <stdint.h> types and size_t. */
#include <stddef.h>
#include <stdint.h>
/* Implement compiler and linker macros needed for APIs. */
/*
* MOZ_EXPORT is used to declare and define a symbol or type which is externally
* visible to users of the current library. It encapsulates various decorations
* needed to properly export the method's symbol.
*
* api.h:
* extern MOZ_EXPORT int MeaningOfLife(void);
* extern MOZ_EXPORT int LuggageCombination;
*
* api.c:
* int MeaningOfLife(void) { return 42; }
* int LuggageCombination = 12345;
*
* If you are merely sharing a method across files, just use plain |extern|.
* These macros are designed for use by library interfaces -- not for normal
* methods or data used cross-file.
*/
#if defined(WIN32)
# define MOZ_EXPORT __declspec(dllexport)
#else /* Unix */
# ifdef HAVE_VISIBILITY_ATTRIBUTE
# define MOZ_EXPORT __attribute__((visibility("default")))
# elif defined(__SUNPRO_C) || defined(__SUNPRO_CC)
# define MOZ_EXPORT __global
# else
# define MOZ_EXPORT /* nothing */
# endif
#endif
/*
* Whereas implementers use MOZ_EXPORT to declare and define library symbols,
* users use MOZ_IMPORT_API and MOZ_IMPORT_DATA to access them. Most often the
* implementer of the library will expose an API macro which expands to either
* the export or import version of the macro, depending upon the compilation
* mode.
*/
#ifdef _WIN32
# if defined(__MWERKS__)
# define MOZ_IMPORT_API /* nothing */
# else
# define MOZ_IMPORT_API __declspec(dllimport)
# endif
#else
# define MOZ_IMPORT_API MOZ_EXPORT
#endif
#if defined(_WIN32) && !defined(__MWERKS__)
# define MOZ_IMPORT_DATA __declspec(dllimport)
#else
# define MOZ_IMPORT_DATA MOZ_EXPORT
#endif
/*
* Consistent with the above comment, the MFBT_API and MFBT_DATA macros expose
* export mfbt declarations when building mfbt, and they expose import mfbt
* declarations when using mfbt.
*/
#if defined(IMPL_MFBT)
# define MFBT_API MOZ_EXPORT
# define MFBT_DATA MOZ_EXPORT
#else
/*
* On linux mozglue is linked in the program and we link libxul.so with
* -z,defs. Normally that causes the linker to reject undefined references in
* libxul.so, but as a loophole it allows undefined references to weak
* symbols. We add the weak attribute to the import version of the MFBT API
* macros to exploit this.
*/
# if defined(MOZ_GLUE_IN_PROGRAM) && !defined(MOZILLA_XPCOMRT_API)
# define MFBT_API __attribute__((weak)) MOZ_IMPORT_API
# define MFBT_DATA __attribute__((weak)) MOZ_IMPORT_DATA
# else
# define MFBT_API MOZ_IMPORT_API
# define MFBT_DATA MOZ_IMPORT_DATA
# endif
#endif
/*
* C symbols in C++ code must be declared immediately within |extern "C"|
* blocks. However, in C code, they need not be declared specially. This
* difference is abstracted behind the MOZ_BEGIN_EXTERN_C and MOZ_END_EXTERN_C
* macros, so that the user need not know whether he is being used in C or C++
* code.
*
* MOZ_BEGIN_EXTERN_C
*
* extern MOZ_EXPORT int MostRandomNumber(void);
* ...other declarations...
*
* MOZ_END_EXTERN_C
*
* This said, it is preferable to just use |extern "C"| in C++ header files for
* its greater clarity.
*/
#ifdef __cplusplus
# define MOZ_BEGIN_EXTERN_C extern "C" {
# define MOZ_END_EXTERN_C }
#else
# define MOZ_BEGIN_EXTERN_C
# define MOZ_END_EXTERN_C
#endif
/*
* GCC's typeof is available when decltype is not.
*/
#if defined(__GNUC__) && defined(__cplusplus) && \
!defined(__GXX_EXPERIMENTAL_CXX0X__) && __cplusplus < 201103L
# define decltype __typeof__
#endif
#endif /* mozilla_Types_h */