/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
/*
 * Copyright (c) 2009 University of Washington
 *
 * 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
 */

#ifndef OBJECT_NAMES_H
#define OBJECT_NAMES_H

#include "ptr.h"
#include "object.h"

/**
 * \file
 * \ingroup config
 * Declaration of class ns3::Names.
 */

namespace ns3 {

/**
 * \ingroup config
 * \brief A directory of name and Ptr<Object> associations that allows us to
 * give any ns3 Object a name.
 */
class Names
{
public:

  /**
   * \brief Add the association between the string "name" and the Ptr<Object> obj.
   *
   * The name may begin either with "/Names" to explicitly call out the fact 
   * that the name provided is installed under the root of the name space, 
   * or it may begin with the name of the first object in the path.  For example, 
   * Names::Add ("/Names/client", obj) and Names::Add ("client", obj) accomplish 
   * exactly the same thing.  A name at a given level in the name space path must
   * be unique.  In the case of the example above, it would be illegal to try and
   * associate a different object with the same name: "client" at the same level 
   * ("/Names") in the path.
   *
   * As well as specifying a name at the root of the "/Names" namespace, the 
   * name parameter can contain a path that fully qualifies the name to 
   * be added.  For example, if you previously have named an object "client"
   * in the root namespace as above, you could name an object "under" that
   * name by making a call like Names::Add ("/Names/client/eth0", obj).  This 
   * will define the name "eth0" and make it reachable using the path specified.
   * Note that Names::Add ("client/eth0", obj) would accomplish exactly the same 
   * thing.
   *
   * Duplicate names are not allowed at the same level in a path, however you may
   * associate similar names with different paths.  For example, if you define
   * "/Names/Client", you may not define another "/Names/Client" just as you may
   * not have two files with the same name in a classical filesystem.  However,
   * you may have "/Names/Client/eth0" and "/Names/Server/eth0" defined at the 
   * same time just as you might have different files of the same name under 
   * different directories.
   *
   * \param name The name of the object you want to associate; which may be 
   *             prepended with a path to that object.
   * \param object A smart pointer to the object itself.
   */
  static void Add (std::string name, Ptr<Object> object);

  /**
   * \brief An intermediate form of Names::Add allowing you to provide a path to
   * the parent object (under which you want this name to be defined) in the form
   * of a name path string.
   *
   * In some cases, it is desirable to break up the path used to describe an item
   * in the names namespace into a path and a name.  This is analogous to a
   * file system operation in which you provide a directory name and a file name.
   *
   * For example, consider a situation where you have previously named an object
   * "/Names/server".  If you further want to create an association for between a 
   * Ptr<Object> object that you want to live "under" the server in the name space
   * -- perhaps "eth0" -- you could do this in two ways, depending on which was 
   * more convenient: Names::Add ("/Names/server/eth0", object) or, using the split
   * path and name approach, Names::Add ("/Names/server", "eth0", object).
   *
   * Duplicate names are not allowed at the same level in a path, however you may
   * associate similar names with different paths.  For example, if you define
   * "/Names/Client", you may not define another "/Names/Client" just as you may
   * not have two files with the same name in a classical filesystem.  However,
   * you may have "/Names/Client/eth0" and "/Names/Server/eth0" defined at the 
   * same time just as you might have different files of the same name under 
   * different directories.
   *
   * \param path A path name describing a previously named object under which 
   *             you want this new name to be defined.
   * \param name The name of the object you want to associate.
   * \param object A smart pointer to the object itself.
   *
   * \see Names::Add (Ptr<Object> context, std::string name, Ptr<Object> object);
   */
  static void Add (std::string path, std::string name, Ptr<Object> object);

