--- /dev/null
+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.lang.ref.WeakReference;
+import java.util.Iterator;
+import java.util.LinkedList;
+import java.util.List;
+
+import org.apache.lucene.util.AttributeImpl;
+import org.apache.lucene.util.AttributeSource;
+
+/**
+ * This TokenFilter provides the ability to set aside attribute states
+ * that have already been analyzed. This is useful in situations where multiple fields share
+ * many common analysis steps and then go their separate ways.
+ * <p/>
+ * It is also useful for doing things like entity extraction or proper noun analysis as
+ * part of the analysis workflow and saving off those tokens for use in another field.
+ *
+ * <pre>
+TeeSinkTokenFilter source1 = new TeeSinkTokenFilter(new WhitespaceTokenizer(reader1));
+TeeSinkTokenFilter.SinkTokenStream sink1 = source1.newSinkTokenStream();
+TeeSinkTokenFilter.SinkTokenStream sink2 = source1.newSinkTokenStream();
+
+TeeSinkTokenFilter source2 = new TeeSinkTokenFilter(new WhitespaceTokenizer(reader2));
+source2.addSinkTokenStream(sink1);
+source2.addSinkTokenStream(sink2);
+
+TokenStream final1 = new LowerCaseFilter(source1);
+TokenStream final2 = source2;
+TokenStream final3 = new EntityDetect(sink1);
+TokenStream final4 = new URLDetect(sink2);
+
+d.add(new Field("f1", final1));
+d.add(new Field("f2", final2));
+d.add(new Field("f3", final3));
+d.add(new Field("f4", final4));
+ * </pre>
+ * In this example, <code>sink1</code> and <code>sink2</code> will both get tokens from both
+ * <code>reader1</code> and <code>reader2</code> after whitespace tokenizer
+ * and now we can further wrap any of these in extra analysis, and more "sources" can be inserted if desired.
+ * It is important, that tees are consumed before sinks (in the above example, the field names must be
+ * less the sink's field names). If you are not sure, which stream is consumed first, you can simply
+ * add another sink and then pass all tokens to the sinks at once using {@link #consumeAllTokens}.
+ * This TokenFilter is exhausted after this. In the above example, change
+ * the example above to:
+ * <pre>
+...
+TokenStream final1 = new LowerCaseFilter(source1.newSinkTokenStream());
+TokenStream final2 = source2.newSinkTokenStream();
+sink1.consumeAllTokens();
+sink2.consumeAllTokens();
+...
+ * </pre>
+ * In this case, the fields can be added in any order, because the sources are not used anymore and all sinks are ready.
+ * <p>Note, the EntityDetect and URLDetect TokenStreams are for the example and do not currently exist in Lucene.
+ */
+public final class TeeSinkTokenFilter extends TokenFilter {
+ private final List<WeakReference<SinkTokenStream>> sinks = new LinkedList<WeakReference<SinkTokenStream>>();
+
+ /**
+ * Instantiates a new TeeSinkTokenFilter.
+ */
+ public TeeSinkTokenFilter(TokenStream input) {
+ super(input);
+ }
+
+ /**
+ * Returns a new {@link SinkTokenStream} that receives all tokens consumed by this stream.
+ */
+ public SinkTokenStream newSinkTokenStream() {
+ return newSinkTokenStream(ACCEPT_ALL_FILTER);
+ }
+
+ /**
+ * Returns a new {@link SinkTokenStream} that receives all tokens consumed by this stream
+ * that pass the supplied filter.
+ * @see SinkFilter
+ */
+ public SinkTokenStream newSinkTokenStream(SinkFilter filter) {
+ SinkTokenStream sink = new SinkTokenStream(this.cloneAttributes(), filter);
+ this.sinks.add(new WeakReference<SinkTokenStream>(sink));
+ return sink;
+ }
+
+ /**
+ * Adds a {@link SinkTokenStream} created by another <code>TeeSinkTokenFilter</code>
+ * to this one. The supplied stream will also receive all consumed tokens.
+ * This method can be used to pass tokens from two different tees to one sink.
