refactor(iterator): add iterator example class and split iterator library into multiple files

Redcraft.Utility/Source/Public/Iterator/BidirectionalIterator.h

@@ -0,0 +1,75 @@
+#pragma once
+
+#include "CoreTypes.h"
+#include "Iterator/Utility.h"
+#include "Iterator/Sentinel.h"
+#include "Iterator/ForwardIterator.h"
+#include "TypeTraits/TypeTraits.h"
+
+NAMESPACE_REDCRAFT_BEGIN
+NAMESPACE_MODULE_BEGIN(Redcraft)
+NAMESPACE_MODULE_BEGIN(Utility)
+
+#if PLATFORM_COMPILER_GCC
+#	pragma GCC diagnostic push
+#	pragma GCC diagnostic ignored "-Wnon-template-friend"
+#endif
+
+/** A concept specifies a type is a bidirectional iterator. Add the decrement operator to the forward iterator. */
+template <typename I>
+concept CBidirectionalIterator = CForwardIterator<I>
+	&& requires(I Iter) {
+		{ --Iter } -> CSameAs<I&>;
+		{ Iter-- } -> CSameAs<I >;
+	};
+
+/**
+ * This is an example of a bidirectional iterator, indicate the traits that define a bidirectional iterator.
+ * Regardless of the order in which the increment and decrement operators are applied,
+ * the result is always the same if both operations are performed the same number of times.
+ */
+template <CReference T>
+struct IBidirectionalIterator /* : IForwardIterator<T> */
+{
+	/** The element type of the indirectly readable type. See 'IIndirectlyReadable'. */
+	using ElementType = TRemoveCVRef<T>;
+
+	/** Default constructor. See 'IIncrementable' and 'ISentinelFor'. */
+	IBidirectionalIterator();
+
+	/** Copy constructor. See 'IIncrementable' and 'ISentinelFor'. */
+	IBidirectionalIterator(const IBidirectionalIterator&);
+
+	/** Copy assignment operator. See 'IIncrementable' and 'ISentinelFor'. */
+	IBidirectionalIterator* operator=(const IBidirectionalIterator&);
+
+	/** Equality operator. See 'IIncrementable' and 'ISentinelFor'. */
+	friend bool operator==(const IBidirectionalIterator&, const IBidirectionalIterator&);
+
+	/** Dereference operator. See 'IForwardIterator'. */
+	T operator*() const;
+
+	/** Pre-increment operator. See 'IWeaklyIncrementable'. */
+	IBidirectionalIterator& operator++();
+
+	/** Pre-decrement operator. */
+	IBidirectionalIterator& operator--();
+
+	/** Post-increment operator. See 'IIncrementable'. */
+	IBidirectionalIterator operator++(int);
+
+	/** Post-decrement operator. */
+	IBidirectionalIterator operator--(int);
+};
+
+// Use 'IBidirectionalIterator<int>' represents a bidirectional iterator.
+static_assert(CBidirectionalIterator<IBidirectionalIterator<int&>>);
+static_assert(       COutputIterator<IBidirectionalIterator<int&>, int>);
+
+#if PLATFORM_COMPILER_GCC
+#	pragma GCC diagnostic pop
+#endif
+
+NAMESPACE_MODULE_END(Utility)
+NAMESPACE_MODULE_END(Redcraft)
+NAMESPACE_REDCRAFT_END

