/* -*- C++ -*-

 * src/lemon/skeletons/maps.h - Part of LEMON, a generic C++ optimization library

 *

 * Copyright (C) 2004 Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport

 * (Egervary Combinatorial Optimization Research Group, EGRES).

 *

 * Permission to use, modify and distribute this software is granted

 * provided that this copyright notice appears in all copies. For

 * precise terms see the accompanying LICENSE file.

 *

 * This software is provided "AS IS" with no warranty of any kind,

 * express or implied, and with no claim as to its suitability for any

 * purpose.

 *

 */

#ifndef LEMON_MAPSKELETON_H

#define LEMON_MAPSKELETON_H

#include <lemon/concept_check.h>

///\ingroup skeletons

///\file

///\brief Map concepts checking classes for testing and documenting.

namespace lemon {

  namespace skeleton {

    /// \addtogroup skeletons

    /// @{

    /// Readable map concept

    template<typename K, typename T>

    class ReadMap

    {

    public:

      /// Map's key type.

      typedef K KeyType;    

      /// Map's value type. (The type of objects associated with the keys).

      typedef T ValueType;

      /// Returns the value associated with a key.

      ValueType operator[](const KeyType &k) const {return ValueType();}

      ///Default constructor

      ReadMap() {}

    };

    /// Writable map concept

    template<typename K, typename T>

    class WriteMap

    {

    public:

      /// Map's key type.

      typedef K KeyType;    

      /// Map's value type. (The type of objects associated with the keys).

      typedef T ValueType;

      /// Sets the value associated with a key.

      void set(const KeyType &k,const ValueType &t) {}

      ///Default constructor

      WriteMap() {}

    };

    ///Read/Writable map concept

    template<typename K, typename T>

    class ReadWriteMap : public ReadMap<K,T>,

			    public WriteMap<K,T>

    {

    public:

      /// Map's key type.

      typedef K KeyType;    

      /// Map's value type. (The type of objects associated with the keys).

      typedef T ValueType;

      /// Returns the value associated with a key.

      ValueType operator[](const KeyType &k) const {return ValueType();}

      /// Sets the value associated with a key.

      void set(const KeyType &k,const ValueType &t) {}

      ///Default constructor

      ReadWriteMap() {}

    };

    ///Dereferable map concept

    template<typename K, typename T>

    class ReferenceMap : public ReadWriteMap<K,T>

    {

    public:

      /// Map's key type.

      typedef K KeyType;    

      /// Map's value type. (The type of objects associated with the keys).

      typedef T ValueType;

    protected:

      ValueType tmp;

    public:

      typedef ValueType& ReferenceType;

      /// Map's const reference type.

      typedef const ValueType& ConstReferenceType;

      ///Returns a reference to the value associated to a key.

      ReferenceType operator[](const KeyType &i) { return tmp; }

      ///Returns a const reference to the value associated to a key.

      ConstReferenceType operator[](const KeyType &i) const

      { return tmp; }

      /// Sets the value associated with a key.

      void set(const KeyType &k,const ValueType &t) { operator[](k)=t; }

      ///Default constructor

      ReferenceMap() {}

    };

    template<typename Item, typename T, typename Graph>

    class GraphMap : public ReadWriteMap<Item, T> {

      // I really, really don't like the idea that every graph should have

      // reference maps! --klao

    private:

      // We state explicitly that graph maps have no default constructor?

      GraphMap();

    public:

      explicit GraphMap(Graph const&) {}

      // value for initializing

      GraphMap(Graph const&, T) {}

      // this probably should be required:

      GraphMap(GraphMap const&) {}

      GraphMap& operator=(GraphMap const&) { return *this; }

      // but this is a absolute no-op! We should provide a more generic

      // graph-map-copy operation.

      //

      // template<typename TT>

      // GraphMap(GraphMap<TT> const&);

      //

      // template<typename TT>

      // GraphMap& operator=(const GraphMap<TT>&);

    };

    /****************  Concept-checking classes  ****************/

    template<typename ReadMap>

    struct ReadMapConcept {

      typedef typename ReadMap::KeyType KeyType;

      typedef typename ReadMap::ValueType ValueType;

      void constraints() {

	// No constraints for constructor.

	// What are the requirement for the ValueType?

	// CopyConstructible? Assignable? None of these?

	ValueType v = m[k];

	v = m[k];

	// FIXME:

	ignore_unused_variable_warning(v);

      }

      ReadMap m;

      KeyType k;

    };

    template<typename WriteMap>

    struct WriteMapConcept {

      typedef typename WriteMap::KeyType KeyType;

      typedef typename WriteMap::ValueType ValueType;

      void constraints() {

	// No constraints for constructor.

	m.set(k, v);

      }

      WriteMap m;

      KeyType k;

      ValueType v;

    };

    template<typename ReadWriteMap>

    struct ReadWriteMapConcept {

      void constraints() {

	function_requires< ReadMapConcept<ReadWriteMap> >();

	function_requires< WriteMapConcept<ReadWriteMap> >();

      }

    };

    template<typename ReferenceMap>

    struct ReferenceMapConcept {

      typedef typename ReferenceMap::KeyType KeyType;

      typedef typename ReferenceMap::ValueType ValueType;

      typedef typename ReferenceMap::ReferenceType ReferenceType;

      // What for is this?

      typedef typename ReferenceMap::ConstReferenceType ConstReferenceType;

      void constraints() {

	function_requires< ReadWriteMapConcept<ReferenceMap> >();

	m[k] = v;

	// Or should we require real reference?

	// Like this:

	// ValueType &vv = m[k];

	// ignore_unused_variable_warning(vv);

      }

      ReferenceMap m;

      KeyType k;

      ValueType v;

    };

    /// \todo GraphMapConceptCheck

    template<typename GraphMap, typename Graph>

    struct GraphMapConcept {

      void constraints() {

	function_requires< ReadWriteMapConcept<GraphMap> >();

	// Construction with a graph parameter

	GraphMap a(g);

	// Ctor with a graph and a default value parameter

	GraphMap a2(g,t);

	// Copy ctor. Do we need it?

	GraphMap b=c;

	// Copy operator. Do we need it?

	a=b;

	ignore_unused_variable_warning(a2);

      }

      const GraphMap &c;

      const Graph &g;

      const typename GraphMap::ValueType &t;

    };

    // @}

  } //namespace skeleton

} //namespace lemon

#endif // LEMON_MAPSKELETON_H