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

/*

 * Copyright (c) 2008 INRIA

 *

 * 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

 *

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

 */

#ifndef ATTRIBUTE_H

#define ATTRIBUTE_H

#include <string>

#include <stdint.h>

#include "ptr.h"

#include "simple-ref-count.h"

namespace ns3 {

class AttributeAccessor;

class AttributeChecker;

class Attribute;

class ObjectBase;

/**

 *

 * \ingroup core

 * \defgroup attribute Attributes

 *

 * The \c ns-3 attribute system is the mechanism used in \c ns-3 to

 * organize, document, and modify the *values* used by the various

 * component models.

 *

 * Attributes also enable the tracing and statistics gathering

 * in the simulator.

 *

 * See \ref attributehelper for macros to ease the declaration

 * and definition of Attributes.

 */

/**

 *

 * \ingroup attribute

 *

 * \brief Hold a value for an Attribute.

 *

 * Instances of this class should always be wrapped into an Attribute object.

 * Most subclasses of this base class are implemented by the 

 * ATTRIBUTE_HELPER_* macros.

 */

class AttributeValue : public SimpleRefCount<AttributeValue>

{

public:

  AttributeValue ();

  virtual ~AttributeValue ();

  /**

   * \returns a deep copy of this class, wrapped into an Attribute object.

   */

  virtual Ptr<AttributeValue> Copy (void) const = 0;

  /**

   * \param checker the checker associated to the attribute

   * \returns a string representation of this value.

   *

   * In most cases, this method will not make any use of the checker argument.

   * However, in a very limited set of cases, the checker argument is needed to

   * perform proper serialization. A nice example of code which needs it is

   * the EnumValue::SerializeToString code.

   */

  virtual std::string SerializeToString (Ptr<const AttributeChecker> checker) const = 0;

  /**

   * \param value a string representation of the value

   * \param checker a pointer to the checker associated to the attribute.

   * \returns true if the input string was correctly-formatted and could be

   *          successfully deserialized, false otherwise.

   *

   * Upon return of this function, this AttributeValue instance contains

   * the deserialized value.

   * In most cases, this method will not make any use of the checker argument.

   * However, in a very limited set of cases, the checker argument is needed to

   * perform proper serialization. A nice example of code which needs it is

   * the EnumValue::SerializeToString code.

   */

  virtual bool DeserializeFromString (std::string value, Ptr<const AttributeChecker> checker) = 0;

};

/**

 * \brief allow setting and getting the value of an attribute.

 *

 * \ingroup attribute

 *

 * The goal of this class is to hide from the user how an attribute

 * is actually set or get to or from a class instance. Implementations

 * of this base class are usually provided through the MakeAccessorHelper

 * template functions, hidden behind an ATTRIBUTE_HELPER_* macro.

 */

class AttributeAccessor : public SimpleRefCount<AttributeAccessor>

{

public:

  AttributeAccessor ();

  virtual ~AttributeAccessor ();

  /**

   * \param object the object instance to set the value in

   * \param value the value to set

   * \returns true if the value could be set successfully, false otherwise.

   *

   * This method expects that the caller has checked that the input value is

   * valid with AttributeChecker::Check.

   */

  virtual bool Set (ObjectBase * object, const AttributeValue &value) const = 0;

  /**

   * \param object the object instance to get the value from

   * \param attribute a pointer to where the value should be set.

   * \returns true if the value could be read successfully, and

   *          stored in the input value, false otherwise.

   *

   * This method expects that the caller has checked that the input value is

   * valid with AttributeChecker::Check.

   */

  virtual bool Get (const ObjectBase * object, AttributeValue &attribute) const = 0;

  /**

   * \return true if this accessor supports the Get operation, false

   *         otherwise.

   */

  virtual bool HasGetter (void) const = 0;

  /**

   * \return true if this accessor supports the Set operation, false

   *         otherwise.

   */

  virtual bool HasSetter (void) const = 0;

};

/**

 * \brief Represent the type of an attribute

 *

 * \ingroup attribute

 *

 * Each type of attribute has an associated unique AttributeChecker

 * subclass. The type of the subclass can be safely used by users

 * to infer the type of the associated attribute. i.e., we expect

 * binding authors to use the checker associated to an attribute

 * to detect the type of the associated attribute.

 *

 * Most subclasses of this base class are implemented by the 

 * ATTRIBUTE_HELPER_HEADER and ATTRIBUTE_HELPER_CPP macros.

 */

class AttributeChecker : public SimpleRefCount<AttributeChecker>

{

public:

  AttributeChecker ();

  virtual ~AttributeChecker ();

  /**

   * Create a valid value from the argument value,

   * or reinterpret the argument as a string.

   *

   * \param value the AttributeValue to check

   * \return Ptr to a valid value

   */

  Ptr<AttributeValue> CreateValidValue (const AttributeValue &value) const;

  /**

   * \param value a pointer to the value to check

   * \returns true if the input value is both of the right type

   *          and if its value is within the requested range. Returns

   *          false otherwise.

   */

  virtual bool Check (const AttributeValue &value) const = 0;

  /**

   * \returns the c++ fully-qualified typename of the subclass

   *          of the ns3::AttributeValue base class which is associated

   *          to this checker.

   *

   * A typical return value here is FooValue where Foo is the name of the

   * type being wrapped.

   */

  virtual std::string GetValueTypeName (void) const = 0;

  /**

   * \returns true if this checker has information about the underlying

   *          C++ type, false otherwise.

   *

   * If this method returns false, the return value of the GetUnderlyingTypeInformation

   * method cannot be relied upon.

   */

  virtual bool HasUnderlyingTypeInformation (void) const = 0;

  /**

   * \returns a human-readable representation of information about

   *          the underlying C++ type.

   */

  virtual std::string GetUnderlyingTypeInformation (void) const = 0;

  /**

   * \returns a new instance of an AttributeValue (wrapper in an Attribute 

   *          instance) which matches the type of the underlying attribute.

   *

   * This method is typically used to create a temporary variable prior

   * to calling Attribute::DeserializeFromString.

   */

  virtual Ptr<AttributeValue> Create (void) const = 0;

  /**

   * Copy the source to the destination

   * \param source source AttributeValue

   * \param destination destination AttributeValue

   * \return true if copy was successful

   */

  virtual bool Copy (const AttributeValue &source, AttributeValue &destination) const = 0;

};

class EmptyAttributeValue : public AttributeValue

{

public:

  /** Default constructor. */

  EmptyAttributeValue ();

private:

  /**

   * \returns a deep copy of this class, wrapped into an Attribute object.

   */

  virtual Ptr<AttributeValue> Copy (void) const;

  /**

   * \param checker the checker associated to the attribute

   * \returns a string representation of this value.

   *

   * In the EmptyAttributeValue case, the string returned will be simply ""

   */

  virtual std::string SerializeToString (Ptr<const AttributeChecker> checker) const;

  /**

   * \param value a string representation of the value

   * \param checker a pointer to the checker associated to the attribute.

   * \returns true if the input string was correctly-formatted and could be

   *          successfully deserialized, false otherwise.

   *

   * In the trivial case of EmptyAttributeValue, this should always return true

   */

  virtual bool DeserializeFromString (std::string value, Ptr<const AttributeChecker> checker);

};

} // namespace ns3

#endif /* ATTRIBUTE_H */