org.jaxen.function

Class BooleanFunction

java.lang.Object

org.jaxen.function.BooleanFunction

All Implemented Interfaces:

Function

public class BooleanFunction
extends Object
implements Function

4.3 boolean boolean(object)

The boolean function converts its argument to a boolean as follows:

• a number is true if and only if it is neither positive or negative zero nor NaN

• a node-set is true if and only if it is non-empty

• a string is true if and only if its length is non-zero

• an object of a type other than the four basic types is converted to a boolean in a way that is dependent on that type

Author:

bob mcwhirter (bob @ werken.com)

See Also:

Section 4.3 of the XPath Specification

Constructor Summary

Constructors

Constructor and Description
BooleanFunction() Create a new BooleanFunction object.

Method Summary

Methods

Modifier and Type	Method and Description
Object	call(Context context, List args) Convert the argument to a Boolean
static Boolean	evaluate(Object obj, Navigator nav) Convert the argument obj to a Boolean according to the following rules:

Methods inherited from class java.lang.Object

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

Constructor Detail

BooleanFunction

public BooleanFunction()

Create a new BooleanFunction object.

Method Detail

call

public Object call(Context context,
          List args)
            throws FunctionCallException

Convert the argument to a Boolean

Specified by:

call in interface Function

Parameters:

context - the context at the point in the expression when the function is called

args - a list with exactly one item which will be converted to a Boolean

Returns:

the result of evaluating the function; Boolean.TRUE or Boolean.FALSE

Throws:

FunctionCallException - if args has more or less than one item

evaluate

public static Boolean evaluate(Object obj,
               Navigator nav)

Convert the argument obj to a Boolean according to the following rules:

• Lists are false if they're empty; true if they're not.
• Booleans are false if they're false; true if they're true.
• Strings are false if they're empty; true if they're not.
• Numbers are false if they're 0 or NaN; true if they're not.
• All other objects are true.

Parameters:

obj - the object to convert to a boolean

nav - ignored

Returns:

Boolean.TRUE or Boolean.FALSE