com.icl.saxon.functions
Class Key

java.lang.Object
  com.icl.saxon.expr.Expression
      com.icl.saxon.expr.Function
          com.icl.saxon.functions.Key

public class Key

extends Function

Field Summary

Fields inherited from class com.icl.saxon.expr.Function

argument

Fields inherited from class com.icl.saxon.expr.Expression

staticContext

Constructor Summary

Key()

Method Summary

NodeEnumeration	enumerate(Context context, boolean sorted) Enumerate the expression
Value	evaluate(Context context) Evaluate the expression
int	getDataType() Determine the data type of the expression
int	getDependencies() Determine which aspects of the context the expression depends on.
java.lang.String	getName() Get the name of the function.
boolean	isContextDocumentNodeSet() Determine, in the case of an expression whose data type is Value.NODESET, whether all the nodes in the node-set are guaranteed to come from the same document as the context node.
Expression	reduce(int dep, Context context) Remove specified dependencies.
Expression	simplify() Simplify and validate

Methods inherited from class com.icl.saxon.expr.Function

addArgument, checkArgumentCount, display, getNumberOfArguments

Methods inherited from class com.icl.saxon.expr.Expression

containsReferences, evaluateAsBoolean, evaluateAsNodeSet, evaluateAsNumber, evaluateAsString, getStaticContext, indent, make, outputStringValue, setStaticContext, usesCurrent

Methods inherited from class java.lang.Object

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

Constructor Detail

Key

public Key()

Method Detail

getName

public java.lang.String getName()

Description copied from class: Function

Get the name of the function. This method must be implemented in all subclasses.

Specified by:

getName in class Function

Returns:

the name of the function, as used in XSL expressions, but excluding its namespace prefix

getDataType

public int getDataType()

Determine the data type of the expression

Specified by:

getDataType in class Expression

Returns:

Value.NODESET

isContextDocumentNodeSet

public boolean isContextDocumentNodeSet()

Determine, in the case of an expression whose data type is Value.NODESET, whether all the nodes in the node-set are guaranteed to come from the same document as the context node. Used for optimization.

Overrides:

isContextDocumentNodeSet in class Expression

simplify

public Expression simplify()
                    throws XPathException

Simplify and validate

Overrides:

simplify in class Expression

Returns:

the simplified expression

Throws:

XPathException

evaluate

public Value evaluate(Context context)
               throws XPathException

Evaluate the expression

Specified by:

evaluate in class Expression

Parameters:

context - The context in which the expression is to be evaluated

Returns:

the value of the expression, evaluated in the current context

Throws:

XPathException

enumerate

public NodeEnumeration enumerate(Context context,
                                 boolean sorted)
                          throws XPathException

Enumerate the expression

Overrides:

enumerate in class Expression

Parameters:

context - The context in which the expression is to be evaluated

sorted - Indicates whether the nodes are required in document order. If this is false, they may come in any order, but there will be no duplicates.

Throws:

XPathException - when the expression does not return a nodeset.

getDependencies

public int getDependencies()

Determine which aspects of the context the expression depends on. The result is a bitwise-or'ed value composed from constants such as Context.VARIABLES and Context.CURRENT_NODE

Specified by:

getDependencies in class Expression

reduce

public Expression reduce(int dep,
                         Context context)
                  throws XPathException

Remove specified dependencies.

Specified by:

reduce in class Expression

Parameters:

dep - The dependencies to be removed, e.g. Context.VARIABLES

context - The context to be used for the partial evaluation

Returns:

a new expression (or Value) that does not have any of the specified dependencies

Throws:

XPathException