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 /* wxCONCAT works like preprocessor ## operator but also works with macros */
  17 #define wxCONCAT_HELPER(text, line) text ## line
  18
  19 #define wxCONCAT(x1, x2) \
  20     wxCONCAT_HELPER(x1, x2)
  21 #define wxCONCAT3(x1, x2, x3) \
  22     wxCONCAT(wxCONCAT(x1, x2), x3)
  23 #define wxCONCAT4(x1, x2, x3, x4) \
  24     wxCONCAT(wxCONCAT3(x1, x2, x3), x4)
  25 #define wxCONCAT5(x1, x2, x3, x4, x5) \
  26     wxCONCAT(wxCONCAT4(x1, x2, x3, x4), x5)
  27 #define wxCONCAT6(x1, x2, x3, x4, x5, x6) \
  28     wxCONCAT(wxCONCAT5(x1, x2, x3, x4, x5), x6)
  29 #define wxCONCAT7(x1, x2, x3, x4, x5, x6, x7) \
  30     wxCONCAT(wxCONCAT6(x1, x2, x3, x4, x5, x6), x7)
  31 #define wxCONCAT8(x1, x2, x3, x4, x5, x6, x7, x8) \
  32     wxCONCAT(wxCONCAT7(x1, x2, x3, x4, x5, x6, x7), x8)
  33 #define wxCONCAT9(x1, x2, x3, x4, x5, x6, x7, x8, x9) \
  34     wxCONCAT(wxCONCAT8(x1, x2, x3, x4, x5, x6, x7, x8), x9)
  35
  36 /* wxSTRINGIZE works as the preprocessor # operator but also works with macros */
  37 #define wxSTRINGIZE_HELPER(x)       #x
  38 #define wxSTRINGIZE(x)              wxSTRINGIZE_HELPER(x)
  39
  40 /* a Unicode-friendly version of wxSTRINGIZE_T */
  41 #define wxSTRINGIZE_T(x)            wxAPPLY_T(wxSTRINGIZE(x))
  42
  43 /*
  44     Special workarounds for compilers with broken "##" operator. For all the
  45     other ones we can just use it directly.
  46  */
  47 #ifdef wxCOMPILER_BROKEN_CONCAT_OPER
  48     #define wxPREPEND_L(x)      L ## x
  49     #define wxAPPEND_i64(x)     x ## i64
  50     #define wxAPPEND_ui64(x)    x ## ui64
  51 #endif /* wxCOMPILER_BROKEN_CONCAT_OPER */
  52
  53 /*
  54    Helper macros for wxMAKE_UNIQUE_NAME: normally this works by appending the
  55    current line number to the given identifier to reduce the probability of the
  56    conflict (it may still happen if this is used in the headers, hence you
  57    should avoid doing it or provide unique prefixes then) but we have to do it
  58    differently for VC++
  59   */
  60 #if defined(__VISUALC__) && (__VISUALC__ >= 1300)
  61     /*
  62        __LINE__ handling is completely broken in VC++ when using "Edit and
  63        Continue" (/ZI option) and results in preprocessor errors if we use it
  64        inside the macros. Luckily VC7 has another standard macro which can be
  65        used like this and is even better than __LINE__ because it is globally
  66        unique.
  67      */
  68 #   define wxCONCAT_LINE(text)         wxCONCAT(text, __COUNTER__)
  69 #else /* normal compilers */
  70 #   define wxCONCAT_LINE(text)         wxCONCAT(text, __LINE__)
  71 #endif
  72
  73 /* Create a "unique" name with the given prefix */
  74 #define wxMAKE_UNIQUE_NAME(text)    wxCONCAT_LINE(text)
  75
  76 /*
  77    This macro can be passed as argument to another macro when you don't have
  78    anything to pass in fact.
  79  */
  80 #define wxEMPTY_PARAMETER_VALUE /* Fake macro parameter value */
  81
  82 /*
  83     Helpers for defining macros that expand into a single statement.
  84
  85     The standatd solution is to use "do { ... } while (0)" statement but MSVC
  86     generates a C4127 "condition expression is constant" warning for it so we
  87     use something which is just complicated enough to not be recognized as a
  88     constant but still simple enough to be optimized away.
  89
  90     Another solution would be to use __pragma() to temporarily disable C4127.
  91
  92     Notice that wxASSERT_ARG_TYPE in wx/strvargarg.h relies on these macros
  93     creating some kind of a loop because it uses "break".
