org.apache.xpath.axes
Class MatchPatternIterator

java.lang.Object
  org.apache.xpath.Expression
      org.apache.xpath.patterns.NodeTest
          org.apache.xpath.axes.PredicatedNodeTest
              org.apache.xpath.axes.LocPathIterator
                  org.apache.xpath.axes.MatchPatternIterator

All Implemented Interfaces:

java.io.Serializable, java.lang.Cloneable, javax.xml.transform.SourceLocator, DTMIterator, PathComponent, SubContextList, ExpressionNode, XPathVisitable

public class MatchPatternIterator
extends LocPathIterator

This class treats a LocationPath as a filtered iteration over the tree, evaluating each node in a super axis traversal against the LocationPath interpreted as a match pattern. This class is useful to find nodes in document order that are complex paths whose steps probably criss-cross each other.

See Also:

Serialized Form

Nested Class Summary

Nested classes/interfaces inherited from class org.apache.xpath.axes.PredicatedNodeTest

PredicatedNodeTest.PredOwner

Field Summary

private static boolean	DEBUG DEBUG flag for diagnostic dumps.
protected StepPattern	m_pattern This is the select pattern, translated into a match pattern.
protected int	m_superAxis The traversal axis from where the nodes will be filtered.
protected DTMAxisTraverser	m_traverser The DTM inner traversal class, that corresponds to the super axis.
(package private) static long	serialVersionUID

Fields inherited from class org.apache.xpath.axes.LocPathIterator

m_allowDetach, m_cdtm, m_clones, m_context, m_currentContextNode, m_execContext, m_lastFetched, m_length, m_pos, m_stackFrame

Fields inherited from class org.apache.xpath.axes.PredicatedNodeTest

DEBUG_PREDICATECOUNTING, m_foundLast, m_lpi, m_predCount, m_predicateIndex, m_proximityPositions

Fields inherited from class org.apache.xpath.patterns.NodeTest

m_name, m_whatToShow, SCORE_NODETEST, SCORE_NONE, SCORE_NSWILD, SCORE_OTHER, SCORE_QNAME, SHOW_BYFUNCTION, SUPPORTS_PRE_STRIPPING, WILD

Fields inherited from interface org.apache.xml.dtm.DTMIterator

FILTER_ACCEPT, FILTER_REJECT, FILTER_SKIP

Constructor Summary

MatchPatternIterator(Compiler compiler, int opPos, int analysis)
Create a LocPathIterator object, including creation of step walkers from the opcode list, and call back into the Compiler to create predicate expressions.

Method Summary

short	acceptNode(int n, XPathContext xctxt) Test whether a specified node is visible in the logical view of a TreeWalker or NodeIterator.
void	detach() Detaches the iterator from the set which it iterated over, releasing any computational resources and placing the iterator in the INVALID state.
protected int	getNextNode() Get the next node via getNextXXX.
int	nextNode() Returns the next node in the set and advances the position of the iterator in the set.
void	setRoot(int context, java.lang.Object environment) Initialize the context values for this expression after it is cloned.

Methods inherited from class org.apache.xpath.axes.LocPathIterator

allowDetachToRelease, asIterator, asNode, bool, callVisitors, cloneWithReset, execute, executeCharsToContentHandler, getAnalysisBits, getAxis, getContext, getCurrentContextNode, getCurrentNode, getCurrentPos, getDTM, getDTMManager, getExpandEntityReferences, getFilter, getFoundLast, getIsTopLevel, getLastPos, getLength, getPrefixResolver, getRoot, getWhatToShow, getXPathContext, incrementCurrentPos, isDocOrdered, isFresh, isMutable, isNodesetExpr, item, previousNode, reset, returnNextNode, runTo, setCurrentContextNode, setCurrentPos, setEnvironment, setIsTopLevel, setItem, setNextPosition, setShouldCacheNodes, size

