src/hugo/maps.h
author alpar
Tue, 27 Jul 2004 16:04:21 +0000
changeset 741 aa700e5c47b5
parent 539 fb261e3a9a0f
child 805 59b8cb2cb2f8
permissions -rw-r--r--
A very flexible bfs function using named parameters and impicit map types.
     1 // -*- C++ -*- //
     2 #ifndef HUGO_MAPS_H
     3 #define HUGO_MAPS_H
     4 
     5 ///\file
     6 ///\brief Miscellaneous property maps
     7 ///
     8 ///\todo This file has the same name as the concept file in skeletons,
     9 /// and this is not easily detectable in docs...
    10 
    11 #include <map>
    12 
    13 namespace hugo {
    14 
    15   /// Base class of maps.
    16 
    17   template<typename K, typename T>
    18   class MapBase
    19   {
    20   public:
    21     ///
    22     typedef K KeyType;
    23     ///
    24     typedef T ValueType;
    25   };
    26 
    27   /// Null map. (aka DoNothingMap)
    28 
    29   /// If you have to provide a map only for its type definitions,
    30   /// or if you have to provide a writable map, but will not use the
    31   /// data written to it...
    32   template<typename K, typename T>
    33   class NullMap : public MapBase<K,T>
    34   {
    35   public:
    36 
    37     T operator[](const K&) const { return T(); }
    38     void set(const K&, const T&) {}
    39     ///\bug when update is removed from map concepts by being dynamic
    40     ///stuffs, this line have to be removed.
    41     void update() { }
    42   };
    43 
    44 
    45   /// Constant map.
    46 
    47   /// This is a readable map which assignes a specified value to each key.
    48   /// In other aspects it is equivalent to the \ref NullMap
    49   template<typename K, typename T>
    50   class ConstMap : public MapBase<K,T>
    51   {
    52     T v;
    53   public:
    54 
    55     ConstMap() {}
    56     ConstMap(const T &_v) : v(_v) {}
    57 
    58     T operator[](const K&) const { return v; }
    59     void set(const K&, const T&) {}
    60 
    61     template<typename T1>
    62     struct rebind {
    63       typedef ConstMap<K,T1> other;
    64     };
    65 
    66     template<typename T1>
    67     ConstMap(const ConstMap<K,T1> &, const T &_v) : v(_v) {}
    68   };
    69 
    70 
    71 
    72   /// \c std::map wrapper
    73 
    74   /// This is essentially a wrapper for \c std::map. With addition that
    75   /// you can specify a default value different from \c ValueType() .
    76   ///
    77   /// \todo Provide allocator parameter...
    78   template <typename Key, typename T, typename Compare = std::less<Key> >
    79   class StdMap : public std::map<Key,T,Compare> {
    80     typedef std::map<Key,T,Compare> parent;
    81     T v;
    82     typedef typename parent::value_type PairType;
    83 
    84   public:
    85     typedef Key KeyType;
    86     typedef T ValueType;
    87     typedef T& ReferenceType;
    88     typedef const T& ConstReferenceType;
    89 
    90 
    91     StdMap() : v() {}
    92     /// Constructor with specified default value
    93     StdMap(const T& _v) : v(_v) {}
    94 
    95     /// \brief Constructs the map from an appropriate std::map.
    96     ///
    97     /// \warning Inefficient: copies the content of \c m !
    98     StdMap(const parent &m) : parent(m) {}
    99     /// \brief Constructs the map from an appropriate std::map, and explicitly
   100     /// specifies a default value.
   101     ///
   102     /// \warning Inefficient: copies the content of \c m !
   103     StdMap(const parent &m, const T& _v) : parent(m), v(_v) {}
   104     
   105     template<typename T1, typename Comp1>
   106     StdMap(const StdMap<Key,T1,Comp1> &m, const T &_v) { 
   107       //FIXME; 
   108     }
   109 
   110     ReferenceType operator[](const Key &k) {
   111       return insert(PairType(k,v)).first -> second;
   112     }
   113     ConstReferenceType operator[](const Key &k) const {
   114       typename parent::iterator i = lower_bound(k);
   115       if (i == parent::end() || parent::key_comp()(k, (*i).first))
   116 	return v;
   117       return (*i).second;
   118     }
   119     void set(const Key &k, const T &t) {
   120       parent::operator[](k) = t;
   121     }
   122 
   123     /// Changes the default value of the map.
   124     /// \return Returns the previous default value.
   125     ///
   126     /// \warning The value of some keys (which has alredy been queried, but
   127     /// the value has been unchanged from the default) may change!
   128     T setDefault(const T &_v) { T old=v; v=_v; return old; }
   129 
   130     template<typename T1>
   131     struct rebind {
   132       typedef StdMap<Key,T1,Compare> other;
   133     };
   134   };
   135   
   136 }
   137 #endif // HUGO_MAPS_H