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functortraits.hxx
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3/* Copyright 1998-2005 by Ullrich Koethe */
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34/************************************************************************/
35
36
37#ifndef VIGRA_FUNCTORTRAITS_HXX
38#define VIGRA_FUNCTORTRAITS_HXX
39
40#include <functional>
41#include "metaprogramming.hxx"
42
43namespace vigra {
44
45struct InitializerTag {};
46struct UnaryFunctorTag {};
47struct BinaryFunctorTag {};
48struct TernaryFunctorTag {};
49struct UnaryAnalyserTag {};
50struct BinaryAnalyserTag {};
51struct TernaryAnalyserTag {};
52
53struct UnaryReduceFunctorTag
54: public InitializerTag, public UnaryAnalyserTag
55{};
56
57struct BinaryReduceFunctorTag
58: public InitializerTag, public BinaryAnalyserTag
59{};
60
61typedef UnaryFunctorTag UnaryExpandFunctorTag;
62typedef BinaryFunctorTag BinaryExpandFunctorTag;
63
64template <class T>
65class FunctorTraitsBase
66{
67 public:
68 typedef T type;
69
70 typedef typename IsDerivedFrom<T, InitializerTag>::result isInitializer;
71
72 typedef typename IsDerivedFrom<T, UnaryFunctorTag>::result isUnaryFunctor;
73 typedef typename IsDerivedFrom<T, BinaryFunctorTag>::result isBinaryFunctor;
74 typedef typename IsDerivedFrom<T, TernaryFunctorTag>::result isTernaryFunctor;
75
76 typedef typename IsDerivedFrom<T, UnaryAnalyserTag>::result isUnaryAnalyser;
77 typedef typename IsDerivedFrom<T, BinaryAnalyserTag>::result isBinaryAnalyser;
78 typedef typename IsDerivedFrom<T, TernaryAnalyserTag>::result isTernaryAnalyser;
79};
80
81
82
83/** \addtogroup Functors
84*/
85//@{
86/** \brief Export associated information for a functor.
87
88 The FunctorTraits class contains the following fields:
89
90 \code
91 template <class T>
92 struct FunctorTraits
93 {
94 typedef T type;
95
96 typedef ... isInitializer;
97
98 typedef ... isUnaryFunctor;
99 typedef ... isBinaryFunctor;
100 typedef ... isTernaryFunctor;
101
102 typedef ... isUnaryAnalyser;
103 typedef ... isBinaryAnalyser;
104 typedef ... isTernaryAnalyser;
105 };
106 \endcode
107
108 where the dots are either <tt>VigraTrueType</tt> or <tt>VigraFalseType</tt>
109 depending on whether the functor supports the respective functionality or not.
110 Note that these traits are automatically defined correctly when your functor is derived
111 from the appropriate functor tag classes:
112
113 \code
114 struct InitializerTag {};
115 struct UnaryFunctorTag {};
116 struct BinaryFunctorTag {};
117 struct TernaryFunctorTag {};
118 struct UnaryAnalyserTag {};
119 struct BinaryAnalyserTag {};
120 struct TernaryAnalyserTag {};
121 struct UnaryReduceFunctorTag : public InitializerTag, public UnaryAnalyserTag {};
122 struct BinaryReduceFunctorTag : public InitializerTag, public BinaryAnalyserTag {};
123 \endcode
124
125 If a functor <tt>f</tt> is a model of these categories, it supports the following
126 calls (<tt>v</tt> is a variable such that the result type of the functor
127 calls can be converted into <tt>v</tt>'s type, and <tt>a1, a2, a3</tt> are
128 variables convertible into the functor's argument types):
129
130 <DL>
131 <DT><b>Initializer</b>
132 <DD> <tt>v = f()</tt> (used with initImageWithFunctor())
133 <DT><b>UnaryFunctor</b>
134 <DD> <tt>v = f(a1)</tt> (used with transformImage())
135 <DT><b>BinaryFunctor</b>
136 <DD> <tt>v = f(a1, a2)</tt> (used with combineTwoImages())
137 <DT><b>TernaryFunctor</b>
138 <DD> <tt>v = f(a1, a2, a3)</tt> (used with combineThreeImages())
139 <DT><b>UnaryAnalyser</b>
140 <DD> <tt>f(a1)</tt> (return type <tt>void</tt>, used with inspectImage())
141 <DT><b>BinaryAnalyser</b>
142 <DD> <tt>f(a1, a2)</tt> (return type <tt>void</tt>, used with inspectTwoImages())
143 <DT><b>TernaryAnalyser</b>
144 <DD> <tt>f(a1, a2, a3)</tt> (return type <tt>void</tt>)
145 </DL>
146
147 It should be noted that the functor's argument and result types are not contained
148 in the traits class: Since the function calls are often member template functions in
149 VIGRA, many functors do not have fixed argument types. Neither are the result
150 types fixed in this case because they are computed (via a template meta-program)
151 from the argument types.
