source: lemon-0.x/src/lemon/maps.h @ 987:87f7c54892df

/* -*- C++ -*-
 * src/lemon/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_MAPS_H
#define LEMON_MAPS_H

///\file
///\brief Miscellaneous property maps
///
///\todo This file has the same name as the concept file in concept/,
/// and this is not easily detectable in docs...

#include <map>

namespace lemon {

  /// Base class of maps.

  /// Base class of maps.
  /// It provides the necessary <tt>typedef</tt>s required by the map concept.
  template<typename K, typename T>
  class MapBase
  {
  public:
    ///\e
    typedef K Key;
    ///\e
    typedef T Value;
  };

  /// Null map. (a.k.a. DoNothingMap)

  /// If you have to provide a map only for its type definitions,
  /// or if you have to provide a writable map, but
  /// data written to it will sent to <tt>/dev/null</tt>...
  template<typename K, typename T>
  class NullMap : public MapBase<K,T>
  {
  public:

    /// Gives back a default constructed element.
    T operator[](const K&) const { return T(); }
    /// Absorbs the value.
    void set(const K&, const T&) {}
  };


  /// Constant map.

  /// This is a readable map which assigns a specified value to each key.
  /// In other aspects it is equivalent to the \ref NullMap.
  /// \todo set could be used to set the value.
  template<typename K, typename T>
  class ConstMap : public MapBase<K,T>
  {
    T v;
  public:

    /// Default constructor

    /// The value of the map will be uninitialized. 
    /// (More exactly it will be default constructed.)
    ConstMap() {}
    ///\e

    /// \param _v The initial value of the map.
    ///
    ConstMap(const T &_v) : v(_v) {}

    T operator[](const K&) const { return v; }
    void set(const K&, const T&) {}

    template<typename T1>
    struct rebind {
      typedef ConstMap<K,T1> other;
    };

    template<typename T1>
    ConstMap(const ConstMap<K,T1> &, const T &_v) : v(_v) {}
  };

  //to document later
  template<typename T, T v>
  struct Const { };
  //to document later
  template<typename K, typename V, V v>
  class ConstMap<K, Const<V, v> > : public MapBase<K, V>
  {
  public:
    ConstMap() { }
    V operator[](const K&) const { return v; }
    void set(const K&, const V&) { }
  };

  /// \c std::map wrapper

  /// This is essentially a wrapper for \c std::map. With addition that
  /// you can specify a default value different from \c Value() .
  ///
  /// \todo Provide allocator parameter...
  template <typename K, typename T, typename Compare = std::less<K> >
  class StdMap : public std::map<K,T,Compare> {
    typedef std::map<K,T,Compare> parent;
    T v;
    typedef typename parent::value_type PairType;

  public:
    typedef K Key;
    typedef T Value;
    typedef T& Reference;
    typedef const T& ConstReference;


    StdMap() : v() {}
    /// Constructor with specified default value
    StdMap(const T& _v) : v(_v) {}

    /// \brief Constructs the map from an appropriate std::map.
    ///
    /// \warning Inefficient: copies the content of \c m !
    StdMap(const parent &m) : parent(m) {}
    /// \brief Constructs the map from an appropriate std::map, and explicitly
    /// specifies a default value.
    ///
    /// \warning Inefficient: copies the content of \c m !
    StdMap(const parent &m, const T& _v) : parent(m), v(_v) {}
    
    template<typename T1, typename Comp1>
    StdMap(const StdMap<Key,T1,Comp1> &m, const T &_v) { 
      //FIXME; 
    }

    Reference operator[](const Key &k) {
      return insert(PairType(k,v)).first -> second;
    }
    ConstReference operator[](const Key &k) const {
      typename parent::iterator i = lower_bound(k);
      if (i == parent::end() || parent::key_comp()(k, (*i).first))
        return v;
      return (*i).second;
    }
    void set(const Key &k, const T &t) {
      parent::operator[](k) = t;
    }

    /// Changes the default value of the map.
    /// \return Returns the previous default value.
    ///
    /// \warning The value of some keys (which has already been queried, but
    /// the value has been unchanged from the default) may change!
    T setDefault(const T &_v) { T old=v; v=_v; return old; }

    template<typename T1>
    struct rebind {
      typedef StdMap<Key,T1,Compare> other;
    };
  };
  
}
#endif // LEMON_MAPS_H