com.novell.xml.xpath
Interface ExpressionValue

All Known Implementing Classes:

BooleanValue, JavaObject, JavaVoid, NodeSet, NumberValue, ResultTreeFragment, StringValue

public interface ExpressionValue

Interface allowing discovery of and access to expression values. Implementing classes must provide an argumentless constructor for use in casting expression types. For casting, the appropriate type is constructed, then the castFrom() member defined by this interface is called.

Field Summary

static int	BOOLEAN Represents a boolean value
static int	EXTENDED Represents a non-XPath defined type
static int	NATIVE Represents a native (extension) type
static int	NODE_SET Represents a node-set value
static int	NUMBER Represents a number value
static int	STRING Represents a string value

Method Summary

void	castFrom(Object type) Convert from a different type of expression value to the type of the class implementing the ExpressionValue interface.
void	dump(PrintWriter writer) Output a human-readable form for the value
boolean	getBooleanValue() Return boolean value of expression value (will convert to boolean if value is not of type boolean)
Object	getNativeValue() return the underlying native value (java.lang.Boolean, java.lang.Double, etc.)
NodeSet	getNodeSetValue() Return node-set value of this ExpressionValue.
double	getNumberValue() Return numeric value of ExpressionValue.
String	getStringValue() Return string value of this ExpressionValue.
int	getValueType() Return type of expression value

Field Detail

BOOLEAN

public static final int BOOLEAN

Represents a boolean value

See Also:

Constant Field Values

NUMBER

public static final int NUMBER

Represents a number value

See Also:

Constant Field Values

STRING

public static final int STRING

Represents a string value

See Also:

Constant Field Values

NODE_SET

public static final int NODE_SET

Represents a node-set value

See Also:

Constant Field Values

EXTENDED

public static final int EXTENDED

Represents a non-XPath defined type

See Also:

Constant Field Values

NATIVE

public static final int NATIVE

Represents a native (extension) type

See Also:

Constant Field Values

Method Detail

getValueType

public int getValueType()

Return type of expression value

Returns:

ExpressionValue.BOOLEAN, ExpressionValue.NUMBER, etc.

castFrom

public void castFrom(Object type)
              throws XPathConversionException

Convert from a different type of expression value to the type of the class implementing the ExpressionValue interface. This is used primarily for converting parameters for function calls. The XPath basic types (Boolean, Number, String, Node-set) use the required methods of ExpressionValue to perform this function. Extended types must implement this according to their language definitions.

Parameters:

type - The object to convert from.

Throws:

XPathConversionException

getBooleanValue

public boolean getBooleanValue()
                        throws XPathConversionException

Return boolean value of expression value (will convert to boolean if value is not of type boolean)

Returns:

true or false

Throws:

XPathConversionException

getNumberValue

public double getNumberValue()
                      throws XPathConversionException

Return numeric value of ExpressionValue. Will convert to a number if value is not of NUMBER type

Returns:

numeric value

Throws:

XPathConversionException

getStringValue

public String getStringValue()

Return string value of this ExpressionValue. Will convert to a string if underlying type is not string.

Returns:

String value of ExpressionValue

getNodeSetValue

public NodeSet getNodeSetValue()
                        throws XPathConversionException

Return node-set value of this ExpressionValue. Will NOT convert an underlying type to a node-set.

Throws:

XPathConversionException

getNativeValue

public Object getNativeValue()

return the underlying native value (java.lang.Boolean, java.lang.Double, etc.)

Returns:

The native java class that is the value

dump

public void dump(PrintWriter writer)

Output a human-readable form for the value

Parameters:

writer - Output device