Join.hpp

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//
//  CeresEngine - A game development framework
//
//  Created by Rogiel Sulzbach.
//  Copyright (c) 2018-2022 Rogiel Sulzbach. All rights reserved.
//
 
#pragma once
 
#include "CeresEngine/Foundation/Container/Array.hpp"
 
#include <iterator>
 
namespace CeresEngine {
 
    // compacted syntax for brevity...
    template<typename T1, typename T2> struct JoinIterator {
    public:
        using iterator_category = std::forward_iterator_tag;
        using value_type = typename std::iterator_traits<T1>::value_type;
        using pointer = typename std::iterator_traits<T1>::pointer;
        using reference = typename std::iterator_traits<T1>::reference;
        using difference_type = typename std::iterator_traits<T1>::difference_type;
        using iterator = JoinIterator;
 
        JoinIterator(T1 b1, T1 e1, T2 b2, T2 e2) : seq1(b1), seq1end(e1), seq2(b2), seq2end(e2) {}
 
        iterator& operator++() {
            if(seq1 != seq1end) {
                ++seq1;
            } else {
                ++seq2;
            }
            return *this;
        }
 
        reference operator*() const {
            if(seq1 != seq1end) {
                return *seq1;
            }
            return *seq2;
        }
 
        pointer operator->() const {
            if(seq1 != seq1end) {
                return &(*seq1);
            }
            return &(*seq2);
        }
 
        bool operator==(const JoinIterator& rhs) const {
            return std::tie(seq1, seq1end, seq2, seq2end) == std::tie(rhs.seq1, rhs.seq1end, rhs.seq2, rhs.seq2end);
        }
        bool operator!=(const JoinIterator& rhs) const { return !(*this == rhs); }
 
    private:
        T1 seq1;
        T1 seq1end;
        T2 seq2;
        T2 seq2end;
    };
 
    template<typename Range1, typename Range2> class JoinIteratorRange {
    private:
        Range1& mRange1;
        Range2& mRange2;
 
    public:
        JoinIteratorRange(Range1& range1, Range2& range2) : mRange1(range1), mRange2(range2) {}
 
        [[nodiscard]] auto begin() const {
            using std::begin;
            using std::end;
            return JoinIterator(begin(mRange1), end(mRange1), begin(mRange2), end(mRange2));
        }
 
        [[nodiscard]] auto end() const {
            using std::begin;
            using std::end;
            return JoinIterator(end(mRange1), end(mRange1), end(mRange2), end(mRange2));
        }
    };
 
    template<typename Range1, typename Range2> inline JoinIteratorRange<Range1, Range2> join(Range1& range1, Range2& range2) {
        return JoinIteratorRange<Range1, Range2>(range1, range2);
    }
 
    template<typename Range1, typename Range2> inline JoinIteratorRange<const Range1, const Range2> join(const Range1& range1, const Range2& range2) {
        return JoinIteratorRange<const Range1, const Range2>(range1, range2);
    }
 
    template<typename Range1, typename Range2, std::size_t L>
    inline JoinIteratorRange<Range1, const Array<Range2&, L>> join(Range1& range1, const Array<Range2&, L>& range2) {
        return JoinIteratorRange<Range1, const Array<Range2&, L>>(range1, range2);
    }
 
    template<typename Range1, typename Range2, std::size_t L>
    inline JoinIteratorRange<Range1, const Array<const Range2&, L>> join(Range1& range1, const Array<const Range2&, L>& range2) {
        return JoinIteratorRange<Range1, const Array<const Range2&, L>>(range1, range2);
    }
 
    template<typename Range1, typename Other> inline auto joinWith(Range1& range1, const std::initializer_list<Other> range2) {
        return JoinIteratorRange<Range1, const std::initializer_list<Other>>(range1, range2);
    }
 
    //    template<typename Range1, typename Range2>
    //    inline JoinIteratorRange<Range1, const std::initializer_list<Range2>> join(Range1& range1, const
    //    std::initializer_list<Range2>& range2) {
    //        return JoinIteratorRange<Range1, const std::initializer_list<Range2>>(range1, range2);
    //    }
 
    //    template<typename Range1, typename Range2>
    //    inline JoinIteratorRange<const Range1, const std::initializer_list<const Range2>> join(const Range1& range1,
    //    const std::initializer_list<const Range2>& range2) {
    //        return JoinIteratorRange<const Range1, const std::initializer_list<const Range2>>(range1, range2);
    //    }
 
} // namespace CeresEngine