Redcraft.Utility/Source/Public/Iterator/ContiguousIterator.h

@@ -0,0 +1,109 @@
+#pragma once
+
+#include "CoreTypes.h"
+#include "Iterator/Utility.h"
+#include "Iterator/Sentinel.h"
+#include "Iterator/RandomAccessIterator.h"
+#include "TypeTraits/TypeTraits.h"
+
+NAMESPACE_REDCRAFT_BEGIN
+NAMESPACE_MODULE_BEGIN(Redcraft)
+NAMESPACE_MODULE_BEGIN(Utility)
+
+#if PLATFORM_COMPILER_GCC
+#	pragma GCC diagnostic push
+#	pragma GCC diagnostic ignored "-Wnon-template-friend"
+#endif
+
+/**
+ * A concept specifies a type is a contiguous iterator.
+ * Add the 'operator->' to the random access iterator and requires the 'operator*' returns a true reference type.
+ */
+template <typename I>
+concept CContiguousIterator = CRandomAccessIterator<I> && CLValueReference<TIteratorReference<I>>
+	&& CSameAs<TIteratorElement<I>, TRemoveCVRef<TIteratorReference<I>>>
+	&& CSameAs<TIteratorPointer<I>,  TAddPointer<TIteratorReference<I>>>
+	&& requires(I& Iter)
+	{
+		{ ToAddress(Iter) } -> CSameAs<TAddPointer<TIteratorReference<I>>>;
+	};
+
+/** This is an example of a contiguous iterator, indicate the traits that define a contiguous iterator. */
+template <CLValueReference T>
+struct IContiguousIterator /* : IBidirectionalIterator<T> */
+{
+	/** The element type of the indirectly readable type. See 'IIndirectlyReadable'. */
+	using ElementType = TRemoveCVRef<T>;
+
+	/** Default constructor. See 'IIncrementable' and 'ISentinelFor'. */
+	IContiguousIterator();
+
+	/** Copy constructor. See 'IIncrementable' and 'ISentinelFor'. */
+	IContiguousIterator(const IContiguousIterator&);
+
+	/** Copy assignment operator. See 'IIncrementable' and 'ISentinelFor'. */
+	IContiguousIterator* operator=(const IContiguousIterator&);
+
+	/** Equality operator. See 'IIncrementable' and 'ISentinelFor'. */
+	friend bool operator==(const IContiguousIterator&, const IContiguousIterator&);
+
+	/** Three-way comparison operator. See 'IRandomAccessIterator'. */
+	friend strong_ordering operator<=>(const IContiguousIterator& LHS, const IContiguousIterator& RHS);
+
+	/**
+	 * Dereference operator. See 'IForwardIterator'.
+	 * Specify, the return type must be a true reference type and refer to an element of a contiguous sequence, not a proxy class.
+	 */
+	T operator*() const;
+
+	/** Indirection operator. Return the address of the element that the iterator is pointing to. */
+	TAddPointer<T> operator->() const;
+
+	/** Pre-increment operator. See 'IWeaklyIncrementable'. */
+	IContiguousIterator& operator++();
+
+	/** Pre-decrement operator. See 'IBidirectionalIterator'. */
+	IContiguousIterator& operator--();
+
+	/** Post-increment operator. See 'IIncrementable'. */
+	IContiguousIterator operator++(int);
+
+	/** Post-decrement operator. See 'IBidirectionalIterator'. */
+	IContiguousIterator operator--(int);
+
+	/** Addition assignment operator. See 'IRandomAccessIterator'. */
+	IContiguousIterator& operator+=(ptrdiff);
+
+	/** Subtraction assignment operator. See 'IRandomAccessIterator'. */
+	IContiguousIterator& operator-=(ptrdiff);
+
+	/** Addition operator. See 'IRandomAccessIterator'. */
+	IContiguousIterator operator+(ptrdiff) const;
+
+	/** Subtraction operator. See 'IRandomAccessIterator'. */
+	IContiguousIterator operator-(ptrdiff) const;
+
+	/** Addition operator. See 'IRandomAccessIterator'. */
+	friend IContiguousIterator operator+(ptrdiff, const IContiguousIterator&);
+
+	/** Subtraction operator. See 'IRandomAccessIterator'. */
+	friend ptrdiff operator-(const IContiguousIterator&, const IContiguousIterator&);
+
+	/** Subscript operator. See 'IRandomAccessIterator'. */
+	T operator[](ptrdiff) const;
+};
+
+// Use 'IContiguousIterator<int>' represents a contiguous iterator
+static_assert(CContiguousIterator<IContiguousIterator<int&>>);
+static_assert(    COutputIterator<IContiguousIterator<int&>, int>);
+
+// The 'int*' is the most typical example of a contiguous iterator
+static_assert(CContiguousIterator<int*>);
+
+#if PLATFORM_COMPILER_GCC
+#	pragma GCC diagnostic pop
+#endif
+
+NAMESPACE_MODULE_END(Utility)
+NAMESPACE_MODULE_END(Redcraft)
+NAMESPACE_REDCRAFT_END

Redcraft.Utility/Source/Public/Iterator/ForwardIterator.h

@@ -0,0 +1,63 @@
+#pragma once
+
+#include "CoreTypes.h"
+#include "Iterator/Utility.h"
+#include "Iterator/Sentinel.h"
+#include "TypeTraits/TypeTraits.h"
+
+NAMESPACE_REDCRAFT_BEGIN
+NAMESPACE_MODULE_BEGIN(Redcraft)
+NAMESPACE_MODULE_BEGIN(Utility)
+
+#if PLATFORM_COMPILER_GCC
+#	pragma GCC diagnostic push
+#	pragma GCC diagnostic ignored "-Wnon-template-friend"
+#endif
+
+/** A concept specifies a type is an input iterator. It is input iterator, incrementable, and sentinel for itself. */
+template <typename I>
+concept CForwardIterator = CInputIterator<I> && CIncrementable<I> && CSentinelFor<I, I>;
+
+/** This is an example of a forward iterator, indicate the traits that define a forward iterator. */
+template <CReference T>
+struct IForwardIterator /* : IInputIterator<T>, IIncrementable, ISentinelFor<I> */
+{
+	/** The element type of the indirectly readable type. See 'IIndirectlyReadable'. */
+	using ElementType = TRemoveCVRef<T>;
+
+	/** Default constructor. See 'IIncrementable' and 'ISentinelFor'. */
+	IForwardIterator();
+
+	/** Copy constructor. See 'IIncrementable' and 'ISentinelFor'. */
+	IForwardIterator(const IForwardIterator&);
+
+	/** Copy assignment operator. See 'IIncrementable' and 'ISentinelFor'. */
+	IForwardIterator* operator=(const IForwardIterator&);
+
+	/** Equality operator. See 'IIncrementable' and 'ISentinelFor'. */
+	friend bool operator==(const IForwardIterator&, const IForwardIterator&);
+
+	/**
+	 * Indirectly read the element from the indirectly readable type. See 'IIndirectlyReadable'.
+	 * Indirectly write the element if the type is also an indirectly writable type. See 'IIndirectlyWritable'.
+	 */
+	T operator*() const;
+
+	/** Pre-increment operator. See 'IWeaklyIncrementable'. */
+	IForwardIterator& operator++();
+
+	/** Post-increment operator. See 'IIncrementable'. */
+	IForwardIterator operator++(int);
+};
+
+// Use 'IForwardIterator<int>' represents a forward iterator.
+static_assert(CForwardIterator<IForwardIterator<int&>>);
+static_assert( COutputIterator<IForwardIterator<int&>, int>);
+
+#if PLATFORM_COMPILER_GCC
+#	pragma GCC diagnostic pop
+#endif
+
+NAMESPACE_MODULE_END(Utility)
+NAMESPACE_MODULE_END(Redcraft)
+NAMESPACE_REDCRAFT_END

