scram::mef::Expression

Abstract base class for all sorts of expressions to describe events. More...

#include <expression.h>

Inherits from boost::noncopyable

Inherited by scram::mef::ExpressionFormula< Exponential >, scram::mef::ExpressionFormula< ExternExpression< R, Args... > >, scram::mef::ExpressionFormula< Glm >, scram::mef::ExpressionFormula< Ite >, scram::mef::ExpressionFormula< Mean >, scram::mef::ExpressionFormula< NaryExpression< T, -1 > >, scram::mef::ExpressionFormula< NaryExpression< T, 1 > >, scram::mef::ExpressionFormula< NaryExpression< T, 2 > >, scram::mef::ExpressionFormula< Switch >, scram::mef::ExpressionFormula< Weibull >, scram::mef::ConstantExpression, scram::mef::ExpressionFormula< T >, scram::mef::MissionTime, scram::mef::Parameter, scram::mef::PeriodicTest, scram::mef::RandomDeviate, scram::mef::TestEvent

Public Functions

	Name
	Expression(std::vector< Expression * > args ={})<br>Constructor for use by derived classes to register their arguments.
virtual	~Expression() =default
const std::vector< Expression * > &	args() const
virtual void	Validate() const<br>Validates the expression.
virtual double	value() =0
virtual Interval	interval()
virtual bool	IsDeviate()<br>Determines if the value of the expression contains deviate expressions.
double	Sample()
void	Reset()<br>This routine resets the sampling to get new values.

Protected Functions

	Name
void	AddArg(Expression * arg)<br>Registers an additional argument expression.

Detailed Description

class scram::mef::Expression;

Abstract base class for all sorts of expressions to describe events.

This class also acts like a connector for parameter nodes and may create cycles. Expressions are not expected to be shared except for parameters. In addition, expressions are not expected to be changed after validation phases.

Public Functions Documentation

function Expression

explicit Expression(
    std::vector< Expression * > args ={}
)

Constructor for use by derived classes to register their arguments.

Parameters:

• args Arguments of this expression.

function ~Expression

virtual ~Expression() =default

function args

inline const std::vector< Expression * > & args() const

Return: A set of arguments of the expression.

function Validate

inline virtual void Validate() const

Validates the expression.

Exceptions:

• DomainError The argument value domains are invalid.
• ValidityError The arguments are invalid for setup.

Reimplemented by: scram::mef::NaryExpression< T, 1 >::Validate, scram::mef::NaryExpression< T, 2 >::Validate, scram::mef::NaryExpression< T, -1 >::Validate, scram::mef::Exponential::Validate, scram::mef::Glm::Validate, scram::mef::Weibull::Validate, scram::mef::PeriodicTest::Validate, scram::mef::UniformDeviate::Validate, scram::mef::NormalDeviate::Validate, scram::mef::LognormalDeviate::Validate, scram::mef::GammaDeviate::Validate, scram::mef::BetaDeviate::Validate, scram::mef::Histogram::Validate

This late validation is due to parameters that are defined late.

function value

virtual double value() =0

Return: The mean value of this expression.

Reimplemented by: scram::mef::ExpressionFormula::value, scram::mef::ExpressionFormula::value, scram::mef::ExpressionFormula::value, scram::mef::ExpressionFormula::value, scram::mef::ExpressionFormula::value, scram::mef::ExpressionFormula::value, scram::mef::ExpressionFormula::value, scram::mef::ExpressionFormula::value, scram::mef::ExpressionFormula::value, scram::mef::ExpressionFormula::value, scram::mef::ExpressionFormula::value, scram::mef::ConstantExpression::value, scram::mef::PeriodicTest::value, scram::mef::UniformDeviate::value, scram::mef::NormalDeviate::value, scram::mef::LognormalDeviate::value, scram::mef::GammaDeviate::value, scram::mef::BetaDeviate::value, scram::mef::Histogram::value, scram::mef::TestInitiatingEvent::value, scram::mef::TestFunctionalEvent::value, scram::mef::MissionTime::value, scram::mef::Parameter::value

function interval

inline virtual Interval interval()

Return: The domain interval for validation purposes only.

Reimplemented by: scram::mef::NaryExpression< T, 1 >::interval, scram::mef::NaryExpression< T, 2 >::interval, scram::mef::NaryExpression< T, -1 >::interval, scram::mef::Ite::interval, scram::mef::Switch::interval, scram::mef::Exponential::interval, scram::mef::Glm::interval, scram::mef::Weibull::interval, scram::mef::PeriodicTest::interval, scram::mef::Mean::interval, scram::mef::UniformDeviate::interval, scram::mef::NormalDeviate::interval, scram::mef::LognormalDeviate::interval, scram::mef::GammaDeviate::interval, scram::mef::BetaDeviate::interval, scram::mef::Histogram::interval, scram::mef::TestEvent::interval, scram::mef::MissionTime::interval, scram::mef::Parameter::interval

function IsDeviate

virtual bool IsDeviate()

Determines if the value of the expression contains deviate expressions.

Return:

• true if the expression's value deviates from its mean.
• false if the expression's value does not need sampling.

Warning: Improper registration of arguments may yield silent failure.

Reimplemented by: scram::mef::ConstantExpression::IsDeviate, scram::mef::RandomDeviate::IsDeviate, scram::mef::TestEvent::IsDeviate, scram::mef::MissionTime::IsDeviate

The default logic is to check arguments with uncertainties for sampling. Derived expression classes must decide if they don't have arguments, or if they are random deviates.

function Sample

double Sample()

Return: A sampled value of this expression.

function Reset

void Reset()

This routine resets the sampling to get new values.

All the arguments are called to reset themselves. If this expression was not sampled, its arguments are not going to get any calls.

Protected Functions Documentation

function AddArg

inline void AddArg(
    Expression * arg
)

Registers an additional argument expression.

Parameters:

• arg An argument expression used by this expression.

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Updated on 2025-11-11 at 16:51:08 +0000