Java tutorial
/** * 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; } }