Redcraft.Utility/Source/Public/Iterator/Iterator.h

@@ -0,0 +1,9 @@
+#pragma once
+
+#include "CoreTypes.h"
+#include "Iterator/Utility.h"
+#include "Iterator/Sentinel.h"
+#include "Iterator/ForwardIterator.h"
+#include "Iterator/BidirectionalIterator.h"
+#include "Iterator/RandomAccessIterator.h"
+#include "Iterator/ContiguousIterator.h"

Redcraft.Utility/Source/Public/Iterator/RandomAccessIterator.h

@@ -0,0 +1,103 @@
+#pragma once
+
+#include "CoreTypes.h"
+#include "Iterator/Utility.h"
+#include "Iterator/Sentinel.h"
+#include "Iterator/BidirectionalIterator.h"
+#include "Miscellaneous/Compare.h"
+#include "TypeTraits/TypeTraits.h"
+
+NAMESPACE_REDCRAFT_BEGIN
+NAMESPACE_MODULE_BEGIN(Redcraft)
+NAMESPACE_MODULE_BEGIN(Utility)
+
+#if PLATFORM_COMPILER_GCC
+#	pragma GCC diagnostic push
+#	pragma GCC diagnostic ignored "-Wnon-template-friend"
+#endif
+
+/**
+ * A concept specifies a type is a random access iterator.
+ * Add the three-way comparison, addition, subtraction and subscript operators to the bidirectional iterator.
+ */
+template <typename I>
+concept CRandomAccessIterator = CBidirectionalIterator<I> && CTotallyOrdered<I> && CSizedSentinelFor<I, I>
+	&& requires(I Iter, const I Jter, const ptrdiff N) {
+		{ Iter   += N } -> CSameAs<I&>;
+		{ Jter   +  N } -> CSameAs<I >;
+		{ N +  Jter   } -> CSameAs<I >;
+		{ Iter   -= N } -> CSameAs<I&>;
+		{ Jter   -  N } -> CSameAs<I >;
+		{   Jter[N]   } -> CSameAs<TIteratorReference<I>>;
+	};
+
+/** This is an example of a random access iterator, indicate the traits that define a random access iterator. */
+template <CReference T>
+struct IRandomAccessIterator /* : IBidirectionalIterator<T> */
+{
+	/** The element type of the indirectly readable type. See 'IIndirectlyReadable'. */
+	using ElementType = TRemoveCVRef<T>;
+
+	/** Default constructor. See 'IIncrementable' and 'ISentinelFor'. */
+	IRandomAccessIterator();
+
+	/** Copy constructor. See 'IIncrementable' and 'ISentinelFor'. */
+	IRandomAccessIterator(const IRandomAccessIterator&);
+
+	/** Copy assignment operator. See 'IIncrementable' and 'ISentinelFor'. */
+	IRandomAccessIterator* operator=(const IRandomAccessIterator&);
+
+	/** Equality operator. See 'IIncrementable' and 'ISentinelFor'. */
+	friend bool operator==(const IRandomAccessIterator&, const IRandomAccessIterator&);
+
+	/** Three-way comparison operator. */
+	friend strong_ordering operator<=>(const IRandomAccessIterator& LHS, const IRandomAccessIterator& RHS);
+
+	/** Dereference operator. See 'IForwardIterator'. */
+	T operator*() const;
+
+	/** Pre-increment operator. See 'IWeaklyIncrementable'. */
+	IRandomAccessIterator& operator++();
+
+	/** Pre-decrement operator. See 'IBidirectionalIterator'. */
+	IRandomAccessIterator& operator--();
+
+	/** Post-increment operator. See 'IIncrementable'. */
+	IRandomAccessIterator operator++(int);
+
+	/** Post-decrement operator. See 'IBidirectionalIterator'. */
+	IRandomAccessIterator operator--(int);
+
+	/** Addition assignment operator. */
+	IRandomAccessIterator& operator+=(ptrdiff);
+
+	/** Subtraction assignment operator. */
+	IRandomAccessIterator& operator-=(ptrdiff);
+
+	/** Addition operator. */
+	IRandomAccessIterator operator+(ptrdiff) const;
+
+	/** Subtraction operator. */
+	IRandomAccessIterator operator-(ptrdiff) const;
+
+	/** Addition operator. */
+	friend IRandomAccessIterator operator+(ptrdiff, const IRandomAccessIterator&);
+
+	/** Subtraction operator. */
+	friend ptrdiff operator-(const IRandomAccessIterator&, const IRandomAccessIterator&);
+
+	/** Subscript operator. */
+	T operator[](ptrdiff) const;
+};
+
+// Use 'IRandomAccessIterator<int>' represents a random access iterator
+static_assert(CRandomAccessIterator<IRandomAccessIterator<int&>>);
+static_assert(      COutputIterator<IRandomAccessIterator<int&>, int>);
+
+#if PLATFORM_COMPILER_GCC
+#	pragma GCC diagnostic pop
+#endif
+
+NAMESPACE_MODULE_END(Utility)
+NAMESPACE_MODULE_END(Redcraft)
+NAMESPACE_REDCRAFT_END

