pylucene 3.5.0-3

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

diff --git a/lucene-java-3.5.0/lucene/src/java/org/apache/lucene/search/function/ValueSource.java b/lucene-java-3.5.0/lucene/src/java/org/apache/lucene/search/function/ValueSource.java
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+package org.apache.lucene.search.function;
+
+/**
+ * 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.
+ */
+
+import org.apache.lucene.index.IndexReader;
+import org.apache.lucene.search.function.DocValues;
+
+import java.io.IOException;
+import java.io.Serializable;
+
+/**
+ * Expert: source of values for basic function queries.
+ * <P>At its default/simplest form, values - one per doc - are used as the score of that doc.
+ * <P>Values are instantiated as 
+ * {@link org.apache.lucene.search.function.DocValues DocValues} for a particular reader.
+ * <P>ValueSource implementations differ in RAM requirements: it would always be a factor
+ * of the number of documents, but for each document the number of bytes can be 1, 2, 4, or 8. 
+ *
+ * @lucene.experimental
+ *
+ *
+ */
+public abstract class ValueSource implements Serializable {
+
+  /**
+   * Return the DocValues used by the function query.
+   * @param reader the IndexReader used to read these values.
+   * If any caching is involved, that caching would also be IndexReader based.  
+   * @throws IOException for any error.
+   */
+  public abstract DocValues getValues(IndexReader reader) throws IOException;
+
+  /** 
+   * description of field, used in explain() 
+   */
+  public abstract String description();
+
+  /* (non-Javadoc) @see java.lang.Object#toString() */
+  @Override
+  public String toString() {
+    return description();
+  }
+
+  /**
+   * Needed for possible caching of query results - used by {@link ValueSourceQuery#equals(Object)}.
+   * @see Object#equals(Object)
+   */
+  @Override
+  public abstract boolean equals(Object o);
+
+  /**
+   * Needed for possible caching of query results - used by {@link ValueSourceQuery#hashCode()}.
+   * @see Object#hashCode()
+   */
+  @Override
+  public abstract int hashCode();
+  
+}