net.sf.saxon.expr
Class RootExpression

java.lang.Object
  net.sf.saxon.expr.Expression
      net.sf.saxon.expr.SingleNodeExpression
          net.sf.saxon.expr.RootExpression

All Implemented Interfaces:

Serializable, SourceLocator, Container, EvaluableItem, SequenceIterable, InstructionInfoProvider

public class RootExpression
extends SingleNodeExpression

An expression whose value is always a set of nodes containing a single node, the document root. This corresponds to the XPath Expression "/", including the implicit "/" at the start of a path expression with a leading "/".

See Also:

Serialized Form

Field Summary

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

EVALUATE_METHOD, ITERATE_METHOD, PROCESS_METHOD

Constructor Summary

RootExpression()

Method Summary

int	computeCardinality() Specify that the expression returns a singleton
void	display(int level, PrintStream out, Configuration config) Diagnostic print of expression structure
boolean	equals(Object other) Is this expression the same as another expression?
int	getIntrinsicDependencies() Determine which aspects of the context the expression depends on.
ItemType	getItemType(TypeHierarchy th) Determine the data type of the items returned by this expression
NodeInfo	getNode(XPathContext context) Return the first element selected by this Expression
int	hashCode() get HashCode for comparing two expressions

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

computeSpecialProperties, effectiveBooleanValue, evaluateItem, iterate, optimize, typeCheck

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

adoptChildExpression, checkPermittedContents, computeDependencies, computeStaticProperties, doPromotion, evaluateAsString, getCardinality, getColumnNumber, getContainingProcedure, getDependencies, getExecutable, getHostLanguage, getImplementationMethod, getInstructionInfo, getLineNumber, getLocationId, getLocationProvider, getParentExpression, getPublicId, getSlotsUsed, getSpecialProperties, getSystemId, hasBadParentPointer, iterateSubExpressions, markTailFunctionCalls, process, promote, replaceSubExpression, resetStaticProperties, setLocationId, setParentExpression, setParentExpression, simplify, suppressValidation

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

RootExpression

public RootExpression()

Method Detail

equals

public boolean equals(Object other)

Is this expression the same as another expression?

Overrides:

equals in class Object

computeCardinality

public final int computeCardinality()

Specify that the expression returns a singleton

Overrides:

computeCardinality in class SingleNodeExpression

getItemType

public ItemType getItemType(TypeHierarchy th)

Determine the data type of the items returned by this expression

Overrides:

getItemType in class SingleNodeExpression

Parameters:

th -

Returns:

Type.NODE

hashCode

public int hashCode()

get HashCode for comparing two expressions

Overrides:

hashCode in class Object

getNode

public NodeInfo getNode(XPathContext context)
                 throws XPathException

Return the first element selected by this Expression

Specified by:

getNode in class SingleNodeExpression

Parameters:

context - The evaluation context

Returns:

the NodeInfo of the first selected element, or null if no element is selected

Throws:

XPathException

getIntrinsicDependencies

public int getIntrinsicDependencies()

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

Overrides:

getIntrinsicDependencies in class SingleNodeExpression

Returns:

a set of bit-significant flags identifying the "intrinsic" dependencies. The flags are documented in class net.sf.saxon.value.StaticProperty

display

public void display(int level,
                    PrintStream out,
                    Configuration config)

Diagnostic print of expression structure

Specified by:

display in class Expression

Parameters:

level - indentation level for this expression

out - Output destination