Redcraft.Utility/Source/Public/Iterator/Sentinel.h

@@ -0,0 +1,111 @@
+#pragma once
+
+#include "CoreTypes.h"
+#include "Iterator/Utility.h"
+#include "TypeTraits/TypeTraits.h"
+
+NAMESPACE_REDCRAFT_BEGIN
+NAMESPACE_MODULE_BEGIN(Redcraft)
+NAMESPACE_MODULE_BEGIN(Utility)
+
+#if PLATFORM_COMPILER_GCC
+#	pragma GCC diagnostic push
+#	pragma GCC diagnostic ignored "-Wnon-template-friend"
+#endif
+
+/**
+ * A concept specifies a type is a sentinel for an iterator and expression 'Iter == Sentinel' is valid.
+ * In addition, the type must be default constructible and copyable.
+ */
+template <typename S, typename I>
+concept CSentinelFor = CSemiregular<S> && CInputOrOutputIterator<I> && CWeaklyEqualityComparable<S, I>;
+
+/** This is an example of a sentinel for an iterator, indicate the traits that define a sentinel for an iterator. */
+template <CInputOrOutputIterator I>
+struct ISentinelFor
+{
+	/** Default constructor. */
+	ISentinelFor();
+
+	/** Copy constructor. */
+	ISentinelFor(const ISentinelFor&);
+
+	/** Copy assignment operator. */
+	ISentinelFor* operator=(const ISentinelFor&);
+
+	/** Equality operator. */
+	bool operator==(const I&) const&;
+};
+
+// Use 'ISentinelFor' represents a sentinel for an iterator.
+static_assert(CSentinelFor<ISentinelFor<IInputOrOutputIterator<int>>, IInputOrOutputIterator<int>>);
+
+// The 'CSentinelFor' requires this code is valid.
+static_assert(
+	requires(ISentinelFor<IInputOrOutputIterator<int>> Sentinel, IInputOrOutputIterator<int> Iter)
+	{
+		{ Iter == Sentinel } -> CBooleanTestable;
+		{ Sentinel == Iter } -> CBooleanTestable;
+	}
+);
+
+/** Disable the 'CSizedSentinelFor' concept for specific types. */
+template <typename S, typename I>
+inline constexpr bool bDisableSizedSentinelFor = false;
+
+/**
+ * A concept specifies a type is a sized sentinel for an iterator and expressions 'Sentinel - Iter' and 'Iter - Sentinel' are valid,
+ * and the 'Sentinel - Iter' is equal to negative 'Iter - Sentinel'.
+ * In addition, the type must be default constructible and copyable.
+ */
+template <typename S, typename I>
+concept CSizedSentinelFor = CSentinelFor<S, I>
+	&& !bDisableSizedSentinelFor<TRemoveCVRef<S>, TRemoveCVRef<I>>
+	&& requires(const I& Iter, const S& Sentinel)
+	{
+		{ Sentinel - Iter } -> CSameAs<ptrdiff>;
+		{ Iter - Sentinel } -> CSameAs<ptrdiff>;
+	};
+
+/** This is an example of a sized sentinel for an iterator, indicate the traits that define a sized sentinel for an iterator. */
+template <CInputOrOutputIterator I>
+struct ISizedSentinelFor /* : ISentinelFor<I> */
+{
+	/** Default constructor. */
+	ISizedSentinelFor();
+
+	/** Copy constructor. */
+	ISizedSentinelFor(const ISizedSentinelFor&);
+
+	/** Copy assignment operator. */
+	ISizedSentinelFor& operator=(const ISizedSentinelFor&);
+
+	/** Equality operator. */
+	bool operator==(const I&) const&;
+
+	/** Subtraction operator. The 'Sentinel - Iter' is equal to negative 'Iter - Sentinel'. */
+	friend ptrdiff operator-(const I&, const ISizedSentinelFor&);
+	friend ptrdiff operator-(const ISizedSentinelFor&, const I&);
+};
+
+// Use 'ISizedSentinelFor' represents a sized sentinel for an iterator.
+static_assert(CSizedSentinelFor<ISizedSentinelFor<IInputOrOutputIterator<int>>, IInputOrOutputIterator<int>>);
+
+// The 'CSentinelFor' requires this code is valid.
+static_assert(
+	requires(ISizedSentinelFor<IInputOrOutputIterator<int>> Sentinel, IInputOrOutputIterator<int> Iter)
+	{
+		{ Iter == Sentinel } -> CBooleanTestable;
+		{ Sentinel == Iter } -> CBooleanTestable;
+		{ Iter - Sentinel }  -> CSameAs<ptrdiff>;
+		{ Sentinel - Iter }  -> CSameAs<ptrdiff>;
+	}
+);
+
+#if PLATFORM_COMPILER_GCC
+#	pragma GCC diagnostic pop
+#endif
+
+NAMESPACE_MODULE_END(Utility)
+NAMESPACE_MODULE_END(Redcraft)
+NAMESPACE_REDCRAFT_END

