/*
    Copyright (C) 2001 by Martin Geisse <mgeisse@gmx.net>

    This library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Library General Public
    License as published by the Free Software Foundation; either
    version 2 of the License, or (at your option) any later version.

    This library is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
    Library General Public License for more details.

    You should have received a copy of the GNU Library General Public
    License along with this library; if not, write to the Free
    Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/

#ifndef __CS_STRSET_H__
#define __CS_STRSET_H__

#include "csextern.h"
#include "csutil/strhash.h"

/**\file
 * String-to-ID hash table.
 */
 
/**
 * The string set is a collection of unique strings. Each string has an ID
 * number. The most important operation is to request a string, which means to
 * return the ID for the string, adding it to the collection if not already
 * present.  This is useful when you need to work with strings but want the
 * performance characteristics of simple numeric comparisons.  Rather than
 * performing string comparisons, you instead compare the numeric string ID's.
 * \sa csStringHash
 * \sa iStringSet
 */
class CS_CRYSTALSPACE_EXPORT csStringSet
{
 private:
  csStringHash registry;
  csHash<const char*, csStringID> reverse; // ID to string mapping.
  csStringID next_id;

  void Copy(csStringSet const&);

public:
  typedef csStringHash::GlobalIterator GlobalIterator;

public:
  /// Constructor.
  csStringSet (size_t size = 23);
  /// Copy constructor.
  csStringSet (csStringSet const& s) { Copy(s); }
  /// Destructor.
  ~csStringSet ();
  /// Assignment operator.
  csStringSet& operator=(csStringSet const& s) { Copy(s); return *this; }

  /**
   * Request the numeric ID for the given string.
   * \return The ID of the string.
   * \remarks Creates a new ID if the string is not yet present in the set,
   *   else returns the previously assigned ID.
   */
  csStringID Request (const char*);

  /**
   * Request the string corresponding to the given ID.
   * \return Null if the string * has not been requested (yet), else the string
   *   corresponding to the ID.
   */
  char const* Request (csStringID) const;

  /**
   * Check if the set contains a particular string.
   */
  bool Contains(char const*) const;

  /**
   * Check if the set contains a string with a particular ID.
   * \remarks This is rigidly equivalent to
   *   <tt>return Request(id) != NULL</tt>, but more idomatic.
   */
  bool Contains(csStringID id) const
  { return Request(id) != 0; }

  /**
   * Remove specified string.
   * \return True if a matching string was in thet set; else false.
   */
  bool Delete(char const* s);

  /**
   * Remove a string with the specified ID.
   * \return True if a matching string was in thet set; else false.
   */
  bool Delete(csStringID id);

  /**
   * Remove all stored strings. When new strings are registered again, new
   * ID values will be used; the old ID's will not be re-used.
   */
  void Empty ();

  /**
   * Remove all stored strings.
   * \deprecated Use Empty() instead.
   */
  /*CS_DEPRECATED_METHOD("Use Empty() instead.")*/
  void Clear ()
  { Empty(); }

  /// Get the number of elements in the hash.
  size_t GetSize () const
  { return registry.GetSize (); }

  /**
   * Return true if the hash is empty.
   * \remarks Rigidly equivalent to <tt>return GetSize() == 0</tt>, but more
   *   idiomatic.
   */
  bool IsEmpty() const
  { return GetSize() == 0; }

  /**
   * Return an iterator for the set which iterates over all strings.
   * \warning Modifying the set while you have open iterators will result
   *   undefined behaviour.
   */
  GlobalIterator GetIterator () const
  { return registry.GetIterator(); }
};

#endif // __CS_STRSET_H__
