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@wxwidgets.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 Helper macros for wxMAKE_UNIQUE_NAME: normally this works by appending the 46 current line number to the given identifier to reduce the probability of the 47 conflict (it may still happen if this is used in the headers, hence you 48 should avoid doing it or provide unique prefixes then) but we have to do it 49 differently for VC++ 50 */ 51 #if defined(__VISUALC__) 52 /* 53 __LINE__ handling is completely broken in VC++ when using "Edit and 54 Continue" (/ZI option) and results in preprocessor errors if we use it 55 inside the macros. Luckily VC7 has another standard macro which can be 56 used like this and is even better than __LINE__ because it is globally 57 unique. 58 */ 59 # define wxCONCAT_LINE(text) wxCONCAT(text, __COUNTER__) 60 #else /* normal compilers */ 61 # define wxCONCAT_LINE(text) wxCONCAT(text, __LINE__) 62 #endif 63 64 /* Create a "unique" name with the given prefix */ 65 #define wxMAKE_UNIQUE_NAME(text) wxCONCAT_LINE(text) 66 67 /* 68 This macro can be passed as argument to another macro when you don't have 69 anything to pass in fact. 70 */ 71 #define wxEMPTY_PARAMETER_VALUE /* Fake macro parameter value */ 72 73 /* 74 Helpers for defining macros that expand into a single statement. 75 76 The standard solution is to use "do { ... } while (0)" statement but MSVC 77 generates a C4127 "condition expression is constant" warning for it so we 78 use something which is just complicated enough to not be recognized as a 79 constant but still simple enough to be optimized away. 80 81 Another solution would be to use __pragma() to temporarily disable C4127. 82 83 Notice that wxASSERT_ARG_TYPE in wx/strvargarg.h relies on these macros 84 creating some kind of a loop because it uses "break". 85 */ 86 #define wxSTATEMENT_MACRO_BEGIN do { 87 #define wxSTATEMENT_MACRO_END } while ( (void)0, 0 ) 88 89 /* 90 Helper for executing the following statement conditionally without using 91 conditional statements. 92 93 This strange macro is needed in the first place to avoid the problems due 94 to nested if/else inside macros. E.g. if some MACRO started with "if", then 95 96 if ( cond ) 97 MACRO(); 98 else 99 ... 100 101 would be broken because "..." would bind to the wrong "if" inside the macro 102 rather than the visible one. So we use wxDO_IF() inside the macro instead 103 to avoid this problem. 104 */ 105 #define wxDO_IF_HELPER(loopvar, condition) \ 106 for ( bool loopvar = false; !loopvar && condition; loopvar = true ) 107 108 #define wxDO_IF(condition) wxDO_IF_HELPER(wxMAKE_UNIQUE_NAME(wxdoif), condition) 109 110 /* 111 Define __WXFUNCTION__ which is like standard __FUNCTION__ but defined as 112 NULL for the compilers which don't support the latter. 