net.sf.saxon.functions
Class Root

java.lang.Object
  net.sf.saxon.expr.ComputedExpression
      net.sf.saxon.expr.FunctionCall
          net.sf.saxon.functions.SystemFunction
              net.sf.saxon.functions.Root

All Implemented Interfaces:

Expression, java.io.Serializable

public class Root

extends SystemFunction

Implement the XPath 2.0 root() function

See Also:

Serialized Form

Field Summary

Fields inherited from class net.sf.saxon.functions.SystemFunction

operation

Fields inherited from class net.sf.saxon.expr.FunctionCall

argument

Fields inherited from class net.sf.saxon.expr.ComputedExpression

lineNumber, NO_ARGUMENTS, staticProperties

Constructor Summary

Root()

Method Summary

int	computeSpecialProperties() Get the static properties of this expression (other than its type).
Item	evaluateItem(XPathContext c) Evaluate in a general context
SequenceIterator	iterate(XPathContext c) Return an Iterator to iterate over the values of a sequence.
Expression	simplify() Simplify and validate.

Methods inherited from class net.sf.saxon.functions.SystemFunction

addContextDocumentArgument, checkArguments, computeCardinality, display, getDetails, getItemType, getName, getRequiredType, main, makeSystemFunction, useContextItemAsDefault

Methods inherited from class net.sf.saxon.expr.FunctionCall

analyze, checkArgumentCount, getNumberOfArguments, getSubExpressions, preEvaluate, promote, setArguments, simplifyArguments

Methods inherited from class net.sf.saxon.expr.ComputedExpression

computeDependencies, computeStaticProperties, dynamicError, effectiveBooleanValue, evaluateAsString, getCardinality, getDependencies, getIntrinsicDependencies, getLineNumber, getSpecialProperties, markTailFunctionCalls, setLineNumber, typeError

Methods inherited from class java.lang.Object

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

Constructor Detail

Root

public Root()

Method Detail

simplify

public Expression simplify()
                    throws XPathException

Simplify and validate.

Specified by:

simplify in interface Expression

Overrides:

simplify in class FunctionCall

Throws:

XPathException

computeSpecialProperties

public int computeSpecialProperties()

Get the static properties of this expression (other than its type). The result is bit-significant. These properties are used for optimizations. In general, if property bit is set, it is true, but if it is unset, the value is unknown.

Overrides:

computeSpecialProperties in class ComputedExpression

evaluateItem

public Item evaluateItem(XPathContext c)
                  throws XPathException

Evaluate in a general context

Specified by:

evaluateItem in interface Expression

Overrides:

evaluateItem in class ComputedExpression

Parameters:

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

Returns:

the node or atomic value that results from evaluating the expression; or null to indicate that the result is an empty sequence

Throws:

XPathException - if any dynamic error occurs evaluating the expression

iterate

public SequenceIterator iterate(XPathContext c)
                         throws XPathException

Description copied from class: ComputedExpression

Return an Iterator to iterate over the values of a sequence. The value of every expression can be regarded as a sequence, so this method is supported for all expressions. This default implementation handles iteration for expressions that return singleton values: for non-singleton expressions, the subclass must provide its own implementation.

Specified by:

iterate in interface Expression

Overrides:

iterate in class ComputedExpression

Parameters:

c - supplies the context for evaluation

Returns:

a SequenceIterator that can be used to iterate over the result of the expression

Throws:

XPathException - if any dynamic error occurs evaluating the expression