/* 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 INDEXEDTOPDUCONTEXT_H
#define INDEXEDTOPDUCONTEXT_H

#include <QMetaType>
#include <QPair>

#include "../languageexport.h"

namespace KDevelop {

class IndexedString;
class IndexedTopDUContextEmbeddedTreeHandler;
class TopDUContext;

/**
 * Allows simple indirect access to top-contexts with on-demand loading
 */
class KDEVPLATFORMLANGUAGE_EXPORT IndexedTopDUContext
{
  public:
    inline IndexedTopDUContext(uint index) : m_index(index) {
      if(!index)
        setIsDummy(true);
    }
    IndexedTopDUContext(TopDUContext* context = 0);

    enum {
      DummyMask = 1u<<31u
    };

    /**
     * Returns the top-context represented by this indexed top-context. If it wasn't loaded yet, it is loaded.
     *
     * The duchain must be read-locked when this is called!
     * To prevent it from being unloaded, store it into a ReferencedTopDUContext before
     * releasing the duchain lock.
     */
    TopDUContext* data() const;

    /**
     * Returns whether the top-context is currently loaded.
     *
     * If not, it will be loaded when you call data().
     */
    bool isLoaded() const;

    inline bool operator==(const IndexedTopDUContext& rhs) const {
      return m_index == rhs.m_index;
    }

    inline bool operator!=(const IndexedTopDUContext& rhs) const {
      return m_index != rhs.m_index;
    }

    inline bool operator<(const IndexedTopDUContext& rhs) const {
      return m_index < rhs.m_index;
    }

    inline bool isValid() const {
      return m_index && !isDummy();
    }

    inline uint index() const {
      if(isDummy())
        return 0;
      else
        return m_index;
    }

    inline bool isDummy() const {
      return m_index & DummyMask;
    }

    void setIsDummy(bool isDummy) {
      if(isDummy)
        m_index |= DummyMask;
      else
        m_index &= ~((uint)DummyMask);
    }

    /**
     * Allows giving this IndexedTopDUContext some data while logically keeping it invalid.
     *
     * It will still return zero on index(), data(), etc.
     *
     * @param first The highest of this value bit will be removed.
     */
    void setDummyData(ushort first, ushort second) {
      Q_ASSERT(isDummy());
      m_index = ((((uint)first)<<16) + second) | DummyMask;
    }

    /**
     * The data previously set through setDummyData(). Initially 0.
     */
    QPair<ushort, ushort> dummyData() const {
      uint withoutMask = m_index & (~((uint)DummyMask));
      return qMakePair((ushort)(withoutMask >> 16), (ushort)withoutMask);
    }

    IndexedString url() const;

  private:
    uint m_index;
    friend class IndexedTopDUContextEmbeddedTreeHandler;
};


struct IndexedTopDUContextIndexConversion {
  inline static uint toIndex(const IndexedTopDUContext& top) {
    return top.index();
  }

  inline static IndexedTopDUContext toItem(uint index) {
    return IndexedTopDUContext(index);
  }
};

}

Q_DECLARE_METATYPE(KDevelop::IndexedTopDUContext);

#endif // INDEXEDTOPDUCONTEXT_H
