| /* |
| * 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.directory.server.xdbm.search.evaluator; |
| |
| |
| import java.util.ArrayList; |
| import java.util.Collections; |
| import java.util.List; |
| |
| import org.apache.directory.api.ldap.model.entry.Entry; |
| import org.apache.directory.api.ldap.model.exception.LdapException; |
| import org.apache.directory.api.ldap.model.filter.ExprNode; |
| import org.apache.directory.api.ldap.model.filter.OrNode; |
| import org.apache.directory.server.xdbm.IndexEntry; |
| import org.apache.directory.server.xdbm.search.Evaluator; |
| import org.apache.directory.server.xdbm.search.impl.ScanCountComparator; |
| |
| |
| /** |
| * An Evaluator for logical disjunction (OR) expressions. |
| * |
| * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a> |
| */ |
| public class OrEvaluator implements Evaluator<OrNode> |
| { |
| /** The list of evaluators associated with each of the children */ |
| private final List<Evaluator<? extends ExprNode>> evaluators; |
| |
| /** The OrNode */ |
| private final OrNode node; |
| |
| |
| public OrEvaluator( OrNode node, List<Evaluator<? extends ExprNode>> evaluators ) |
| { |
| this.node = node; |
| this.evaluators = optimize( evaluators ); |
| } |
| |
| |
| /** |
| * Takes a set of Evaluators and copies then sorts them in a new list with |
| * decreasing scan counts on their expression nodes. This is done to have |
| * the Evaluators with the greatest scan counts which have the highest |
| * probability of accepting a candidate first. That will increase the |
| * chance of shorting the checks on evaluators early so extra lookups and |
| * comparisons are avoided. |
| * |
| * @param unoptimized the unoptimized list of Evaluators |
| * @return optimized Evaluator list with decreasing scan count ordering |
| */ |
| private List<Evaluator<? extends ExprNode>> optimize( |
| List<Evaluator<? extends ExprNode>> unoptimized ) |
| { |
| List<Evaluator<? extends ExprNode>> optimized = new ArrayList<Evaluator<? extends ExprNode>>( |
| unoptimized.size() ); |
| optimized.addAll( unoptimized ); |
| |
| Collections.sort( optimized, new ScanCountComparator() ); |
| |
| return optimized; |
| } |
| |
| |
| public boolean evaluate( IndexEntry<?, String> indexEntry ) throws LdapException |
| { |
| for ( Evaluator<?> evaluator : evaluators ) |
| { |
| if ( evaluator.evaluate( indexEntry ) ) |
| { |
| return true; |
| } |
| } |
| |
| return false; |
| } |
| |
| |
| public boolean evaluate( Entry entry ) throws Exception |
| { |
| for ( Evaluator<?> evaluator : evaluators ) |
| { |
| if ( evaluator.evaluate( entry ) ) |
| { |
| return true; |
| } |
| } |
| |
| return false; |
| } |
| |
| |
| public OrNode getExpression() |
| { |
| return node; |
| } |
| |
| |
| /** |
| * Dumps the evaluators |
| */ |
| private String dumpEvaluators( String tabs ) |
| { |
| StringBuilder sb = new StringBuilder(); |
| |
| for ( Evaluator<? extends ExprNode> evaluator : evaluators ) |
| { |
| sb.append( evaluator.toString( tabs + " " ) ); |
| } |
| |
| return sb.toString(); |
| } |
| |
| |
| /** |
| * @see Object#toString() |
| */ |
| public String toString( String tabs ) |
| { |
| StringBuilder sb = new StringBuilder(); |
| |
| sb.append( tabs ).append( "OrEvaluator : " ).append( node ).append( "\n" ); |
| |
| if ( ( evaluators != null ) && ( evaluators.size() > 0 ) ) |
| { |
| sb.append( dumpEvaluators( tabs ) ); |
| } |
| |
| return sb.toString(); |
| } |
| |
| |
| /** |
| * @see Object#toString() |
| */ |
| public String toString() |
| { |
| return toString( "" ); |
| } |
| } |