/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */

/*

 * Copyright (c) 2007 INRIA

 * All rights reserved.

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License version 2 as

 * published by the Free Software Foundation;

 *

 * This program 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 General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program; if not, write to the Free Software

 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

 *

 * Author: Mathieu Lacage <mathieu.lacage@sophia.inria.fr>

 */

#ifndef TRACE_CONTEXT_H

#define TRACE_CONTEXT_H

#include <stdint.h>

#include <vector>

#include "fatal-error.h"

#include "trace-context-element.h"

namespace ns3 {

/**

 * \brief Provide context to trace sources

 * \ingroup lowleveltracing

 *

 * Instances of this class are used to hold context

 * for each trace source. Each instance holds a list of

 * 'contexts'. Trace sinks can lookup these contexts

 * from this list with the ns3::TraceContext::Get method.

 *

 * This class is implemented

 * using Copy On Write which means that copying unmodified

 * versions of this class is very cheap. However, modifying

 * the content of this class through a call 

 * to ns3::TraceContext::AddElement or ns3::TraceContext::Union 

 * will trigger a costly memory reallocation if needed.

 */

class TraceContext

{

public:

  TraceContext ();

  TraceContext (TraceContext const &o);

  TraceContext const & operator = (TraceContext const &o);

  ~TraceContext ();

  /**

   * \param context add context to list of trace contexts.

   */

  template <typename T>

  void AddElement (T const &context);

  /**

   * \param o the other context

   *

   * Perform the Union operation (in the sense of set theory) on the

   * two input lists of elements. This method is used in the

   * ns3::CallbackTraceSourceSource class when multiple sinks are connected

   * to a single source to ensure that the source does not need

   * to store a single TraceContext instance per connected sink.

   * Instead, all sinks share the same TraceContext.

   */

  void Union (TraceContext const &o);

  /**

   * \param context context to get from this list of trace contexts.

   *

   * This method cannot fail. If the requested trace context is not

   * stored in this TraceContext, then, the program will halt.

   */

  template <typename T>

  void Get (T &context) const;

  void Print (std::ostream &os) const;

  void PrintAvailable (std::ostream &os, std::string separator) const;

private:

  friend class TraceContextTest;

  // used exclusively for testing code.

  template <typename T>

  bool SafeGet (T &context) const;

  template <typename T>

  bool SafeAdd (const T &context);

  uint8_t *CheckPresent (uint8_t uid) const;

  bool DoAdd (uint8_t uid, uint8_t const *buffer);

  bool DoGet (uint8_t uid, uint8_t *buffer) const;

  struct Data {

    uint16_t count;

    uint16_t size;

    uint8_t data[4];

  } * m_data;

};

std::ostream& operator<< (std::ostream& os, const TraceContext &context);

}//namespace ns3

namespace ns3 {

template <typename T>

void 

TraceContext::AddElement (T const &context)

{

  const TraceContextElement *parent;

  // if the following assignment fails, it is because the input

  // to this function is not a subclass of the TraceContextElement class.

  parent = &context;

  uint8_t *data = (uint8_t *) &context;

  bool ok = DoAdd (T::GetUid (), data);

  if (!ok)

    {

      NS_FATAL_ERROR ("Trying to add twice the same type with different values is invalid.");

    }

}

template <typename T>

void

TraceContext::Get (T &context) const

{

  TraceContextElement *parent;

  // if the following assignment fails, it is because the input

  // to this function is not a subclass of the TraceContextElement class.

  parent = &context;

  uint8_t *data = (uint8_t *) &context;

  bool found = DoGet (T::GetUid (), data);

  if (!found)

    {

      NS_FATAL_ERROR ("Type not stored in TraceContext");

    }

}

template <typename T>

bool

TraceContext::SafeGet (T &context) const

{

  TraceContextElement *parent;

  // if the following assignment fails, it is because the input

  // to this function is not a subclass of the TraceContextElement class.

  parent = &context;

  uint8_t *data = (uint8_t *) &context;

  bool found = DoGet (T::GetUid (), data);

  return found;

}

template <typename T>

bool

TraceContext::SafeAdd (const T &context)

{

  const TraceContextElement *parent;

  // if the following assignment fails, it is because the input

  // to this function is not a subclass of the TraceContextElement class.

  parent = &context;

  uint8_t *data = (uint8_t *) &context;

  bool ok = DoAdd (T::GetUid (), data);

  return ok;

}

}//namespace ns3

#endif /* TRACE_CONTEXT_H */