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diff --git a/lucene-java-3.5.0/lucene/src/java/org/apache/lucene/analysis/TokenStream.java b/lucene-java-3.5.0/lucene/src/java/org/apache/lucene/analysis/TokenStream.java
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+package org.apache.lucene.analysis;
+
+/**
+ * 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 java.io.IOException;
+import java.io.Closeable;
+import java.lang.reflect.Modifier;
+
+import org.apache.lucene.document.Document;
+import org.apache.lucene.document.Field;
+import org.apache.lucene.index.IndexWriter;
+import org.apache.lucene.util.Attribute;
+import org.apache.lucene.util.AttributeImpl;
+import org.apache.lucene.util.AttributeSource;
+
+/**
+ * A TokenStream
enumerates the sequence of tokens, either from
+ * {@link Field}s of a {@link Document} or from query text.
+ *
+ * This is an abstract class; concrete subclasses are: + *
TokenStream
whose input is a Reader; and
+ * TokenStream
whose input is another
+ * TokenStream
.
+ * TokenStream
API has been introduced with Lucene 2.9. This API
+ * has moved from being {@link Token}-based to {@link Attribute}-based. While
+ * {@link Token} still exists in 2.9 as a convenience class, the preferred way
+ * to store the information of a {@link Token} is to use {@link AttributeImpl}s.
+ *
+ * TokenStream
now extends {@link AttributeSource}, which provides
+ * access to all of the token {@link Attribute}s for the TokenStream
.
+ * Note that only one instance per {@link AttributeImpl} is created and reused
+ * for every token. This approach reduces object creation and allows local
+ * caching of references to the {@link AttributeImpl}s. See
+ * {@link #incrementToken()} for further details.
+ *
+ * The workflow of the new TokenStream
API is as follows:
+ *
TokenStream
/{@link TokenFilter}s which add/get
+ * attributes to/from the {@link AttributeSource}.
+ * TokenStream
.
+ * + * You can find some example code for the new API in the analysis package level + * Javadoc. + *
+ * Sometimes it is desirable to capture a current state of a TokenStream
,
+ * e.g., for buffering purposes (see {@link CachingTokenFilter},
+ * {@link TeeSinkTokenFilter}). For this usecase
+ * {@link AttributeSource#captureState} and {@link AttributeSource#restoreState}
+ * can be used.
+ *
The {@code TokenStream}-API in Lucene is based on the decorator pattern. + * Therefore all non-abstract subclasses must be final or have at least a final + * implementation of {@link #incrementToken}! This is checked when Java + * assertions are enabled. + */ +public abstract class TokenStream extends AttributeSource implements Closeable { + + /** + * A TokenStream using the default attribute factory. + */ + protected TokenStream() { + super(); + assert assertFinal(); + } + + /** + * A TokenStream that uses the same attributes as the supplied one. + */ + protected TokenStream(AttributeSource input) { + super(input); + assert assertFinal(); + } + + /** + * A TokenStream using the supplied AttributeFactory for creating new {@link Attribute} instances. + */ + protected TokenStream(AttributeFactory factory) { + super(factory); + assert assertFinal(); + } + + private boolean assertFinal() { + try { + final Class> clazz = getClass(); + if (!clazz.desiredAssertionStatus()) + return true; + assert clazz.isAnonymousClass() || + (clazz.getModifiers() & (Modifier.FINAL | Modifier.PRIVATE)) != 0 || + Modifier.isFinal(clazz.getMethod("incrementToken").getModifiers()) : + "TokenStream implementation classes or at least their incrementToken() implementation must be final"; + return true; + } catch (NoSuchMethodException nsme) { + return false; + } + } + + /** + * Consumers (i.e., {@link IndexWriter}) use this method to advance the stream to + * the next token. Implementing classes must implement this method and update + * the appropriate {@link AttributeImpl}s with the attributes of the next + * token. + *
+ * The producer must make no assumptions about the attributes after the method + * has been returned: the caller may arbitrarily change it. If the producer + * needs to preserve the state for subsequent calls, it can use + * {@link #captureState} to create a copy of the current attribute state. + *
+ * This method is called for every token of a document, so an efficient + * implementation is crucial for good performance. To avoid calls to + * {@link #addAttribute(Class)} and {@link #getAttribute(Class)}, + * references to all {@link AttributeImpl}s that this stream uses should be + * retrieved during instantiation. + *
+ * To ensure that filters and consumers know which attributes are available,
+ * the attributes must be added during instantiation. Filters and consumers
+ * are not required to check for availability of attributes in
+ * {@link #incrementToken()}.
+ *
+ * @return false for end of stream; true otherwise
+ */
+ public abstract boolean incrementToken() throws IOException;
+
+ /**
+ * This method is called by the consumer after the last token has been
+ * consumed, after {@link #incrementToken()} returned false
+ * (using the new TokenStream
API). Streams implementing the old API
+ * should upgrade to use this feature.
+ *
TokenStream
are intended to be consumed more than once, it is
+ * necessary to implement {@link #reset()}. Note that if your TokenStream
+ * caches tokens and feeds them back again after a reset, it is imperative
+ * that you clone the tokens when you store them away (on the first pass) as
+ * well as when you return them (on future passes after {@link #reset()}).
+ */
+ public void reset() throws IOException {}
+
+ /** Releases resources associated with this stream. */
+ public void close() throws IOException {}
+
+}