/**
* Copyright 2014 National University of Ireland, Galway.
*
* This file is part of the SIREn project. Project and contact information:
*
* https://github.com/rdelbru/SIREn
*
* Licensed 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.sindice.siren.qparser.json.builders;
import java.util.List;
import org.apache.lucene.queryparser.flexible.core.QueryNodeException;
import org.apache.lucene.queryparser.flexible.core.builders.QueryTreeBuilder;
import org.apache.lucene.queryparser.flexible.core.messages.QueryParserMessages;
import org.apache.lucene.queryparser.flexible.core.nodes.ModifierQueryNode;
import org.apache.lucene.queryparser.flexible.core.nodes.QueryNode;
import org.apache.lucene.queryparser.flexible.messages.MessageImpl;
import org.apache.lucene.queryparser.flexible.standard.parser.EscapeQuerySyntaxImpl;
import org.apache.lucene.search.BooleanQuery;
import org.apache.lucene.search.BooleanQuery.TooManyClauses;
import org.sindice.siren.qparser.json.nodes.ChildQueryNode;
import org.sindice.siren.qparser.json.nodes.DescendantQueryNode;
import org.sindice.siren.qparser.json.nodes.TwigQueryNode;
import org.sindice.siren.qparser.json.parser.LevelPropertyParser;
import org.sindice.siren.qparser.json.parser.RangePropertyParser;
import org.sindice.siren.qparser.keyword.KeywordQueryParser;
import org.sindice.siren.search.node.NodeBooleanClause;
import org.sindice.siren.search.node.NodeQuery;
import org.sindice.siren.search.node.TwigQuery;
/**
* Builds a {@link TwigQuery} object from a {@link TwigQueryNode} object.
* <p>
* Every children in the {@link TwigQueryNode} object must be already tagged
* using {@link QueryTreeBuilder#QUERY_TREE_BUILDER_TAGID} with a
* {@link NodeQuery} object.
* <p>
* It takes in consideration if the children is a {@link ChildQueryNode} or
* a {@link DescendantQueryNode} to define the clauses of the {@link TwigQuery}
* object.
* <p>
* Relies on a {@link KeywordQueryParser} object to convert the root's node
* boolean expression into a {@link NodeQuery}.
*/
public class TwigQueryNodeBuilder implements JsonQueryBuilder {
private final KeywordQueryParser keywordParser;
public TwigQueryNodeBuilder(final KeywordQueryParser keywordParser) {
this.keywordParser = keywordParser;
}
@Override
public TwigQuery build(final QueryNode queryNode) throws QueryNodeException {
final TwigQueryNode twigNode = (TwigQueryNode) queryNode;
final List<QueryNode> children = twigNode.getChildren();
final TwigQuery query = new TwigQuery();
// check if the node has a level constraint
if (twigNode.getTag(LevelPropertyParser.LEVEL_PROPERTY) != null) {
query.setLevelConstraint((Integer) twigNode.getTag(LevelPropertyParser.LEVEL_PROPERTY));
}
// check if the node has a node range constraint
if (twigNode.getTag(RangePropertyParser.RANGE_PROPERTY) != null) {
final int[] range = (int[]) twigNode.getTag(RangePropertyParser.RANGE_PROPERTY);
query.setNodeConstraint(range[0], range[1]);
}
// process root query
if (twigNode.hasRoot()) {
final String rootExpr = twigNode.getRoot().toString();
final String field = twigNode.getField().toString();
query.addRoot((NodeQuery) keywordParser.parse(rootExpr, field));
}
// process child and descendant queries
try {
processChildren(children, query);
}
catch (final TooManyClauses ex) {
throw new QueryNodeException(new MessageImpl(
QueryParserMessages.TOO_MANY_BOOLEAN_CLAUSES,
BooleanQuery.getMaxClauseCount(),
twigNode.toQueryString(new EscapeQuerySyntaxImpl())), ex);
}
return query;
}
private static void processChildren(final List<QueryNode> children, final TwigQuery query) {
for (final QueryNode child : children) {
final Object obj = child.getTag(QueryTreeBuilder.QUERY_TREE_BUILDER_TAGID);
final NodeQuery nodeQuery = (NodeQuery) obj;
// Append child queries
if (child instanceof ChildQueryNode) {
query.addChild(nodeQuery, getModifierValue(child));
}
// Append descendant queries
else if (child instanceof DescendantQueryNode) {
// A descendant node must always have a level constraint
if (child.getTag(LevelPropertyParser.LEVEL_PROPERTY) == null) {
throw new IllegalArgumentException("Invalid DescendantQueryNode received: no level constraint defined");
}
// set level constraint
final int nodeLevel = (Integer) child.getTag(LevelPropertyParser.LEVEL_PROPERTY);
// add descendant query
query.addDescendant(nodeLevel, nodeQuery, getModifierValue(child));
}
else {
throw new IllegalArgumentException("Invalid QueryNode received: " + child.getClass().getSimpleName());
}
}
}
private static NodeBooleanClause.Occur getModifierValue(final QueryNode node) {
if (node instanceof ModifierQueryNode) {
final ModifierQueryNode mNode = ((ModifierQueryNode) node);
switch (mNode.getModifier()) {
case MOD_REQ:
return NodeBooleanClause.Occur.MUST;
case MOD_NOT:
return NodeBooleanClause.Occur.MUST_NOT;
case MOD_NONE:
return NodeBooleanClause.Occur.SHOULD;
}
}
return NodeBooleanClause.Occur.SHOULD;
}
}