net.sf.saxon.expr
Class RootExpression

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

All Implemented Interfaces:

Expression, java.io.Serializable

public class RootExpression

extends SingleNodeExpression

An expression whose value is always a set of nodes containing a single node, the document root. Note that the root of a tree is not necessarily a document node.

See Also:

Serialized Form

Field Summary

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

lineNumber, NO_ARGUMENTS, staticProperties

Constructor Summary

RootExpression()

Method Summary

int	computeCardinality() Specify that the expression returns a singleton
void	display(int level, NamePool pool) Diagnostic print of expression structure
boolean	equals(java.lang.Object other) Is this expression the same as another expression?
int	getIntrinsicDependencies() Determine which aspects of the context the expression depends on.
NodeInfo	getNode(XPathContext context) Return the first element selected by this Expression
int	hashCode() get HashCode for comparing two expressions
Expression	simplify() Simplify an expression

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

analyze, effectiveBooleanValue, evaluateItem, getItemType, iterate

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

computeDependencies, computeSpecialProperties, computeStaticProperties, dynamicError, evaluateAsString, getCardinality, getDependencies, getLineNumber, getSpecialProperties, getSubExpressions, markTailFunctionCalls, promote, setLineNumber, typeError

Methods inherited from class java.lang.Object

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

Constructor Detail

RootExpression

public RootExpression()

Method Detail

simplify

public Expression simplify()
                    throws XPathException

Simplify an expression

Specified by:

simplify in interface Expression

Overrides:

simplify in class ComputedExpression

Returns:

the simplified expression

Throws:

XPathException - if an error is discovered during expression rewriting

equals

public boolean equals(java.lang.Object other)

Is this expression the same as another expression?

computeCardinality

public final int computeCardinality()

Specify that the expression returns a singleton

Overrides:

computeCardinality in class SingleNodeExpression

hashCode

public int hashCode()

get HashCode for comparing two expressions

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

display

public void display(int level,
                    NamePool pool)

Diagnostic print of expression structure

Parameters:

level - indentation level for this expression