  /**
   * \brief A low-level form of Names::Add allowing you to specify the path to
   * the parent object (under which you want this name to be defined) in the form
   * of a previously named object.
   *
   * In some use cases, it is desirable to break up the path in the names name
   * space into a path and a name.  This is analogous to a file system operation 
   * in which you provide a directory name and a file name.  Recall that the path
   * string actually refers to a previously named object, "under" which you want
   * to accomplish some naming action.
   * 
   * However, the path is sometimes not available, and you only have the object 
   * that is represented by the path in the names name space.  To support this 
   * use-case in a reasonably high-performance way, the path string is can be 
   * replaced by the object pointer to which that path would refer.  In the spirit
   * of the Config code where this use-case is most prominent, we refer to this
   * object as the "context" for the names operation.
   *
   * You can think of the context roughly as the inode number of a directory file
   * in Unix.  The inode number can be used to look up the directory file which 
   * contains the list of file names defined at that directory level.  Similarly
   * the context is used to look up an internal name service entry which contains
   * the names defined for that context.
   *
   * For example, consider a situation where you have previously named an object
   * "/Names/server".  If you further want to create an association for between a 
   * Ptr<Object> object that you want to live "under" the server in the name space
   * -- perhaps "eth0" -- you could do this by providing a complete path to the 
   * new name: Names::Add ("/Names/server/eth0", object).  If, however, somewhere
   * in your code you only had a pointer to the server, say Ptr<Node> node, and 
   * not a handy path string,  you could also accomplish this by 
   * Names::Add (node, "eth0", object).
   *
   * Duplicate names are not allowed at the same level in a path.  In the case
   * of this method, the context object gives the same information as a path
   * string.  You may associate similar names with different paths.  For example,
   *  if you define"/Names/Client", you may not define another "/Names/Client" 
   * just as you may not have two files with the same name in a classical filesystem.
   * However, you may have "/Names/Client/eth0" and "/Names/Server/eth0" defined at 
   * the same time just as you might have different files of the same name under 
   * different directories.
   *
   * \param context A smart pointer to an object that is used in place of the path
   *                under which you want this new name to be defined.
   * \param name The name of the object you want to associate.
   * \param object A smart pointer to the object itself.
   */
  static void Add (Ptr<Object> context, std::string name, Ptr<Object> object);

  /**
   * \brief Rename a previously associated name.
   *
   * The name may begin either with "/Names" to explicitly call out the fact 
   * that the name provided is installed under the root of the name space, 
   * or it may begin with the name of the first object in the path.  For example, 
   * Names::Rename ("/Names/client", "server") and Names::Rename ("client", "server") 
   * accomplish exactly the same thing.  Names at a given level in the name space
   * path must be unique. In the case of the example above, it would be illegal 
   * to try and rename a different object to the same name: "server" at the same 
   * level ("/Names") in the path.
   *
   * As well as specifying a name at the root of the "/Names" namespace, the 
   * name parameter can contain a path that fully qualifies the name to 
   * be changed.  For example, if you previously have (re)named an object 
   * "server" in the root namespace as above, you could then rename an object 
   * "under" that name by making a call like Names::Rename ("/Names/server/csma", "eth0").
   * This will rename the object previously associated with "/Names/server/csma" 
   * to "eth0" and make leave it reachable using the path "/Names/server/eth0".
   * Note that Names::Rename ("server/csma", "eth0") would accomplish exactly the 
   * same thing.
   *
   * \param oldpath The current path name to the object you want to change.
   * \param newname The new name of the object you want to change.
   *
   * \see Names::Add (std::string name, Ptr<Object> obj)
   */
  static void Rename (std::string oldpath, std::string newname);

  /**
   * \brief An intermediate form of Names::Rename allowing you to provide a path to
   * the parent object (under which you want this name to be changed) in the form
   * of a name path string.
   *
   * In some cases, it is desirable to break up the path used to describe an item
   * in the names namespace into a path and a name.  This is analogous to a
   * file system operation in which you provide a directory name and a file name.
   *
   * For example, consider a situation where you have previously named an object
   * "/Names/server/csma".  If you want to change the name "csma" to "eth0", you
   * could do this in two ways, depending on which was more convenient: 
   * Names::Rename ("/Names/server/csma", "eth0") or, using the split
   * path and name approach, Names::Rename ("/Names/server", "csma", "eth0").
   *
   * \param path A path name describing a previously named object under which 
   *             you want this name change to occur (cf. directory).
   * \param oldname The currently defined name of the object.
   * \param newname The new name you want the object to have.
   */
  static void Rename (std::string path, std::string oldname, std::string newname);

