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