src/Lucene.Net.Core/Index/SortedTermVectorMapper.cs

/* 
 * 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.Support;

namespace Lucene.Net.Index
{
    
    /// <summary> Store a sorted collection of <see cref="Lucene.Net.Index.TermVectorEntry" />s.  Collects all term information
    /// into a single, SortedSet.
    /// <br/>
    /// NOTE: This Mapper ignores all Field information for the Document.  This means that if you are using offset/positions you will not
    /// know what Fields they correlate with.
    /// <br/>
    /// This is not thread-safe  
    /// </summary>
    public class SortedTermVectorMapper:TermVectorMapper
    {
        private SortedSet<TermVectorEntry> currentSet;
        private IDictionary<string, TermVectorEntry> termToTVE = new HashMap<string, TermVectorEntry>();
        private bool storeOffsets;
        private bool storePositions;
        /// <summary> Stand-in name for the field in <see cref="TermVectorEntry" />.</summary>
        public const System.String ALL = "_ALL_";
        
        /// <summary> </summary>
        /// <param name="comparator">A Comparator for sorting <see cref="TermVectorEntry" />s
        /// </param>
        public SortedTermVectorMapper(IComparer<TermVectorEntry> comparator)
            : this(false, false, comparator)
        {
        }


        public SortedTermVectorMapper(bool ignoringPositions, bool ignoringOffsets, IComparer<TermVectorEntry> comparator)
            : base(ignoringPositions, ignoringOffsets)
        {
            currentSet = new SortedSet<TermVectorEntry>(comparator);
        }
        
        /// <summary> </summary>
        /// <param name="term">The term to map
        /// </param>
        /// <param name="frequency">The frequency of the term
        /// </param>
        /// <param name="offsets">Offset information, may be null
        /// </param>
        /// <param name="positions">Position information, may be null
        /// </param>
        //We need to combine any previous mentions of the term
        public override void  Map(System.String term, int frequency, TermVectorOffsetInfo[] offsets, int[] positions)
        {
            TermVectorEntry entry = termToTVE[term];
            if (entry == null)
            {
                entry = new TermVectorEntry(ALL, term, frequency, storeOffsets == true?offsets:null, storePositions == true?positions:null);
                termToTVE[term] = entry;
                currentSet.Add(entry);
            }
            else
            {
                entry.Frequency = entry.Frequency + frequency;
                if (storeOffsets)
                {
                    TermVectorOffsetInfo[] existingOffsets = entry.GetOffsets();
                    //A few diff. cases here:  offsets is null, existing offsets is null, both are null, same for positions
                    if (existingOffsets != null && offsets != null && offsets.Length > 0)
                    {
                        //copy over the existing offsets
                        TermVectorOffsetInfo[] newOffsets = new TermVectorOffsetInfo[existingOffsets.Length + offsets.Length];
                        Array.Copy(existingOffsets, 0, newOffsets, 0, existingOffsets.Length);
                        Array.Copy(offsets, 0, newOffsets, existingOffsets.Length, offsets.Length);
                        entry.SetOffsets(newOffsets);
                    }
                    else if (existingOffsets == null && offsets != null && offsets.Length > 0)
                    {
                        entry.SetOffsets(offsets);
                    }
                    //else leave it alone
                }
                if (storePositions)
                {
                    int[] existingPositions = entry.GetPositions();
                    if (existingPositions != null && positions != null && positions.Length > 0)
                    {
                        int[] newPositions = new int[existingPositions.Length + positions.Length];
                        Array.Copy(existingPositions, 0, newPositions, 0, existingPositions.Length);
                        Array.Copy(positions, 0, newPositions, existingPositions.Length, positions.Length);
                        entry.SetPositions(newPositions);
                    }
                    else if (existingPositions == null && positions != null && positions.Length > 0)
                    {
                        entry.SetPositions(positions);
                    }
                }
            }
        }
        
        public override void  SetExpectations(System.String field, int numTerms, bool storeOffsets, bool storePositions)
        {
            
            this.storeOffsets = storeOffsets;
            this.storePositions = storePositions;
        }

        /// <summary> The TermVectorEntrySet.  A SortedSet of <see cref="TermVectorEntry" /> objects.  Sort is by the comparator passed into the constructor.
        /// <br/>
        /// This set will be empty until after the mapping process takes place.
        /// 
        /// </summary>
        /// <value> The SortedSet of &lt;see cref=&quot;TermVectorEntry&quot; /&gt;. </value>
        public virtual SortedSet<TermVectorEntry> TermVectorEntrySet
        {
            get { return currentSet; }
        }
    }
}