113 */ 114 #ifndef __WXFUNCTION__ 115 #if defined(__GNUC__) || \ 116 defined(__VISUALC__) || \ 117 defined(__FUNCTION__) 118 #define __WXFUNCTION__ __FUNCTION__ 119 #else 120 /* still define __WXFUNCTION__ to avoid #ifdefs elsewhere */ 121 #define __WXFUNCTION__ (NULL) 122 #endif 123 #endif /* __WXFUNCTION__ already defined */ 124 125 126 /* Auto-detect variadic macros support unless explicitly disabled. */ 127 #if !defined(HAVE_VARIADIC_MACROS) && !defined(wxNO_VARIADIC_MACROS) 128 /* Any C99 or C++11 compiler should have them. */ 129 #if (defined(__STDC_VERSION__) && __STDC_VERSION__ >= 199901L) || \ 130 (defined(__cplusplus) && __cplusplus >= 201103L) 131 #define HAVE_VARIADIC_MACROS 1 132 #elif defined(__GNUC__) 133 #define HAVE_VARIADIC_MACROS 1 134 #elif wxCHECK_VISUALC_VERSION(8) 135 #define HAVE_VARIADIC_MACROS 1 136 #endif 137 #endif /* !HAVE_VARIADIC_MACROS */ 138 139 140 141 #ifdef HAVE_VARIADIC_MACROS 142 143 /* 144 wxCALL_FOR_EACH(what, ...) calls the macro from its first argument, what(pos, x), 145 for every remaining argument 'x', with 'pos' being its 1-based index in 146 *reverse* order (with the last argument being numbered 1). 147 148 For example, wxCALL_FOR_EACH(test, a, b, c) expands into this: 149 150 test(3, a) \ 151 test(2, b) \ 152 test(1, c) 153 154 Up to eight arguments are supported. 155 156 (With thanks to https://groups.google.com/d/topic/comp.std.c/d-6Mj5Lko_s/discussion 157 and https://stackoverflow.com/questions/1872220/is-it-possible-to-iterate-over-arguments-in-variadic-macros) 158 */ 159 #define wxCALL_FOR_EACH_NARG(...) wxCALL_FOR_EACH_NARG_((__VA_ARGS__, wxCALL_FOR_EACH_RSEQ_N())) 160 #define wxCALL_FOR_EACH_NARG_(args) wxCALL_FOR_EACH_ARG_N args 161 #define wxCALL_FOR_EACH_ARG_N(_1, _2, _3, _4, _5, _6, _7, _8, N, ...) N 162 #define wxCALL_FOR_EACH_RSEQ_N() 8, 7, 6, 5, 4, 3, 2, 1, 0 163 164 #define wxCALL_FOR_EACH_1_(args) wxCALL_FOR_EACH_1 args 165 #define wxCALL_FOR_EACH_2_(args) wxCALL_FOR_EACH_2 args 166 #define wxCALL_FOR_EACH_3_(args) wxCALL_FOR_EACH_3 args 167 #define wxCALL_FOR_EACH_4_(args) wxCALL_FOR_EACH_4 args 168 #define wxCALL_FOR_EACH_5_(args) wxCALL_FOR_EACH_5 args 169 #define wxCALL_FOR_EACH_6_(args) wxCALL_FOR_EACH_6 args 170 #define wxCALL_FOR_EACH_7_(args) wxCALL_FOR_EACH_7 args 171 #define wxCALL_FOR_EACH_8_(args) wxCALL_FOR_EACH_8 args 172 173 #define wxCALL_FOR_EACH_1(what, x) what(1, x) 174 #define wxCALL_FOR_EACH_2(what, x, ...) what(2, x) wxCALL_FOR_EACH_1_((what, __VA_ARGS__)) 175 #define wxCALL_FOR_EACH_3(what, x, ...) what(3, x) wxCALL_FOR_EACH_2_((what, __VA_ARGS__)) 176 #define wxCALL_FOR_EACH_4(what, x, ...) what(4, x) wxCALL_FOR_EACH_3_((what, __VA_ARGS__)) 177 #define wxCALL_FOR_EACH_5(what, x, ...) what(5, x) wxCALL_FOR_EACH_4_((what, __VA_ARGS__)) 178 #define wxCALL_FOR_EACH_6(what, x, ...) what(6, x) wxCALL_FOR_EACH_5_((what, __VA_ARGS__)) 179 #define wxCALL_FOR_EACH_7(what, x, ...) what(7, x) wxCALL_FOR_EACH_6_((what, __VA_ARGS__)) 180 #define wxCALL_FOR_EACH_8(what, x, ...) what(8, x) wxCALL_FOR_EACH_7_((what, __VA_ARGS__)) 181 182 #define wxCALL_FOR_EACH_(N, args) \ 183 wxCONCAT(wxCALL_FOR_EACH_, N) args 184 185 #define wxCALL_FOR_EACH(what, ...) \ 186 wxCALL_FOR_EACH_(wxCALL_FOR_EACH_NARG(__VA_ARGS__), (what, __VA_ARGS__)) 187 188 #else 189 #define wxCALL_FOR_EACH Error_wx_CALL_FOR_EACH_requires_variadic_macros_support 190 #endif /* HAVE_VARIADIC_MACROS */ 191 192 #endif /* _WX_CPP_H_ */ 193 194