pylucene 3.5.0-3

[pylucene.git] / lucene-java-3.5.0 / lucene / src / java / org / apache / lucene / search / SpanFilter.java

diff --git a/lucene-java-3.5.0/lucene/src/java/org/apache/lucene/search/SpanFilter.java b/lucene-java-3.5.0/lucene/src/java/org/apache/lucene/search/SpanFilter.java
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+package org.apache.lucene.search;
+/**
+ * Copyright 2007 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.
+ */
+
+import org.apache.lucene.index.IndexReader;
+
+import java.io.IOException;
+
+/** Abstract base class providing a mechanism to restrict searches to a subset
+ of an index and also maintains and returns position information.
+
+ This is useful if you want to compare the positions from a SpanQuery with the positions of items in
+ a filter.  For instance, if you had a SpanFilter that marked all the occurrences of the word "foo" in documents,
+ and then you entered a new SpanQuery containing bar, you could not only filter by the word foo, but you could
+ then compare position information for post processing.
+ */
+public abstract class SpanFilter extends Filter{
+  /** Returns a SpanFilterResult with true for documents which should be permitted in
+    search results, and false for those that should not and Spans for where the true docs match.
+   * @param reader The {@link org.apache.lucene.index.IndexReader} to load position and DocIdSet information from
+   * @return A {@link SpanFilterResult}
+   * @throws java.io.IOException if there was an issue accessing the necessary information
+   * */
+  public abstract SpanFilterResult bitSpans(IndexReader reader) throws IOException;
+}