152
153 <b>\#include</b> <vigra/functortraits.hxx> <br/>
154 Namespace: vigra
155*/
156template <class T>
158: public FunctorTraitsBase<T>
159{};
160
161#define VIGRA_DEFINE_STL_FUNCTOR(name, unary, binary) \
162template <class T> \
163class FunctorTraits<name<T> > \
164{ \
165 public: \
166 typedef T type; \
167 \
168 typedef VigraFalseType isInitializer; \
169 \
170 typedef unary isUnaryFunctor; \
171 typedef binary isBinaryFunctor; \
172 typedef VigraFalseType isTernaryFunctor; \
173 \
174 typedef VigraFalseType isUnaryAnalyser; \
175 typedef VigraFalseType isBinaryAnalyser; \
176 typedef VigraFalseType isTernaryAnalyser; \
177};
178
179// ???TODO: these should also be specialized for the ptr_fun and mem_fun_ptr wrappers
180VIGRA_DEFINE_STL_FUNCTOR(std::plus, VigraFalseType, VigraTrueType)
181VIGRA_DEFINE_STL_FUNCTOR(std::minus, VigraFalseType, VigraTrueType)
182VIGRA_DEFINE_STL_FUNCTOR(std::multiplies, VigraFalseType, VigraTrueType)
183VIGRA_DEFINE_STL_FUNCTOR(std::divides, VigraFalseType, VigraTrueType)
184VIGRA_DEFINE_STL_FUNCTOR(std::modulus, VigraFalseType, VigraTrueType)
185VIGRA_DEFINE_STL_FUNCTOR(std::equal_to, VigraFalseType, VigraTrueType)
186VIGRA_DEFINE_STL_FUNCTOR(std::not_equal_to, VigraFalseType, VigraTrueType)
187VIGRA_DEFINE_STL_FUNCTOR(std::greater, VigraFalseType, VigraTrueType)
188VIGRA_DEFINE_STL_FUNCTOR(std::less, VigraFalseType, VigraTrueType)
189VIGRA_DEFINE_STL_FUNCTOR(std::greater_equal, VigraFalseType, VigraTrueType)
190VIGRA_DEFINE_STL_FUNCTOR(std::less_equal, VigraFalseType, VigraTrueType)
191VIGRA_DEFINE_STL_FUNCTOR(std::logical_and, VigraFalseType, VigraTrueType)
192VIGRA_DEFINE_STL_FUNCTOR(std::logical_or, VigraFalseType, VigraTrueType)
193VIGRA_DEFINE_STL_FUNCTOR(std::binary_negate, VigraFalseType, VigraTrueType)
194
195VIGRA_DEFINE_STL_FUNCTOR(std::negate, VigraTrueType, VigraFalseType)
196VIGRA_DEFINE_STL_FUNCTOR(std::logical_not, VigraTrueType, VigraFalseType)
197VIGRA_DEFINE_STL_FUNCTOR(std::unary_negate, VigraTrueType, VigraFalseType)
198#undef VIGRA_DEFINE_STL_FUNCTOR
199
200template <class R>
201class FunctorTraits<R (*)()>
202{
203 public:
204 typedef R (*type)();
205
206 typedef VigraTrueType isInitializer;
207 typedef VigraFalseType isUnaryFunctor;
208 typedef VigraFalseType isBinaryFunctor;
209 typedef VigraFalseType isTernaryFunctor;
210 typedef VigraFalseType isUnaryAnalyser;
211 typedef VigraFalseType isBinaryAnalyser;
212 typedef VigraFalseType isTernaryAnalyser;
213};
214
215template <class R, class T>
216class FunctorTraits<R (*)(T)>
217{
218 public:
219 typedef R (*type)(T);
220
221 typedef VigraFalseType isInitializer;
222 typedef VigraTrueType isUnaryFunctor;
223 typedef VigraFalseType isBinaryFunctor;
224 typedef VigraFalseType isTernaryFunctor;
225 typedef VigraFalseType isUnaryAnalyser;
226 typedef VigraFalseType isBinaryAnalyser;
227 typedef VigraFalseType isTernaryAnalyser;
228};
229
230template <class R, class T1, class T2>
231class FunctorTraits<R (*)(T1, T2)>
232{
233 public:
234 typedef R (*type)(T1, T2);
235
236 typedef VigraFalseType isInitializer;
237 typedef VigraFalseType isUnaryFunctor;
238 typedef VigraTrueType isBinaryFunctor;
239 typedef VigraFalseType isTernaryFunctor;
240 typedef VigraFalseType isUnaryAnalyser;
241 typedef VigraFalseType isBinaryAnalyser;
242 typedef VigraFalseType isTernaryAnalyser;
243};
244
245template <class R, class T1, class T2, class T3>
246class FunctorTraits<R (*)(T1, T2, T3)>
247{
248 public:
249 typedef R (*type)(T1, T2, T3);
250
251 typedef VigraFalseType isInitializer;
252 typedef VigraFalseType isUnaryFunctor;
253 typedef VigraFalseType isBinaryFunctor;
254 typedef VigraTrueType isTernaryFunctor;
255 typedef VigraFalseType isUnaryAnalyser;
256 typedef VigraFalseType isBinaryAnalyser;
257 typedef VigraFalseType isTernaryAnalyser;
258};
259
260//@}
261
262} // namespace vigra
263
264#endif // VIGRA_FUNCTORTRAITS_HXX
Export associated information for a functor.
Definition functortraits.hxx:159

© Ullrich Köthe (ullrich.koethe@iwr.uni-heidelberg.de)
Heidelberg Collaboratory for Image Processing, University of Heidelberg, Germany

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