255 lines
8.0 KiB
C++
255 lines
8.0 KiB
C++
/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
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/*
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* Copyright (c) 2008 INRIA
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation;
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*
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* Authors: Mathieu Lacage <mathieu.lacage@sophia.inria.fr>
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*/
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#ifndef ATTRIBUTE_H
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#define ATTRIBUTE_H
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#include <string>
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#include <stdint.h>
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#include "ptr.h"
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namespace ns3 {
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class AttributeAccessor;
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class AttributeChecker;
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class Attribute;
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class ObjectBase;
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/**
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* \brief Hold a value for an Attribute.
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*
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* Instances of this class are usually created by Attribute::Create<> and
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* should always be wrapped into an Attribute object.
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* Most subclasses of this base class are implemented by the
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* ATTRIBUTE_HELPER_* macros.
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*/
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class AttributeValue
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{
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public:
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AttributeValue ();
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AttributeValue (const AttributeValue &o);
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AttributeValue &operator = (const AttributeValue &o);
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virtual ~AttributeValue ();
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/**
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* \returns a deep copy of this class, wrapped into an Attribute object.
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*/
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virtual Attribute Copy (void) const = 0;
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/**
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* \param checker the checker associated to the attribute
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* \returns a string representation of this value.
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*
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* In most cases, this method will not make any use of the checker argument.
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* However, in a very limited set of cases, the checker argument is needed to
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* perform proper serialization. A nice example of code which needs it is
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* the EnumValue::SerializeToString code.
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*/
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virtual std::string SerializeToString (Ptr<const AttributeChecker> checker) const = 0;
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/**
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* \param value a string representation of the value
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* \param checker a pointer to the checker associated to the attribute.
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* \returns true if the input string was correctly-formatted and could be
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* successfully deserialized, false otherwise.
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*
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* Upon return of this function, this AttributeValue instance contains
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* the deserialized value.
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* In most cases, this method will not make any use of the checker argument.
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* However, in a very limited set of cases, the checker argument is needed to
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* perform proper serialization. A nice example of code which needs it is
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* the EnumValue::SerializeToString code.
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*/
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virtual bool DeserializeFromString (std::string value, Ptr<const AttributeChecker> checker) = 0;
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private:
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friend class Attribute;
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uint32_t m_count;
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};
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/**
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* \brief an opaque wrapper around a value to set or retrieved
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* from an attribute.
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*
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* This class is really a smart pointer to an instance of AttributeValue.
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* Of course, the question is "why not use a Ptr<AttributeValue>" ?. The
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* answer is long and complicated but the crux of the issue is that if we
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* do not reproduce the smart pointer code in this class, we cannot provide
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* transparent handling of Ptr<T> values through the attribute system.
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*/
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class Attribute
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{
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public:
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Attribute ();
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Attribute (const Attribute &o);
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Attribute &operator = (const Attribute &o);
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~Attribute ();
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/**
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* Forward to AttributeValue::Copy
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*/
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Attribute Copy (void) const;
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/**
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* Forward to AttributeValue::SerializeToString
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*/
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std::string SerializeToString (Ptr<const AttributeChecker> checker) const;
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/**
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* Forward to AttributeValue::DeserializeFromString
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*/
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bool DeserializeFromString (std::string value, Ptr<const AttributeChecker> checker);
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/**
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* \returns a new Attribute object which wraps an instance of the requested
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* subclass of AttributeValue.
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*/
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template <typename T>
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static Attribute Create (void);
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/**
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* \param a1 a value to pass through to the constructor of the class T.
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* \returns a new Attribute object which wraps an instance of the requested
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* subclass of AttributeValue.
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*/
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template <typename T, typename T1>
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static Attribute Create (T1 a1);
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/**
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* This method performs a dynamic_cast on the underlying AttributeValue.
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* This method is typically used to implement conversion operators
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* from the type Attribute. In most cases, these conversion operators
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* will be generated for you by the ATTRIBUTE_HELPER_* macros.
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* \returns the casted pointer.
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*/
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template <typename T>
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T DynCast (void) const;
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private:
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Attribute (AttributeValue *value);
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AttributeValue *m_value;
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};
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/**
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* \brief allow setting and getting the value of an attribute.
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*
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* The goal of this class is to hide from the user how an attribute
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* is actually set or get to or from a class instance. Implementations
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* of this base class are usually provided through the MakeAccessorHelper
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* template functions, hidden behind an ATTRIBUTE_HELPER_* macro.
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*/
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class AttributeAccessor
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{
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public:
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AttributeAccessor ();
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void Ref (void) const;
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void Unref (void) const;
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virtual ~AttributeAccessor ();
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/**
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* \param object the object instance to set the value in
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* \param value the value to set
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* \returns true if the value could be set successfully, false otherwise.
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*
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* This method expects that the caller has checked that the input value is
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* valid with AttributeChecker::Check.
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*/
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virtual bool Set (ObjectBase * object, Attribute value) const = 0;
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/**
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* \param object the object instance to get the value from
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* \param attribute a pointer to where the value should be set.
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* \returns true if the value could be read successfully, and
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* stored in the input value, false otherwise.
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*
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* This method expects that the caller has checked that the input value is
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* valid with AttributeChecker::Check.
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*/
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virtual bool Get (const ObjectBase * object, Attribute attribute) const = 0;
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private:
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mutable uint32_t m_count;
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};
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/**
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* \brief Represent the type of an attribute
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*
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* Each type of attribute has an associated unique AttributeChecker
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* subclass. The type of the subclass can be safely used by users
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* to infer the type of the associated attribute. i.e., we expect
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* binding authors to use the checker associated to an attribute
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* to detect the type of the associated attribute.
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*
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* Most subclasses of this base class are implemented by the
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* ATTRIBUTE_HELPER_* macros.
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*/
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class AttributeChecker
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{
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public:
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AttributeChecker ();
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void Ref (void) const;
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void Unref (void) const;
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virtual ~AttributeChecker ();
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/**
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* \param value a pointer to the value to check
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* \returns true if the input value is both of the right type
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* and if its value is within the requested range. Returns
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* false otherwise.
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*/
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virtual bool Check (Attribute value) const = 0;
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virtual std::string GetType (void) const = 0;
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virtual bool HasTypeConstraints (void) const = 0;
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virtual std::string GetTypeConstraints (void) const = 0;
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/**
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* \returns a new instance of an AttributeValue (wrapper in an Attribute
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* instance) which matches the type of the underlying attribute.
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*
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* This method is typically used to create a temporary variable prior
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* to calling Attribute::DeserializeFromString.
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*/
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virtual Attribute Create (void) const = 0;
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private:
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mutable uint32_t m_count;
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};
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} // namespace ns3
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namespace ns3 {
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/********************************************************
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* The implementation of the Attribute
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* class template methods.
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********************************************************/
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template <typename T>
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Attribute
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Attribute::Create (void)
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{
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return Attribute (new T ());
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}
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template <typename T, typename T1>
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Attribute
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Attribute::Create (T1 a1)
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{
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return Attribute (new T (a1));
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}
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template <typename T>
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T
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Attribute::DynCast (void) const
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{
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return dynamic_cast<T> (m_value);
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}
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} // namespace ns3
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#endif /* ATTRIBUTE_H */
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