[80] | 1 | // |
---|
| 2 | // MetaObject.h |
---|
| 3 | // |
---|
| 4 | // $Id: //poco/1.3/Foundation/include/Poco/MetaObject.h#1 $ |
---|
| 5 | // |
---|
| 6 | // Library: Foundation |
---|
| 7 | // Package: SharedLibrary |
---|
| 8 | // Module: ClassLoader |
---|
| 9 | // |
---|
| 10 | // Definition of the MetaObject class. |
---|
| 11 | // |
---|
| 12 | // Copyright (c) 2004-2006, Applied Informatics Software Engineering GmbH. |
---|
| 13 | // and Contributors. |
---|
| 14 | // |
---|
| 15 | // Permission is hereby granted, free of charge, to any person or organization |
---|
| 16 | // obtaining a copy of the software and accompanying documentation covered by |
---|
| 17 | // this license (the "Software") to use, reproduce, display, distribute, |
---|
| 18 | // execute, and transmit the Software, and to prepare derivative works of the |
---|
| 19 | // Software, and to permit third-parties to whom the Software is furnished to |
---|
| 20 | // do so, all subject to the following: |
---|
| 21 | // |
---|
| 22 | // The copyright notices in the Software and this entire statement, including |
---|
| 23 | // the above license grant, this restriction and the following disclaimer, |
---|
| 24 | // must be included in all copies of the Software, in whole or in part, and |
---|
| 25 | // all derivative works of the Software, unless such copies or derivative |
---|
| 26 | // works are solely in the form of machine-executable object code generated by |
---|
| 27 | // a source language processor. |
---|
| 28 | // |
---|
| 29 | // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR |
---|
| 30 | // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, |
---|
| 31 | // FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT |
---|
| 32 | // SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE |
---|
| 33 | // FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE, |
---|
| 34 | // ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER |
---|
| 35 | // DEALINGS IN THE SOFTWARE. |
---|
| 36 | // |
---|
| 37 | |
---|
| 38 | |
---|
| 39 | #ifndef Foundation_MetaObject_INCLUDED |
---|
| 40 | #define Foundation_MetaObject_INCLUDED |
---|
| 41 | |
---|
| 42 | |
---|
| 43 | #include "Poco/Foundation.h" |
---|
| 44 | #include "Poco/Exception.h" |
---|
| 45 | #include "Poco/SingletonHolder.h" |
---|
| 46 | #include <set> |
---|
| 47 | |
---|
| 48 | |
---|
| 49 | namespace Poco { |
---|
| 50 | |
---|
| 51 | |
---|
| 52 | template <class B> |
---|
| 53 | class AbstractMetaObject |
---|
| 54 | /// A MetaObject stores some information |
---|
| 55 | /// about a C++ class. The MetaObject class |
---|
| 56 | /// is used by the Manifest class. |
---|
| 57 | /// AbstractMetaObject is a common base class |
---|
| 58 | /// for all MetaObject in a rooted class hierarchy. |
---|
| 59 | /// A MetaObject can also be used as an object |
---|
| 60 | /// factory for its class. |
---|
| 61 | { |
---|
| 62 | public: |
---|
| 63 | AbstractMetaObject(const char* name): _name(name) |
---|
| 64 | { |
---|
| 65 | } |
---|
| 66 | |
---|
| 67 | virtual ~AbstractMetaObject() |
---|
| 68 | { |
---|
| 69 | for (typename ObjectSet::iterator it = _deleteSet.begin(); it != _deleteSet.end(); ++it) |
---|
| 70 | { |
---|
| 71 | delete *it; |
---|
| 72 | } |
---|
| 73 | } |
---|
| 74 | |
---|
| 75 | const char* name() const |
---|
| 76 | { |
---|
| 77 | return _name; |
---|
| 78 | } |
---|
| 79 | |
---|
| 80 | virtual B* create() const = 0; |
---|
| 81 | /// Create a new instance of a class. |
---|
| 82 | /// Cannot be used for singletons. |
---|
| 83 | |
---|
| 84 | virtual B& instance() const = 0; |
---|
| 85 | /// Returns a reference to the only instance |
---|
| 86 | /// of the class. Used for singletons only. |
---|
| 87 | |
---|
| 88 | virtual bool canCreate() const = 0; |
---|
| 89 | /// Returns true iff the create method can be used |
---|
| 90 | /// to create instances of the class. |
---|
| 91 | /// Returns false if the class is a singleton. |
---|
| 92 | |
---|
| 93 | virtual void destroy(B* pObject) const |
---|
| 94 | /// If pObject was owned by meta object, the |
---|
| 95 | /// ownership of the deleted object is removed |
---|
| 96 | /// and the object is deleted. |
