JHashMap.hh

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#ifndef __JTOOLS__JHASHMAP__
#define __JTOOLS__JHASHMAP__

#include <utility>

#include "JLang/JException.hh"
#include "JLang/JClass.hh"
#include "JTools/JMappableCollection.hh"
#include "JTools/JHashCollection.hh"
#include "JTools/JHashEvaluator.hh"
#include "JTools/JRouter.hh"


/**
 * \file
 *
 * General purpose class for hash map of unique elements.
 * \author mdejong
 */
namespace JTOOLS {}
namespace JPP { using namespace JTOOLS; }

namespace JTOOLS {

  using JLANG::JClass;
  using JLANG::JIndexOutOfRange;

  /**
   * Auxiliary class for hash evaluation of map keys and elements.
   */
  template<class JEvaluator_t>
  struct JHashMapEvaluator :
    public JEvaluator_t
  {
    using JEvaluator_t::operator();

    /**
     * Constructor.
     * 
     * \param  evaluator       evaluator
     */
    JHashMapEvaluator(const JEvaluator_t& evaluator) :
      JEvaluator_t(evaluator)
    {}


    /**
     * Get hash value of given pair.
     *
     * \param  pair            pair
     * \return                 hash value
     */
    template<class JKey_t, class JValue_t>
    inline int operator()(const std::pair<JKey_t, JValue_t>& pair)
    {
      return JEvaluator_t::operator()(pair.first);
    }
  };
  

  /**
   * General purpose class for hash map of unique keys.
   *
   * The keys in a hash collection are unique according to the specified evaluation.
   * The evaluation of keys corresponds to a unary method returning an integer value for a given key;
   * The default evaluator is JHashEvaluator. 
   *
   * This class implements the JMappableCollection interface.
   */
  template<class JKey_t, class JValue_t, class JEvaluator_t = JHashEvaluator>
  struct JHashMap :
    public JHashCollection<std::pair<JKey_t, JValue_t>, JHashMapEvaluator<JEvaluator_t> >,
    public JMappableCollection<JKey_t, JValue_t>
  {
  public:

    typedef JKey_t                                               key_type;
    typedef JValue_t                                             mapped_type;
    typedef std::pair<JKey_t, JValue_t>                          value_type;
    typedef JHashMapEvaluator<JEvaluator_t>                      evaluator_type;
    
    typedef JHashCollection<value_type, evaluator_type>          collection_type;
    typedef typename collection_type::container_type             container_type;

    typedef typename container_type::const_iterator              const_iterator;
    typedef typename container_type::const_reverse_iterator      const_reverse_iterator;
    typedef typename container_type::iterator                    iterator;
    typedef typename container_type::reverse_iterator            reverse_iterator;

    using JMappableCollection<key_type, mapped_type>::operator[];


    /**
     * Constructor.
     *
     * \param  evaluator       evaluator
     */
    JHashMap(const JEvaluator_t& evaluator = JEvaluator_t()) :
      collection_type(evaluator)
    {}


    /**
     * Clear.
     */
    virtual void clear() override 
    {
      collection_type::clear();
    }


    /**
     * Get mapped value.
     *
     * \param  key             key
     * \return                 mapped value
     */
    virtual mapped_type& get(typename JClass<key_type>::argument_type key) override 
    {
      const int ival = this->getValue(key);
      
      if (!this->router.has(ival)) {
        collection_type::insert(value_type(key, mapped_type()));
      }

      return container_type::operator[](this->router.get(ival)).second;
    }


    /**
     * Get mapped value.
     *
     * This method will throw an exception if given key is not present following the prerequisite of constness.
     *
     * \param  key             key
     * \return                 mapped value
     */
    virtual const mapped_type& get(typename JClass<key_type>::argument_type key) const override 
    {
      const int ival = this->getValue(key);

      if (this->router.has(ival))
        return container_type::operator[](this->router.get(ival)).second;
      else
        THROW(JIndexOutOfRange, "JHasMap::get(): invalid key.");
    }
  };
}

#endif