package org.apache.lucene.queryParser.core.builders;
/**
* 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.
*/
import java.util.HashMap;
import java.util.List;
import org.apache.lucene.messages.MessageImpl;
import org.apache.lucene.queryParser.core.QueryNodeException;
import org.apache.lucene.queryParser.core.messages.QueryParserMessages;
import org.apache.lucene.queryParser.core.nodes.FieldableNode;
import org.apache.lucene.queryParser.core.nodes.QueryNode;
import org.apache.lucene.queryParser.standard.parser.EscapeQuerySyntaxImpl;
/**
* This class should be used when there is a builder for each type of node.
*
* The type of node may be defined in 2 different ways: - by the field name,
* when the node implements the {@link FieldableNode} interface - by its class,
* it keeps checking the class and all the interfaces and classes this class
* implements/extends until it finds a builder for that class/interface
*
* This class always check if there is a builder for the field name before it
* checks for the node class. So, field name builders have precedence over class
* builders.
*
* When a builder is found for a node, it's called and the node is passed to the
* builder. If the returned built object is not <code>null</code>, it's tagged
* on the node using the tag {@link QueryTreeBuilder#QUERY_TREE_BUILDER_TAGID}.
*
* The children are usually built before the parent node. However, if a builder
* associated to a node is an instance of {@link QueryTreeBuilder}, the node is
* delegated to this builder and it's responsible to build the node and its
* children.
*
* @see QueryBuilder
*/
public class QueryTreeBuilder implements QueryBuilder {
/**
* This tag is used to tag the nodes in a query tree with the built objects
* produced from their own associated builder.
*/
public static final String QUERY_TREE_BUILDER_TAGID = QueryTreeBuilder.class
.getName();
private HashMap<Class<? extends QueryNode>, QueryBuilder> queryNodeBuilders;
private HashMap<CharSequence, QueryBuilder> fieldNameBuilders;
/**
* {@link QueryTreeBuilder} constructor.
*/
public QueryTreeBuilder() {
// empty constructor
}
/**
* Associates a field name with a builder.
*
* @param fieldName
* the field name
* @param builder
* the builder to be associated
*/
public void setBuilder(CharSequence fieldName, QueryBuilder builder) {
if (this.fieldNameBuilders == null) {
this.fieldNameBuilders = new HashMap<CharSequence, QueryBuilder>();
}
this.fieldNameBuilders.put(fieldName, builder);
}
/**
* Associates a class with a builder
*
* @param queryNodeClass
* the class
* @param builder
* the builder to be associated
*/
public void setBuilder(Class<? extends QueryNode> queryNodeClass,
QueryBuilder builder) {
if (this.queryNodeBuilders == null) {
this.queryNodeBuilders = new HashMap<Class<? extends QueryNode>, QueryBuilder>();
}
this.queryNodeBuilders.put(queryNodeClass, builder);
}
private void process(QueryNode node) throws QueryNodeException {
if (node != null) {
QueryBuilder builder = getBuilder(node);
if (!(builder instanceof QueryTreeBuilder)) {
List<QueryNode> children = node.getChildren();
if (children != null) {
for (QueryNode child : children) {
process(child);
}
}
}
processNode(node, builder);
}
}
private QueryBuilder getBuilder(QueryNode node) {
QueryBuilder builder = null;
if (this.fieldNameBuilders != null && node instanceof FieldableNode) {
builder = this.fieldNameBuilders.get(((FieldableNode) node).getField());
}
if (builder == null && this.queryNodeBuilders != null) {
Class<?> clazz = node.getClass();
do {
builder = getQueryBuilder(clazz);
if (builder == null) {
Class<?>[] classes = node.getClass().getInterfaces();
for (Class<?> actualClass : classes) {
builder = getQueryBuilder(actualClass);
if (builder != null) {
break;
}
}
}
} while (builder == null && (clazz = clazz.getSuperclass()) != null);
}
return builder;
}
private void processNode(QueryNode node, QueryBuilder builder)
throws QueryNodeException {
if (builder == null) {
throw new QueryNodeException(new MessageImpl(
QueryParserMessages.LUCENE_QUERY_CONVERSION_ERROR, new Object[]{node
.toQueryString(new EscapeQuerySyntaxImpl()), node.getClass()
.getName()}));
}
Object obj = builder.build(node);
if (obj != null) {
node.setTag(QUERY_TREE_BUILDER_TAGID, obj);
}
}
private QueryBuilder getQueryBuilder(Class<?> clazz) {
if (QueryNode.class.isAssignableFrom(clazz)) {
return this.queryNodeBuilders.get(clazz);
}
return null;
}
/**
* Builds some kind of object from a query tree. Each node in the query tree
* is built using an specific builder associated to it.
*
* @param queryNode
* the query tree root node
*
* @return the built object
*
* @throws QueryNodeException
* if some node builder throws a {@link QueryNodeException} or if
* there is a node which had no builder associated to it
*/
public Object build(QueryNode queryNode) throws QueryNodeException {
process(queryNode);
return queryNode.getTag(QUERY_TREE_BUILDER_TAGID);
}
}