  /**
   * \brief A low-level form of Names::Rename allowing you to specify the path to
   * the parent object (under which you want this name to be changed) in the form
   * of a previously named object.
   *
   * In some use cases, it is desirable to break up the path in the names name
   * space into a path and a name.  This is analogous to a file system operation 
   * in which you provide a directory name and a file name.  Recall that the path
   * string actually refers to a previously named object, "under" which you want
   * to accomplish some naming action.
   * 
   * However, the path is sometimes not available, and you only have the object 
   * that is represented by the path in the names name space.  To support this 
   * use-case in a reasonably high-performance way, the path string is can be 
   * replaced by the object pointer to which that path would refer.  In the spirit
   * of the Config code where this use-case is most prominent, we refer to this
   * object as the "context" for the names operation.
   *
   * You can think of the context roughly as the inode number of a directory file
   * in Unix.  The inode number can be used to look up the directory file which 
   * contains the list of file names defined at that directory level.  Similarly
   * the context is used to look up an internal name service entry which contains
   * the names defined for that context.
   *
   * For example, consider a situation where you have previously named an object
   * "/Names/server/csma".  If you later decide to rename the csma object to say
   * "eth0" -- you could do this by providing a complete path as in
   * Names::Rename ("/Names/server/csma", "eth0").  If, however, somewhere
   * in your code you only had a pointer to the server, and not a handy path 
   * string, say Ptr<Node> node, you could also accomplish this by 
   * Names::Rename (node, "csma", "eth0").
   *
   * \param context A smart pointer to an object that is used in place of the path
   *                under which you want this new name to be defined.
   * \param oldname The current shortname of the object you want to change.
   * \param newname The new shortname of the object you want to change.
   */
  static void Rename (Ptr<Object> context, std::string oldname, std::string newname);

  /**
   * \brief Given a pointer to an object, look to see if that object has a name
   * associated with it and, if so, return the name of the object otherwise
   * return an empty string.
   *
   * An object can be referred to in two ways.  Either you can talk about it
   * using its fully qualified path name, for example, "/Names/client/eth0"
   * or you can refer to it by its name, in this case "eth0".
   *
   * This method returns the name of the object, e.g., "eth0".
   *
   * \param object A smart pointer to an object for which you want to find
   *               its name.
   *
   * \returns a string containing the name of the object if found, otherwise
   *          the empty string.
   */
  static std::string FindName (Ptr<Object> object);

  /**
   * \brief Given a pointer to an object, look to see if that object has a name
   * associated with it and return the fully qualified name path of the 
   * object otherwise return an empty string.
   *
   * An object can be referred to in two ways.  Either you can talk about it
   * using its fully qualified path name, for example, "/Names/client/eth0"
   * or you can refer to it by its name, in this case "eth0".
   *
   * This method returns the name path of the object, e.g., "Names/client/eth0".
   *
   * \param object A smart pointer to an object for which you want to find
   *               its fullname.
   *
   * \returns a string containing the name path of the object, otherwise
   *          the empty string.
   */
  static std::string FindPath (Ptr<Object> object);

  /**
   * \brief Clear the list of objects associated with names.
   */

  static void Clear (void);

  /**
   * \brief Given a name path string, look to see if there's an object in the system
   * with that associated to it.  If there is, do a GetObject on the resulting
   * object to convert it to the requested typename and return it.
   * 
   * An object can be referred to in two ways.  Either you can talk about it
   * using its fully qualified path name, for example, "/Names/client/eth0"
   * or you can refer to it by its name, in this case "eth0".
   *
   * This method requires that the name path of the object be provided, e.g., 
   * "Names/client/eth0".
   *
   * \param path A string containing a name space path used to locate the object.
   *
   * \returns a smart pointer to the named object converted to the requested
   *          type.
   */
  template <typename T>
  static Ptr<T> Find (std::string path);

