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, getSourceLocator, 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
Returns:
the simplified expression
Throws:
XPathException - if an error is discovered during expression rewriting

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