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/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.jackrabbit.oak.query.xpath;
import java.util.ArrayList;
import org.apache.jackrabbit.oak.query.QueryOptions;
import org.apache.jackrabbit.oak.query.QueryOptions.Traversal;
import org.apache.jackrabbit.oak.query.xpath.Expression.AndCondition;
import org.apache.jackrabbit.oak.query.xpath.Expression.OrCondition;
import org.apache.jackrabbit.oak.query.xpath.Expression.Property;
import org.apache.jackrabbit.oak.spi.query.QueryConstants;
/**
* An xpath statement.
*/
public class Statement {
private static final UnsupportedOperationException TOO_MANY_UNION =
new UnsupportedOperationException("Too many union queries");
private final static int MAX_UNION = Integer.getInteger("oak.xpathMaxUnion", 1000);
boolean explain;
boolean measure;
/**
* The selector to get the columns from (the selector used in the select
* column list).
*/
private Selector columnSelector;
private ArrayList columnList = new ArrayList();
/**
* All selectors.
*/
private ArrayList selectors;
private Expression where;
ArrayList orderList = new ArrayList();
String xpathQuery;
QueryOptions queryOptions;
public Statement optimize() {
ignoreOrderByScoreDesc();
if (where == null) {
return this;
}
where = where.optimize();
optimizeSelectorNodeTypes();
ArrayList unionList = new ArrayList();
try {
addToUnionList(where, unionList);
} catch (UnsupportedOperationException e) {
// too many union
return this;
}
if (unionList.size() == 1) {
return this;
}
Statement union = null;
for (int i = 0; i < unionList.size(); i++) {
Expression e = unionList.get(i);
Statement s = new Statement();
s.columnSelector = new Selector(columnSelector);
s.selectors = cloneSelectors();
s.columnList = columnList;
s.where = e;
if (union == null) {
union = s;
} else {
union = new UnionStatement(union.optimize(), s.optimize());
}
}
union.orderList = orderList;
union.xpathQuery = xpathQuery;
union.measure = measure;
union.explain = explain;
union.queryOptions = queryOptions;
return union;
}
private ArrayList cloneSelectors() {
ArrayList list = new ArrayList();
for (Selector s : selectors) {
list.add(new Selector(s));
}
return list;
}
private void optimizeSelectorNodeTypes() {
if (!XPathToSQL2Converter.NODETYPE_OPTIMIZATION) {
return;
}
for (int i = 0; i < selectors.size(); i++) {
Selector s = selectors.get(i);
if (s.nodeType != null && !"nt:base".equals(s.nodeType)) {
// explicit node type: ignore
continue;
}
// only filter by selectorName if there are multiple selectors
String selectorName = selectors.size() == 1 ? null : s.name;
String nodeType = where.getMostSpecificNodeType(selectorName);
if (nodeType != null) {
s.nodeType = nodeType;
}
}
}
private static void addToUnionList(Expression condition, ArrayList unionList) {
if (condition instanceof OrCondition) {
OrCondition or = (OrCondition) condition;
// conditions of type
// @x = 1 or @y = 2
// or similar are converted to
// (@x = 1) union (@y = 2)
addToUnionList(or.left, unionList);
addToUnionList(or.right, unionList);
return;
} else if (condition instanceof AndCondition) {
// conditions of type
// @a = 1 and (@x = 1 or @y = 2)
// are automatically converted to
// (@a = 1 and @x = 1) union (@a = 1 and @y = 2)
AndCondition and = (AndCondition) condition;
and = and.pullOrRight();
if (and.right instanceof OrCondition) {
OrCondition or = (OrCondition) and.right;
// same as above, but with the added "and"
addToUnionList(new AndCondition(and.left, or.left), unionList);
addToUnionList(new AndCondition(and.left, or.right), unionList);
return;
}
}
if (unionList.size() > MAX_UNION) {
throw TOO_MANY_UNION;
}
unionList.add(condition);
}
@Override
public String toString() {
StringBuilder buff = new StringBuilder();
// explain | measure ...
if (explain) {
buff.append("explain ");
}
if (measure) {
buff.append("measure ");
}
// select ...
buff.append("select ");
buff.append(new Expression.Property(columnSelector, QueryConstants.JCR_PATH, false).toString());
if (selectors.size() > 1) {
buff.append(" as ").append('[').append(QueryConstants.JCR_PATH).append(']');
}
buff.append(", ");
buff.append(new Expression.Property(columnSelector, QueryConstants.JCR_SCORE, false).toString());
if (selectors.size() > 1) {
buff.append(" as ").append('[').append(QueryConstants.JCR_SCORE).append(']');
}
if (columnList.isEmpty()) {
buff.append(", ");
buff.append(new Expression.Property(columnSelector, "*", false).toString());
} else {
for (int i = 0; i < columnList.size(); i++) {
buff.append(", ");
Expression e = columnList.get(i);
String columnName = e.toString();
buff.append(columnName);
if (selectors.size() > 1) {
buff.append(" as [").append(e.getColumnAliasName()).append("]");
}
}
}
// from ...
