/* -*- 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 "ref-count-base.h"

 namespace ns3 {

 class AttributeAccessor;

 class AttributeChecker;

 class Attribute;

 class ObjectBase;

 /**

  *

  * \ingroup core

  * \defgroup attribute Attribute

  */

 /**

  *

  * \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 RefCountBase

 {

 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 RefCountBase

 {

 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 

  * \ref ATTRIBUTE_HELPER_HEADER and \ref ATTRIBUTE_HELPER_CPP macros.

  */

 class AttributeChecker : public RefCountBase

 {

 public:

   AttributeChecker ();

   virtual ~AttributeChecker ();

   /**

    * \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;

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

 };

 /**

  * \brief A class for an empty attribute value

  *

  * \ingroup attribute

  */

 class EmptyAttributeValue : public AttributeValue

 {

 public:

   EmptyAttributeValue ();

 private:

   virtual Ptr<AttributeValue> Copy (void) const;

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

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

 };

 } // namespace ns3

 #endif /* ATTRIBUTE_H */