com.adobe.cq.searchcollections.qom.JoinMerger Maven / Gradle / Ivy
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package com.adobe.cq.searchcollections.qom;
import static javax.jcr.query.qom.QueryObjectModelConstants.JCR_JOIN_TYPE_LEFT_OUTER;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.LinkedHashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;
import javax.jcr.RepositoryException;
import javax.jcr.UnsupportedRepositoryOperationException;
import javax.jcr.query.QueryResult;
import javax.jcr.query.Row;
import javax.jcr.query.RowIterator;
import javax.jcr.query.qom.ChildNodeJoinCondition;
import javax.jcr.query.qom.Constraint;
import javax.jcr.query.qom.DescendantNodeJoinCondition;
import javax.jcr.query.qom.EquiJoinCondition;
import javax.jcr.query.qom.Join;
import javax.jcr.query.qom.JoinCondition;
import javax.jcr.query.qom.PropertyValue;
import javax.jcr.query.qom.QueryObjectModelFactory;
import javax.jcr.query.qom.SameNodeJoinCondition;
import javax.jcr.query.qom.Selector;
import javax.jcr.query.qom.Source;
import org.apache.jackrabbit.commons.iterator.RowIterable;
import org.apache.jackrabbit.commons.iterator.RowIteratorAdapter;
/**
* A join merger is used by the {@link QueryEngine} class to efficiently
* merge together two parts of a join query.
*
* Each join condition type ({@link EquiJoinCondition equi-} and
* {@link SameNodeJoinCondition same}, {@link ChildNodeJoinCondition child}
* or {@link DescendantJoinCondition descendant} node joins) has it's own
* merger class that extends the functionality of this abstract base class
* with functionality specific to that join condition.
*
* @deprecated
*/
public abstract class JoinMerger {
/**
* Static factory method for creating a merger for the given join.
*
* @param join join
* @param columns columns of the query
* @param evaluator operand evaluator
* @param factory QOM factory
* @return join merger
* @throws RepositoryException if the merger can not be created
*/
public static JoinMerger getJoinMerger(
Join join, Map columns,
OperandEvaluator evaluator, QueryObjectModelFactory factory)
throws RepositoryException {
JoinCondition condition = join.getJoinCondition();
if (condition instanceof EquiJoinCondition) {
return new EquiJoinMerger(
join, columns, evaluator, factory,
(EquiJoinCondition) condition);
} else if (condition instanceof SameNodeJoinCondition) {
return new SameNodeJoinMerger(
join, columns, evaluator, factory,
(SameNodeJoinCondition) condition);
} else if (condition instanceof ChildNodeJoinCondition) {
return new ChildNodeJoinMerger(
join, columns, evaluator, factory,
(ChildNodeJoinCondition) condition);
} else if (condition instanceof DescendantNodeJoinCondition) {
return new DescendantNodeJoinMerger(
join, columns, evaluator, factory,
(DescendantNodeJoinCondition) condition);
} else {
throw new UnsupportedRepositoryOperationException(
"Unsupported join condition type: " + condition);
}
}
private final String type;
protected final Set leftSelectors;
protected final Set rightSelectors;
private final String[] selectorNames;
private final Map columns;
private final String[] columnNames;
protected final OperandEvaluator evaluator;
protected final QueryObjectModelFactory factory;
protected JoinMerger(
Join join, Map columns,
OperandEvaluator evaluator, QueryObjectModelFactory factory)
throws RepositoryException {
this.type = join.getJoinType();
this.leftSelectors = getSelectorNames(join.getLeft());
this.rightSelectors = getSelectorNames(join.getRight());
Set selectors = new LinkedHashSet();
selectors.addAll(leftSelectors);
selectors.addAll(rightSelectors);
this.selectorNames =
selectors.toArray(new String[selectors.size()]);
this.columns = columns;
this.columnNames =
columns.keySet().toArray(new String[columns.size()]);
this.evaluator = evaluator;
this.factory = factory;
}
public Set getLeftSelectors() {
return leftSelectors;
}
public Set getRightSelectors() {
return rightSelectors;
}
private Set getSelectorNames(Source source)
throws RepositoryException {
if (source instanceof Selector) {
Selector selector = (Selector) source;
return Collections.singleton(selector.getSelectorName());
} else if (source instanceof Join) {
Join join = (Join) source;
Set set = new LinkedHashSet();
set.addAll(getSelectorNames(join.getLeft()));
set.addAll(getSelectorNames(join.getRight()));
return set;
} else {
throw new UnsupportedRepositoryOperationException(
"Unknown source type: " + source);
}
}
public QueryResult merge(RowIterator leftRows, RowIterator rightRows)
throws RepositoryException {
RowIterator joinRows;
Map> map = new HashMap>();
for (Row row : new RowIterable(rightRows)) {
for (String value : getRightValues(row)) {
List rows = map.get(value);
if (rows == null) {
rows = new ArrayList();
map.put(value, rows);
}
rows.add(row);
}
}
if (!map.isEmpty()) {
List rows = new ArrayList();
for (Row leftRow : new RowIterable(leftRows)) {
for (String value : getLeftValues(leftRow)) {
List matchingRows = map.get(value);
if (matchingRows != null) {
for (Row rightRow : matchingRows) {
rows.add(mergeRow(leftRow, rightRow));
}
} else if (JCR_JOIN_TYPE_LEFT_OUTER.equals(type)) {
// No matches in an outer join -> add a null row
rows.add(mergeRow(leftRow, null));
}
}
}
joinRows = new RowIteratorAdapter(rows);
} else if (JCR_JOIN_TYPE_LEFT_OUTER.equals(type)) {
joinRows = new RowIteratorAdapter(leftRows) {
@Override
public Object next() {
return mergeRow((Row) super.next(), null);
}
};
} else {
joinRows = new RowIteratorAdapter(Collections.emptySet());
}
return new SimpleQueryResult(columnNames, selectorNames, joinRows, joinRows.getSize());
}
/**
* Merges the given left and right rows to a single joined row.
*
* @param left left row, possibly null in a right outer join
* @param right right row, possibly null in a left outer join
* @return joined row
*/
private Row mergeRow(Row left, Row right) {
return new JoinRow(
columns, evaluator,
left, leftSelectors, right, rightSelectors);
}
public abstract Set getLeftValues(Row row)
throws RepositoryException;
public abstract Set getRightValues(Row row)
throws RepositoryException;
public abstract List getRightJoinConstraints(List leftRows)
throws RepositoryException;
}