---|
| 97 | { |
---|
| 98 | typename ObjectSet::iterator it = _deleteSet.find(pObject); |
---|
| 99 | |
---|
| 100 | if (it != _deleteSet.end()) |
---|
| 101 | { |
---|
| 102 | _deleteSet.erase(pObject); |
---|
| 103 | delete pObject; |
---|
| 104 | } |
---|
| 105 | } |
---|
| 106 | |
---|
| 107 | B* autoDelete(B* pObject) const |
---|
| 108 | /// Give ownership of pObject to the meta object. |
---|
| 109 | /// The meta object will delete all objects it owns |
---|
| 110 | /// when it is destroyed. |
---|
| 111 | /// |
---|
| 112 | /// Returns pObject. |
---|
| 113 | { |
---|
| 114 | if (this->canCreate()) // guard against singleton |
---|
| 115 | { |
---|
| 116 | poco_check_ptr (pObject); |
---|
| 117 | _deleteSet.insert(pObject); |
---|
| 118 | } |
---|
| 119 | else throw InvalidAccessException("Cannot take ownership of", this->name()); |
---|
| 120 | |
---|
| 121 | return pObject; |
---|
| 122 | } |
---|
| 123 | |
---|
| 124 | virtual bool isAutoDelete(B* pObject) const |
---|
| 125 | /// Returns true if the object is owned |
---|
| 126 | /// by meta object. |
---|
| 127 | /// |
---|
| 128 | /// Overloaded in MetaSingleton - returns true |
---|
| 129 | /// if the class is a singleton. |
---|
| 130 | { |
---|
| 131 | return _deleteSet.find(pObject) != _deleteSet.end(); |
---|
| 132 | } |
---|
| 133 | |
---|
| 134 | private: |
---|
| 135 | AbstractMetaObject(); |
---|
| 136 | AbstractMetaObject(const AbstractMetaObject&); |
---|
| 137 | AbstractMetaObject& operator = (const AbstractMetaObject&); |
---|
| 138 | |
---|
| 139 | typedef std::set<B*> ObjectSet; |
---|
| 140 | |
---|
| 141 | const char* _name; |
---|
| 142 | mutable ObjectSet _deleteSet; |
---|
| 143 | }; |
---|
| 144 | |
---|
| 145 | |
---|
| 146 | template <class C, class B> |
---|
| 147 | class MetaObject: public AbstractMetaObject<B> |
---|
| 148 | /// A MetaObject stores some information |
---|
| 149 | /// about a C++ class. The MetaObject class |
---|
| 150 | /// is used by the Manifest class. |
---|
| 151 | /// A MetaObject can also be used as an object |
---|
| 152 | /// factory for its class. |
---|
| 153 | { |
---|
| 154 | public: |
---|
| 155 | MetaObject(const char* name): AbstractMetaObject<B>(name) |
---|
| 156 | { |
---|
| 157 | } |
---|
| 158 | |
---|
| 159 | ~MetaObject() |
---|
| 160 | { |
---|
| 161 | } |
---|
| 162 | |
---|
| 163 | B* create() const |
---|
| 164 | { |
---|
| 165 | return new C; |
---|
| 166 | } |
---|
| 167 | |
---|
| 168 | B& instance() const |
---|
| 169 | { |
---|
| 170 | throw InvalidAccessException("Not a singleton. Use create() to create instances of", this->name()); |
---|
| 171 | } |
---|
| 172 | |
---|
| 173 | bool canCreate() const |
---|
| 174 | { |
---|
| 175 | return true; |
---|
| 176 | } |
---|
| 177 | }; |
---|
| 178 | |
---|
| 179 | |
---|
| 180 | template <class C, class B> |
---|
| 181 | class MetaSingleton: public AbstractMetaObject<B> |
---|
| 182 | /// A SingletonMetaObject disables the create() method |
---|
| 183 | /// and instead offers an instance() method to access |
---|
| 184 | /// the single instance of its class. |
---|
| 185 | { |
---|
| 186 | public: |
---|
| 187 | MetaSingleton(const char* name): AbstractMetaObject<B>(name) |
---|
| 188 | { |
---|
| 189 | } |
---|
| 190 | |
---|
| 191 | ~MetaSingleton() |
---|
| 192 | { |
---|
| 193 | } |
---|
| 194 | |
---|
| 195 | B* create() const |
---|
| 196 | { |
---|
| 197 | throw InvalidAccessException("Cannot create instances of a singleton class. Use instance() to obtain a", this->name()); |
---|
| 198 | } |
---|
| 199 | |
---|
| 200 | bool canCreate() const |
---|
| 201 | { |
---|
| 202 | return false; |
---|
| 203 | } |
---|
| 204 | |
---|
| 205 | B& instance() const |
---|
| 206 | { |
---|
| 207 | return *_object.get(); |
---|
| 208 | } |
---|
| 209 | |
---|
| 210 | bool isAutoDelete(B* pObject) const |
---|
| 211 | { |
---|
| 212 | return true; |
---|
| 213 | } |
---|
| 214 | |
---|
| 215 | private: |
---|
| 216 | mutable SingletonHolder<C> _object; |
---|
| 217 | }; |
---|
| 218 | |
---|
| 219 | |
---|
| 220 | } // namespace Poco |
---|
| 221 | |
---|
| 222 | |
---|
| 223 | #endif // Foundation_MetaObject_INCLUDED |
---|