net.sf.saxon.functions
Class Root

java.lang.Object
  extended by net.sf.saxon.expr.Expression
      extended by net.sf.saxon.expr.FunctionCall
          extended by net.sf.saxon.functions.SystemFunction
              extended by net.sf.saxon.functions.Root
All Implemented Interfaces:
Serializable, SourceLocator, Container, EvaluableItem, SequenceIterable, InstructionInfoProvider

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.expr.Expression
EVALUATE_METHOD, ITERATE_METHOD, PROCESS_METHOD
 
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
 Expression simplify(StaticContext env)
          Simplify and validate.
 
Methods inherited from class net.sf.saxon.functions.SystemFunction
checkArguments, computeCardinality, display, getDetails, getErrorCodeForTypeErrors, getItemType, main, makeSystemFunction, optimize, setDetails
 
Methods inherited from class net.sf.saxon.expr.FunctionCall
getArguments, getDisplayName, getFunctionNameCode, getNumberOfArguments, iterateSubExpressions, preEvaluate, promote, replaceSubExpression, setArguments, setFunctionNameCode, typeCheck
 
Methods inherited from class net.sf.saxon.expr.Expression
adoptChildExpression, checkPermittedContents, computeDependencies, computeStaticProperties, doPromotion, effectiveBooleanValue, evaluateAsString, getCardinality, getColumnNumber, getContainingProcedure, getDependencies, getExecutable, getHostLanguage, getImplementationMethod, getInstructionInfo, getIntrinsicDependencies, getLineNumber, getLocationId, getLocationProvider, getParentExpression, getPublicId, getSlotsUsed, getSpecialProperties, getSystemId, hasBadParentPointer, iterate, markTailFunctionCalls, process, resetStaticProperties, setLocationId, setParentExpression, setParentExpression, suppressValidation
 
Methods inherited from class java.lang.Object
equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

Root

public Root()
Method Detail

simplify

public Expression simplify(StaticContext env)
                    throws XPathException
Simplify and validate.

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 SystemFunction

evaluateItem

public Item evaluateItem(XPathContext c)
                  throws XPathException
Evaluate in a general context

Specified by:
evaluateItem in interface EvaluableItem
Overrides:
evaluateItem in class Expression
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


Copyright (C) Michael H. Kay. All rights reserved.