org.exist.xquery
Class LocationStep

java.lang.Object
  org.exist.xquery.AbstractExpression
      org.exist.xquery.Step
          org.exist.xquery.LocationStep

All Implemented Interfaces:

Expression

public class LocationStep
extends Step

Processes all location path steps (like descendant::*, ancestor::XXX). The results of the first evaluation of the expression are cached for the lifetime of the object and only reloaded if the context sequence (as passed to the eval(Sequence, Item) method) has changed.

Author:

wolf

Field Summary

Fields inherited from interface org.exist.xquery.Expression

DOT_TEST, EXPRESSION_ID_INVALID, IGNORE_CONTEXT, IN_PREDICATE, IN_UPDATE, IN_WHERE_CLAUSE, NEED_INDEX_INFO, NO_CONTEXT_ID, SINGLE_STEP_EXECUTION

Constructor Summary

LocationStep(XQueryContext context, int axis)
Creates a new LocationStep instance.

LocationStep(XQueryContext context, int axis, NodeTest test)
Creates a new LocationStep instance.

Method Summary

void	accept(ExpressionVisitor visitor) The method accept
void	analyze(AnalyzeContextInfo contextInfo) Statically analyze the expression and its subexpressions.
Sequence	eval(Sequence contextSequence, Item contextItem) The method eval
int	getDependencies() Returns Dependency.DEFAULT_DEPENDENCIES.
Expression	getParent() The method getParent
void	resetState() Called to inform an expression that it should reset to its initial state.
void	setPreloadedData(DocumentSet docs, NodeSet nodes) The method setPreloadedData
void	setPreloadNodeSets(boolean doPreload) The method setPreloadNodeSets
void	setUseDirectAttrSelect(boolean useDirectAttrSelect) The method setUseDirectAttrSelect

Methods inherited from class org.exist.xquery.Step

addPredicate, dump, getAxis, getCardinality, getPredicates, getTest, hasPredicates, insertPredicate, returnsType, setAxis, setPrimaryAxis, setTest, toString

Methods inherited from class org.exist.xquery.AbstractExpression

eval, getASTNode, getContextDocSet, getContextId, getExpressionId, setASTNode, setContextDocSet

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

LocationStep

public LocationStep(XQueryContext context,
                    int axis)

Creates a new LocationStep instance.

Parameters:

context - a XQueryContext value

axis - an int value

LocationStep

public LocationStep(XQueryContext context,
                    int axis,
                    NodeTest test)

Creates a new LocationStep instance.

Parameters:

context - a XQueryContext value

axis - an int value

test - a NodeTest value

Method Detail

getDependencies

public int getDependencies()

Description copied from class: AbstractExpression

Returns Dependency.DEFAULT_DEPENDENCIES.

Specified by:

getDependencies in interface Expression

Overrides:

getDependencies in class AbstractExpression

Returns:

set of bit-flags

See Also:

Expression.getDependencies()

setPreloadNodeSets

public void setPreloadNodeSets(boolean doPreload)

The method setPreloadNodeSets

Parameters:

doPreload - a boolean value

setPreloadedData

public void setPreloadedData(DocumentSet docs,
                             NodeSet nodes)

The method setPreloadedData

Parameters:

docs - a DocumentSet value

nodes - a NodeSet value

analyze

public void analyze(AnalyzeContextInfo contextInfo)
             throws XPathException

Description copied from interface: Expression

Statically analyze the expression and its subexpressions. During the static analysis phase, the query engine can detect unknown variables and some type errors.

Specified by:

analyze in interface Expression

Overrides:

analyze in class Step

Throws:

XPathException

eval

public Sequence eval(Sequence contextSequence,
                     Item contextItem)
              throws XPathException

The method eval

Specified by:

eval in interface Expression

Specified by:

eval in class Step

Parameters:

contextSequence - a Sequence value

contextItem - an Item value

Returns:

a Sequence value

Throws:

XPathException - if an error occurs

getParent

public Expression getParent()

The method getParent

Returns:

an Expression value

setUseDirectAttrSelect

public void setUseDirectAttrSelect(boolean useDirectAttrSelect)

The method setUseDirectAttrSelect

Parameters:

useDirectAttrSelect - a boolean value

accept

public void accept(ExpressionVisitor visitor)

The method accept

Specified by:

accept in interface Expression

Overrides:

accept in class AbstractExpression

Parameters:

visitor - an ExpressionVisitor value

resetState

public void resetState()

Description copied from interface: Expression

Called to inform an expression that it should reset to its initial state. All cached data in the expression object should be dropped. For example, the document() function calls this method whenever the input document set has changed.

Specified by:

resetState in interface Expression

Overrides:

resetState in class Step