include/wx/cpp.h

   1 /*
   2  *  Name:        wx/cpp.h
   3  *  Purpose:     Various preprocessor helpers
   4  *  Author:      Vadim Zeitlin
   5  *  Created:     2006-09-30
   6  *  RCS-ID:      $Id$
   7  *  Copyright:   (c) 2006 Vadim Zeitlin <vadim@wxwindows.org>
   8  *  Licence:     wxWindows licence
   9  */
  10
  11 /* THIS IS A C FILE, DON'T USE C++ FEATURES (IN PARTICULAR COMMENTS) IN IT */
  12
  13 #ifndef _WX_CPP_H_
  14 #define _WX_CPP_H_
  15
  16 #include "wx/compiler.h"    /* wxCHECK_XXX_VERSION() macros */
  17
  18 /* wxCONCAT works like preprocessor ## operator but also works with macros */
  19 #define wxCONCAT_HELPER(text, line) text ## line
  20
  21 #define wxCONCAT(x1, x2) \
  22     wxCONCAT_HELPER(x1, x2)
  23 #define wxCONCAT3(x1, x2, x3) \
  24     wxCONCAT(wxCONCAT(x1, x2), x3)
  25 #define wxCONCAT4(x1, x2, x3, x4) \
  26     wxCONCAT(wxCONCAT3(x1, x2, x3), x4)
  27 #define wxCONCAT5(x1, x2, x3, x4, x5) \
  28     wxCONCAT(wxCONCAT4(x1, x2, x3, x4), x5)
  29 #define wxCONCAT6(x1, x2, x3, x4, x5, x6) \
  30     wxCONCAT(wxCONCAT5(x1, x2, x3, x4, x5), x6)
  31 #define wxCONCAT7(x1, x2, x3, x4, x5, x6, x7) \
  32     wxCONCAT(wxCONCAT6(x1, x2, x3, x4, x5, x6), x7)
  33 #define wxCONCAT8(x1, x2, x3, x4, x5, x6, x7, x8) \
  34     wxCONCAT(wxCONCAT7(x1, x2, x3, x4, x5, x6, x7), x8)
  35 #define wxCONCAT9(x1, x2, x3, x4, x5, x6, x7, x8, x9) \
  36     wxCONCAT(wxCONCAT8(x1, x2, x3, x4, x5, x6, x7, x8), x9)
  37
  38 /* wxSTRINGIZE works as the preprocessor # operator but also works with macros */
  39 #define wxSTRINGIZE_HELPER(x)       #x
  40 #define wxSTRINGIZE(x)              wxSTRINGIZE_HELPER(x)
  41
  42 /* a Unicode-friendly version of wxSTRINGIZE_T */
  43 #define wxSTRINGIZE_T(x)            wxAPPLY_T(wxSTRINGIZE(x))
  44
  45 /*
  46     Special workarounds for compilers with broken "##" operator. For all the
  47     other ones we can just use it directly.
  48  */
  49 #ifdef wxCOMPILER_BROKEN_CONCAT_OPER
  50     #define wxPREPEND_L(x)      L ## x
  51     #define wxAPPEND_i64(x)     x ## i64
  52     #define wxAPPEND_ui64(x)    x ## ui64
  53 #endif /* wxCOMPILER_BROKEN_CONCAT_OPER */
  54
  55 /*
  56    Helper macros for wxMAKE_UNIQUE_NAME: normally this works by appending the
  57    current line number to the given identifier to reduce the probability of the
  58    conflict (it may still happen if this is used in the headers, hence you
  59    should avoid doing it or provide unique prefixes then) but we have to do it
  60    differently for VC++
  61   */
  62 #if defined(__VISUALC__) && (__VISUALC__ >= 1300)
  63     /*
  64        __LINE__ handling is completely broken in VC++ when using "Edit and
  65        Continue" (/ZI option) and results in preprocessor errors if we use it
  66        inside the macros. Luckily VC7 has another standard macro which can be
  67        used like this and is even better than __LINE__ because it is globally
  68        unique.
  69      */
  70 #   define wxCONCAT_LINE(text)         wxCONCAT(text, __COUNTER__)
  71 #else /* normal compilers */
  72 #   define wxCONCAT_LINE(text)         wxCONCAT(text, __LINE__)
  73 #endif
  74
  75 /* Create a "unique" name with the given prefix */
  76 #define wxMAKE_UNIQUE_NAME(text)    wxCONCAT_LINE(text)
  77
  78 /*
  79    This macro can be passed as argument to another macro when you don't have
  80    anything to pass in fact.
  81  */
  82 #define wxEMPTY_PARAMETER_VALUE /* Fake macro parameter value */
  83
  84 /*
  85     Helpers for defining macros that expand into a single statement.
  86
  87     The standatd solution is to use "do { ... } while (0)" statement but MSVC
  88     generates a C4127 "condition expression is constant" warning for it so we
  89     use something which is just complicated enough to not be recognized as a
  90     constant but still simple enough to be optimized away.
  91
  92     Another solution would be to use __pragma() to temporarily disable C4127.
  93
  94     Notice that wxASSERT_ARG_TYPE in wx/strvargarg.h relies on these macros
  95     creating some kind of a loop because it uses "break".
