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  1. #include <iostream>
  2. #include <cstdlib>
  3. #include <cstdio>
  4. #include <vector>
  5.  
  6. using namespace std;
  7.  
  8. class Query;
  9.  
  10. class IFilter
  11. {
  12. public:
  13.   virtual void modifyQuery(Query* query) = 0;
  14. };
  15.  
  16. template <typename T>
  17. class Filter : public IFilter
  18. {
  19. public:
  20.   virtual void modifyQuery(Query* query);
  21. };
  22.  
  23. class DateFilter;
  24. class NameFilter;
  25.  
  26. class Query
  27. {
  28. public:
  29.  
  30.   void applyFilter(IFilter* filter)
  31.   {
  32.     cout << "applying Filter" << endl;
  33.     filter->modifyQuery(this);
  34.   }
  35.  
  36.   void applyFilter(NameFilter* filter)
  37.   {
  38.     cout << "applying NameFilter" << endl;
  39.   }
  40.  
  41.   void applyFilter(DateFilter* filter)
  42.   {
  43.     cout << "applying DateFilter" << endl;
  44.   }
  45. };
  46.  
  47. template <typename T>
  48. void Filter<T>::modifyQuery(Query* query)
  49. {
  50.   query->applyFilter(dynamic_cast<T*> (this));
  51. }
  52.  
  53. class DateFilter : public Filter<DateFilter>
  54. {
  55. };
  56.  
  57. class NameFilter : public Filter<NameFilter>
  58. {
  59. };
  60.  
  61. int main()
  62. {
  63.   Query* query = new Query();
  64.   IFilter* nameFilter = new NameFilter();
  65.   IFilter* dateFilter = new DateFilter();
  66.  
  67.   std::vector<IFilter*> filterList;
  68.   filterList.push_back(nameFilter);
  69.   filterList.push_back(dateFilter);
  70.  
  71.   for (int i = 0; i < 2; ++i)
  72.   {
  73.     query->applyFilter(filterList[i]);
  74.   }
  75.   return 0;
  76. }
Success #stdin #stdout 0.02s 2860KB
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stdin
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Standard input is empty
stdout
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applying Filter
applying NameFilter
applying Filter
applying DateFilter
https://ideone.com/SLWUQT
language:
C++ (gcc 8.3)
created:
11 years ago
visibility:
public

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