Package com.singularsys.jep.misc.functions

Class Case

java.lang.Object

com.singularsys.jep.functions.PostfixMathCommand

com.singularsys.jep.misc.functions.Case

All Implemented Interfaces:

CallbackEvaluationI, PostfixMathCommandI, java.io.Serializable

public class Case
extends PostfixMathCommand
implements CallbackEvaluationI

A case statement. The argument first argument is evaluated and then checked against the 2nd, 4th, 6th argument if the two are equal then the 3rd, 5th, 7th argument is returned. If no arguments match then the last argument is returned (if the number of args is even) for example case("c","a",5,"b",6,"c",7,8) will return 7.

Author:

Richard Morris

See Also:

Switch, Serialized Form

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	Case.NullBehaviour	Action to take if first argument is null.

Field Summary

Fields inherited from class com.singularsys.jep.functions.PostfixMathCommand

curNumberOfParameters, name, NaN, numberOfParameters

Constructor Summary

Constructors

Constructor	Description
Case()	Standard constructor with no default value and errors if null if found.
Case(Case.NullBehaviour nullBehaviour)	Constructor with defined behaviour for null.
Case(java.lang.Object defaultVal)	A case statement with a predefined default value and errors if null if found.
Case(java.lang.Object defaultVal, Case.NullBehaviour nullBehaviour)	Case statement with given default value and defined null behaviour.

Method Summary

Modifier and Type	Method	Description
boolean	checkNumberOfParameters(int n)	Must have at least 3 parameters.
java.lang.Object	evaluate(Node node, Evaluator pv)	Performs some special evaluation on the node.
java.lang.Object	getDefaultVal()	The default value, only meaningful if isHasDefault() is true.
Case.NullBehaviour	getNullBehaviour()	Behaviour when passed zero arguments.
boolean	isHasDefault()	Whether a default value is set

Methods inherited from class com.singularsys.jep.functions.PostfixMathCommand

asArray, asBool, asDouble, asInt, asLong, asStrictInt, asString, getName, getNumberOfParameters, run, setCurNumberOfParameters, setName, toString, toString

Methods inherited from class java.lang.Object

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

Constructor Detail

Case

public Case()

Standard constructor with no default value and errors if null if found.

Case

public Case(Case.NullBehaviour nullBehaviour)

Constructor with defined behaviour for null.

Parameters:

nullBehaviour - action to take if first argument is null

Since:

Jep 3.5

Case

public Case(java.lang.Object defaultVal)

A case statement with a predefined default value and errors if null if found.

Parameters:

defaultVal - The default value to return when no cases match

Since:

Jep 3.5

Case

public Case(java.lang.Object defaultVal,
            Case.NullBehaviour nullBehaviour)

Case statement with given default value and defined null behaviour.

Parameters:

defaultVal - The default value to return when no cases match

nullBehaviour - action to take if first argument is null

Since:

Jep 3.5

Method Detail

isHasDefault

public boolean isHasDefault()

Whether a default value is set

Returns:

true if a default value is set

Since:

Jep 3.5

getDefaultVal

public java.lang.Object getDefaultVal()

The default value, only meaningful if isHasDefault() is true.

Returns:

the default value used.

Since:

Jep 3.5

getNullBehaviour

public Case.NullBehaviour getNullBehaviour()

Behaviour when passed zero arguments.

Returns:

code indicating behaviour type

Since:

Jep 3.5

checkNumberOfParameters

public boolean checkNumberOfParameters(int n)

Must have at least 3 parameters.

Specified by:

checkNumberOfParameters in interface PostfixMathCommandI

Overrides:

checkNumberOfParameters in class PostfixMathCommand

Parameters:

n - number of parameters function will be called with.

Returns:

false if an illegal number of parameters is supplied, true otherwise.

evaluate

public java.lang.Object evaluate(Node node,
                                 Evaluator pv)
                          throws EvaluationException

Description copied from interface: CallbackEvaluationI

Performs some special evaluation on the node. This method has the responsibility for evaluating the children of the node and it should generally call

 pv.eval(node.jjtGetChild(i))   
 

for each child. The SymbolTable is not passed as an argument. This is because it is better practice to get and set variable values by using node.getVar().setValue() rather that through the SymbolTable with requires a hashtable lookup.

Specified by:

evaluate in interface CallbackEvaluationI

Parameters:

node - The current node

pv - The visitor, can be used evaluate the children

Returns:

the value after evaluation. This value will be passed to other functions higher up the node tree. The value can be any type including Double or Vector<Object>

Throws:

EvaluationException - if the calculation cannot be performed

See Also:

Evaluator