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unison/src/core/model/global-value.h
2022-10-14 14:13:12 +00:00

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/*
* 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 GLOBAL_VALUE_H
#define GLOBAL_VALUE_H
#include "attribute.h"
#include "ptr.h"
#include <string>
#include <vector>
/**
* \file
* \ingroup core
* ns3::GlobalValue declaration.
*/
namespace ns3
{
/* Forward declaration */
namespace tests
{
class GlobalValueTestCase;
}
/**
* \ingroup Core
*
* \brief Hold a so-called 'global value'.
*
* A GlobalValue will get its value from (in order):
* - The initial value configured where it is defined,
* - From the \c NS_GLOBAL_VALUE environment variable,
* - From the command line,
* - By explicit call to SetValue() or Bind().
*
* Instances of this class are expected to be allocated as static
* global variables and should be used to store configurable global state.
* For example:
* \code
* // source.cc:
* static GlobalValue g_myGlobal =
* GlobalValue ("myGlobal", "My global value for ...",
* IntegerValue (12),
* MakeIntegerChecker ());
* \endcode
*
* GlobalValues can be set directly by calling GlobalValue::SetValue()
* but they can also be set through the \c NS_GLOBAL_VALUE environment variable.
* For example, \c NS_GLOBAL_VALUE='Name=Value;OtherName=OtherValue;' would set
* global values \c Name and \c OtherName to \c Value and \c OtherValue,
* respectively.
*
* Users of the CommandLine class also get the ability to set global
* values through command line arguments to their program:
* \c --Name=Value will set global value \c Name to \c Value.
*/
class GlobalValue
{
/** Container type for holding all the GlobalValues. */
typedef std::vector<GlobalValue*> Vector;
public:
/** Iterator type for the list of all global values. */
typedef Vector::const_iterator Iterator;
/**
* Constructor.
* \param [in] name the name of this global value.
* \param [in] help some help text which describes the purpose of this
* global value.
* \param [in] initialValue the value to assign to this global value
* during construction.
* \param [in] checker a pointer to an AttributeChecker which can verify
* that any user-supplied value to override the initial
* value matches the requested type constraints.
*/
GlobalValue(std::string name,
std::string help,
const AttributeValue& initialValue,
Ptr<const AttributeChecker> checker);
/**
* Get the name.
* \returns The name of this GlobalValue.
*/
std::string GetName() const;
/**
* Get the help string.
* \returns The help text of this GlobalValue.
*/
std::string GetHelp() const;
/**
* Get the value.
* \param [out] value The AttributeValue to set to the value
* of this GlobalValue
*/
void GetValue(AttributeValue& value) const;
/**
* Get the AttributeChecker.
* \returns The checker associated to this GlobalValue.
*/
Ptr<const AttributeChecker> GetChecker() const;
/**
* Set the value of this GlobalValue.
* \param [in] value the new value to set in this GlobalValue.
* \returns \c true if the Global Value was set successfully.
*/
bool SetValue(const AttributeValue& value);
/** Reset to the initial value. */
void ResetInitialValue();
/**
* Iterate over the set of GlobalValues until a matching name is found
* and then set its value with GlobalValue::SetValue.
*
* \param [in] name the name of the global value
* \param [in] value the value to set in the requested global value.
*
* This method cannot fail. It will crash if the input is not valid.
*/
static void Bind(std::string name, const AttributeValue& value);
/**
* Iterate over the set of GlobalValues until a matching name is found
* and then set its value with GlobalValue::SetValue.
*
* \param [in] name the name of the global value
* \param [in] value the value to set in the requested global value.
* \returns \c true if the value could be set successfully,
* \c false otherwise.
*/
static bool BindFailSafe(std::string name, const AttributeValue& value);
/**
* The Begin iterator.
* \returns An iterator which represents a pointer to the first GlobalValue registered.
*/
static Iterator Begin();
/**
* The End iterator.
* \returns An iterator which represents a pointer to the last GlobalValue registered.
*/
static Iterator End();
/**
* Finds the GlobalValue with the given name and returns its value
*
* \param [in] name the name of the GlobalValue to be found
* \param [out] value where to store the value of the found GlobalValue
*
* \return \c true if the GlobalValue was found, \c false otherwise
*/
static bool GetValueByNameFailSafe(std::string name, AttributeValue& value);
/**
* Finds the GlobalValue with the given name and returns its
* value.
*
* This method cannot fail, i.e., it will trigger a
* NS_FATAL_ERROR if the requested GlobalValue is not found.
*
* \param [in] name the name of the GlobalValue to be found
* \param [out] value where to store the value of the found GlobalValue
*/
static void GetValueByName(std::string name, AttributeValue& value);
private:
/** Test case needs direct access to GetVector() */
friend class tests::GlobalValueTestCase;
/**
* Get the static vector of all GlobalValues.
*
* \returns The vector.
*/
static Vector* GetVector();
/** Initialize from the \c NS_GLOBAL_VALUE environment variable. */
void InitializeFromEnv();
/** The name of this GlobalValue. */
std::string m_name;
/** The help string. */
std::string m_help;
/** The initial value. */
Ptr<AttributeValue> m_initialValue;
/** The current value. */
Ptr<AttributeValue> m_currentValue;
/** The AttributeChecker for this GlobalValue. */
Ptr<const AttributeChecker> m_checker;
};
} // namespace ns3
#endif /* GLOBAL_VALUE_H */