/* * Copyright 2004 The Apache Software Foundation * * Licensed 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.Runtime.InteropServices; using IndexReader = Lucene.Net.Index.IndexReader; namespace Lucene.Net.Search { /// Constrains search results to only match those which also match a provided /// query. Results are cached, so that searches after the first on the same /// index using this filter are much faster. /// ///

This could be used, for example, with a {@link RangeQuery} on a suitably /// formatted date Field to implement date filtering. One could re-use a single /// QueryFilter that matches, e.g., only documents modified within the last /// week. The QueryFilter and RangeQuery would only need to be reconstructed /// once per day. /// ///

/// $Id: QueryFilter.cs,v 1.3 2005/10/06 19:29:57 dsd Exp $ /// [Serializable] public class QueryFilter:Filter { private class AnonymousClassHitCollector:HitCollector { public AnonymousClassHitCollector(System.Collections.BitArray bits, QueryFilter enclosingInstance) { InitBlock(bits, enclosingInstance); } private void InitBlock(System.Collections.BitArray bits, QueryFilter enclosingInstance) { this.bits = bits; this.enclosingInstance = enclosingInstance; } private System.Collections.BitArray bits; private QueryFilter enclosingInstance; public QueryFilter Enclosing_Instance { get { return enclosingInstance; } } public override void Collect(int doc, float score) { bits.Set(doc, true); // set bit for hit } } private Query query; [NonSerialized] private System.Collections.Hashtable cache = null; /// Constructs a filter which only matches documents matching /// query. /// public QueryFilter(Query query) { this.query = query; } public override System.Collections.BitArray Bits(IndexReader reader) { if (cache == null) { cache = new System.Collections.Hashtable(); } lock (cache.SyncRoot) { // check cache System.Collections.BitArray cached = (System.Collections.BitArray) cache[reader]; if (cached != null) { return cached; } } System.Collections.BitArray bits = new System.Collections.BitArray((reader.MaxDoc() % 64 == 0?reader.MaxDoc() / 64:reader.MaxDoc() / 64 + 1) * 64); new IndexSearcher(reader).Search(query, new AnonymousClassHitCollector(bits, this)); lock (cache.SyncRoot) { // update cache cache[reader] = bits; } return bits; } public override System.String ToString() { return "QueryFilter(" + query + ")"; } } }