PayloadSpanUtil.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.
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using System;
using System.Collections.Generic;
using System.Linq;
using IndexReader = Lucene.Net.Index.IndexReader;
using Term = Lucene.Net.Index.Term;
using BooleanClause = Lucene.Net.Search.BooleanClause;
using BooleanQuery = Lucene.Net.Search.BooleanQuery;
using DisjunctionMaxQuery = Lucene.Net.Search.DisjunctionMaxQuery;
using FilteredQuery = Lucene.Net.Search.FilteredQuery;
using MultiPhraseQuery = Lucene.Net.Search.MultiPhraseQuery;
using PhraseQuery = Lucene.Net.Search.PhraseQuery;
using Query = Lucene.Net.Search.Query;
using TermQuery = Lucene.Net.Search.TermQuery;
using SpanNearQuery = Lucene.Net.Search.Spans.SpanNearQuery;
using SpanOrQuery = Lucene.Net.Search.Spans.SpanOrQuery;
using SpanQuery = Lucene.Net.Search.Spans.SpanQuery;
using SpanTermQuery = Lucene.Net.Search.Spans.SpanTermQuery;

namespace Lucene.Net.Search.Payloads
{
    
    /// <summary> Experimental class to get set of payloads for most standard Lucene queries.
    /// Operates like Highlighter - IndexReader should only contain doc of interest,
    /// best to use MemoryIndex.
    /// 
    /// <p/>
    /// <font color="#FF0000">
    /// WARNING: The status of the <b>Payloads</b> feature is experimental.
    /// The APIs introduced here might change in the future and will not be
    /// supported anymore in such a case.</font>
    /// 
    /// </summary>
    public class PayloadSpanUtil
    {
        private IndexReader reader;
        
        /// <param name="reader">that contains doc with payloads to extract
        /// </param>
        public PayloadSpanUtil(IndexReader reader)
        {
            this.reader = reader;
        }
        
        /// <summary> Query should be rewritten for wild/fuzzy support.
        /// 
        /// </summary>
        /// <param name="query">
        /// </param>
        /// <returns> payloads Collection
        /// </returns>
        /// <throws>  IOException </throws>
        public virtual ICollection<byte[]> GetPayloadsForQuery(Query query)
        {
            ICollection<byte[]> payloads = new List<byte[]>();
            QueryToSpanQuery(query, payloads);
            return payloads;
        }
        
        private void  QueryToSpanQuery(Query query, ICollection<byte[]> payloads)
        {
            if (query is BooleanQuery)
            {
                BooleanClause[] queryClauses = ((BooleanQuery) query).GetClauses();
                
                for (int i = 0; i < queryClauses.Length; i++)
                {
                    if (!queryClauses[i].IsProhibited)
                    {
                        QueryToSpanQuery(queryClauses[i].Query, payloads);
                    }
                }
            }
            else if (query is PhraseQuery)
            {
                Term[] phraseQueryTerms = ((PhraseQuery) query).GetTerms();
                SpanQuery[] clauses = new SpanQuery[phraseQueryTerms.Length];
                for (int i = 0; i < phraseQueryTerms.Length; i++)
                {
                    clauses[i] = new SpanTermQuery(phraseQueryTerms[i]);
                }
                
                int slop = ((PhraseQuery) query).Slop;
                bool inorder = false;
                
                if (slop == 0)
                {
                    inorder = true;
                }
                
                SpanNearQuery sp = new SpanNearQuery(clauses, slop, inorder);
                sp.Boost = query.Boost;
                GetPayloads(payloads, sp);
            }
            else if (query is TermQuery)
            {
                SpanTermQuery stq = new SpanTermQuery(((TermQuery) query).Term);
                stq.Boost = query.Boost;
                GetPayloads(payloads, stq);
            }
            else if (query is SpanQuery)
            {
                GetPayloads(payloads, (SpanQuery) query);
            }
            else if (query is FilteredQuery)
            {
                QueryToSpanQuery(((FilteredQuery) query).Query, payloads);
            }
            else if (query is DisjunctionMaxQuery)
            {

                for (IEnumerator<Query> iterator = ((DisjunctionMaxQuery)query).GetEnumerator(); iterator.MoveNext(); )
                {
                    QueryToSpanQuery(iterator.Current, payloads);
                }
            }
            else if (query is MultiPhraseQuery)
            {
                MultiPhraseQuery mpq = (MultiPhraseQuery) query;
                System.Collections.Generic.IList<Term[]> termArrays = mpq.GetTermArrays();
                int[] positions = mpq.GetPositions();
                if (positions.Length > 0)
                {
                    
                    int maxPosition = positions[positions.Length - 1];
                    for (int i = 0; i < positions.Length - 1; ++i)
                    {
                        if (positions[i] > maxPosition)
                        {
                            maxPosition = positions[i];
                        }
                    }

                    IList<Query>[] disjunctLists = new IList<Query>[maxPosition + 1];
                    int distinctPositions = 0;
                    
                    for (int i = 0; i < termArrays.Count; ++i)
                    {
                        Term[] termArray = termArrays[i];
                        IList<Query> disjuncts = disjunctLists[positions[i]];
                        if (disjuncts == null)
                        {
                            disjuncts = (disjunctLists[positions[i]] = new List<Query>(termArray.Length));
                            ++distinctPositions;
                        }
                        foreach(Term term in termArray)
                        {
                            disjuncts.Add(new SpanTermQuery(term));
                        }
                    }
                    
                    int positionGaps = 0;
                    int position = 0;
                    SpanQuery[] clauses = new SpanQuery[distinctPositions];
                    for (int i = 0; i < disjunctLists.Length; ++i)
                    {
                        IList<Query> disjuncts = disjunctLists[i];
                        if (disjuncts != null)
                        {
                            clauses[position++] = new SpanOrQuery((SpanQuery[]) (disjuncts.ToArray()));
                        }
                        else
                        {
                            ++positionGaps;
                        }
                    }
                    
                    int slop = mpq.Slop;
                    bool inorder = (slop == 0);
                    
                    SpanNearQuery sp = new SpanNearQuery(clauses, slop + positionGaps, inorder);
                    sp.Boost = query.Boost;
                    GetPayloads(payloads, sp);
                }
            }
        }
        
        private void  GetPayloads(ICollection<byte[]> payloads, SpanQuery query)
        {
            Spans.Spans spans = query.GetSpans(reader);
            
            while (spans.Next() == true)
            {
                if (spans.IsPayloadAvailable())
                {
                    ICollection<byte[]> payload = spans.GetPayload();
                    foreach (byte[] bytes in payload)
                    {
                        payloads.Add(bytes);
                    }
                }
            }
        }
    }
}