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  1. #include <vector> 
  2. #include <algorithm> 
  3. using namespace std; 
  4.  
  5. template <bool flag, class IsTrue, class IsFalse> 
  6. struct choose; 
  7.  
  8. template <class IsTrue, class IsFalse> 
  9. struct choose<true, IsTrue, IsFalse> { 
  10.    typedef IsTrue type; 
  11. }; 
  12.  
  13. template <class IsTrue, class IsFalse> 
  14. struct choose<false, IsTrue, IsFalse> { 
  15.    typedef IsFalse type; 
  16. }; 
  17.  
  18. class DefaultOrder { 
  19. public: 
  20.     bool operator()(int i1,int i2) {return i1 < i2;} 
  21. }; 
  22.  
  23. template<typename K, typename V, typename Order=DefaultOrder> 
  24. struct multimap { 
  25.     struct pair { 
  26.         pair(K key, V value):first(key),second(value) {} 
  27.         K first; 
  28.         V second; 
  29.         bool operator<(pair other) { 
  30.             Order order; 
  31.             return order(first,other.first); 
  32.         } 
  33.     }; 
  34.     template<bool isconst = false> 
  35.     struct Iterator { 
  36.         typedef typename choose<isconst, const pair&, pair&>::type 
  37.             reference; 
  38.         typedef typename choose<isconst, const pair*, pair*>::type 
  39.             pointer; 
  40.  
  41.         typedef typename vector<pair>::iterator it; 
  42.         struct ActualIterator { 
  43.             it i; 
  44.             vector<pair>& pairs; 
  45.             ActualIterator(vector<pair>& pairs,it i):pairs(pairs),i(i) {} 
  46.             bool operator!=(ActualIterator other) { 
  47.                 return i != other.i; 
  48.             } 
  49.             pair& operator*() { 
  50.                 auto& bla = *i; 
  51.                 return bla; 
  52.             } 
  53.             virtual ActualIterator& operator++() = 0; 
  54.         }; 
  55.         struct OneKeyIterator : public ActualIterator { 
  56.             K key; 
  57.             OneKeyIterator(vector<pair>& pairs, K key):ActualIterator(pairs,pairs.end()),key(key) { 
  58.                 auto end = pairs.end(); 
  59.                 for(auto i_ = pairs.begin(); i_ != end; ++i_) 
  60.                     if(i_->first == key) { 
  61.                         i = i_; 
  62.                         return; 
  63.                     } 
  64.             } 
  65.             ActualIterator& operator++() { 
  66.                 ++i; 
  67.                 if(i != pairs.end() && i->first != key) 
  68.                     i = pairs.end(); 
  69.                 return *this; 
  70.             } 
  71.         }; 
  72.         struct WholeMapIterator : public ActualIterator { 
  73.             WholeMapIterator(vector<pair>& pairs, it i):ActualIterator(pairs,i){} 
  74.             ActualIterator& operator++() { 
  75.                 ++i; 
  76.                 return *this; 
  77.             } 
  78.         }; 
  79.  
  80.         ActualIterator* actualIterator; 
  81.  
  82.         Iterator(vector<pair>& pairs, it i):actualIterator(new WholeMapIterator(pairs,i)) { 
  83.  
  84.         } 
  85.         Iterator(vector<pair>& pairs, K key):actualIterator(new OneKeyIterator(pairs,key)) { 
  86.         } 
  87.         Iterator(const Iterator<false>& i):actualIterator(i.actualIterator){} 
  88.         pointer operator->() { 
  89.             return &**actualIterator; 
  90.         } 
  91.         reference operator*() { 
  92.                 return *actualIterator; 
  93.         } 
  94.         Iterator& operator++() { 
  95.             ++(*actualIterator); 
  96.             return *this; 
  97.         } 
  98.         bool operator!=(const Iterator& other) const { 
  99.             return *actualIterator != *other.actualIterator; 
  100.         } 
  101.         bool operator==(const Iterator& other) const { 
  102.             return !(*this != other); 
  103.         } 
  104.     }; 
  105.  
  106.     typedef Iterator<false> MutableIterator; 
  107.     typedef Iterator<true> ConstIterator; 
  108.  
  109.     vector<pair> pairs; 
  110.     void insert(K key, V value) { 
  111.         pairs.push_back(pair(key,value)); 
  112.         sort(pairs.begin(), pairs.end()); 
  113.     } 
  114.     MutableIterator find(K key) { 
  115.         //auto end = pairs.end(); 
  116.         //for(auto i = pairs.begin(); i != end; ++i) 
  117.             //auto p = *i; 
  118.         //    if(i->first == key) { 
  119.                 return MutableIterator(pairs,key); 
  120.         //    } 
  121.     } 
  122.     MutableIterator begin() { 
  123.         return MutableIterator(pairs,pairs.begin()); 
  124.     } 
  125.     MutableIterator end() { 
  126.         return MutableIterator(pairs,pairs.end()); 
  127.     } 
  128. };
  129.  
  130. int main()
  131. {
  132.   multimap<int,int> mm;
  133. }
  134.  
Compilation error #stdin compilation error #stdout 0s 0KB
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Standard input is empty
compilation info 
prog.cpp:46:18: error: cannot declare parameter 'other' to be of abstract type 'multimap<K, V, Order>::Iterator<isconst>::ActualIterator'
prog.cpp:42:31: note:   because the following virtual functions are pure within 'multimap<K, V, Order>::Iterator<isconst>::ActualIterator':
prog.cpp:53:37: note: 	virtual multimap<K, V, Order>::Iterator<isconst>::ActualIterator& multimap<K, V, Order>::Iterator<isconst>::ActualIterator::operator++()
prog.cpp: In constructor 'multimap<K, V, Order>::Iterator<isconst>::OneKeyIterator::OneKeyIterator(std::vector<multimap<K, V, Order>::pair>&, K)':
prog.cpp:61:25: error: 'i' was not declared in this scope
prog.cpp: In member function 'multimap<K, V, Order>::Iterator<isconst>::ActualIterator& multimap<K, V, Order>::Iterator<isconst>::OneKeyIterator::operator++()':
prog.cpp:66:19: error: 'i' was not declared in this scope
prog.cpp: In member function 'multimap<K, V, Order>::Iterator<isconst>::ActualIterator& multimap<K, V, Order>::Iterator<isconst>::WholeMapIterator::operator++()':
prog.cpp:75:19: error: 'i' was not declared in this scope
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Standard output is empty
https://ideone.com/Df3jt
language:
C++14 (gcc 8.3)
created:
13 years ago
visibility:
public

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