DtSTLUtilities.h

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/****************************************************************************** 
** Copyright (c) 2017 MAK Technologies, Inc. 
** All rights reserved. 
******************************************************************************/ 

#pragma once

#include <boost/unordered_map.hpp>
#include <boost/unordered_set.hpp>

#include <utility>
#include <functional>
#include <map>
#include <vector>
#include <list>

namespace makVrv
{
   template<typename P>
   struct extract_first
   {
      const typename P::first_type&
         operator()(const P& p) const
      {
         return p.first;
      }
   };

   template<typename P>
   struct extract_second
   {
      const typename P::second_type&
         operator()(const P& p) const
      {
         return p.second;
      }
   };

   template<class _Fn>
   class binderNoArgs
      : public std::unary_function<typename _Fn::argument_type, typename _Fn::result_type>
   {  // functor adapter _Func(stored, right)
   public:
      typedef std::unary_function<typename _Fn::argument_type,
         typename _Fn::result_type> _Base;
      typedef typename _Base::argument_type argument_type;
      typedef typename _Base::result_type result_type;

      binderNoArgs(const _Fn& _Func,
         const typename _Fn::argument_type& _Left)
         : op(_Func), value(_Left)
      {  // construct from functor and left operand
      }

      result_type operator()(void) const
      {  // apply functor to operands
         return (op(value));
      }

      result_type operator()(void) 
      {  // apply functor to operands
         return (op(value));
      }

   protected:
      _Fn op;  // the functor to apply
      typename _Fn::argument_type value;  // the left operand
   };

   // TEMPLATE FUNCTION bind (based upon std::bind1st)
   template<class _Fn,
   class _Ty> inline
      binderNoArgs<_Fn> bind(const _Fn& _Func, const _Ty& _Left)
   {  // return a binderNoArgs functor adapter
      typename _Fn::argument_type _Val(_Left);
      return (binderNoArgs<_Fn>(_Func, _Val));
   }


   template <class T> struct DeletePtr
   {
      void operator()(T* obj)
      {
         delete obj;
      }
   };

   template <class T>
   void verify_index_for_container(size_t index, const T& t)
   {
#ifndef _DEBUG
      static_cast<void>(t);
      static_cast<void>(index);
#endif
      Assert((index==0&&t.size()==1)
         || (t.size()>1 && index<=t.size()-1));
   }

   template <class C, class T> void destroy_from_container(C& _container, T* pT)
   {
      typename C::iterator it = std::find(_container.begin(), _container.end(), pT);
      if (it!=_container.end())
      {
         delete pT;pT=0;
         _container.erase(it);
      }
   }

   template <class C, class T> void remove_from_container(C& _container, T* pT)
   {
      typename C::iterator it = std::find(_container.begin(), _container.end(), pT);
      if (it!=_container.end())
      {
         delete pT;pT=0;
         _container.erase(it);
      }
   }

   template <class K, class T> T* get_from_map(std::map<K, T*>& _map, const K& key)
   {
      typename std::map<K, T*>::const_iterator it = _map.find(key);
      if (it==_map.end())
         return 0;
      return it->second;
   }

   template <class K, class T> void destroy_from_map(std::map<K, T*>& _map, const K& key)
   {
      typename std::map<K, T*>::iterator it = _map.find(key);
      Assert(it!=_map.end());

      T* pT= it->second;

      _map.erase(key);

      delete pT; pT = 0;
   }

   template <class T> void destroy_all_from_vector(std::vector<T*>& _vector)
   {
      while(_vector.empty()==false)
      {
         makVrv::destroy_from_container(_vector, *_vector.begin());
      }
   };

   template <class T> void destroy_all_from_list(std::list<T*>& _list)
   {
      while(_list.empty()==false)
      {
         makVrv::destroy_from_container(_list, *_list.begin());
      }
   }

   template <class T> void destroy_all_from_unordered_set(boost::unordered_set<T*>& _set)
   {
      while(_set.empty()==false)
      {
         makVrv::destroy_from_container(_set, *_set.begin());
      }
   }

   template <class K, class T> void destroy_all_from_map(std::map<K, T*>& _map)
   {
      while(_map.empty()==false)
      {
         typename std::map<K, T*>::iterator it = _map.begin();

         T* pT = it->second;
         delete pT; pT = 0;

         _map.erase(it);
      }
      _map.clear();
   }

   template <class T> T* get_nth_item(boost::unordered_set<T*>& _set, size_t index)
   {
      if (_set.empty())
         return 0;

      makVrv::verify_index_for_container(index, _set);

      typename std::list<T*>::const_iterator it = _set.begin();
      std::advance(it, index);
      return *it;
   }

   template <class T> T* get_nth_item(std::list<T*>& _list, size_t index)
   {
      if (_list.empty())
         return 0;

      makVrv::verify_index_for_container(index, _list);

      typename std::list<T*>::const_iterator it = _list.begin();
      std::advance(it, index);
      return *it;
   }

   template <class T> const T* get_nth_item(const std::list<T*>& _list, size_t index)
   {
      if (_list.empty())
         return 0;

      makVrv::verify_index_for_container(index, _list);

      typename std::list<T*>::const_iterator it = _list.begin();
      std::advance(it, index);
      return *it;
   }

   template <class T> T* get_nth_item(std::vector<T*>& _vector, size_t index)
   {
      if (_vector.empty())
         return 0;

      makVrv::verify_index_for_container(index, _vector);

      return _vector[index];
   }

   template <class T> T* get_nth_item(const std::vector<T*>& _vector, size_t index)
   {
      if (_vector.empty())
         return 0;

      makVrv::verify_index_for_container(index, _vector);

      return _vector[index];
   }

   template <class K, class T> T* get_nth_item(std::map<K, T*>& _map, size_t index)
   {
      if (_map.empty())
         return 0;

      makVrv::verify_index_for_container(index, _map);

      typename std::map<K, T*>::const_iterator it = _map.begin();
      std::advance(it, index);
      return it->second;
   }

   template <class K, class T> T* get_nth_item(const std::map<K, T*>& _map, size_t index)
   {
      if (_map.empty())
         return 0;

      makVrv::verify_index_for_container(index, _map);

      typename std::map<K, T*>::const_iterator it = _map.begin();
      std::advance(it, index);
      return it->second;
   }
}