Methods inherited from class org.apache.xpath.axes.PredicatedNodeTest

acceptNode, callPredicateVisitors, canTraverseOutsideSubtree, clone, countProximityPosition, deepEquals, executePredicates, fixupVariables, getLocPathIterator, getPredicate, getPredicateCount, getPredicateIndex, getProximityPosition, getProximityPosition, getProximityPosition, initPredicateInfo, initProximityPosition, isReverseAxes, nodeToString, resetProximityPositions, setLocPathIterator, setPredicateCount

Methods inherited from class org.apache.xpath.patterns.NodeTest

calcScore, debugWhatToShow, execute, execute, getDefaultScore, getLocalName, getNamespace, getNodeTypeTest, getStaticScore, initNodeTest, initNodeTest, setLocalName, setNamespace, setStaticScore, setWhatToShow

Methods inherited from class org.apache.xpath.Expression

asIteratorRaw, assertion, error, execute, exprAddChild, exprGetChild, exprGetNumChildren, exprGetParent, exprSetParent, getColumnNumber, getExpressionOwner, getLineNumber, getPublicId, getSystemId, isSameClass, isStableNumber, num, warn, xstr

Methods inherited from class java.lang.Object

equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface org.apache.xml.dtm.DTMIterator

clone

Field Detail

serialVersionUID

static final long serialVersionUID

See Also:

Constant Field Values

m_pattern

protected StepPattern m_pattern

This is the select pattern, translated into a match pattern.

m_superAxis

protected int m_superAxis

The traversal axis from where the nodes will be filtered.

m_traverser

protected DTMAxisTraverser m_traverser

The DTM inner traversal class, that corresponds to the super axis.

DEBUG

private static final boolean DEBUG

DEBUG flag for diagnostic dumps.

See Also:

Constant Field Values

Constructor Detail

MatchPatternIterator

MatchPatternIterator(Compiler compiler,
                     int opPos,
                     int analysis)
               throws javax.xml.transform.TransformerException

Create a LocPathIterator object, including creation of step walkers from the opcode list, and call back into the Compiler to create predicate expressions.

Parameters:

compiler - The Compiler which is creating this expression.

opPos - The position of this iterator in the opcode list from the compiler.

analysis - Analysis bits that give general information about the LocationPath.

Throws:

javax.xml.transform.TransformerException

Method Detail

setRoot

public void setRoot(int context,
                    java.lang.Object environment)

Initialize the context values for this expression after it is cloned.

Specified by:

setRoot in interface DTMIterator

Overrides:

setRoot in class LocPathIterator

Parameters:

context - The XPath runtime context for this transformation.

environment - The environment object. The environment in which this iterator operates, which should provide:

• a node (the context node... same value as "root" defined below)
• a pair of non-zero positive integers (the context position and the context size)
• a set of variable bindings
• a function library
• the set of namespace declarations in scope for the expression.

At this time the exact implementation of this environment is application dependent. Probably a proper interface will be created fairly soon.

detach

public void detach()

Detaches the iterator from the set which it iterated over, releasing any computational resources and placing the iterator in the INVALID state. Afterdetach has been invoked, calls to nextNode orpreviousNode will raise the exception INVALID_STATE_ERR.

Specified by:

detach in interface DTMIterator

Overrides:

detach in class LocPathIterator

getNextNode

protected int getNextNode()

Get the next node via getNextXXX. Bottlenecked for derived class override.

Returns:

The next node on the axis, or DTM.NULL.

nextNode

public int nextNode()

Returns the next node in the set and advances the position of the iterator in the set. After a NodeIterator is created, the first call to nextNode() returns the first node in the set.

Specified by:

nextNode in interface DTMIterator

Specified by:

nextNode in class LocPathIterator

Returns:

The next Node in the set being iterated over, or null if there are no more members in that set.

acceptNode

public short acceptNode(int n,
                        XPathContext xctxt)

Test whether a specified node is visible in the logical view of a TreeWalker or NodeIterator. This function will be called by the implementation of TreeWalker and NodeIterator; it is not intended to be called directly from user code.

Parameters:

n - The node to check to see if it passes the filter or not.

Returns:

a constant to determine whether the node is accepted, rejected, or skipped, as defined above .