  96  */
  97 #ifdef __WATCOMC__
  98     #define wxFOR_ONCE(name) for(int name=0; name<1; name++)
  99     #define wxSTATEMENT_MACRO_BEGIN wxFOR_ONCE(wxMAKE_UNIQUE_NAME(wxmacro)) {
 100     #define wxSTATEMENT_MACRO_END }
 101 #else
 102     #define wxSTATEMENT_MACRO_BEGIN  do {
 103     #define wxSTATEMENT_MACRO_END } while ( (void)0, 0 )
 104 #endif
 105
 106 /*
 107     Define __WXFUNCTION__ which is like standard __FUNCTION__ but defined as
 108     NULL for the compilers which don't support the latter.
 109  */
 110 #ifndef __WXFUNCTION__
 111     /* TODO: add more compilers supporting __FUNCTION__ */
 112     #if defined(__DMC__)
 113         /*
 114            __FUNCTION__ happens to be not defined within class members
 115            http://www.digitalmars.com/drn-bin/wwwnews?c%2B%2B.beta/485
 116         */
 117         #define __WXFUNCTION__ (NULL)
 118     #elif defined(__GNUC__) || \
 119           (defined(_MSC_VER) && _MSC_VER >= 1300) || \
 120           defined(__FUNCTION__)
 121         #define __WXFUNCTION__ __FUNCTION__
 122     #else
 123         /* still define __WXFUNCTION__ to avoid #ifdefs elsewhere */
 124         #define __WXFUNCTION__ (NULL)
 125     #endif
 126 #endif /* __WXFUNCTION__ already defined */
 127
 128
 129 /* Auto-detect variadic macros support unless explicitly disabled. */
 130 #if !defined(HAVE_VARIADIC_MACROS) && !defined(wxNO_VARIADIC_MACROS)
 131     /* Any C99 or C++11 compiler should have them. */
 132     #if (defined(__STDC_VERSION__) && __STDC_VERSION__ >= 199901L) || \
 133         (defined(__cplusplus) && __cplusplus >= 201103L)
 134         #define HAVE_VARIADIC_MACROS
 135     #elif wxCHECK_GCC_VERSION(3,0)
 136         #define HAVE_VARIADIC_MACROS
 137     #elif wxCHECK_VISUALC_VERSION(8)
 138         #define HAVE_VARIADIC_MACROS
 139     #elif wxCHECK_WATCOM_VERSION(1,2)
 140         #define HAVE_VARIADIC_MACROS
 141     #endif
 142 #endif /* !HAVE_VARIADIC_MACROS */
 143
 144
 145
 146 #ifdef HAVE_VARIADIC_MACROS
 147 /*
 148    wxCALL_FOR_EACH(what, ...) calls the macro from its first argument, what(pos, x),
 149    for every remaining argument 'x', with 'pos' being its 1-based index in
 150    *reverse* order (with the last argument being numbered 1).
 151
 152    For example, wxCALL_FOR_EACH(test, a, b, c) expands into this:
 153
 154        test(3, a) \
 155        test(2, b) \
 156        test(1, c)
 157
 158    Up to eight arguments are supported.
 159
 160    (With thanks to https://groups.google.com/d/topic/comp.std.c/d-6Mj5Lko_s/discussion
 161    and http://stackoverflow.com/questions/1872220/is-it-possible-to-iterate-over-arguments-in-variadic-macros)
 162 */
 163 #define wxCALL_FOR_EACH_NARG(...)   wxCALL_FOR_EACH_NARG_((__VA_ARGS__, wxCALL_FOR_EACH_RSEQ_N()))
 164 #define wxCALL_FOR_EACH_NARG_(args) wxCALL_FOR_EACH_ARG_N args
 165 #define wxCALL_FOR_EACH_ARG_N(_1, _2, _3, _4, _5, _6, _7, _8, N, ...) N
 166 #define wxCALL_FOR_EACH_RSEQ_N() 8, 7, 6, 5, 4, 3, 2, 1, 0
 167
 168 #define wxCALL_FOR_EACH_1(what, x)        what(1, x)
 169 #define wxCALL_FOR_EACH_2(what, x, ...)   what(2, x)  wxCALL_FOR_EACH_1(what,  __VA_ARGS__)
 170 #define wxCALL_FOR_EACH_3(what, x, ...)   what(3, x)  wxCALL_FOR_EACH_2(what,  __VA_ARGS__)
 171 #define wxCALL_FOR_EACH_4(what, x, ...)   what(4, x)  wxCALL_FOR_EACH_3(what,  __VA_ARGS__)
 172 #define wxCALL_FOR_EACH_5(what, x, ...)   what(5, x)  wxCALL_FOR_EACH_4(what,  __VA_ARGS__)
 173 #define wxCALL_FOR_EACH_6(what, x, ...)   what(6, x)  wxCALL_FOR_EACH_5(what,  __VA_ARGS__)
 174 #define wxCALL_FOR_EACH_7(what, x, ...)   what(7, x)  wxCALL_FOR_EACH_6(what,  __VA_ARGS__)
 175 #define wxCALL_FOR_EACH_8(what, x, ...)   what(8, x)  wxCALL_FOR_EACH_7(what,  __VA_ARGS__)
 176
 177 #define wxCALL_FOR_EACH_(N, args) \
 178     wxCONCAT(wxCALL_FOR_EACH_, N) args
 179
 180 #define wxCALL_FOR_EACH(what, ...) \
 181     wxCALL_FOR_EACH_(wxCALL_FOR_EACH_NARG(__VA_ARGS__), (what, __VA_ARGS__))
 182
 183 #else
 184     #define wxCALL_FOR_EACH  Error_wx_CALL_FOR_EACH_requires_variadic_macros_support
 185 #endif /* HAVE_VARIADIC_MACROS */
 186
 187 #endif /* _WX_CPP_H_ */
 188