views.h

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/**********************************************************************
 * LeechCraft - modular cross-platform feature rich internet client.
 * Copyright (C) 2006-2014  Georg Rudoy
 *
 * Distributed under the Boost Software License, Version 1.0.
 * (See accompanying file LICENSE or copy at https://www.boost.org/LICENSE_1_0.txt)
 **********************************************************************/
 
#pragma once
 
#include <iterator>
#include <boost/iterator/zip_iterator.hpp>
#include <boost/range.hpp>
 
namespace LC
{
namespace Util
{
namespace Views
{
    namespace detail
    {
        template<template<typename, typename> class PairType, typename FirstIt, typename SecondIt>
        using ValueType_t = PairType<typename std::iterator_traits<FirstIt>::value_type, typename std::iterator_traits<SecondIt>::value_type>;
 
        template<template<typename, typename> class PairType, typename FirstIt, typename SecondIt>
        class PairIterator : public std::iterator<std::forward_iterator_tag, ValueType_t<PairType, FirstIt, SecondIt>>
        {
            bool IsSentinel_;
 
            FirstIt First_;
            FirstIt FirstEnd_;
            SecondIt Second_;
            SecondIt SecondEnd_;
        public:
            PairIterator ()
            : IsSentinel_ { true }
            {
            }
 
            PairIterator (const FirstIt& first, const FirstIt& firstEnd,
                    const SecondIt& second, const SecondIt& secondEnd)
            : IsSentinel_ { false }
            , First_ { first }
            , FirstEnd_ { firstEnd }
            , Second_ { second }
            , SecondEnd_ { secondEnd }
            {
            }
 
            bool operator== (const PairIterator& other) const
            {
                return (IsSentinel () && other.IsSentinel ()) ||
                        (First_ == other.First_ && Second_ == other.Second_);
            }
 
            bool operator!= (const PairIterator& other) const
            {
                return !(*this == other);
            }
 
            bool IsSentinel () const
            {
                return IsSentinel_ || First_ == FirstEnd_ || Second_ == SecondEnd_;
            }
 
            PairIterator& operator++ ()
            {
                ++First_;
                ++Second_;
                return *this;
            }
 
            PairIterator operator++ (int)
            {
                auto it = *this;
 
                ++First_;
                ++Second_;
 
                return it;
            }
 
            PairType<typename std::iterator_traits<FirstIt>::value_type, typename std::iterator_traits<SecondIt>::value_type> operator* () const
            {
                return { *First_, *Second_ };
            }
        };
 
        template<typename I1, typename I2, template<typename, typename> class PairType>
        class ZipRange : public boost::iterator_range<PairIterator<PairType, I1, I2>>
        {
            using IteratorType_t = PairIterator<PairType, I1, I2>;
        public:
            template<typename C1, typename C2>
            ZipRange (C1&& c1, C2&& c2)
            : boost::iterator_range<IteratorType_t>
            {
                IteratorType_t { c1.begin (), c1.end (), c2.begin (), c2.end () },
                IteratorType_t {}
            }
            {
            }
        };
    }
 
    template<template<typename, typename> class PairType = QPair, typename C1, typename C2>
    detail::ZipRange<typename C1::const_iterator, typename C2::const_iterator, PairType> Zip (const C1& c1, const C2& c2)
    {
        return { c1, c2 };
    }
}
}
}