org.modeshape.jcr.query.process
Class JoinComponent

java.lang.Object
  org.modeshape.jcr.query.process.ProcessingComponent
      org.modeshape.jcr.query.process.JoinComponent

Direct Known Subclasses:

MergeJoinComponent, NestedLoopJoinComponent

public abstract class JoinComponent
extends ProcessingComponent

Nested Class Summary

protected static interface	JoinComponent.Joinable Interface defining the value of a tuple that is used in the join condition.
protected static interface	JoinComponent.TupleMerger A component that will merge the supplied tuple on the left side of a join with the supplied tuple on the right side of the join, to produce a single tuple with all components from the left and right tuples.
protected static interface	JoinComponent.ValueSelector Interface defining the value of a tuple that is used in the join condition.

Nested classes/interfaces inherited from class org.modeshape.jcr.query.process.ProcessingComponent

ProcessingComponent.DynamicOperation

Field Summary

protected static Comparator<QueryResults.Location>

LOCATION_COMPARATOR

Constructor Summary

protected

JoinComponent(QueryContext context, ProcessingComponent left, ProcessingComponent right, JoinCondition condition, JoinType joinType)

Method Summary

protected static Comparator<Object>	comparatorFor(QueryContext context, ProcessingComponent left, ProcessingComponent right, JoinCondition condition) Create a Comparable that can be used to compare the values required to evaluate the supplied join condition.
protected static JoinComponent.TupleMerger	createMerger(QueryResults.Columns joinColumns, QueryResults.Columns leftColumns, QueryResults.Columns rightColumns) Create a JoinComponent.TupleMerger implementation that will combine a tuple fitting the left columns with a tuple fitting the right columns.
JoinCondition	getJoinCondition() Get the join condition.
JoinType	getJoinType() Get the type of join this processor represents.
protected static JoinComponent.Joinable	joinableFor(ProcessingComponent left, ProcessingComponent right, JoinCondition condition) Create a JoinComponent.ValueSelector that obtains the value required to use the supplied join condition.
protected ProcessingComponent	left() Get the processing component that serves as the left side of the join.
protected QueryResults.Columns	leftColunns() Get the columns definition for the results from the left side of the join.
protected ProcessingComponent	right() Get the processing component that serves as the right side of the join.
protected QueryResults.Columns	rightColumns() Get the columns definition for the results from the right side of the join.
protected static JoinComponent.ValueSelector	valueSelectorFor(ProcessingComponent source, JoinCondition condition) Create a JoinComponent.ValueSelector that obtains the value required to use the supplied join condition.

Methods inherited from class org.modeshape.jcr.query.process.ProcessingComponent

close, createDynamicOperation, createSortComparator, emptyTuples, execute, getColumns, getContext, problems

Methods inherited from class java.lang.Object

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

Field Detail

LOCATION_COMPARATOR

protected static final Comparator<QueryResults.Location> LOCATION_COMPARATOR

Constructor Detail

JoinComponent

protected JoinComponent(QueryContext context,
                        ProcessingComponent left,
                        ProcessingComponent right,
                        JoinCondition condition,
                        JoinType joinType)

Method Detail

getJoinType

public final JoinType getJoinType()

Get the type of join this processor represents.

Returns:

the join type; never null

getJoinCondition

public final JoinCondition getJoinCondition()

Get the join condition.

Returns:

the join condition; never null

left

protected final ProcessingComponent left()

Get the processing component that serves as the left side of the join.

Returns:

the left-side processing component; never null

right

protected final ProcessingComponent right()

Get the processing component that serves as the right side of the join.

Returns:

the right-side processing component; never null

leftColunns

protected final QueryResults.Columns leftColunns()

Get the columns definition for the results from the left side of the join.

Returns:

the left-side columns that feed this join; never null

rightColumns

protected final QueryResults.Columns rightColumns()

Get the columns definition for the results from the right side of the join.

Returns:

the right-side columns that feed this join; never null

createMerger

protected static JoinComponent.TupleMerger createMerger(QueryResults.Columns joinColumns,
                                                        QueryResults.Columns leftColumns,
                                                        QueryResults.Columns rightColumns)

Create a JoinComponent.TupleMerger implementation that will combine a tuple fitting the left columns with a tuple fitting the right columns. This merger will properly place all of the values, locations, and scores such that the tuples always have this arrangement:

    [ v1, v2, ..., vM, loc1, loc2, ..., locN, s1, s2, ..., sN ]
 

where M is the number of values in the tuple, and N is the number of sources in the tuple.

Note that this merger does not actually reduce or combine values. That is done with a particular JoinComponent subclass.

Parameters:

joinColumns - the Columns specification for the joined/merged tuples; may not be null

leftColumns - the Columns specification for the tuple on the left side of the join; may not be null

rightColumns - the Columns specification for the tuple on the right side of the join; may not be null

Returns:

the merger implementation that will combine tuples from the left and right to form the merged tuples; never null

valueSelectorFor

protected static JoinComponent.ValueSelector valueSelectorFor(ProcessingComponent source,
                                                              JoinCondition condition)

Create a JoinComponent.ValueSelector that obtains the value required to use the supplied join condition.

Parameters:

source - the source component; may not be null

condition - the join condition; may not be null

Returns:

the value selector; never null

joinableFor

protected static JoinComponent.Joinable joinableFor(ProcessingComponent left,
                                                    ProcessingComponent right,
                                                    JoinCondition condition)

Create a JoinComponent.ValueSelector that obtains the value required to use the supplied join condition.

Parameters:

left - the left source component; may not be null

right - the left source component; may not be null

condition - the join condition; may not be null

Returns:

the value selector; never null

comparatorFor

protected static Comparator<Object> comparatorFor(QueryContext context,
                                                  ProcessingComponent left,
                                                  ProcessingComponent right,
                                                  JoinCondition condition)

Create a Comparable that can be used to compare the values required to evaluate the supplied join condition.

Parameters:

context - the context in which this query is being evaluated; may not be null

left - the left source component; may not be null

right - the left source component; may not be null

condition - the join condition; may not be null

Returns:

the comparator; never null