#include <vector>
#include <utility>
#include <iostream>
template <class RandomAccessCollection>
class RandomAccessContextIterator {
public:
RandomAccessContextIterator( RandomAccessCollection &c, size_t index ):
m_collection ( c ),
m_index ( index )
{}
std::pair<size_t, typename RandomAccessCollection::value_type&> operator*() {
return { m_index, m_collection[m_index] };
}
void operator++() {
++m_index;
}
bool operator!=( RandomAccessContextIterator const &other ) const {
return m_index != other.m_index;
}
private:
size_t m_index;
RandomAccessCollection &m_collection;
};
template <class RandomAccessCollection>
class RandomAccessContext {
public:
RandomAccessContext( RandomAccessCollection &c ):
m_collection ( c )
{}
RandomAccessContextIterator<RandomAccessCollection> begin() {
return { m_collection, 0 };
}
RandomAccessContextIterator<RandomAccessCollection> end() {
return { m_collection, m_collection.size() };
}
private:
RandomAccessCollection &m_collection;
};
template <class T>
class Vector : public std::vector<T> {
public:
Vector( std::initializer_list<T> list ):
std::vector<T>( list )
{}
auto context() {
return RandomAccessContext( *this );
}
};
int main( int argc, char **argv )
{
Vector v = { "Never", "gonna", "give", "you", "up" };
for ( auto &&[i,e] : v.context() )
std::cout << "Element at index " << i << " has value: " << e << "\n";
return 0;
}
