org.apache.lucene.spatial.prefix

Class AbstractVisitingPrefixTreeQuery.VisitorTemplate

java.lang.Object

org.apache.lucene.spatial.prefix.AbstractPrefixTreeQuery.BaseTermsEnumTraverser

org.apache.lucene.spatial.prefix.AbstractVisitingPrefixTreeQuery.VisitorTemplate

Enclosing class:

AbstractVisitingPrefixTreeQuery

public abstract class AbstractVisitingPrefixTreeQuery.VisitorTemplate
extends AbstractPrefixTreeQuery.BaseTermsEnumTraverser

An abstract class designed to make it easy to implement predicates or other operations on a SpatialPrefixTree indexed field. An instance of this class is not designed to be re-used across LeafReaderContext instances so simply create a new one per-leaf. The getDocIdSet() method here starts the work. It first checks that there are indexed terms; if not it quickly returns null. Then it calls start() so a subclass can set up a return value, like an FixedBitSet. Then it starts the traversal process, calling findSubCellsToVisit(org.apache.lucene.spatial.prefix.tree.Cell) which by default finds the top cells that intersect queryShape. If there isn't an indexed cell for a corresponding cell returned for this method then it's short-circuited until it finds one, at which point visitPrefix(org.apache.lucene.spatial.prefix.tree.Cell) is called. At some depths, of the tree, the algorithm switches to a scanning mode that calls visitScanned(org.apache.lucene.spatial.prefix.tree.Cell) for each leaf cell found.

NOTE: This API is for internal purposes only and might change in incompatible ways in the next release.

Field Summary

Fields inherited from class org.apache.lucene.spatial.prefix.AbstractPrefixTreeQuery.BaseTermsEnumTraverser

context, maxDoc, postingsEnum, terms, termsEnum

Constructor Summary

Constructors

Constructor and Description
VisitorTemplate(LeafReaderContext context)

Method Summary

Modifier and Type	Method and Description
protected CellIterator	findSubCellsToVisit(Cell cell) Called when doing a divide and conquer to find the next intersecting cells of the query shape that are beneath cell.
protected abstract DocIdSet	finish() Called last to return the result.
DocIdSet	getDocIdSet()
protected void	postSiblings(AbstractVisitingPrefixTreeQuery.VNode vNode)
protected void	preSiblings(AbstractVisitingPrefixTreeQuery.VNode vNode)
protected void	scan(int scanDetailLevel) Scans (termsEnum.next()) terms until a term is found that does not start with curVNode's cell.
protected abstract void	start() Called first to setup things.
protected abstract void	visitLeaf(Cell cell) Called when an indexed leaf cell is found.
protected abstract boolean	visitPrefix(Cell cell) Visit an indexed non-leaf cell.
protected void	visitScanned(Cell cell) The cell is either indexed as a leaf or is the last level of detail.

Methods inherited from class org.apache.lucene.spatial.prefix.AbstractPrefixTreeQuery.BaseTermsEnumTraverser

collectDocs, collectDocs

Methods inherited from class java.lang.Object

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

Constructor Detail

VisitorTemplate

public VisitorTemplate(LeafReaderContext context)
                throws IOException

Throws:

IOException

Method Detail

getDocIdSet

public DocIdSet getDocIdSet()
                     throws IOException

Throws:

IOException

findSubCellsToVisit

protected CellIterator findSubCellsToVisit(Cell cell)

Called when doing a divide and conquer to find the next intersecting cells of the query shape that are beneath cell. cell is guaranteed to have an intersection and thus this must return some number of nodes.

scan

protected void scan(int scanDetailLevel)
             throws IOException

Scans (termsEnum.next()) terms until a term is found that does not start with curVNode's cell. If it finds a leaf cell or a cell at level scanDetailLevel then it calls visitScanned(org.apache.lucene.spatial.prefix.tree.Cell).

Throws:

IOException

start

protected abstract void start()
                       throws IOException

Called first to setup things.

Throws:

IOException

finish

protected abstract DocIdSet finish()
                            throws IOException

Called last to return the result.

Throws:

IOException

visitPrefix

protected abstract boolean visitPrefix(Cell cell)
                                throws IOException

Visit an indexed non-leaf cell. The presence of a prefix cell implies there are leaf cells at further levels. The cell passed should have it's Cell.getShapeRel() set relative to the filtered shape.

Parameters:

cell - An intersecting cell; not a leaf.

Returns:

true to descend to more levels.

Throws:

IOException

visitLeaf

protected abstract void visitLeaf(Cell cell)
                           throws IOException

Called when an indexed leaf cell is found. An indexed leaf cell usually means associated documents won't be found at further detail levels. However, if a document has multiple overlapping shapes at different resolutions, then this isn't true.

Throws:

IOException

visitScanned

protected void visitScanned(Cell cell)
                     throws IOException

The cell is either indexed as a leaf or is the last level of detail. It might not even intersect the query shape, so be sure to check for that. The default implementation will check that and if passes then call visitLeaf(org.apache.lucene.spatial.prefix.tree.Cell) or visitPrefix(org.apache.lucene.spatial.prefix.tree.Cell).

Throws:

IOException

preSiblings

protected void preSiblings(AbstractVisitingPrefixTreeQuery.VNode vNode)
                    throws IOException

Throws:

IOException

postSiblings

protected void postSiblings(AbstractVisitingPrefixTreeQuery.VNode vNode)
                     throws IOException

Throws:

IOException