feat(miscellaneous): add TConstantIterator
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Redcraft.Utility/Source/Public/Miscellaneous/ConstantIterator.h
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Redcraft.Utility/Source/Public/Miscellaneous/ConstantIterator.h
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#pragma once
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#include "CoreTypes.h"
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#include "Templates/Utility.h"
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#include "Containers/Iterator.h"
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#include "Miscellaneous/Compare.h"
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#include "TypeTraits/TypeTraits.h"
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NAMESPACE_REDCRAFT_BEGIN
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NAMESPACE_MODULE_BEGIN(Redcraft)
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NAMESPACE_MODULE_BEGIN(Utility)
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/** An iterator that always points to the same value. */
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template <typename T> requires (CDestructible<T> || CLValueReference<T>)
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class TConstantIterator final
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{
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public:
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using ElementType = T;
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FORCEINLINE constexpr TConstantIterator() = default;
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FORCEINLINE constexpr ~TConstantIterator() = default;
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template <typename U = T> requires (!CSameAs<TConstantIterator, TRemoveCVRef<U>> && CConstructibleFrom<T, U&&>)
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FORCEINLINE constexpr explicit TConstantIterator(U&& InValue) : Value(Forward<U>(InValue)) { }
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template <typename U> requires (CConstructibleFrom<T, const U&>)
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FORCEINLINE constexpr explicit (!CConvertibleTo<const U&, T>) TConstantIterator(const TConstantIterator<U>& InValue) : Value(InValue.Value) { }
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template <typename U> requires (CConstructibleFrom<T, U&&>)
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FORCEINLINE constexpr explicit (!CConvertibleTo<U&&, T>) TConstantIterator(TConstantIterator<U>&& InValue) : Value(MoveTemp(InValue.Value)) { }
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FORCEINLINE constexpr TConstantIterator(const TConstantIterator&) requires (CCopyConstructible<T>) = default;
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FORCEINLINE constexpr TConstantIterator(TConstantIterator&&) requires (CMoveConstructible<T>) = default;
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template <typename U> requires (CConvertibleTo<const U&, T> && CAssignableFrom<T&, const U&>)
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FORCEINLINE constexpr TConstantIterator& operator=(const TConstantIterator<U>& InValue) { Value = InValue.Value; return *this; }
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template <typename U> requires (CConvertibleTo<U&&, T> && CAssignableFrom<T&, U&&>)
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FORCEINLINE constexpr TConstantIterator& operator=(TConstantIterator<U>&& InValue) { Value = MoveTemp(InValue.Value); return *this; }
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FORCEINLINE constexpr TConstantIterator& operator=(const TConstantIterator&) requires (CCopyAssignable<T>) = default;
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FORCEINLINE constexpr TConstantIterator& operator=(TConstantIterator&&) requires (CMoveAssignable<T>) = default;
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NODISCARD FORCEINLINE constexpr const T& operator*() const { return Value; }
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FORCEINLINE constexpr TConstantIterator& operator++() { return *this; }
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FORCEINLINE constexpr void operator++(int) { }
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private:
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T Value;
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template <typename U> requires (CDestructible<U> || CLValueReference<U>)
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friend class TConstantIterator;
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};
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static_assert(CInputIterator<TConstantIterator<int>>);
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/** An iterator that always points to the same value. */
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template <typename T>
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class TConstantIterator<T&> final
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{
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public:
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using ElementType = T;
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FORCEINLINE constexpr TConstantIterator() = default;
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FORCEINLINE constexpr TConstantIterator(const TConstantIterator&) = default;
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FORCEINLINE constexpr TConstantIterator(TConstantIterator&&) = default;
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FORCEINLINE constexpr TConstantIterator& operator=(const TConstantIterator&) = default;
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FORCEINLINE constexpr TConstantIterator& operator=(TConstantIterator&&) = default;
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FORCEINLINE constexpr ~TConstantIterator() = default;
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FORCEINLINE constexpr explicit TConstantIterator(const T& InValue) : Ptr(AddressOf(InValue)) { }