+ */
+ public void addSinkTokenStream(final SinkTokenStream sink) {
+ // check that sink has correct factory
+ if (!this.getAttributeFactory().equals(sink.getAttributeFactory())) {
+ throw new IllegalArgumentException("The supplied sink is not compatible to this tee");
+ }
+ // add eventually missing attribute impls to the existing sink
+ for (Iterator<AttributeImpl> it = this.cloneAttributes().getAttributeImplsIterator(); it.hasNext(); ) {
+ sink.addAttributeImpl(it.next());
+ }
+ this.sinks.add(new WeakReference<SinkTokenStream>(sink));
+ }
+
+ /**
+ * <code>TeeSinkTokenFilter</code> passes all tokens to the added sinks
+ * when itself is consumed. To be sure, that all tokens from the input
+ * stream are passed to the sinks, you can call this methods.
+ * This instance is exhausted after this, but all sinks are instant available.
+ */
+ public void consumeAllTokens() throws IOException {
+ while (incrementToken()) {}
+ }
+
+ @Override
+ public boolean incrementToken() throws IOException {
+ if (input.incrementToken()) {
+ // capture state lazily - maybe no SinkFilter accepts this state
+ AttributeSource.State state = null;
+ for (WeakReference<SinkTokenStream> ref : sinks) {
+ final SinkTokenStream sink = ref.get();
+ if (sink != null) {
+ if (sink.accept(this)) {
+ if (state == null) {
+ state = this.captureState();
+ }
+ sink.addState(state);
+ }
+ }
+ }
+ return true;
+ }
+
+ return false;
+ }
+
+ @Override
+ public final void end() throws IOException {
+ super.end();
+ AttributeSource.State finalState = captureState();
+ for (WeakReference<SinkTokenStream> ref : sinks) {
+ final SinkTokenStream sink = ref.get();
+ if (sink != null) {
+ sink.setFinalState(finalState);
+ }
+ }
+ }
+
+ /**
+ * A filter that decides which {@link AttributeSource} states to store in the sink.
+ */
+ public static abstract class SinkFilter {
+ /**
+ * Returns true, iff the current state of the passed-in {@link AttributeSource} shall be stored
+ * in the sink.
+ */
+ public abstract boolean accept(AttributeSource source);
+
+ /**
+ * Called by {@link SinkTokenStream#reset()}. This method does nothing by default
+ * and can optionally be overridden.
+ */
+ public void reset() throws IOException {
+ // nothing to do; can be overridden
+ }
+ }
+
+ public static final class SinkTokenStream extends TokenStream {
+ private final List<AttributeSource.State> cachedStates = new LinkedList<AttributeSource.State>();
+ private AttributeSource.State finalState;
+ private Iterator<AttributeSource.State> it = null;
+ private SinkFilter filter;
+
+ private SinkTokenStream(AttributeSource source, SinkFilter filter) {
+ super(source);
+ this.filter = filter;
+ }
+
+ private boolean accept(AttributeSource source) {
+ return filter.accept(source);
+ }
+
+ private void addState(AttributeSource.State state) {
+ if (it != null) {
+ throw new IllegalStateException("The tee must be consumed before sinks are consumed.");
+ }
+ cachedStates.add(state);
+ }
+
+ private void setFinalState(AttributeSource.State finalState) {
+ this.finalState = finalState;
+ }
+
+ @Override
+ public final boolean incrementToken() throws IOException {
+ // lazy init the iterator
+ if (it == null) {
+ it = cachedStates.iterator();
+ }
+
+ if (!it.hasNext()) {
+ return false;
+ }
+
+ AttributeSource.State state = it.next();
+ restoreState(state);
+ return true;
+ }
+
+ @Override
+ public final void end() throws IOException {
+ if (finalState != null) {
+ restoreState(finalState);
+ }
+ }
+
+ @Override
+ public final void reset() {
+ it = cachedStates.iterator();
+ }
+ }
+
+ private static final SinkFilter ACCEPT_ALL_FILTER = new SinkFilter() {
+ @Override
+ public boolean accept(AttributeSource source) {
+ return true;
+ }
+ };
+
+}
fnp / pylucene.git / blobdiff