range.hpp

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/*
 * iterator_range.hpp as proposed http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2012/n3350.html by Jeffrey Yasskin <jyasskin@google.com>
 */
 
#pragma once
 
#include <utility>
#include "iterator.hpp"
 
namespace ext {
 
template < typename Iterator >
class iterator_range {
    Iterator m_begin;
 
    Iterator m_end;
public:
    typedef Iterator iterator;
 
    typedef Iterator const_iterator;
 
    typedef typename std::iterator_traits< Iterator >::value_type value_type;
 
    iterator_range ( ) = default;
 
    constexpr iterator_range(Iterator begin, Iterator end) : m_begin ( begin ), m_end ( end ) {
    }
 
    constexpr Iterator begin() const {
        return m_begin;
    }
 
    constexpr Iterator end() const {
        return m_end;
    }
 
    constexpr typename std::iterator_traits< Iterator >::reference front() const {
        return * m_begin;
    }
 
    constexpr typename std::iterator_traits< Iterator >::reference back() const {
        return * ( m_end - 1 );
    }
 
    constexpr typename std::iterator_traits< Iterator >::reference operator[](typename std::iterator_traits< Iterator >::difference_type index) const {
        return m_begin [ index ];
    }
 
    constexpr bool empty() const {
        return m_begin == m_end;
    }
 
    constexpr size_t size() const {
        return std::distance ( m_begin, m_end );
    }
 
    void pop_front() {
        ++ m_begin;
    }
 
    void pop_front(typename std::iterator_traits< Iterator >::difference_type n) {
        m_begin = m_begin + n;
    }
 
    void pop_back() {
        -- m_end;
    }
 
    void pop_back(typename std::iterator_traits< Iterator >::difference_type n) {
        m_end = m_end - n;
    }
 
    std::pair< iterator_range, iterator_range > split(typename std::iterator_traits< Iterator >::difference_type index) const {
        return std::make_pair ( slice ( 0, index ), slice ( index, 0 ) );
    }
 
    iterator_range slice(typename std::iterator_traits< Iterator >::difference_type start, typename std::iterator_traits< Iterator >::difference_type stop) const {
        return iterator_range ( ( start >= 0 ? m_begin : m_end ) + start, ( stop > 0 ? m_begin : m_end ) + stop );
    }
 
    iterator_range slice( typename std::iterator_traits< Iterator >::difference_type start) const {
        return slice ( start, 0 );
    }
};
 
template < typename Iter >
iterator_range < Iter > make_iterator_range ( Iter begin, Iter end ) {
    return iterator_range < Iter > ( begin, end );
}
 
template <class Container>
auto range ( Container && cont ) -> decltype ( std::forward < Container > ( cont ).range ( ) ) {
    return ext::make_iterator_range ( std::forward < Container > ( cont ).begin ( ), std::forward < Container > ( cont ).end ( ) );
}
 
} /* namespace ext */