Package com.singularsys.jep.standard

Class FastEvaluator

java.lang.Object

com.singularsys.jep.standard.FastEvaluator

All Implemented Interfaces:

Evaluator, GenericVisitor<Object,Void,EvaluationException>, JepComponent, Serializable

Direct Known Subclasses:

MonitoringEvaluator, ThreadSafeEvaluator

public class FastEvaluator
extends Object
implements Evaluator, GenericVisitor<Object,Void,EvaluationException>

A fast evaluator for Jep expressions. This is the default evaluator used by Jep.

It differs from StandardEvaluator in the evaluation of functions. It uses the UnaryFunction.eval(Object), BinaryFunction.eval(Object, Object), NaryBinaryFunction.eval(Object, Object), NaryFunction.eval(Object[]) methods instead of the PostfixMathCommandI.run(Stack) method. It can be up-to 6 times generally faster than the StandardEvaluator but if most functions don't use these interfaces then it can be marginally slower.

The UncheckedEvaluator uses a similar approach but does fewer intermediate checks and is about 5% faster than this class.

Since Jep 4.1, extension 2.2, this now implements GenericVisitor some method signatures have changed to be more specific.

Since:

Jep 3.3

See Also:

• Serialized Form

Field Summary

Fields

Modifier and Type	Field	Description
protected boolean	trapInfinity
protected boolean	trapNaN
protected boolean	trapNullValues
protected boolean	trapUnsetValues	Whether null values for variables are trapped

Constructor Summary

Constructors

Constructor	Description
FastEvaluator()

Method Summary

Modifier and Type	Method	Description
Object	eval(Node node)	Evaluates a sub expression.
Object	evaluate(Node node)	Main entry point, evaluates a node and returns and object with the value of the node.
JepComponent	getLightWeightInstance()	Gets a light-weight instance suitable for using in multiple threads.
void	init(Jep jep)	Initialize the component.
boolean	isTrapInfinity()
boolean	isTrapNaN()
boolean	isTrapNullValues()	Whether null values for variables are trapped.
boolean	isTrapUnsetValues()	Whether variables with unset values are trapped.
EvaluationException	makeException(String message)	Create an Exception of the correct type.
protected Object	nodeAccept(Node node)
void	setTrapInfinity(boolean trapInfinity)
void	setTrapNaN(boolean trapNaN)
void	setTrapNullValues(boolean trapNullValues)	Sets whether null values for variables are trapped.
void	setTrapUnsetValues(boolean trapUnsetValues)	Sets whether unset variable values are trapped.
Object	visit(ASTConstant node, Void data)	Visit a constant node
Object	visit(ASTFunNode node, Void data)	Visit a function node
Object	visit(ASTOpNode node, Void data)	Visit an operator node
Object	visit(ASTVarNode node, Void data)	Visit a variable node
Object	visitConstant(Node node)
protected Object	visitFun(Node node)	Visits a function/operator node.
Object	visitVar(Node node)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface com.singularsys.jep.Evaluator

eval

Methods inherited from interface com.singularsys.jep.GenericVisitor

makeException, visit, visitChildren

Field Details

trapUnsetValues

protected boolean trapUnsetValues

Whether null values for variables are trapped

trapNullValues

protected boolean trapNullValues

trapNaN

protected boolean trapNaN

trapInfinity

protected boolean trapInfinity

Constructor Details

FastEvaluator

public FastEvaluator()

Method Details

init

public void init(Jep jep)

Description copied from interface: JepComponent

Initialize the component. This method is called whenever a component is added to Jep. Hence, it allows components to keep track of the other components they may rely on.

Specified by:

init in interface JepComponent

Parameters:

jep - the current Jep instance

eval

public Object eval(Node node)
            throws EvaluationException

Description copied from interface: Evaluator

Evaluates a sub expression. This method can be called by PostfixMathCommands which implement CallbackEvaluationI

Specified by:

eval in interface Evaluator

Parameters:

node - node to evaluate

Returns:

The value after evaluating the sub expression.