Redcraft.Utility/Source/Public/Iterator/Utility.h

@@ -0,0 +1,325 @@
+#pragma once
+
+#include "CoreTypes.h"
+#include "Templates/Utility.h"
+#include "TypeTraits/TypeTraits.h"
+
+NAMESPACE_REDCRAFT_BEGIN
+NAMESPACE_MODULE_BEGIN(Redcraft)
+NAMESPACE_MODULE_BEGIN(Utility)
+
+NAMESPACE_PRIVATE_BEGIN
+
+template <typename T> using TWithReference = T&;
+
+template <typename I> struct TIteratorElementImpl     { using Type = typename I::ElementType; };
+template <typename T> struct TIteratorElementImpl<T*> { using Type = TRemoveCV<T>;            };
+
+template <typename I> struct TIteratorPointerImpl     { using Type = void; };
+template <typename T> struct TIteratorPointerImpl<T*> { using Type = T*;   };
+
+template <typename I> requires (requires(I& Iter) { { Iter.operator->() } -> CPointer; })
+struct TIteratorPointerImpl<I> { using Type = decltype(DeclVal<I&>().operator->()); };
+
+NAMESPACE_PRIVATE_END
+
+template <typename T>
+concept CReferenceable = requires { typename NAMESPACE_PRIVATE::TWithReference<T>; };
+
+template <typename T>
+concept CDereferenceable = requires(T& A) { { *A } -> CReferenceable; };
+
+template <typename I>
+using TIteratorElement = typename NAMESPACE_PRIVATE::TIteratorElementImpl<TRemoveCVRef<I>>::Type;
+
+template <typename I>
+using TIteratorPointer = typename NAMESPACE_PRIVATE::TIteratorPointerImpl<TRemoveCVRef<I>>::Type;
+
+template <CReferenceable I>
+using TIteratorReference = decltype(*DeclVal<I&>());
+
+template <CReferenceable I> requires (requires(I& Iter) { { MoveTemp(*Iter) } -> CReferenceable; })
+using TIteratorRValueReference = decltype(MoveTemp(*DeclVal<I&>()));
+
+NAMESPACE_PRIVATE_BEGIN
+
+template <typename I>
+concept CIndirectlyReadable =
+	requires(const I Iter)
+	{
+		typename TIteratorElement<I>;
+		typename TIteratorReference<I>;
+		typename TIteratorRValueReference<I>;
+		{          *Iter  } -> CSameAs<TIteratorReference<I>>;
+		{ MoveTemp(*Iter) } -> CSameAs<TIteratorRValueReference<I>>;
+	}
+	&& CSameAs<TIteratorElement<I>, TRemoveCVRef<TIteratorElement<I>>>
+	&& CCommonReference<TIteratorReference<I>&&, TIteratorElement<I>&>
+	&& CCommonReference<TIteratorReference<I>&&, TIteratorRValueReference<I>&&>
+	&& CCommonReference<TIteratorRValueReference<I>&&, const TIteratorElement<I>&>;
+
+NAMESPACE_PRIVATE_END
+
+/** A concept specifies a type is indirectly readable by expression '*Iter'. */
+template <typename I>
+concept CIndirectlyReadable = NAMESPACE_PRIVATE::CIndirectlyReadable<TRemoveCVRef<I>>;
+
+/** This is an example of an indirectly readable type, indicate the traits that define an indirectly readable type. */
+template <CReferenceable T>
+struct IIndirectlyReadable
+{
+	/**
+	 * The element type of the indirectly readable type.
+	 * It must be a non-const, non-volatile and non-reference type and can be referenced, i.e. not a void type.
+	 */
+	using ElementType = TRemoveCVRef<T>;
+
+	/**
+	 * Indirectly read the element from the indirectly readable type.
+	 * The return type may not be 'const ElementType&', this concept only requires that the return type
+	 * and 'ElementType' has some relationship, such as copy constructible to 'ElementType' if the type is copyable.
+	 * This means that returning a proxy class castable to 'ElementType' is also valid.
+	 * If this is an iterator adaptor, use 'decltype(auto)' to forward the return value.
+	 */
+	T operator*() const;
+};
+
+// Use 'IIndirectlyReadable<int>' represents an indirectly readable type and 'int' is the regular element type.
+static_assert(CIndirectlyReadable<IIndirectlyReadable<int>> && CRegular<int>);
+
+// The 'CIndirectlyReadable' requires this code is valid.
+static_assert(
+	requires(IIndirectlyReadable<int> Iter, int& A)
+	{
+		A = *Iter;
+	}
+);
+
+/** A concept specifies a type is indirectly writable by expression '*Iter = A'. */
+template <typename I, typename T>
+concept CIndirectlyWritable =
+	requires(I&& Iter, T&& A)
+	{
+		*Iter             = Forward<T>(A);
+		*Forward<I>(Iter) = Forward<T>(A);
+		const_cast<const TIteratorReference<I>&&>(*Iter)             = Forward<T>(A);
+		const_cast<const TIteratorReference<I>&&>(*Forward<I>(Iter)) = Forward<T>(A);
+	};
+
+/** This is an example of an indirectly writable type, indicate the traits that define an indirectly writable type. */
+template <CReference T>
+struct IIndirectlyWritable
+{
+	/**
+	 * Indirectly write the element from the indirectly writable type.
+	 * The return type may not be 'T&', this concept only requires that the return type and 'T' has some relationship,
+	 * such as can be assigned from 'T&' if the type is copyable or 'T&&' if the type is movable.
+	 * This means that returning a proxy class can be assigned from 'T' is also valid.
+	 * If this is also an indirectly readable type, the equivalent value is read after writing.
+	 * If this is an iterator adaptor, use 'decltype(auto)' to forward the return value.
+	 */
+	T operator*() const;
+};
+
+// Use 'IIndirectlyWritable<int>' represents an indirectly writable type and 'int' is the regular element type.
+static_assert(CIndirectlyWritable<IIndirectlyWritable<int&>, int> && CRegular<int>);
+
+// The 'CIndirectlyWritable' requires this code is valid.
+static_assert(
+	requires(IIndirectlyWritable<int&> Iter, int& A)
+	{
+		*Iter = A;
+	}
+);
+
+/** A concept specifies a type is incrementable by expression '++Iter' and the type must be movable. */
+template <typename I>
+concept CWeaklyIncrementable = CMovable<I>
+	&& requires(I Iter) { { ++Iter } -> CSameAs<I&>; Iter++; };
+
+/** This is an example of a weakly incrementable type, indicate the traits that define a weakly incrementable type. */
+struct IWeaklyIncrementable
+{
+	/** Move constructor. */
+	IWeaklyIncrementable(IWeaklyIncrementable&&);
+
+	/** Move assignment operator. */
+	IWeaklyIncrementable* operator=(IWeaklyIncrementable&&);
+
+	/** Pre-increment operator. */
+	IWeaklyIncrementable& operator++();
+
+	/**
+	 * Post-increment operator.
+	 * Specify, the concept not requires the return type is any specific type, so the return type can be 'void'.
+	 */
+	void operator++(int);
+};
+
+// Use 'IWeaklyIncrementable' represents a weakly incrementable type.