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FORCEINLINE constexpr explicit TConstantIterator(const T&& InValue) = delete;
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template <typename U> requires (CConvertibleTo<U*, T*>)
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FORCEINLINE constexpr TConstantIterator(const TConstantIterator<U>& InValue) : Ptr(InValue.Ptr) { }
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template <typename U> requires (CConvertibleTo<U*, T*>)
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FORCEINLINE constexpr TConstantIterator& operator=(const TConstantIterator<U>& InValue) { Ptr = InValue.Ptr; return *this; }
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NODISCARD FORCEINLINE constexpr const T& operator*() const { return *Ptr; }
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FORCEINLINE constexpr TConstantIterator& operator++() { return *this; }
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FORCEINLINE constexpr void operator++(int) { }
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private:
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const T* Ptr;
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template <typename U> requires (CDestructible<U> || CLValueReference<U>)
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friend class TConstantIterator;
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};
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static_assert(CInputIterator<TConstantIterator<int&>>);
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/** An iterator adapter specialization that tracks the distance of a constant iterator to the end of the range. */
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template <typename T> requires (CDestructible<T> || CLValueReference<T>)
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class TCountedIterator<TConstantIterator<T>> final
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{
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public:
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using IteratorType = TConstantIterator<T>;
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using ElementType = typename TConstantIterator<T>::ElementType;
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# if DO_CHECK
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FORCEINLINE constexpr TCountedIterator() requires (CDefaultConstructible<IteratorType>) : Length(1), MaxLength(0) { }
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# else
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FORCEINLINE constexpr TCountedIterator() requires (CDefaultConstructible<IteratorType>) = default;
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# endif
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FORCEINLINE constexpr TCountedIterator(const TCountedIterator&) = default;
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FORCEINLINE constexpr TCountedIterator(TCountedIterator&&) = default;
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FORCEINLINE constexpr TCountedIterator& operator=(const TCountedIterator&) = default;
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FORCEINLINE constexpr TCountedIterator& operator=(TCountedIterator&&) = default;
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FORCEINLINE constexpr ~TCountedIterator() = default;
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template <typename U = IteratorType> requires (!CSameAs<TCountedIterator, TRemoveCVRef<U>> && CConstructibleFrom<IteratorType, U>)
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FORCEINLINE constexpr explicit TCountedIterator(U&& InValue, ptrdiff N) : Current(Forward<U>(InValue)), Length(N) { check_code({ MaxLength = N; }); }
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template <CInputOrOutputIterator J> requires (!CSameAs<IteratorType, J> && CConstructibleFrom<IteratorType, const J&>)
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FORCEINLINE constexpr explicit (!CConvertibleTo<const J&, IteratorType>) TCountedIterator(const TCountedIterator<J>& InValue) : Current(InValue.GetBase()), Length(InValue.Num()) { check_code({ MaxLength = InValue.MaxLength; }); }
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template <CInputOrOutputIterator J> requires (!CSameAs<IteratorType, J> && CConstructibleFrom<IteratorType, J>)
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FORCEINLINE constexpr explicit (!CConvertibleTo<J&&, IteratorType>) TCountedIterator(TCountedIterator<J>&& InValue) : Current(MoveTemp(InValue).GetBase()), Length(InValue.Num()) { check_code({ MaxLength = InValue.MaxLength; }); }
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template <CInputOrOutputIterator J> requires (!CSameAs<IteratorType, J> && CConvertibleTo<const J&, IteratorType> && CAssignableFrom<IteratorType&, const J&>)
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FORCEINLINE constexpr TCountedIterator& operator=(const TCountedIterator<J>& InValue) { Current = InValue.GetBase(); Length = InValue.Num(); check_code({ MaxLength = InValue.MaxLength; }); return *this; }
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template <CInputOrOutputIterator J> requires (!CSameAs<IteratorType, J> && CConvertibleTo<J&&, IteratorType> && CAssignableFrom<IteratorType&, J&&>)
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FORCEINLINE constexpr TCountedIterator& operator=(TCountedIterator<J>&& InValue) { Current = MoveTemp(InValue).GetBase(); Length = InValue.Num(); check_code({ MaxLength = InValue.MaxLength; }); return *this; }
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template <CCommonType<IteratorType> J>
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NODISCARD friend FORCEINLINE constexpr bool operator==(const TCountedIterator& LHS, const TCountedIterator<J>& RHS) { return LHS.Length == RHS.Length; }
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template <CCommonType<IteratorType> J>
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NODISCARD friend FORCEINLINE constexpr strong_ordering operator<=>(const TCountedIterator& LHS, const TCountedIterator<J>& RHS) { return LHS.Length <=> RHS.Length; }
