/* This file is part of KDevelop
    Copyright 2007 David Nolden <david.nolden.kdevelop@art-master.de>

   This library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Library General Public
   License version 2 as published by the Free Software Foundation.

   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; see the file COPYING.LIB.  If not, write to
   the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
   Boston, MA 02110-1301, USA.
*/

#ifndef INDEXEDDECLARATION_H
#define INDEXEDDECLARATION_H

#include "../languageexport.h"

#include "indexedtopducontext.h"

namespace KDevelop {

class Declaration;

/**
 * Represents a declaration only by its global indices
 */
class KDEVPLATFORMLANGUAGE_EXPORT IndexedDeclaration {
  public:
    IndexedDeclaration(Declaration* decl = 0);
    IndexedDeclaration(uint topContext, uint declarationIndex);

    /**
     * \warning Duchain must be read locked
     */
    Declaration* declaration() const;

    /**
     * \warning Duchain must be read locked
     */
    Declaration* data() const {
      return declaration();
    }

    inline bool operator==(const IndexedDeclaration& rhs) const {
      return m_topContext == rhs.m_topContext && m_declarationIndex == rhs.m_declarationIndex;
    }

    inline uint hash() const {
      if(isDummy())
        return 0;
      return (m_topContext * 53 + m_declarationIndex) * 23;
    }

    ///@warning The duchain needs to be locked when this is called
    inline bool isValid() const {
      return !isDummy() && declaration() != 0;
    }

    inline bool operator<(const IndexedDeclaration& rhs) const {
      Q_ASSERT(!isDummy());
      return m_topContext < rhs.m_topContext || (m_topContext == rhs.m_topContext && m_declarationIndex < rhs.m_declarationIndex);
    }

    /**
     * \return Index of the Declaration within the top context
     */
    inline uint localIndex() const {
      if(isDummy())
        return 0;
      else
        return m_declarationIndex;
    }

    inline uint topContextIndex() const {
      if(isDummy())
        return 0;
      else
        return m_topContext;
    }

    inline IndexedTopDUContext indexedTopContext() const {
      if(isDummy())
        return IndexedTopDUContext();
      else
        return IndexedTopDUContext(m_topContext);
    }

    /**
     * The following functions allow storing 2 integers in this object and marking it as a dummy,
     * which makes the isValid() function always return false for this object, and use the integers
     * for other purposes.
     *
     * Clears the contained data
     */
    void setIsDummy(bool dummy) {
      if(isDummy() == dummy)
        return;
      if(dummy)
        m_topContext = 1u << 31u;
      else
        m_topContext = 0;
      m_declarationIndex = 0;
    }

    inline bool isDummy() const {
      //We use the second highest bit to mark dummies, because the highest is used for the sign bit of stored
      //integers
      return (bool)(m_topContext & static_cast<uint>(1u << 31u));
    }

    inline QPair<uint, uint> dummyData() const {
      Q_ASSERT(isDummy());
      return qMakePair(m_topContext & (~(1u<<31u)), m_declarationIndex);
    }

    /**
     * \warning Do not call this when this object is valid.
     *
     * The first integer loses one bit of precision.
     */
    void setDummyData(QPair<uint, uint> data) {
      Q_ASSERT(isDummy());

      m_topContext = data.first;
      m_declarationIndex = data.second;
      Q_ASSERT(!isDummy());
      m_topContext |= (1u << 31u); //Mark as dummy
      Q_ASSERT(isDummy());
      Q_ASSERT(dummyData() == data);
    }

  private:
    uint m_topContext;
    uint m_declarationIndex;
};

}

Q_DECLARE_METATYPE(KDevelop::IndexedDeclaration)
Q_DECLARE_TYPEINFO(KDevelop::IndexedDeclaration, Q_MOVABLE_TYPE);

#endif // INDEXEDDECLARATION_H