  94  */
  95 #ifdef __WATCOMC__
  96     #define wxFOR_ONCE(name) for(int name=0; name<1; name++)
  97     #define wxSTATEMENT_MACRO_BEGIN wxFOR_ONCE(wxMAKE_UNIQUE_NAME(wxmacro)) {
  98     #define wxSTATEMENT_MACRO_END }
  99 #else
 100     #define wxSTATEMENT_MACRO_BEGIN  do {
 101     #define wxSTATEMENT_MACRO_END } while ( (void)0, 0 )
 102 #endif
 103
 104 /*
 105     Define __WXFUNCTION__ which is like standard __FUNCTION__ but defined as
 106     NULL for the compilers which don't support the latter.
 107  */
 108 #ifndef __WXFUNCTION__
 109     /* TODO: add more compilers supporting __FUNCTION__ */
 110     #if defined(__DMC__)
 111         /*
 112            __FUNCTION__ happens to be not defined within class members
 113            http://www.digitalmars.com/drn-bin/wwwnews?c%2B%2B.beta/485
 114         */
 115         #define __WXFUNCTION__ (NULL)
 116     #elif defined(__GNUC__) || \
 117           (defined(_MSC_VER) && _MSC_VER >= 1300) || \
 118           defined(__FUNCTION__)
 119         #define __WXFUNCTION__ __FUNCTION__
 120     #else
 121         /* still define __WXFUNCTION__ to avoid #ifdefs elsewhere */
 122         #define __WXFUNCTION__ (NULL)
 123     #endif
 124 #endif /* __WXFUNCTION__ already defined */
 125
 126
 127 #if (defined(__STDC_VERSION__) && __STDC_VERSION__ >= 199901L) || \
 128     (defined(__cplusplus) && __cplusplus >= 201103L)
 129     #define wxHAS_VARIADIC_MACROS
 130 #elif defined(__GNUC__) && __GNUC__ >= 3
 131     #define wxHAS_VARIADIC_MACROS
 132 #elif defined(_MSC_VER) && _MSC_VER >= 1400
 133     #define wxHAS_VARIADIC_MACROS
 134 #endif
 135
 136 #ifdef wxHAS_VARIADIC_MACROS
 137 /*
 138    wxCALL_FOR_EACH(what, ...) calls the macro from its first argument, what(pos, x),
 139    for every remaining argument 'x', with 'pos' being its 1-based index in
 140    *reverse* order (with the last argument being numbered 1).
 141
 142    For example, wxCALL_FOR_EACH(test, a, b, c) expands into this:
 143
 144        test(3, a) \
 145        test(2, b) \
 146        test(1, c)
 147
 148    Up to eight arguments are supported.
 149
 150    (With thanks to https://groups.google.com/d/topic/comp.std.c/d-6Mj5Lko_s/discussion
 151    and http://stackoverflow.com/questions/1872220/is-it-possible-to-iterate-over-arguments-in-variadic-macros)
 152 */
 153 #define wxCALL_FOR_EACH_NARG(...)   wxCALL_FOR_EACH_NARG_((__VA_ARGS__, wxCALL_FOR_EACH_RSEQ_N()))
 154 #define wxCALL_FOR_EACH_NARG_(args) wxCALL_FOR_EACH_ARG_N args
 155 #define wxCALL_FOR_EACH_ARG_N(_1, _2, _3, _4, _5, _6, _7, _8, N, ...) N
 156 #define wxCALL_FOR_EACH_RSEQ_N() 8, 7, 6, 5, 4, 3, 2, 1, 0
 157
 158 #define wxCALL_FOR_EACH_1(what, x)        what(1, x)
 159 #define wxCALL_FOR_EACH_2(what, x, ...)   what(2, x)  wxCALL_FOR_EACH_1(what,  __VA_ARGS__)
 160 #define wxCALL_FOR_EACH_3(what, x, ...)   what(3, x)  wxCALL_FOR_EACH_2(what,  __VA_ARGS__)
 161 #define wxCALL_FOR_EACH_4(what, x, ...)   what(4, x)  wxCALL_FOR_EACH_3(what,  __VA_ARGS__)
 162 #define wxCALL_FOR_EACH_5(what, x, ...)   what(5, x)  wxCALL_FOR_EACH_4(what,  __VA_ARGS__)
 163 #define wxCALL_FOR_EACH_6(what, x, ...)   what(6, x)  wxCALL_FOR_EACH_5(what,  __VA_ARGS__)
 164 #define wxCALL_FOR_EACH_7(what, x, ...)   what(7, x)  wxCALL_FOR_EACH_6(what,  __VA_ARGS__)
 165 #define wxCALL_FOR_EACH_8(what, x, ...)   what(8, x)  wxCALL_FOR_EACH_7(what,  __VA_ARGS__)
 166
 167 #define wxCALL_FOR_EACH_(N, args) \
 168     wxCONCAT(wxCALL_FOR_EACH_, N) args
 169
 170 #define wxCALL_FOR_EACH(what, ...) \
 171     wxCALL_FOR_EACH_(wxCALL_FOR_EACH_NARG(__VA_ARGS__), (what, __VA_ARGS__))
 172
 173 #else
 174     #define wxCALL_FOR_EACH  Error_wx_CALL_FOR_EACH_requires_variadic_macros_support
 175 #endif /* wxHAS_VARIADIC_MACROS */
 176
 177 #endif /* _WX_CPP_H_ */
 178