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Container/partial-mapping.h

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#ifndef NMWR_GB_PARTIAL_MAPPING_H
#define NMWR_GB_PARTIAL_MAPPING_H


// $LICENSE

#include "my-hash-map.h" // STL

#include "Container/proxies.h"
#include "Utility/pre-post-conditions.h"


//----------------------------------------------------------------
//----------------------------------------------------------------


template<class T1, class T2>
class partial_mapping {
public:
  // STL unary function conformance
  typedef T1                         argument_type;
  typedef T2                         result_type;

private:
  template<class T>
  struct hasher_type {
    size_t operator()(T const& t) const { 
      hash<T> h;
      return h(t);
    }
  };
  template<class T>
  struct hasher_type<T*> {  
    size_t operator()(T const* t) const { 
      hash<unsigned> h;
      return h(reinterpret_cast<unsigned>(t));
    }
  };

  //typedef hash_map<T1,T2,hash<T1>,equal_to<T1> >  map_table_type;
  typedef hash_map<T1,T2,hasher_type<T1>,equal_to<T1> >  map_table_type;

  //   typedef write_only_proxy<T2>                    proxy_type;

  //------ DATA --------
  map_table_type mapping;
  T2             default_val;
public:
  //---------------------- construction --------------------------

  partial_mapping(const T2& def = T2()) : default_val(def) {}

  const T2& set_default(const T2& t2) { default_val = t2; return t2;}

  //---------------------- queries -------------------------------

  int  size_of_dom() const { return mapping.size();}
  bool defined  (const T1& t1) const { return (mapping.find(t1) != mapping.end());}
  bool undefined(const T1& t1) const { return (mapping.find(t1) == mapping.end());}

  const T2& default_value() const { return default_val;}

  //---------------------- data access ---------------------------

  typedef typename map_table_type::iterator       iterator;
  typedef typename map_table_type::const_iterator const_iterator;

  // should use domain/image types
  const_iterator begin() const { return mapping.begin();}
  const_iterator end()   const { return mapping.end();}
  // no non-const versions of begin/end: writing should occur
  // only via mapping interface: op[]/() below.

  //   proxy_type operator[](const T1& t1) { return proxy_type(mapping[t1]);}
  T2      & operator[](T1 const& t1) {
    if(undefined(t1))
      mapping[t1] = default_val;
    return mapping[t1];
  }
  T2 const& operator()(T1 const& t1) const {
    const_iterator i = mapping.find(t1);
    return ( i != mapping.end() ? (*i).second : default_val);
  }

};

#endif

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Copyright (c) Guntram Berti 1997-2002. See the GrAL Homepage for up-to-date information.

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