+static_assert(CWeaklyIncrementable<IWeaklyIncrementable>);
+
+/**
+ * A concept specifies a type is incrementable by expression 'Iter++' and the expression returns the original value.
+ * In addition, the type must be default constructible, copyable and weakly equality comparable.
+ */
+template <typename I>
+concept CIncrementable = CRegular<I> && CWeaklyIncrementable<I>
+	&& requires(I Iter) { { Iter++ } -> CSameAs<I>; };
+
+/**
+ * This is an example of an incrementable type, indicate the traits that define an incrementable type.
+ * The copy object of this type produced by copy constructor, copy assignment or post-increment
+ * should produce the same effect as the original object when incrementing.
+ */
+struct IIncrementable /* : IWeaklyIncrementable */
+{
+	/** Default constructor. */
+	IIncrementable();
+
+	/** Copy constructor. */
+	IIncrementable(const IIncrementable&);
+
+	/** Copy assignment operator. */
+	IIncrementable* operator=(const IIncrementable&);
+
+	/** Equality operator. */
+	friend bool operator==(const IIncrementable&, const IIncrementable&);
+
+	/** Pre-increment operator. See 'IWeaklyIncrementable'. */
+	IIncrementable& operator++();
+
+	/** Post-increment operator. */
+	IIncrementable operator++(int);
+};
+
+// Use 'IIncrementable' represents an incrementable type.
+static_assert(CIncrementable<IIncrementable>);
+
+/**
+ * A concept specifies a type is potentially an iterator. It only requires weakly incrementable and dereferenceable.
+ * This concept should only be used in scenarios where the specific type of the iterator is not important, such as iterator adapters.
+ */
+template <typename I>
+concept CInputOrOutputIterator = CWeaklyIncrementable<I>
+	&& requires(I Iter) { { *Iter } -> CReferenceable; };
+
+/** This is an example of an input or output iterator, indicate the traits that define an input or output iterator. */
+template <CReferenceable T>
+struct IInputOrOutputIterator /* : IWeaklyIncrementable */
+{
+	/** Move constructor. See 'IWeaklyIncrementable'. */
+	IInputOrOutputIterator(IInputOrOutputIterator&&);
+
+	/** Move assignment operator. See 'IWeaklyIncrementable'. */
+	IInputOrOutputIterator* operator=(IInputOrOutputIterator&&);
+
+	/** Pre-increment operator. See 'IWeaklyIncrementable'. */
+	IInputOrOutputIterator& operator++();
+
+	/** Post-increment operator. See 'IWeaklyIncrementable'. */
+	void operator++(int);
+
+	/** Dereference operator. It does not matter what the return type is, as long as it is referenceable. */
+	T operator*() const;
+};
+
+// Use 'IInputOrOutputIterator' represents an input or output iterator.
+static_assert(CInputOrOutputIterator<IInputOrOutputIterator<int>>);
+
+/** A concept specifies a type is an input iterator. */
+template <typename I>
+concept CInputIterator = CInputOrOutputIterator<I> && CIndirectlyReadable<I>;
+
+/** This is an example of an input iterator, indicate the traits that define an input iterator. */
+template <CReferenceable T>
+struct IInputIterator /* : IInputOrOutputIterator, IIndirectlyReadable */
+{
+	/** The element type of the indirectly readable type. See 'IIndirectlyReadable'. */
+	using ElementType = TRemoveCVRef<T>;
+
+	/** Move constructor. See 'IWeaklyIncrementable'. */
+	IInputIterator(IInputIterator&&);
+
+	/** Move assignment operator. See 'IWeaklyIncrementable'. */
+	IInputIterator* operator=(IInputIterator&&);
+
+	/** Indirectly read the element from the indirectly readable type. See 'IIndirectlyReadable'. */
+	T operator*() const;
+
+	/** Pre-increment operator. See 'IWeaklyIncrementable'. */
+	IInputIterator& operator++();
+
+	/** Post-increment operator. See 'IWeaklyIncrementable'. */
+	void operator++(int);
+};
+
+// Use 'IInputIterator<int>' represents an input iterator and 'int' is the regular element type.
+static_assert(CInputIterator<IInputIterator<int>> && CRegular<int>);
+
+// The 'CInputIterator' requires this code is valid.
+static_assert(
+	requires(IInputIterator<int> Iter, int& A)
+	{
+		++Iter;
+		Iter++;
+		A = *++Iter;
+		A =   *Iter;
+	}
+);
+
+/** A concept specifies a type is an output iterator and expression '*Iter++ = A' is valid to write the element. */
+template <typename I, typename T>
+concept COutputIterator = CInputOrOutputIterator<I> && CIndirectlyWritable<I, T>
+	&& requires(I Iter) { { Iter++ } -> CIndirectlyWritable<T>; };
+
+/** This is an example of an output iterator, indicate the traits that define an output iterator. */
+template <CReference T>
+struct IOutputIterator /* : IInputOrOutputIterator, IIndirectlyWritable<T> */
+{
+	/** Move constructor. See 'IWeaklyIncrementable'. */
+	IOutputIterator(IOutputIterator&&);
+
+	/** Move assignment operator. See 'IWeaklyIncrementable'. */
+	IOutputIterator* operator=(IOutputIterator&&);
+
+	/** Indirectly write the element from the indirectly writable type. See 'IIndirectlyWritable'. */
+	T operator*() const;
+
+	/** Pre-increment operator. See 'IWeaklyIncrementable'. */
+	IOutputIterator& operator++();
+
+	/**
+	 * Post-increment operator.
+	 * Specify, the concept not requires the return type is self type,
+	 * but requires the expression '*Iter++ = A;' is equivalent to '*Iter = A; ++Iter;'.
+	 * This means that returning a proxy class that satisfies 'CIndirectlyWritable<T>' is also valid.
+	 * See 'IWeaklyIncrementable'.
+	 */
+	IIndirectlyWritable<T> operator++(int);
+};
+
+// Use 'IOutputIterator<int>' represents an output iterator and 'int' is the regular element type.
+static_assert(COutputIterator<IOutputIterator<int&>, int> && CRegular<int>);
+
+// The 'CInputIterator' requires this code is valid.
+static_assert(
+	requires(IOutputIterator<int&> Iter, int& A)
+	{
+		++Iter;
+		Iter++;
+		*++Iter = A;
+		*Iter++ = A;
+		  *Iter = A;
+	}
+);
+
+#define ENABLE_RANGE_BASED_FOR_LOOP_SUPPORT public:                        \
+	NODISCARD FORCEINLINE constexpr auto begin()       { return Begin(); } \
+	NODISCARD FORCEINLINE constexpr auto begin() const { return Begin(); } \
+	NODISCARD FORCEINLINE constexpr auto end()         { return End();   } \
+	NODISCARD FORCEINLINE constexpr auto end()   const { return End();   }
+
+NAMESPACE_MODULE_END(Utility)
+NAMESPACE_MODULE_END(Redcraft)
+NAMESPACE_REDCRAFT_END

