X-Git-Url: https://git.saurik.com/wxWidgets.git/blobdiff_plain/47eab2f2e5afa8cddeb5fac6a06b27edf3994d45..8e77fd8bca165aab9709649d79a7cbc6a172d4e1:/include/wx/cpp.h

diff --git a/include/wx/cpp.h b/include/wx/cpp.h
index fbcbcaa1fe..9fed106a76 100644
--- a/include/wx/cpp.h
+++ b/include/wx/cpp.h
@@ -79,6 +79,28 @@
  */
 #define wxEMPTY_PARAMETER_VALUE /* Fake macro parameter value */
 
+/*
+    Helpers for defining macros that expand into a single statement.
+
+    The standatd solution is to use "do { ... } while (0)" statement but MSVC
+    generates a C4127 "condition expression is constant" warning for it so we
+    use something which is just complicated enough to not be recognized as a
+    constant but still simple enough to be optimized away.
+
+    Another solution would be to use __pragma() to temporarily disable C4127.
+
+    Notice that wxASSERT_ARG_TYPE in wx/strvargarg.h relies on these macros
+    creating some kind of a loop because it uses "break".
+ */
+#ifdef __WATCOMC__
+    #define wxFOR_ONCE(name) for(int name=0; name<1; name++)
+    #define wxSTATEMENT_MACRO_BEGIN wxFOR_ONCE(wxMAKE_UNIQUE_NAME(wxmacro)) {
+    #define wxSTATEMENT_MACRO_END }
+#else
+    #define wxSTATEMENT_MACRO_BEGIN  do {
+    #define wxSTATEMENT_MACRO_END } while ( (void)0, 0 )
+#endif
+
 /*
     Define __WXFUNCTION__ which is like standard __FUNCTION__ but defined as
     NULL for the compilers which don't support the latter.
@@ -101,5 +123,56 @@
     #endif
 #endif /* __WXFUNCTION__ already defined */
 
+
+#if (defined(__STDC_VERSION__) && __STDC_VERSION__ >= 199901L) || \
+    (defined(__cplusplus) && __cplusplus >= 201103L)
+    #define wxHAS_VARIADIC_MACROS
+#elif defined(__GNUC__) && __GNUC__ >= 3
+    #define wxHAS_VARIADIC_MACROS
+#elif defined(_MSC_VER) && _MSC_VER >= 1400
+    #define wxHAS_VARIADIC_MACROS
+#endif
+
+#ifdef wxHAS_VARIADIC_MACROS
+/*
+   wxCALL_FOR_EACH(what, ...) calls the macro from its first argument, what(pos, x),
+   for every remaining argument 'x', with 'pos' being its 1-based index in
+   *reverse* order (with the last argument being numbered 1).
+
+   For example, wxCALL_FOR_EACH(test, a, b, c) expands into this:
+
+       test(3, a) \
+       test(2, b) \
+       test(1, c)
+
+   Up to eight arguments are supported.
+
+   (With thanks to https://groups.google.com/d/topic/comp.std.c/d-6Mj5Lko_s/discussion
+   and http://stackoverflow.com/questions/1872220/is-it-possible-to-iterate-over-arguments-in-variadic-macros)
+*/
+#define wxCALL_FOR_EACH_NARG(...)   wxCALL_FOR_EACH_NARG_((__VA_ARGS__, wxCALL_FOR_EACH_RSEQ_N()))
+#define wxCALL_FOR_EACH_NARG_(args) wxCALL_FOR_EACH_ARG_N args
+#define wxCALL_FOR_EACH_ARG_N(_1, _2, _3, _4, _5, _6, _7, _8, N, ...) N
+#define wxCALL_FOR_EACH_RSEQ_N() 8, 7, 6, 5, 4, 3, 2, 1, 0
+
+#define wxCALL_FOR_EACH_1(what, x)        what(1, x)
+#define wxCALL_FOR_EACH_2(what, x, ...)   what(2, x)  wxCALL_FOR_EACH_1(what,  __VA_ARGS__)
+#define wxCALL_FOR_EACH_3(what, x, ...)   what(3, x)  wxCALL_FOR_EACH_2(what,  __VA_ARGS__)
+#define wxCALL_FOR_EACH_4(what, x, ...)   what(4, x)  wxCALL_FOR_EACH_3(what,  __VA_ARGS__)
+#define wxCALL_FOR_EACH_5(what, x, ...)   what(5, x)  wxCALL_FOR_EACH_4(what,  __VA_ARGS__)
+#define wxCALL_FOR_EACH_6(what, x, ...)   what(6, x)  wxCALL_FOR_EACH_5(what,  __VA_ARGS__)
+#define wxCALL_FOR_EACH_7(what, x, ...)   what(7, x)  wxCALL_FOR_EACH_6(what,  __VA_ARGS__)
+#define wxCALL_FOR_EACH_8(what, x, ...)   what(8, x)  wxCALL_FOR_EACH_7(what,  __VA_ARGS__)
+
+#define wxCALL_FOR_EACH_(N, args) \
+    wxCONCAT(wxCALL_FOR_EACH_, N) args
+
+#define wxCALL_FOR_EACH(what, ...) \
+    wxCALL_FOR_EACH_(wxCALL_FOR_EACH_NARG(__VA_ARGS__), (what, __VA_ARGS__))
+
+#else
+    #define wxCALL_FOR_EACH  Error_wx_CALL_FOR_EACH_requires_variadic_macros_support
+#endif /* wxHAS_VARIADIC_MACROS */
+
 #endif /* _WX_CPP_H_ */