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File indexing completed on 2023-03-17 10:49:27
0001 #ifndef DataFormats_Common_traits_h 0002 #define DataFormats_Common_traits_h 0003 0004 /*---------------------------------------------------------------------- 0005 0006 Definition of traits templates used in the EDM. 0007 0008 0009 ----------------------------------------------------------------------*/ 0010 0011 #include <deque> 0012 #include <limits> 0013 #include <list> 0014 #include <set> 0015 #include <string> 0016 #include <utility> 0017 #include <vector> 0018 0019 namespace edm { 0020 //------------------------------------------------------------ 0021 // 0022 // The trait struct template key_traits<K> is used to carry 0023 // information relevant to the type K when used as a 'key' in 0024 // RefVector and its related classes and templates. 0025 // 0026 // The general case works only for integral types K; for more 0027 // 'esoteric' types, one must introduce an explicit specialization. 0028 // That specialization must initialize the static data member 0029 // 'value'. 0030 0031 template <class K> 0032 struct key_traits { 0033 typedef K key_type; 0034 static const key_type value; 0035 }; 0036 0037 template <class K> 0038 typename key_traits<K>::key_type const key_traits<K>::value = 0039 std::numeric_limits<typename key_traits<K>::key_type>::max(); 0040 0041 // Partial specialization for std::pair 0042 0043 template <class U, class V> 0044 struct key_traits<std::pair<U, V> > { 0045 typedef std::pair<U, V> key_type; 0046 static const key_type value; 0047 }; 0048 0049 template <class U, class V> 0050 typename key_traits<std::pair<U, V> >::key_type const key_traits<std::pair<U, V> >::value = 0051 std::make_pair(key_traits<U>::value, key_traits<V>::value); 0052 0053 // If we ever need to support instantiations of std::basic_string 0054 // other than std::string, this is the place to do it. 0055 0056 // For value, we make a 1-character long string that contains an 0057 // unprintable character; we are hoping nobody ever uses such a 0058 // string as a legal key. 0059 template <> 0060 struct key_traits<std::string> { 0061 typedef std::string key_type; 0062 static const key_type value; 0063 }; 0064 0065 //------------------------------------------------------------ 0066 // 0067 // DoNotSortUponInsertion is a base class. Derive your own class X 0068 // from DoNotSortUponInsertion when: 0069 // 0070 // 1. You want to use DetSetVector<X> as an EDProduct, but 0071 // 0072 // 2. You do *not* want the Event::put member template to cause the 0073 // DetSet<X> instances within the DetSetVector<X> to be sorted. 0074 // 0075 // DoNotSortUponInsertion has no behavior; it is used at compile 0076 // time to influence the behavior of Event::put. 0077 // 0078 // Usage: 0079 // class MyClass : public edm::DoNotSortUponInsertion { ... } 0080 // 0081 struct DoNotSortUponInsertion {}; 0082 0083 //------------------------------------------------------------ 0084 // 0085 // DoNotRecordParents is a base class. Derive your own (EDProduct) 0086 // class X from DoNotRecordParents when your class already keeps all 0087 // data that are relevant to parentage internally, and the 0088 // information kept by the event model would thus be redundant. 0089 // 0090 // DoNotRecordParents has no behavior; it is used at compile time to 0091 // influence the behavior of Event::put. 0092 // 0093 // Usage: 0094 // class MyClass : public edm::DoNotRecordParents { ... } 0095 struct DoNotRecordParents {}; 0096 0097 // Other is a base class. NEVER USE IT. It is for the 0098 // core of the event model only. 0099 struct Other {}; 0100 0101 //------------------------------------------------------------ 0102 // 0103 // The trait struct template has_fillView<T> is used to 0104 // indicate whether or not the type T has a member function 0105 // 0106 // void T::fillView(std::vector<void const*>&) const 0107 // 0108 // We assume the 'general case' for T is to not support fillView. 0109 // Classes which do support fillView must specialize this trait. 0110 // 0111 //------------------------------------------------------------ 0112 0113 template <class T> 0114 struct has_fillView { 0115 static bool const value = false; 0116 }; 0117 0118 template <class T, class A> 0119 struct has_fillView<std::vector<T, A> > { 0120 static bool const value = true; 0121 }; 0122 0123 template <class A> 0124 struct has_fillView<std::vector<bool, A> > { 0125 static bool const value = false; 0126 }; 0127 0128 template <class T, class A> 0129 struct has_fillView<std::list<T, A> > { 0130 static bool const value = true; 0131 }; 0132 0133 template <class T, class A> 0134 struct has_fillView<std::deque<T, A> > { 0135 static bool const value = true; 0136 }; 0137 0138 template <class T, class A> 0139 struct has_fillView<std::set<T, A> > { 0140 static bool const value = true; 0141 }; 0142 0143 //------------------------------------------------------------ 0144 // 0145 // The trait struct template has_setPtr<T> is used to 0146 // indicate whether or not the type T has a member function 0147 // 0148 // void T::setPtr(const std::type_info&, void const*&) const 0149 // 0150 // We assume the 'general case' for T is to not support setPtr. 0151 // Classes which do support setPtr must specialize this trait. 0152 // 0153 //------------------------------------------------------------ 0154 0155 template <class T> 0156 struct has_setPtr { 0157 static bool const value = false; 0158 }; 0159 0160 template <class T, class A> 0161 struct has_setPtr<std::vector<T, A> > { 0162 static bool const value = true; 0163 }; 0164 0165 template <class A> 0166 struct has_setPtr<std::vector<bool, A> > { 0167 static bool const value = false; 0168 }; 0169 0170 template <class T, class A> 0171 struct has_setPtr<std::list<T, A> > { 0172 static bool const value = true; 0173 }; 0174 0175 template <class T, class A> 0176 struct has_setPtr<std::deque<T, A> > { 0177 static bool const value = true; 0178 }; 0179 0180 template <class T, class A> 0181 struct has_setPtr<std::set<T, A> > { 0182 static bool const value = true; 0183 }; 0184 } // namespace edm 0185 0186 #endif
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