Redcraft.Utility/Source/Public/Miscellaneous/Iterator.h

@@ -3,6 +3,7 @@
 #include "CoreTypes.h"
 #include "Memory/Address.h"
 #include "Templates/Invoke.h"
+#include "Iterator/Iterator.h"
 #include "Templates/Utility.h"
 #include "Templates/Noncopyable.h"
 #include "TypeTraits/TypeTraits.h"
@@ -13,128 +14,17 @@ NAMESPACE_REDCRAFT_BEGIN
 NAMESPACE_MODULE_BEGIN(Redcraft)
 NAMESPACE_MODULE_BEGIN(Utility)
 
-NAMESPACE_PRIVATE_BEGIN
-
-template <typename T> using WithReference = T&;
-
-template <typename I> struct TIteratorElementType     { using Type = typename I::ElementType; };
-template <typename T> struct TIteratorElementType<T*> { using Type = TRemoveCV<T>;            };
-
-template <typename I> struct TIteratorPointerType     { using Type = void; };
-template <typename T> struct TIteratorPointerType<T*> { using Type = T*;   };
-
-template <typename I> requires (requires(I& Iter) { { Iter.operator->() } -> CPointer; })
-struct TIteratorPointerType<I> { using Type = decltype(DeclVal<I&>().operator->()); };
-
-NAMESPACE_PRIVATE_END
-
-template <typename T>
-concept CReferenceable = requires { typename NAMESPACE_PRIVATE::WithReference<T>; };
-
-template <typename T>
-concept CDereferenceable = requires(T& A) { { *A } -> CReferenceable; };
+template <typename I>
+using TIteratorElementType = TIteratorElement<I>;
 
