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/*
* Licensed to Elasticsearch under one or more contributor
* license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright
* ownership. Elasticsearch 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.
*/
package org.elasticsearch.search.suggest.completion;
import org.apache.lucene.analysis.TokenStream;
import org.apache.lucene.analysis.tokenattributes.CharTermAttribute;
import org.apache.lucene.analysis.tokenattributes.PayloadAttribute;
import org.apache.lucene.analysis.tokenattributes.PositionIncrementAttribute;
import org.apache.lucene.analysis.tokenattributes.TermToBytesRefAttribute;
import org.apache.lucene.util.*;
import org.apache.lucene.util.fst.Util;
import java.io.IOException;
import java.util.Iterator;
import java.util.Set;
/**
*
*/
public final class CompletionTokenStream extends TokenStream {
private final PayloadAttribute payloadAttr = addAttribute(PayloadAttribute.class);
private final PositionIncrementAttribute posAttr = addAttribute(PositionIncrementAttribute.class);
private final ByteTermAttribute bytesAtt = addAttribute(ByteTermAttribute.class);;
private final TokenStream input;
private BytesRef payload;
private Iterator<IntsRef> finiteStrings;
private ToFiniteStrings toFiniteStrings;
private int posInc = -1;
private static final int MAX_PATHS = 256;
private CharTermAttribute charTermAttribute;
public CompletionTokenStream(TokenStream input, BytesRef payload, ToFiniteStrings toFiniteStrings) throws IOException {
// Don't call the super(input) ctor - this is a true delegate and has a new attribute source since we consume
// the input stream entirely in toFiniteStrings(input)
this.input = input;
this.payload = payload;
this.toFiniteStrings = toFiniteStrings;
}
@Override
public boolean incrementToken() throws IOException {
clearAttributes();
if (finiteStrings == null) {
Set<IntsRef> strings = toFiniteStrings.toFiniteStrings(input);
if (strings.size() > MAX_PATHS) {
throw new IllegalArgumentException("TokenStream expanded to " + strings.size() + " finite strings. Only <= " + MAX_PATHS
+ " finite strings are supported");
}
posInc = strings.size();
finiteStrings = strings.iterator();
}
if (finiteStrings.hasNext()) {
posAttr.setPositionIncrement(posInc);
/*
* this posInc encodes the number of paths that this surface form
* produced. Multi Fields have the same surface form and therefore sum up
*/
posInc = 0;
Util.toBytesRef(finiteStrings.next(), bytesAtt.builder()); // now we have UTF-8
if (charTermAttribute != null) {
charTermAttribute.setLength(0);
charTermAttribute.append(bytesAtt.toUTF16());
}
if (payload != null) {
payloadAttr.setPayload(this.payload);
}
return true;
}
return false;
}
@Override
public void end() throws IOException {
super.end();
if (posInc == -1) {
input.end();
}
}
@Override
public void close() throws IOException {
input.close();
}
public static interface ToFiniteStrings {
public Set<IntsRef> toFiniteStrings(TokenStream stream) throws IOException;
}
@Override
public void reset() throws IOException {
super.reset();
if (hasAttribute(CharTermAttribute.class)) {
// we only create this if we really need it to safe the UTF-8 to UTF-16 conversion
charTermAttribute = getAttribute(CharTermAttribute.class);
}
finiteStrings = null;
posInc = -1;
}
public interface ByteTermAttribute extends TermToBytesRefAttribute {
// marker interface
/**
* Return the builder from which the term is derived.
*/
public BytesRefBuilder builder();
public CharSequence toUTF16();
}
public static final class ByteTermAttributeImpl extends AttributeImpl implements ByteTermAttribute, TermToBytesRefAttribute {
private final BytesRefBuilder bytes = new BytesRefBuilder();
private CharsRefBuilder charsRef;
@Override
public BytesRefBuilder builder() {
return bytes;
}
@Override
public BytesRef getBytesRef() {
return bytes.get();
}
@Override
public void clear() {
bytes.clear();
}
@Override
public void copyTo(AttributeImpl target) {
ByteTermAttributeImpl other = (ByteTermAttributeImpl) target;
other.bytes.copyBytes(bytes);
}
@Override
public CharSequence toUTF16() {
if (charsRef == null) {
charsRef = new CharsRefBuilder();
}
charsRef.copyUTF8Bytes(getBytesRef());
return charsRef.get();
}
}
}
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