bimap.h

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/* +---------------------------------------------------------------------------+
   |                     Mobile Robot Programming Toolkit (MRPT)               |
   |                          http://www.mrpt.org/                             |
   |                                                                           |
   | Copyright (c) 2005-2017, Individual contributors, see AUTHORS file        |
   | See: http://www.mrpt.org/Authors - All rights reserved.                   |
   | Released under BSD License. See details in http://www.mrpt.org/License    |
   +---------------------------------------------------------------------------+ */
#ifndef  mrpt_bimap_H
#define  mrpt_bimap_H

#include <mrpt/utils/utils_defs.h>
#include <map>

namespace mrpt
{
        namespace utils
        {
                /** A bidirectional version of std::map, declared as bimap<KEY,VALUE> and which actually contains two std::map's, one for keys and another for values.
                  * To use this class, insert new pairs KEY<->VALUE with bimap::insert. Then, you can access the KEY->VALUE map with bimap::direct(), and the VALUE->KEY map with bimap::inverse(). The consistency of the two internal maps is assured at any time.
                  *
                  * \note This class can be accessed through iterators to the map KEY->VALUE only.
                  * \note Both typenames KEY and VALUE must be suitable for being employed as keys in a std::map, i.e. they must be comparable through a "< operator".
                  * \note Defined in #include <mrpt/utils/bimap.h>
                  * \ingroup stlext_grp
                  */
                template <typename KEY,typename VALUE>
                class bimap
                {
                private:
                        std::map<KEY,VALUE>     m_k2v;
                        std::map<VALUE,KEY>     m_v2k;

                public:
                        typedef typename std::map<KEY,VALUE>::const_iterator const_iterator;
                        typedef typename std::map<KEY,VALUE>::iterator iterator;

                        typedef typename std::map<VALUE,KEY>::const_iterator const_iterator_inverse;
                        typedef typename std::map<VALUE,KEY>::iterator iterator_inverse;

                        /** Default constructor - does nothing */
                        bimap() { }

                        inline const_iterator begin() const { return m_k2v.begin(); }
                        inline iterator       begin() { return m_k2v.begin(); }
                        inline const_iterator end() const { return m_k2v.end(); }
                        inline iterator       end() { return m_k2v.end(); }

                        inline const_iterator_inverse inverse_begin() const { return m_v2k.begin(); }
                        inline iterator_inverse       inverse_begin() { return m_v2k.begin(); }
                        inline const_iterator_inverse inverse_end() const { return m_v2k.end(); }
                        inline iterator_inverse       inverse_end() { return m_v2k.end(); }

                        inline size_t size() const { return m_k2v.size(); }
                        inline bool empty() const { return m_k2v.empty(); }

                        /** Return a read-only reference to the internal map KEY->VALUES */
                        const std::map<KEY,VALUE> &getDirectMap() const { return m_k2v; }
                        /** Return a read-only reference to the internal map KEY->VALUES */
                        const std::map<VALUE,KEY> &getInverseMap() const { return m_v2k; }

                        void clear() //!< Clear the contents of the bi-map.
                        {
                                m_k2v.clear();
                                m_v2k.clear();
                        }

                        /** Insert a new pair KEY<->VALUE in the bi-map */
                        void insert(const KEY &k,const VALUE &v)
                        {
                                m_k2v[k]=v;
                                m_v2k[v]=k;
                        }

                        /**  Get the value associated the given key, KEY->VALUE, returning false if not present.
                          *  \sa inverse, hasKey, hasValue
                          * \return false on key not found.
                          */
                        bool direct(const KEY &k, VALUE &out_v) const
                        {
                                const_iterator i=m_k2v.find(k);
                                if (i==m_k2v.end()) return false;
                                out_v = i->second;
                                return true;
                        }

                        /** Return true if the given key 'k' is in the bi-map  \sa hasValue, direct, inverse */
                        inline bool hasKey(const KEY& k) const {
                                return m_k2v.find(k)!=m_k2v.end();
                        }
                        /** Return true if the given value 'v' is in the bi-map \sa hasKey, direct, inverse */
                        inline bool hasValue(const VALUE& v) const {
                                return m_v2k.find(v)!=m_v2k.end();
                        }

                        /**  Get the value associated the given key, KEY->VALUE, raising an exception if not present.
                          *  \sa inverse, hasKey, hasValue
                          * \exception std::exception On key not present in the bi-map.
                          */
                        VALUE direct(const KEY &k) const
                        {
                                const_iterator i=m_k2v.find(k);
                                if (i==m_k2v.end()) THROW_EXCEPTION("Key not found.");
                                return i->second;
                        }

                        /**  Get the key associated the given value, VALUE->KEY, returning false if not present.
                          *  \sa direct, hasKey, hasValue
                          * \return false on value not found.
                          */
                        bool inverse(const VALUE &v, KEY &out_k) const
                        {
                                const_iterator_inverse i=m_v2k.find(v);
                                if (i==m_v2k.end()) return false;
                                out_k = i->second;
                                return true;
                        }

                        /**  Get the key associated the given value, VALUE->KEY, raising an exception if not present.
                          *  \sa direct, hasKey, hasValue
                          * \return false on value not found.
                          */
                        KEY inverse(const VALUE &v) const
                        {
                                const_iterator_inverse i=m_v2k.find(v);
                                if (i==m_v2k.end()) THROW_EXCEPTION("Value not found.");
                                return i->second;
                        }


                        inline const_iterator find_key(const KEY& k) const  { return m_k2v.find(k); }
                        inline iterator       find_key(const KEY& k)        { return m_k2v.find(k); }

                        inline const_iterator_inverse find_value(const VALUE& v) const  { return m_v2k.find(v); }
                        inline iterator_inverse       find_value(const VALUE& v)        { return m_v2k.find(v); }


                };  // end class bimap

        } // End of namespace
} // End of namespace
#endif