BaseSetFindIterator.h

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#pragma once
#include <utility>
 
namespace catapult { namespace deltaset {
 
    namespace detail {
        template<typename TFindTraits, typename TSetTraits, typename TStorageIterator, typename TFindResult>
        class BaseSetSingleIteratorWrapper {
        public:
            BaseSetSingleIteratorWrapper() : m_isSet(false)
            {}
 
            explicit BaseSetSingleIteratorWrapper(TStorageIterator&& storageIter)
                    : m_isSet(true)
                    , m_storageIter(std::move(storageIter))
            {}
 
        public:
            TFindResult get() const {
                return m_isSet ? TFindTraits::ToResult(TSetTraits::ToValue(*m_storageIter)) : nullptr;
            }
 
        private:
            bool m_isSet;
            TStorageIterator m_storageIter;
        };
 
        template<typename TFindTraits, typename TSetTraits, typename TStorageIterator, typename TMemoryIterator, typename TFindResult>
        class BaseSetDualIteratorWrapper {
        public:
            BaseSetDualIteratorWrapper() : m_iteratorType(IteratorType::Unset)
            {}
 
            explicit BaseSetDualIteratorWrapper(TStorageIterator&& storageIter)
                    : m_iteratorType(IteratorType::Storage)
                    , m_storageIter(std::move(storageIter))
            {}
 
            explicit BaseSetDualIteratorWrapper(TMemoryIterator&& memoryIter)
                    : m_iteratorType(IteratorType::Memory)
                    , m_memoryIter(std::move(memoryIter))
            {}
 
        public:
            TFindResult get() const {
                switch (m_iteratorType) {
                case IteratorType::Storage:
                    return TFindTraits::ToResult(TSetTraits::ToValue(*m_storageIter));
                case IteratorType::Memory:
                    return TFindTraits::ToResult(TSetTraits::ToValue(*m_memoryIter));
                default:
                    return nullptr;
                }
            }
 
        private:
            enum class IteratorType { Unset, Storage, Memory };
 
        private:
            IteratorType m_iteratorType;
            TStorageIterator m_storageIter;
            TMemoryIterator m_memoryIter;
        };
 
        template<typename TFindTraits, typename TSetTraits, typename TStorageIterator, typename TMemoryIterator, typename TFindResult>
        using BaseSetConditionalIteratorWrapper = std::conditional_t<
            std::is_same_v<TStorageIterator, TMemoryIterator>,
            BaseSetSingleIteratorWrapper<TFindTraits, TSetTraits, TStorageIterator, TFindResult>,
            BaseSetDualIteratorWrapper<TFindTraits, TSetTraits, TStorageIterator, TMemoryIterator, TFindResult>
        >;
    }
 
    template<typename TFindTraits, typename TSetTraits>
    using BaseSetFindIterator = detail::BaseSetSingleIteratorWrapper<
        TFindTraits,
        TSetTraits,
        typename TSetTraits::SetType::const_iterator,
        typename TFindTraits::ConstResultType
    >;
 
    template<typename TFindTraits, typename TSetTraits>
    using BaseSetDeltaFindIterator = detail::BaseSetSingleIteratorWrapper<
        TFindTraits,
        TSetTraits,
        typename TSetTraits::MemorySetType::iterator,
        typename TFindTraits::ResultType
    >;
 
    template<typename TFindTraits, typename TSetTraits>
    using BaseSetDeltaFindConstIterator = detail::BaseSetConditionalIteratorWrapper<
        TFindTraits,
        TSetTraits,
        typename TSetTraits::SetType::const_iterator,
        typename TSetTraits::MemorySetType::const_iterator,
        typename TFindTraits::ConstResultType
    >;
}}