Package com.singularsys.jep.functions

Class LazyLogical

java.lang.Object

com.singularsys.jep.functions.PostfixMathCommand

com.singularsys.jep.functions.LazyLogical

All Implemented Interfaces:

CallbackEvaluationI, PostfixMathCommandI, Serializable

public class LazyLogical
extends PostfixMathCommand
implements CallbackEvaluationI

A version of the logical operators which use lazy evaluation. The first argument is always evaluated but the second argument is only evaluated if needed. Hence

• 0 || arg2 arg2 is evaluated
• 1 || arg2 arg2 is not evaluated and true is returned
• 0 && arg2 arg2 is not evaluated and false is returned
• 1 && arg2 arg2 is evaluated

Since:

3.1

See Also:

• Serialized Form

Field Summary

Fields

Modifier and Type	Field	Description
protected boolean	allowNumbers
static final int	AND
protected final int	id	Represents which logical operator this is.
static final int	OR

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

curNumberOfParameters, name, NaN, numberOfParameters

Constructor Summary

Constructors

Constructor	Description
LazyLogical(int id_in)	Standard constructor, non-zero Numbers will be treated as true and zero Numbers as false.
LazyLogical(int id_in, boolean disallowNumbers)	Constructor which restricts type of arguments.

Method Summary

Modifier and Type	Method	Description
Object	evaluate(Node node, Evaluator pv)	Performs some special evaluation on the node.
int	getId()	Return a code indicating the type of this operator
boolean	isAllowNumbers()	Returns whether numbers are treated as booleans

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

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

Methods inherited from class java.lang.Object

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

Field Details

id

protected final int id

Represents which logical operator this is.

AND

public static final int AND

See Also:

• Constant Field Values

OR

public static final int OR

See Also:

• Constant Field Values

allowNumbers

protected boolean allowNumbers

Constructor Details

LazyLogical

public LazyLogical(int id_in)

Standard constructor, non-zero Numbers will be treated as true and zero Numbers as false.

Parameters:

id_in - either one of the constants AND or OR.

LazyLogical

public LazyLogical(int id_in,
 boolean disallowNumbers)

Constructor which restricts type of arguments.

Parameters:

id_in - Either AND or OR

disallowNumbers - if true Number arguments will raise exceptions, otherwise as the Standard constructor.

Method Details

evaluate

public 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

getId

public int getId()

Return a code indicating the type of this operator

Returns:

the id

Since:

3.4.0

isAllowNumbers

public boolean isAllowNumbers()

Returns whether numbers are treated as booleans

Returns:

true if numbers can be used

Since:

3.4.0