cached_fn.hh

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/* -*- C++ -*-
 * $Id: cached_fn.hh 957 2005-03-07 16:01:20Z sjoyeux $
 */
#ifndef UTILMM_FUNCTIONAL_CACHED_FN_HEADER
# define UTILMM_FUNCTIONAL_CACHED_FN_HEADER

#include "utilmm/config/config.h"
#include "utilmm/hash/hash_map.hh"

namespace utilmm {

  template< typename Arg, typename Ret, class Hash=hash<Arg>,
            class Equal=std::equal_to<Arg> >
  class cached_fn
    :public std::unary_function<Arg, Ret> {
  private:
    typedef hash_map<Arg, Ret, Hash, Equal> cache_type;
    typedef typename arg_traits<Arg>::type arg_type;
    
    cache_type the_cache;
    
  protected:
    virtual Ret call(Arg const &arg) =0;

  public:
    cached_fn() {}
    virtual ~cached_fn() {}

    Ret const &operator()(arg_type arg);

    void empty_cache() {
      the_cache.clear();
    }
    
    size_t cache_size() const {
      return the_cache.size();
    }
  }; // struct utilmm::cached_fn<>

} // namespace utilmm

# define IN_UTILMM_FUNCTIONAL_CACHED_FN_HEADER
#include "utilmm/functional/bits/cached_fn.tcc" 
# undef IN_UTILMM_FUNCTIONAL_CACHED_FN_HEADER 
#endif // UTILMM_FUNCTIONAL_CACHED_FN_HEADER