Throws:

EvaluationException - if errors occur during evaluation;

evaluate

public Object evaluate(Node node)
                throws EvaluationException

Description copied from interface: Evaluator

Main entry point, evaluates a node and returns and object with the value of the node.

Specified by:

evaluate in interface Evaluator

Parameters:

node - node to evaluate

Returns:

value after evaluation

Throws:

EvaluationException - if errors occur during evaluation;

nodeAccept

protected Object nodeAccept(Node node)
                     throws EvaluationException

Throws:

EvaluationException

visit

public Object visit(ASTConstant node,
 Void data)
             throws EvaluationException

Description copied from interface: GenericVisitor

Visit a constant node

Specified by:

visit in interface GenericVisitor<Object,Void,EvaluationException>

Parameters:

node - current node

data - context data

Returns:

the result of visiting the node

Throws:

EvaluationException

visitConstant

public Object visitConstant(Node node)
                     throws EvaluationException

Throws:

EvaluationException

visit

public Object visit(ASTVarNode node,
 Void data)
             throws EvaluationException

Description copied from interface: GenericVisitor

Visit a variable node

Specified by:

visit in interface GenericVisitor<Object,Void,EvaluationException>

Parameters:

node - current node

data - context data

Returns:

the result of visiting the node

Throws:

EvaluationException

visitVar

public Object visitVar(Node node)
                throws EvaluationException

Throws:

EvaluationException

visit

public Object visit(ASTFunNode node,
 Void data)
             throws EvaluationException

Description copied from interface: GenericVisitor

Visit a function node

Specified by:

visit in interface GenericVisitor<Object,Void,EvaluationException>

Parameters:

node - current node

data - context data

Returns:

the result of visiting the node

Throws:

EvaluationException

visit

public Object visit(ASTOpNode node,
 Void data)
             throws EvaluationException

Description copied from interface: GenericVisitor

Visit an operator node

Specified by:

visit in interface GenericVisitor<Object,Void,EvaluationException>

Parameters:

node - current node

data - context data

Returns:

the result of visiting the node

Throws:

EvaluationException

visitFun

protected Object visitFun(Node node)
                   throws EvaluationException

Visits a function/operator node. This is the most visited method for most expression evaluations. Keeping it fast is important.

Parameters:

node -

Throws:

EvaluationException

isTrapUnsetValues

public boolean isTrapUnsetValues()

Whether variables with unset values are trapped.

Returns:

Since:

3.5

setTrapUnsetValues

public void setTrapUnsetValues(boolean trapUnsetValues)

Sets whether unset variable values are trapped. This flag is set by when the Variable.setValidValue(boolean) or cleared using VariableTable.clearValues().

Parameters:

trapUnsetValues - true to trap unset values, false to ignore them

Since:

3.5

isTrapNullValues

public boolean isTrapNullValues()

Whether null values for variables are trapped.

Returns:

the status if the trap null values flag.

setTrapNullValues

public void setTrapNullValues(boolean trapNullValues)

Sets whether null values for variables are trapped. If set (the default) then an EvaluationException is thrown for null values of variables. If not set then null values are passed to PostfixMathCommands who will need to test for null values.

Parameters:

trapNullValues -

isTrapNaN

public boolean isTrapNaN()

setTrapNaN

public void setTrapNaN(boolean trapNaN)

isTrapInfinity

public boolean isTrapInfinity()

setTrapInfinity

public void setTrapInfinity(boolean trapInfinity)

getLightWeightInstance

public JepComponent getLightWeightInstance()

Description copied from interface: JepComponent

Gets a light-weight instance suitable for using in multiple threads.

Specified by:

getLightWeightInstance in interface JepComponent

Returns:

a new FastEvaluator

makeException

public EvaluationException makeException(String message)

Description copied from interface: GenericVisitor

Create an Exception of the correct type. A typical implementation is

@Override
public JepException makeException(String message) {
 return new JepException(message);
}

Specified by:

makeException in interface GenericVisitor<Object,Void,EvaluationException>

Parameters:

message - error message

Returns:

an Exception