src/Platform/ForEach.h


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/*
 Derived from source code of TrueCrypt 7.1a, which is
 Copyright (c) 2008-2012 TrueCrypt Developers Association and which is governed
 by the TrueCrypt License 3.0.

 Modifications and additions to the original source code (contained in this file)
 and all other portions of this file are Copyright (c) 2013-2017 IDRIX
 and are governed by the Apache License 2.0 the full text of which is
 contained in the file License.txt included in VeraCrypt binary and source
 code distribution packages.
*/

#ifndef TC_HEADER_Platform_ForEach
#define TC_HEADER_Platform_ForEach

namespace VeraCrypt
{
	class ForEach
	{
	public:
		struct Container
		{
			Container () : InnerContinue (true), InnerEndCondition (false) { }
			virtual ~Container () { }

			void Continue () const { InnerContinue = true; }
			bool InnerIsNotEnd () const { return InnerEndCondition = !InnerEndCondition; }
			virtual bool IsNotEnd () const = 0;
			virtual void Next () const = 0;

			mutable bool InnerContinue;
			mutable bool InnerEndCondition;
		};

	protected:
		template <class T>
		struct ContainerForward : Container
		{
			ContainerForward (const T &container)
				: ContainerCopy (container), EndIterator (ContainerCopy.end()), Iterator (ContainerCopy.begin()) { }

			virtual bool IsNotEnd () const { bool r = InnerContinue && Iterator != EndIterator; InnerContinue = false; return r; }
			virtual void Next () const { ++Iterator; }

			const T ContainerCopy;	// Support for temporary objects
			typename T::const_iterator EndIterator;
			mutable typename T::const_iterator Iterator;

		private:
			ContainerForward &operator= (const ContainerForward &);
		};

		template <class T>
		struct ContainerReverse : Container
		{
			ContainerReverse (const T &container)
				: ContainerCopy (container), EndIterator (ContainerCopy.rend()), Iterator (ContainerCopy.rbegin()) { }

			virtual bool IsNotEnd () const { bool r = InnerContinue && Iterator != EndIterator; InnerContinue = false; return r; }
			virtual void Next () const { ++Iterator; }

			const T ContainerCopy;
			typename T::const_reverse_iterator EndIterator;
			mutable typename T::const_reverse_iterator Iterator;

		private:
			ContainerReverse &operator= (const ContainerReverse &);
		};

	public:
		template <class T>
		static ContainerForward <T> GetContainerForward (const T &container)
		{
			return ContainerForward <T> (container);
		}

		template <class T>
		static ContainerReverse <T> GetContainerReverse (const T &container)
		{
			return ContainerReverse <T> (container);
		}

	protected:
		template <class T>
		struct TypeWrapper { };

	public:
		template <class T>
		static TypeWrapper <T> ToTypeWrapper (const T &x) { return TypeWrapper <T> (); }

		struct TypeWrapperDummy
		{
			template <class T>
			operator TypeWrapper <T> () const { return TypeWrapper <T> (); }
		};

		template <class T>
		static const ContainerForward <T> &GetContainerForward (const Container &forEachContainer, const TypeWrapper <T> &)
		{
			return static_cast <const ContainerForward <T> &> (forEachContainer);
		}

		template <class T>
		static const ContainerReverse <T> &GetContainerReverse (const Container &forEachContainer, const TypeWrapper <T> &)
		{
			return static_cast <const ContainerReverse <T> &> (forEachContainer);
		}
	};
}


#define FOREACH_TEMPLATE(dereference,listType,variable,listInstance) \
	for (const ForEach::Container &forEachContainer = ForEach::GetContainer##listType (listInstance); forEachContainer.IsNotEnd(); forEachContainer.Next()) \
		for (variable = dereference(ForEach::GetContainer##listType (forEachContainer, (true ? ForEach::TypeWrapperDummy() : ForEach::ToTypeWrapper (listInstance))).Iterator); forEachContainer.InnerIsNotEnd(); forEachContainer.Continue())

#define foreach(variable,listInstance) FOREACH_TEMPLATE(*, Forward, variable, listInstance)
#define foreach_ref(variable,listInstance) FOREACH_TEMPLATE(**, Forward, variable, listInstance)
#define foreach_reverse(variable,listInstance) FOREACH_TEMPLATE(*, Reverse, variable, listInstance)
#define foreach_reverse_ref(variable,listInstance) FOREACH_TEMPLATE(**, Reverse, variable, listInstance)


#endif // TC_HEADER_Platform_ForEach