com.singularsys.jep.functions
Class LazyLogical

java.lang.Object
  com.singularsys.jep.functions.PostfixMathCommand
      com.singularsys.jep.functions.LazyLogical

All Implemented Interfaces:

CallbackEvaluationI, PostfixMathCommandI, java.io.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

Nested Class Summary

Nested classes/interfaces inherited from interface com.singularsys.jep.functions.CallbackEvaluationI

CallbackEvaluationI.Runnable

Field Summary

protected boolean	allowNumbers
static int	AND
protected int	id Represents which logical operator this is.
static int	OR

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

curNumberOfParameters, name, NaN, numberOfParameters

Constructor Summary

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

java.lang.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
void	run(java.util.Stack<java.lang.Object> inStack) Run the function on the stack.

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

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

Methods inherited from class java.lang.Object

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

Field Detail

id

protected 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 Detail

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 of the constants AND or OR

LazyLogical

public LazyLogical(int id_in,
                   boolean disallowNumbers)

Constructor which restricts type of arguments.

Parameters:

id_in -

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

Method Detail

run

public void run(java.util.Stack<java.lang.Object> inStack)
         throws EvaluationException

Description copied from interface: PostfixMathCommandI

Run the function on the stack. Pops the arguments from the stack, and pushes the result on the top of the stack.

Specified by:

run in interface PostfixMathCommandI

Throws:

EvaluationException

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

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