mfbt/Types.h

   1 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* This Source Code Form is subject to the terms of the Mozilla Public
   3  * License, v. 2.0. If a copy of the MPL was not distributed with this
   4  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   5
   6 /* mfbt foundational types and macros. */
   7
   8 #ifndef mozilla_Types_h_
   9 #define mozilla_Types_h_
  10
  11 /*
  12  * This header must be valid C and C++, includable by code embedding either
  13  * SpiderMonkey or Gecko.
  14  */
  15
  16 /*
  17  * Expose all the integer types defined in C99's <stdint.h> (and the integer
  18  * limit and constant macros, if compiling C code or if compiling C++ code and
  19  * the right __STDC_*_MACRO has been defined for each).  These are all usable
  20  * throughout mfbt code, and throughout Mozilla code more generally.
  21  */
  22 #include "mozilla/StandardInteger.h"
  23
  24 /* Also expose size_t. */
  25 #include <stddef.h>
  26
  27 /* Implement compiler and linker macros needed for APIs. */
  28
  29 /*
  30  * MOZ_EXPORT_API is used to declare and define a method which is externally
  31  * visible to users of the current library.  It encapsulates various decorations
  32  * needed to properly export the method's symbol.  MOZ_EXPORT_DATA serves the
  33  * same purpose for data.
  34  *
  35  *   api.h:
  36  *     extern MOZ_EXPORT_API(int) MeaningOfLife(void);
  37  *     extern MOZ_EXPORT_DATA(int) LuggageCombination;
  38  *
  39  *   api.c:
  40  *     MOZ_EXPORT_API(int) MeaningOfLife(void) { return 42; }
  41  *     MOZ_EXPORT_DATA(int) LuggageCombination = 12345;
  42  *
  43  * If you are merely sharing a method across files, just use plain |extern|.
  44  * These macros are designed for use by library interfaces -- not for normal
  45  * methods or data used cross-file.
  46  */
  47 #if defined(WIN32) || defined(XP_OS2)
  48 #  define MOZ_EXPORT_API(type)    __declspec(dllexport) type
  49 #  define MOZ_EXPORT_DATA(type)   __declspec(dllexport) type
  50 #else /* Unix */
  51 #  ifdef HAVE_VISIBILITY_ATTRIBUTE
  52 #    define MOZ_EXTERNAL_VIS       __attribute__((visibility("default")))
  53 #  elif defined(__SUNPRO_C) || defined(__SUNPRO_CC)
  54 #    define MOZ_EXTERNAL_VIS      __global
  55 #  else
  56 #    define MOZ_EXTERNAL_VIS
  57 #  endif
  58 #  define MOZ_EXPORT_API(type)    MOZ_EXTERNAL_VIS type
  59 #  define MOZ_EXPORT_DATA(type)   MOZ_EXTERNAL_VIS type
  60 #endif
  61
  62 /*
  63  * Whereas implementers use MOZ_EXPORT_API and MOZ_EXPORT_DATA to declare and
  64  * define library symbols, users use MOZ_IMPORT_API and MOZ_IMPORT_DATA to
  65  * access them.  Most often the implementer of the library will expose an API
  66  * macro which expands to either the export or import version of the macro,
  67  * depending upon the compilation mode.
  68  */
  69 #ifdef _WIN32
  70 #  if defined(__MWERKS__)
  71 #    define MOZ_IMPORT_API(x)    x
  72 #  else
  73 #    define MOZ_IMPORT_API(x)    __declspec(dllimport) x
  74 #  endif
  75 #elif defined(XP_OS2)
  76 #  define MOZ_IMPORT_API(x)     __declspec(dllimport) x
  77 #else
  78 #  define MOZ_IMPORT_API(x)     MOZ_EXPORT_API(x)
  79 #endif
  80
  81 #if defined(_WIN32) && !defined(__MWERKS__)
  82 #  define MOZ_IMPORT_DATA(x)     __declspec(dllimport) x
  83 #elif defined(XP_OS2)
  84 #  define MOZ_IMPORT_DATA(x)     __declspec(dllimport) x
  85 #else
  86 #  define MOZ_IMPORT_DATA(x)     MOZ_EXPORT_DATA(x)
  87 #endif
  88
  89 /*
  90  * Consistent with the above comment, the MFBT_API and MFBT_DATA macros expose
  91  * export mfbt declarations when building mfbt, and they expose import mfbt
  92  * declarations when using mfbt.
  93  */
  94 #if defined(IMPL_MFBT)
  95 #  define MFBT_API(type)        MOZ_EXPORT_API(type)
  96 #  define MFBT_DATA(type)       MOZ_EXPORT_DATA(type)
  97 #else
  98   /*
  99    * When mozglue is linked in the program, we need the MFBT API symbols
 100    * to be weak.
 101    */
 102 #  if defined(MOZ_GLUE_IN_PROGRAM)
 103 #    define MFBT_API(type)        __attribute__((weak)) MOZ_IMPORT_API(type)
 104 #    define MFBT_DATA(type)       __attribute__((weak)) MOZ_IMPORT_DATA(type)
 105 #  else
 106 #    define MFBT_API(type)        MOZ_IMPORT_API(type)
 107 #    define MFBT_DATA(type)       MOZ_IMPORT_DATA(type)
 108 #  endif
 109 #endif
 110
 111 /*
 112  * C symbols in C++ code must be declared immediately within |extern "C"|
 113  * blocks.  However, in C code, they need not be declared specially.  This
 114  * difference is abstracted behind the MOZ_BEGIN_EXTERN_C and MOZ_END_EXTERN_C
 115  * macros, so that the user need not know whether he is being used in C or C++
 116  * code.
 117  *
 118  *   MOZ_BEGIN_EXTERN_C
 119  *
 120  *   extern MOZ_EXPORT_API(int) MostRandomNumber(void);
 121  *   ...other declarations...
 122  *
 123  *   MOZ_END_EXTERN_C
 124  *
 125  * This said, it is preferable to just use |extern "C"| in C++ header files for
 126  * its greater clarity.
 127  */
 128 #ifdef __cplusplus
 129 #  define MOZ_BEGIN_EXTERN_C    extern "C" {
 130 #  define MOZ_END_EXTERN_C      }
 131 #else
 132 #  define MOZ_BEGIN_EXTERN_C
 133 #  define MOZ_END_EXTERN_C
 134 #endif
 135
 136 #endif  /* mozilla_Types_h_ */