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Fix missing documentation for several GDI functions.
[wxWidgets.git] / include / wx / meta / if.h
1 /////////////////////////////////////////////////////////////////////////////
2 // Name: wx/meta/if.h
3 // Purpose: declares wxIf<> metaprogramming construct
4 // Author: Vaclav Slavik
5 // Created: 2008-01-22
6 // RCS-ID: $Id$
7 // Copyright: (c) 2008 Vaclav Slavik
8 // Licence: wxWindows licence
9 /////////////////////////////////////////////////////////////////////////////
10
11 #ifndef _WX_META_IF_H_
12 #define _WX_META_IF_H_
13
14 #include "wx/defs.h"
15
16 // NB: This code is intentionally written without partial templates
17 // specialization, because some older compilers (notably VC6) don't
18 // support it.
19
20 namespace wxPrivate
21 {
22
23 template <bool Cond>
24 struct wxIfImpl
25
26 // broken VC6 needs not just an incomplete template class declaration but a
27 // "skeleton" declaration of the specialized versions below as it apparently
28 // tries to look up the types in the generic template definition at some moment
29 // even though it ends up by using the correct specialization in the end -- but
30 // without this skeleton it doesn't recognize Result as a class at all below
31 #if defined(__VISUALC__) && !wxCHECK_VISUALC_VERSION(7)
32 {
33 template<typename TTrue, typename TFalse> struct Result {};
34 }
35 #endif // VC++ <= 6
36 ;
37
38 // specialization for true:
39 template <>
40 struct wxIfImpl<true>
41 {
42 template<typename TTrue, typename TFalse> struct Result
43 {
44 typedef TTrue value;
45 };
46 };
47
48 // specialization for false:
49 template<>
50 struct wxIfImpl<false>
51 {
52 template<typename TTrue, typename TFalse> struct Result
53 {
54 typedef TFalse value;
55 };
56 };
57
58 } // namespace wxPrivate
59
60 // wxIf<> template defines nested type "value" which is the same as
61 // TTrue if the condition Cond (boolean compile-time constant) was met and
62 // TFalse if it wasn't.
63 //
64 // See wxVector<T> in vector.h for usage example
65 template<bool Cond, typename TTrue, typename TFalse>
66 struct wxIf
67 {
68 typedef typename wxPrivate::wxIfImpl<Cond>
69 ::template Result<TTrue, TFalse>::value
70 value;
71 };
72
73 #endif // _WX_META_IF_H_