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NODISCARD FORCEINLINE constexpr bool operator==(FDefaultSentinel) const& { return Length == static_cast<ptrdiff>(0); }
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NODISCARD FORCEINLINE constexpr strong_ordering operator<=>(FDefaultSentinel) const& { return static_cast<ptrdiff>(0) <=> Length; }
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NODISCARD FORCEINLINE constexpr const TRemoveReference<T>& operator*() const { CheckThis(true); return *Current; }
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NODISCARD FORCEINLINE constexpr const TRemoveReference<T>* operator->() const { CheckThis(true); return AddressOf(operator*()); }
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NODISCARD FORCEINLINE constexpr const TRemoveReference<T>& operator[](ptrdiff) const { return *this; }
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FORCEINLINE constexpr TCountedIterator& operator++() { --Length; CheckThis(); return *this; }
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FORCEINLINE constexpr TCountedIterator& operator--() { ++Length; CheckThis(); return *this; }
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FORCEINLINE constexpr TCountedIterator operator++(int) { TCountedIterator Temp = *this; --Length; CheckThis(); return Temp; }
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FORCEINLINE constexpr TCountedIterator operator--(int) { TCountedIterator Temp = *this; ++Length; CheckThis(); return Temp; }
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FORCEINLINE constexpr TCountedIterator& operator+=(ptrdiff Offset) { Length -= Offset; CheckThis(); return *this; }
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FORCEINLINE constexpr TCountedIterator& operator-=(ptrdiff Offset) { Length += Offset; CheckThis(); return *this; }
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NODISCARD friend FORCEINLINE constexpr TCountedIterator operator+(TCountedIterator Iter, ptrdiff Offset) { TCountedIterator Temp = Iter; Temp += Offset; return Temp; }
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NODISCARD friend FORCEINLINE constexpr TCountedIterator operator+(ptrdiff Offset, TCountedIterator Iter) { TCountedIterator Temp = Iter; Temp += Offset; return Temp; }
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NODISCARD FORCEINLINE constexpr TCountedIterator operator-(ptrdiff Offset) const { TCountedIterator Temp = *this; Temp -= Offset; return Temp; }
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template <CCommonType<IteratorType> J>
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NODISCARD friend FORCEINLINE constexpr ptrdiff operator-(const TCountedIterator& LHS, const TCountedIterator<J>& RHS) { LHS.CheckThis(); RHS.CheckThis(); return LHS.Length - RHS.Length; }
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NODISCARD friend FORCEINLINE constexpr ptrdiff operator-(const TCountedIterator& LHS, FDefaultSentinel) { CheckThis(); return -LHS.Num(); }
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NODISCARD friend FORCEINLINE constexpr ptrdiff operator-(FDefaultSentinel, const TCountedIterator& RHS) { CheckThis(); return RHS.Num(); }
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NODISCARD FORCEINLINE constexpr const IteratorType& GetBase() const& { CheckThis(); return Current; }
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NODISCARD FORCEINLINE constexpr IteratorType GetBase() && { CheckThis(); return Current; }
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NODISCARD FORCEINLINE constexpr ptrdiff Num() const { CheckThis(); return Length; }
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private:
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IteratorType Current;
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ptrdiff Length;
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# if DO_CHECK
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ptrdiff MaxLength;
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# endif
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FORCEINLINE void CheckThis(bool bExceptEnd = false) const
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{
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checkf(static_cast<ptrdiff>(0) <= Length && Length <= MaxLength, TEXT("Read access violation. Please check Num()."));
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checkf(!(bExceptEnd && Length == static_cast<ptrdiff>(0)), TEXT("Read access violation. Please check Num()."));
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}
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template <CInputOrOutputIterator J>
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friend class TCountedIterator;
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};
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static_assert(CRandomAccessIterator<TCountedIterator<TConstantIterator<int>>>);
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template <typename T> requires (CDestructible<T> || CLValueReference<T>)
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NODISCARD FORCEINLINE constexpr auto MakeConstantIterator(T&& Value)
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{
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return TConstantIterator<T>(Forward<T>(Value));
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}
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template <typename T> requires (CDestructible<T> || CLValueReference<T>)
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NODISCARD FORCEINLINE constexpr auto MakeCountedConstantIterator(T&& Value, ptrdiff N)
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{
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return TCountedIterator<TConstantIterator<T>>(MakeConstantIterator(Forward<T>(Value)), N);
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}
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NAMESPACE_MODULE_END(Utility)
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NAMESPACE_MODULE_END(Redcraft)
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NAMESPACE_REDCRAFT_END
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