 template <typename I>
-using TIteratorElementType = typename NAMESPACE_PRIVATE::TIteratorElementType<TRemoveCVRef<I>>::Type;
-
-template <typename I>
-using TIteratorPointerType = typename NAMESPACE_PRIVATE::TIteratorPointerType<TRemoveCVRef<I>>::Type;
+using TIteratorPointerType = TIteratorPointer<I>;
 
 template <CReferenceable I>
-using TIteratorReferenceType = decltype(*DeclVal<I&>());
+using TIteratorReferenceType = TIteratorReference<I>;
 
 template <CReferenceable I> requires (requires(I& Iter) { { MoveTemp(*Iter) } -> CReferenceable; })
-using TIteratorRValueReferenceType = decltype(MoveTemp(*DeclVal<I&>()));
-
-template <typename I>
-concept CIndirectlyReadable =
-	requires(const TRemoveCVRef<I> Iter)
-	{
-		typename TIteratorElementType<I>;
-		typename TIteratorReferenceType<I>;
-		typename TIteratorRValueReferenceType<I>;
-		{          *Iter  } -> CSameAs<TIteratorReferenceType<I>>;
-		{ MoveTemp(*Iter) } -> CSameAs<TIteratorRValueReferenceType<I>>;
-	}
-	&& CSameAs<TIteratorElementType<I>, TRemoveCVRef<TIteratorElementType<I>>>
-	&& CCommonReference<TIteratorReferenceType<I>&&, TIteratorElementType<I>&>
-	&& CCommonReference<TIteratorReferenceType<I>&&, TIteratorRValueReferenceType<I>&&>
-	&& CCommonReference<TIteratorRValueReferenceType<I>&&, const TIteratorElementType<I>&>;
-
-template <typename I, typename T>
-concept CIndirectlyWritable =
-	requires(I&& Iter, T&& A)
-	{
-		*Iter             = Forward<T>(A);
-		*Forward<I>(Iter) = Forward<T>(A);
-		const_cast<const TIteratorReferenceType<I>&&>(*Iter)             = Forward<T>(A);
-		const_cast<const TIteratorReferenceType<I>&&>(*Forward<I>(Iter)) = Forward<T>(A);
-	};
-
-template <typename I>
-concept CWeaklyIncrementable = CMovable<I>
-	&& requires(I Iter) { { ++Iter } -> CSameAs<I&>; Iter++; };
-
-template <typename I>
-concept CIncrementable = CRegular<I> && CWeaklyIncrementable<I>
-	&& requires(I Iter) { { Iter++ } -> CSameAs<I>; };
-
-template <typename I>
-concept CInputOrOutputIterator = CWeaklyIncrementable<I>
-	&& requires(I Iter) { { *Iter } -> CReferenceable; };
-
-template <typename S, typename I>
-concept CSentinelFor = CSemiregular<S> && CInputOrOutputIterator<I> && CWeaklyEqualityComparable<S, I>;
-
-template <typename S, typename I>
-inline constexpr bool bDisableSizedSentinelFor = false;
-
-template <typename S, typename I>
-concept CSizedSentinelFor = CSentinelFor<S, I> && CPartiallyOrdered<S, I>
-	&& !bDisableSizedSentinelFor<TRemoveCV<S>, TRemoveCV<I>>
-	&& requires(const I& Iter, const S& Sentinel)
-	{
-		{ Sentinel - Iter } -> CSameAs<ptrdiff>;
-		{ Iter - Sentinel } -> CSameAs<ptrdiff>;
-	};
-
-template <typename I>
-concept CInputIterator = CInputOrOutputIterator<I> && CIndirectlyReadable<I>;
-
-template <typename I, typename T>
-concept COutputIterator = CInputOrOutputIterator<I> && CIndirectlyWritable<I, T>
-	&& requires(I Iter, T&& A) { *Iter++ = Forward<T>(A); };
-
-template <typename I>
-concept CForwardIterator = CInputIterator<I> && CIncrementable<I> && CSentinelFor<I, I>;
-
-template <typename I>
-concept CBidirectionalIterator = CForwardIterator<I>
-	&& requires(I Iter) {
-		{ --Iter } -> CSameAs<I&>;
-		{ Iter-- } -> CSameAs<I >;
-	};
-
-template <typename I>
-concept CRandomAccessIterator = CBidirectionalIterator<I> && CTotallyOrdered<I> && CSizedSentinelFor<I, I>
-	&& requires(I Iter, const I Jter, const ptrdiff N) {
-		{ Iter   += N } -> CSameAs<I&>;
-		{ Jter   +  N } -> CSameAs<I >;
-		{ N +  Jter   } -> CSameAs<I >;
-		{ Iter   -= N } -> CSameAs<I&>;
-		{ Jter   -  N } -> CSameAs<I >;
-		{   Jter[N]   } -> CSameAs<TIteratorReferenceType<I>>;
-	};
-
-template <typename I>
-concept CContiguousIterator = CRandomAccessIterator<I> && CLValueReference<TIteratorReferenceType<I>>
-	&& CSameAs<TIteratorElementType<I>, TRemoveCVRef<TIteratorReferenceType<I>>>
-	&& requires(I& Iter)
-	{
-		{ ToAddress(Iter) } -> CSameAs<TAddPointer<TIteratorReferenceType<I>>>;
-	};
-
-static_assert(CContiguousIterator<int32*>);
+using TIteratorRValueReferenceType = TIteratorRValueReference<I>;
 
 NAMESPACE_BEGIN(Iteration)