  /**
   * \brief Given a path to an object and an object name, look through the names defined
   * under the path to see if there's an object there with the given name.
   *
   * In some cases, it is desirable to break up the path used to describe an item
   * in the names namespace into a path and a name.  This is analogous to a
   * file system operation in which you provide a directory name and a file name.
   *
   * For example, consider a situation where you have previously named an object
   * "/Names/server/eth0".  If you want to discover the object which you associated
   * with this path, you could do this in two ways, depending on which was more 
   * convenient: Names::Find ("/Names/server/eth0") or, using the split path and 
   * name approach, Names::Find ("/Names/server", "eth0").
   *
   * \param path A path name describing a previously named object under which 
   *             you want to look for the specified name.
   * \param name A string containing a name to search for.
   *
   * \returns a smart pointer to the named object converted to the requested
   *          type.
   */
  template <typename T>
  static Ptr<T> Find (std::string path, std::string name);

  /**
   * \brief Given a path to an object and an object name, look through the names defined
   * under the path to see if there's an object there with the given name.
   *
   * In some cases, it is desirable to break up the path used to describe an item
   * in the names namespace into a path and a name.  This is analogous to a
   * file system operation in which you provide a directory name and a file name.
   *
   * For example, consider a situation where you have previously named an object
   * "/Names/server/eth0".  If you want to discover the object which you associated
   * with this path, you could do this in two ways, depending on which was more 
   * convenient: Names::Find ("/Names/server/eth0") or, using the split path and 
   * name approach, Names::Find ("/Names/server", "eth0").
   *
   * However, the path is sometimes not available, and you only have the object 
   * that is represented by the path in the names name space.  To support this 
   * use-case in a reasonably high-performance way, the path string is can be 
   * replaced by the object pointer to which that path would refer.  In the spirit
   * of the Config code where this use-case is most prominent, we refer to this
   * object as the "context" for the names operation.
   *
   * You can think of the context roughly as the inode number of a directory file
   * in Unix.  The inode number can be used to look up the directory file which 
   * contains the list of file names defined at that directory level.  Similarly
   * the context is used to look up an internal name service entry which contains
   * the names defined for that context.
   *
   * \param context A smart pointer to an object that is used in place of the path
   *                under which you want this new name to be defined.
   * \param name A string containing a name to search for.
   *
   * \returns a smart pointer to the named object converted to the requested
   *          type.
   */
  template <typename T>
  static Ptr<T> Find (Ptr<Object> context, std::string name);

private:
  /**
   * \brief Non-templated internal version of Names::Find
   *
   * \param path A string containing the path of the object to look for.
   *
   * \returns a smart pointer to the named object.
   */
  static Ptr<Object> FindInternal (std::string path);

  /**
   * \brief Non-templated internal version of Names::Find
   *
   * \param path A string containing the path to search for the object in.
   * \param name A string containing the name of the object to look for.
   *
   * \returns a smart pointer to the named object.
   */
  static Ptr<Object> FindInternal (std::string path, std::string name);

  /**
   * \brief Non-templated internal version of Names::Find
   *
   * \param context A smart pointer to an object under which you want to look 
   *                for the provided name.
   * \param name A string containing the name to look for.
   *
   * \returns a smart pointer to the named object.
   */
  static Ptr<Object> FindInternal (Ptr<Object> context, std::string name);
};

  
template <typename T>
/* static */
Ptr<T> 
Names::Find (std::string path)
{
  Ptr<Object> obj = FindInternal (path);
  if (obj)
    {
      return obj->GetObject<T> ();
    }
  else
    {
      return 0;
    }
}

template <typename T>
/* static */
Ptr<T> 
Names::Find (std::string path, std::string name)
{
  Ptr<Object> obj = FindInternal (path, name);
  if (obj)
    {
      return obj->GetObject<T> ();
    }
  else
    {
      return 0;
    }
}

template <typename T>
/* static */
Ptr<T> 
Names::Find (Ptr<Object> context, std::string name)
{
  Ptr<Object> obj = FindInternal (context, name);
  if (obj)
    {
      return obj->GetObject<T> ();
    }
  else
    {
      return 0;
    }
}

} // namespace ns3

#endif /* OBJECT_NAMES_H */