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  1. #include <algorithm>
  2. #include <functional>
  3. #include <iostream>
  4. #include <vector>
  5. #include <iterator>
  6.  
  7. struct Foo
  8. {
  9.    int value;
  10.    Foo(int value) : value(value){};
  11. };
  12.  
  13. struct Bar
  14. {
  15.     std::vector<Foo> values;
  16.     size_t size_foo() const {return values.size();}
  17.     Foo& get_foo(size_t index) {return values[index];}
  18. };
  19.  
  20. template <typename TOuter, typename TInner> struct ContainerProxy;
  21.  
  22. template <typename TOuter, typename TInner>
  23. struct ContainerIterator : public std::iterator<std::input_iterator_tag, TInner>
  24. {
  25.     typedef std::function<TInner& (TOuter*, size_t)> getfunc_type;
  26.     TOuter& mContainerRef;
  27.     size_t mIndex;
  28.     getfunc_type mGetfunc;
  29.  
  30.     ContainerIterator(TOuter& containerRef, size_t index, getfunc_type const& getFunc)
  31. 	: mContainerRef(containerRef), mIndex(index), mGetfunc(getFunc)
  32.     {
  33.     }
  34.  
  35.     TInner& operator*() {return mGetfunc(&mContainerRef, mIndex);}
  36.     ContainerIterator<TOuter, TInner>& operator++() {++mIndex; return *this;}
  37.  
  38.     bool operator==(ContainerIterator<TOuter, TInner> const& rhs) const
  39.     {
  40.         return &mContainerRef==&rhs.mContainerRef &&
  41.                mIndex==rhs.mIndex;
  42.     }
  43.  
  44.     bool operator!=(ContainerIterator<TOuter, TInner> const& rhs) const
  45.     {
  46.         return !operator==(rhs);
  47.     }
  48. };
  49.  
  50. template <typename TOuter, typename TInner>
  51. struct ContainerProxy
  52. {
  53.     TOuter& mContainerRef;
  54.  
  55.     typedef std::function<size_t (TOuter*)> sizefunc_type;
  56.     sizefunc_type mSizefunc;
  57.  
  58.     typedef std::function<TInner& (TOuter*, size_t)> getfunc_type;
  59.     getfunc_type mGetfunc;
  60.  
  61.  
  62.     ContainerProxy(TOuter& containerRef, sizefunc_type sizefunc, getfunc_type getfunc) :
  63.         mContainerRef(containerRef), mSizefunc(sizefunc), mGetfunc(getfunc)
  64.     {
  65.     }
  66.  
  67.     ContainerIterator<TOuter, TInner> begin() const
  68.     {
  69.         return ContainerIterator<TOuter, TInner>(mContainerRef, 0, mGetfunc);
  70.     }
  71.  
  72.     ContainerIterator<TOuter, TInner> end() const
  73.     {
  74.         return ContainerIterator<TOuter, TInner>(mContainerRef, mSizefunc(&mContainerRef), mGetfunc);
  75.     }
  76. };
  77.  
  78.  
  79. int main()
  80. {
  81.     Bar b;
  82.     b.values.push_back(Foo(1));
  83.     b.values.push_back(Foo(2));
  84.  
  85.     ContainerProxy<Bar, Foo> proxy(b, &Bar::size_foo, &Bar::get_foo);
  86.  
  87.     std::for_each(proxy.begin(), proxy.end(), [](Foo& f) {std::cout<<f.value<<std::endl;});
  88. }
Success #stdin #stdout 0s 3064KB
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Standard input is empty
stdout 
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https://ideone.com/ulIC7
language:
C++14 (gcc 8.3)
created:
11 years ago
visibility:
public

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