buff.append(" from ");
for (int i = 0; i < selectors.size(); i++) {
Selector s = selectors.get(i);
if (i > 0) {
buff.append(" inner join ");
}
String nodeType = s.nodeType;
if (nodeType == null) {
nodeType = "nt:base";
}
buff.append('[' + nodeType + ']').append(" as ").append(s.name);
if (s.joinCondition != null) {
buff.append(" on ").append(s.joinCondition);
}
}
// where ...
if (where != null) {
buff.append(" where ").append(where.toString());
}
// order by ...
if (!orderList.isEmpty()) {
buff.append(" order by ");
for (int i = 0; i < orderList.size(); i++) {
if (i > 0) {
buff.append(", ");
}
buff.append(orderList.get(i));
}
}
appendQueryOptions(buff, queryOptions);
// leave original xpath string as a comment
appendXPathAsComment(buff, xpathQuery);
return buff.toString();
}
private void ignoreOrderByScoreDesc() {
if (orderList.size() != 1) {
return;
}
Order order = orderList.get(0);
if (!order.descending) {
return;
}
if (!order.expr.toString().equals("[jcr:score]")) {
return;
}
// so we have just one expression,
// and it is "order by @jcr:score desc"
// this we can remove
orderList.remove(0);
}
public void setExplain(boolean explain) {
this.explain = explain;
}
public void setMeasure(boolean measure) {
this.measure = measure;
}
public void addSelectColumn(Property p) {
columnList.add(p);
}
public void setSelectors(ArrayList selectors) {
this.selectors = selectors;
}
public void setWhere(Expression where) {
this.where = where;
}
public void addOrderBy(Order order) {
this.orderList.add(order);
}
public void setColumnSelector(Selector columnSelector) {
this.columnSelector = columnSelector;
}
public void setOriginalQuery(String xpathQuery) {
this.xpathQuery = xpathQuery;
}
/**
* A union statement.
*/
static class UnionStatement extends Statement {
private final Statement s1, s2;
UnionStatement(Statement s1, Statement s2) {
this.s1 = s1;
this.s2 = s2;
}
@Override
public Statement optimize() {
Statement s1b = s1.optimize();
Statement s2b = s2.optimize();
if (s1 == s1b && s2 == s2b) {
// no change
return this;
}
return new UnionStatement(s1b, s2b);
}
@Override
public String toString() {
StringBuilder buff = new StringBuilder();
// explain | measure ...
if (explain) {
buff.append("explain ");
}
if (measure) {
buff.append("measure ");
}
buff.append(s1).append(" union ").append(s2);
// order by ...
if (orderList != null && !orderList.isEmpty()) {
buff.append(" order by ");
for (int i = 0; i < orderList.size(); i++) {
if (i > 0) {
buff.append(", ");
}
buff.append(orderList.get(i));
}
}
appendQueryOptions(buff, queryOptions);
// leave original xpath string as a comment
appendXPathAsComment(buff, xpathQuery);
return buff.toString();
}
}
private static void appendQueryOptions(StringBuilder buff, QueryOptions queryOptions) {
if (queryOptions == null) {
return;
}
buff.append(" option(");
int optionCount = 0;
if (queryOptions.traversal != Traversal.DEFAULT) {
buff.append("traversal " + queryOptions.traversal);
optionCount++;
}
if (queryOptions.indexName != null) {
if (optionCount > 0) {
buff.append(", ");
}
buff.append("index name [");
buff.append(queryOptions.indexName);
buff.append("]");
optionCount++;
}
if (queryOptions.indexTag != null) {
if (optionCount > 0) {
buff.append(", ");
}
buff.append("index tag [");
buff.append(queryOptions.indexTag);
buff.append("]");
optionCount++;
}
buff.append(")");
}
private static void appendXPathAsComment(StringBuilder buff, String xpath) {
if (xpath == null) {
return;
}
buff.append(" /* xpath: ");
// the xpath query may contain the "end comment" marker
String xpathEscaped = xpath.replaceAll("\\*\\/", "* /");
buff.append(xpathEscaped);
buff.append(" */");
}
public void setQueryOptions(QueryOptions options) {
this.queryOptions = options;
}
}
