/** \class PIMap
 * \brief Associative array
 * \details This class used to store Key = Value array of any
 * type of data. \a value() returns value for key and leave map
 * unchaged in any case. \a operator [] create entry in map if
 * there is no entry for given key. You can retrieve all
 * keys by method \a keys() and all values by methos \a values().
 * To iterate all entries use class PIMapIterator, or methods
 * \a makeIterator() and \a makeReverseIterator().

 * \fn PIMap::PIMap();
 * \brief Contructs an empty map

 * \fn PIMap::PIMap(const PIMap & other);
 * \brief Contructs a copy of "other"

 * \fn PIMap & PIMap::operator =(const PIMap & other);
 * \brief Copy operator

 * \fn PIMap::PIMap(const PIMap & other);
 * \brief Contructs a copy of "other"
 *
 *
 *

* \fn PIMapIterator PIMap::makeIterator() const
* \brief Returns PIMapIterator for this map

* \fn PIMapIterator PIMap::makeReverseIterator() const
* \brief Returns reverse PIMapIterator for this map


* \fn size_t PIMap::size() const
* \brief Returns entries count

* \fn int PIMap::size_s() const
* \brief Returns entries count

* \fn size_t PIMap::length() const
* \brief Returns entries count

* \fn bool PIMap::isEmpty() const
* \brief Returns if map is empty


* \fn T & PIMap::operator [](const Key & key)
* \brief Returns value for key "key". If there is no key in map, create one.

* \fn const T PIMap::operator [](const Key & key) const
* \brief Returns value for key "key". If there is no key in map, returns default T().

* \fn T & PIMap::at(const Key & key)
* \brief Equivalent to operator []

* \fn const T PIMap::at(const Key & key) const
* \brief Equivalent to operator []


* \fn PIMap & PIMap::operator <<(const PIMap & other)
* \brief Insert all etries of "other" to this map. Override existing values.

* \fn bool PIMap::operator ==(const PIMap & t) const
* \brief Compare operator

* \fn bool PIMap::operator !=(const PIMap & t) const
* \brief Compare operator

* \fn bool PIMap::contains(const Key & key) const
* \brief Returns "true" if map contains entry with key "key"


* \fn PIMap & PIMap::reserve(size_t new_size)
* \brief Reserve space for "new_size" entries

* \fn PIMap & PIMap::removeOne(const Key & key)
* \brief Remove entry with key "key"

* \fn PIMap & PIMap::remove(const Key & key)
* \brief Equivalent \a removeOne(key)

* \fn PIMap & PIMap::erase(const Key & key)
* \brief Equivalent \a removeOne(key)

* \fn PIMap & PIMap::clear()
* \brief Clear map


* \fn void PIMap::swap(PIMap & other)
* \brief Swap map with "other"


* \fn PIMap & PIMap::insert(const Key & key, const T & value)
* \brief Insert or rewrite entry with key "key" and value "value"

* \fn const T PIMap::value(const Key & key, const T & default = T())
* \brief Returns value for key "key". If there is no key in map, returns "default".

* \fn PIVector<T> PIMap::values() const
* \brief Returns all values as PIVector

* \fn Key PIMap::key(const T & value, const Key & default = Key()) const
* \brief Returns key for first founded value "value". If there is no such value in map, returns "default".

* \fn PIVector<Key> PIMap::keys() const
* \brief Returns all keys as PIVector

 * */




/** \class PIMapIterator
 * \brief Helper class to iterate over PIMap
 * \details This class used to access keys and values in PIMap.
 * You can use constructor to create iterator, or use \a PIMap::makeIterator()
 * and \a PIMap::makeReverseIterator() methods.
 *
 * First usage variant:
 * \code
 * PIMap<int, PIString> m;
 * m[1] = "one";
 * m[2] = "two";
 * m[4] = "four";
 *
 * auto it = m.makeIterator();
 * while (it.next()) {
 *     piCout << it.key() << it.value();
 * }
 * // 1 one
 * // 2 two
 * // 4 four
 * \endcode
 *
 * Using hasNext():
 * \code
 * while (it.hasNext()) {
 *     it.next();
 * \endcode
 *
 * Using constructor:
 * \code
 * PIMapIterator<int, PIString> it(m);
 * \endcode
 *
 * Write access:
 * \code
 * while (it.next()) {
 *     it.valueRef().append("_!");
 *     piCout << it.key() << it.value();
 * }
 *
 * // 1 one_!
 * // 2 two_!
 * // 4 four_!
 * \endcode
 *
 * Reverse iterator:
 * \code
 * auto it = m.makeReverseIterator();
 * while (it.next()) {
 *     piCout << it.key() << it.value();
 * }
 *
 * // 4 four
 * // 2 two
 * // 1 one
 * \endcode

* \fn PIMapIterator(const PIMap & map, bool reverse = false)
* \brief Contructs iterator for "map". Current position is invalid.

* \fn const Key & PIMapIterator::key() const
* \brief Returns current entry key

* \fn const T & PIMapIterator::value() const
* \brief Returns current entry value

* \fn T & PIMapIterator::valueRef() const
* \brief Returns reference to current entry value

* \fn bool PIMapIterator::hasNext()
* \brief Returns if iterator can jump to next entry

* \fn bool PIMapIterator::next()
* \brief Jump to next entry and return if new position is valid.

* \fn void PIMapIterator::reset()
* \brief Reset iterator to initial position.

 * */