language: C++ 4.7.2 (gcc-4.7.2)
date: 148 days 1 hour ago
link:
visibility: public 
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#include <iostream>
#include <cstdlib>
#include <cstdio>
#include <vector>
 
using namespace std;
 
class Query;
 
class IFilter
{
public:
  virtual void modifyQuery(Query* query) = 0;
};
 
template <typename T>
class Filter : public IFilter
{
public:
  virtual void modifyQuery(Query* query);
};
 
class DateFilter;
class NameFilter;
 
class Query
{
public:
 
  void applyFilter(IFilter* filter)
  {
    cout << "applying Filter" << endl;
    filter->modifyQuery(this);
  }
 
  void applyFilter(NameFilter* filter)
  {
    cout << "applying NameFilter" << endl;
  }
 
  void applyFilter(DateFilter* filter)
  {
    cout << "applying DateFilter" << endl;
  }
};
 
template <typename T>
void Filter<T>::modifyQuery(Query* query)
{
  query->applyFilter(dynamic_cast<T*> (this));
}
 
class DateFilter : public Filter<DateFilter>
{
};
 
class NameFilter : public Filter<NameFilter>
{
};
 
int main()
{
  Query* query = new Query();
  IFilter* nameFilter = new NameFilter();
  IFilter* dateFilter = new DateFilter();
 
  std::vector<IFilter*> filterList;
  filterList.push_back(nameFilter);
  filterList.push_back(dateFilter);
 
  for (int i = 0; i < 2; ++i)
  {
    query->applyFilter(filterList[i]);
  }
  return 0;
}