Adding factories

lib/qcd/modules/Factory.h

@@ -0,0 +1,100 @@
+/*************************************************************************************
+Grid physics library, www.github.com/paboyle/Grid 
+Source file: extras/Hadrons/Factory.hpp
+
+Copyright (C) 2015
+Copyright (C) 2016
+
+Author: Antonin Portelli <antonin.portelli@me.com>
+
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2 of the License, or
+(at your option) any later version.
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+You should have received a copy of the GNU General Public License along
+with this program; if not, write to the Free Software Foundation, Inc.,
+51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+See the full license in the file "LICENSE" in the top level distribution directory
+*************************************************************************************/
+/*  END LEGAL */
+
+#ifndef Factory_hpp_
+#define Factory_hpp_
+
+
+namespace Grid{
+
+/******************************************************************************
+ *                        abstract factory class                              *
+ ******************************************************************************/
+template <typename T, typename ProductCreator>
+class Factory
+{
+public:
+    typedef std::function< std::unique_ptr<T> (const ProductCreator&)> Func;
+public:
+    // constructor
+    Factory(void) = default;
+    // destructor
+    virtual ~Factory(void) = default;
+    // registration
+    void registerBuilder(const std::string type, const Func &f);
+    // get builder list
+    std::vector<std::string> getBuilderList(void) const;
+    // factory
+    std::unique_ptr<T> create(const std::string type,
+              const ProductCreator& name) const;
+private:
+    std::map<std::string, Func> builder_;
+};
+
+/******************************************************************************
+ *                         template implementation                            *
+ ******************************************************************************/
+// registration ////////////////////////////////////////////////////////////////
+template <typename T, typename ProductCreator>
+void Factory<T, ProductCreator>::registerBuilder(const std::string type, const Func &f)
+{
+    builder_[type] = f;
+}
+
+// get module list /////////////////////////////////////////////////////////////
+template <typename T, typename ProductCreator>
+std::vector<std::string> Factory<T, ProductCreator>::getBuilderList(void) const
+{
+    std::vector<std::string> list;
+    
+    for (auto &b: builder_)
+    {
+        list.push_back(b.first);
+    }
+    
+    return list;
+}
+
+// factory /////////////////////////////////////////////////////////////////////
+template <typename T, typename ProductCreator>
+std::unique_ptr<T> Factory<T, ProductCreator>::create(const std::string type,
+                                      const ProductCreator& name) const
+{
+    Func func;
+    
+    try
+    {
+        func = builder_.at(type);
+    }
+    catch (std::out_of_range &)
+    {
+        //HADRON_ERROR("object of type '" + type + "' unknown");
+    }
+    
+    return func(name);
+}
+
+}
+
+#endif // Factory_hpp_