MultiFieldQueryParser.cs

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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.
 */

using System;
using System.Collections.Generic;
using Lucene.Net.Search;
using Analyzer = Lucene.Net.Analysis.Analyzer;
using BooleanClause = Lucene.Net.Search.BooleanClause;
using BooleanQuery = Lucene.Net.Search.BooleanQuery;
using MultiPhraseQuery = Lucene.Net.Search.MultiPhraseQuery;
using PhraseQuery = Lucene.Net.Search.PhraseQuery;
using Query = Lucene.Net.Search.Query;
using Version = Lucene.Net.Util.Version;

namespace Lucene.Net.QueryParsers
{

    public class MultiFieldQueryParser : QueryParser
    {
        protected internal string[] fields;
        protected internal IDictionary<string, float> boosts;

        public MultiFieldQueryParser(Version matchVersion, string[] fields, Analyzer analyzer, IDictionary<string, float> boosts)
            : this(matchVersion, fields, analyzer)
        {
            this.boosts = boosts;
        }

        public MultiFieldQueryParser(Version matchVersion, System.String[] fields, Analyzer analyzer)
            : base(matchVersion, null, analyzer)
        {
            this.fields = fields;
        }

        protected internal override Query GetFieldQuery(string field, string queryText, int slop)
        {
            if (field == null)
            {
                IList<BooleanClause> clauses = new List<BooleanClause>();
                for (int i = 0; i < fields.Length; i++)
                {
                    Query q = base.GetFieldQuery(fields[i], queryText);
                    if (q != null)
                    {
                        //If the user passes a map of boosts
                        if (boosts != null)
                        {
                            //Get the boost from the map and apply them
                            Single boost = boosts[fields[i]];
                            q.Boost = boost;
                        }
                        ApplySlop(q, slop);
                        clauses.Add(new BooleanClause(q, Occur.SHOULD));
                    }
                }
                if (clauses.Count == 0)
                    // happens for stopwords
                    return null;
                return GetBooleanQuery(clauses, true);
            }
            Query q2 = base.GetFieldQuery(field, queryText);
            ApplySlop(q2, slop);
            return q2;
        }

        private void ApplySlop(Query q, int slop)
        {
            if (q is PhraseQuery)
            {
                ((PhraseQuery)q).Slop = slop;
            }
            else if (q is MultiPhraseQuery)
            {
                ((MultiPhraseQuery)q).Slop = slop;
            }
        }


        protected internal override Query GetFieldQuery(System.String field, System.String queryText)
        {
            return GetFieldQuery(field, queryText, 0);
        }


        protected internal override Query GetFuzzyQuery(System.String field, System.String termStr, float minSimilarity)
        {
            if (field == null)
            {
                IList<BooleanClause> clauses = new List<BooleanClause>();
                for (int i = 0; i < fields.Length; i++)
                {
                    clauses.Add(new BooleanClause(GetFuzzyQuery(fields[i], termStr, minSimilarity), Occur.SHOULD));
                }
                return GetBooleanQuery(clauses, true);
            }
            return base.GetFuzzyQuery(field, termStr, minSimilarity);
        }

        protected internal override Query GetPrefixQuery(System.String field, System.String termStr)
        {
            if (field == null)
            {
                IList<BooleanClause> clauses = new List<BooleanClause>();
                for (int i = 0; i < fields.Length; i++)
                {
                    clauses.Add(new BooleanClause(GetPrefixQuery(fields[i], termStr), Occur.SHOULD));
                }
                return GetBooleanQuery(clauses, true);
            }
            return base.GetPrefixQuery(field, termStr);
        }

        protected internal override Query GetWildcardQuery(System.String field, System.String termStr)
        {
            if (field == null)
            {
                IList<BooleanClause> clauses = new List<BooleanClause>();
                for (int i = 0; i < fields.Length; i++)
                {
                    clauses.Add(new BooleanClause(GetWildcardQuery(fields[i], termStr), Occur.SHOULD));
                }
                return GetBooleanQuery(clauses, true);
            }
            return base.GetWildcardQuery(field, termStr);
        }


        protected internal override Query GetRangeQuery(System.String field, System.String part1, System.String part2, bool inclusive)
        {
            if (field == null)
            {
                IList<BooleanClause> clauses = new List<BooleanClause>();
                for (int i = 0; i < fields.Length; i++)
                {
                    clauses.Add(new BooleanClause(GetRangeQuery(fields[i], part1, part2, inclusive), Occur.SHOULD));
                }
                return GetBooleanQuery(clauses, true);
            }
            return base.GetRangeQuery(field, part1, part2, inclusive);
        }

        public static Query Parse(Version matchVersion, System.String[] queries, System.String[] fields, Analyzer analyzer)
        {
            if (queries.Length != fields.Length)
                throw new System.ArgumentException("queries.length != fields.length");
            BooleanQuery bQuery = new BooleanQuery();
            for (int i = 0; i < fields.Length; i++)
            {
                QueryParser qp = new QueryParser(matchVersion, fields[i], analyzer);
                Query q = qp.Parse(queries[i]);
                if (q != null && (!(q is BooleanQuery) || ((BooleanQuery)q).GetClauses().Length > 0))
                {
                    bQuery.Add(q, Occur.SHOULD);
                }
            }
            return bQuery;
        }

        public static Query Parse(Version matchVersion, System.String query, System.String[] fields, Occur[] flags, Analyzer analyzer)
        {
            if (fields.Length != flags.Length)
                throw new System.ArgumentException("fields.length != flags.length");
            BooleanQuery bQuery = new BooleanQuery();
            for (int i = 0; i < fields.Length; i++)
            {
                QueryParser qp = new QueryParser(matchVersion, fields[i], analyzer);
                Query q = qp.Parse(query);
                if (q != null && (!(q is BooleanQuery) || ((BooleanQuery)q).GetClauses().Length > 0))
                {
                    bQuery.Add(q, flags[i]);
                }
            }
            return bQuery;
        }

        public static Query Parse(Version matchVersion, System.String[] queries, System.String[] fields, Occur[] flags, Analyzer analyzer)
        {
            if (!(queries.Length == fields.Length && queries.Length == flags.Length))
                throw new System.ArgumentException("queries, fields, and flags array have have different length");
            BooleanQuery bQuery = new BooleanQuery();
            for (int i = 0; i < fields.Length; i++)
            {
                QueryParser qp = new QueryParser(matchVersion, fields[i], analyzer);
                Query q = qp.Parse(queries[i]);
                if (q != null && (!(q is BooleanQuery) || ((BooleanQuery)q).GetClauses().Length > 0))
                {
                    bQuery.Add(q, flags[i]);
                }
            }
            return bQuery;
        }
    }
}