package org.apache.lucene.index;
/*
* 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.util.Iterator;
/** Flex API for access to fields and terms
* @lucene.experimental */
public abstract class Fields implements Iterable<String> {
/** Sole constructor. (For invocation by subclass
* constructors, typically implicit.) */
protected Fields() {
}
/** Returns an iterator that will step through all fields
* names. This will not return null. */
public abstract Iterator<String> iterator();
/** Get the {@link Terms} for this field. This will return
* null if the field does not exist. */
public abstract Terms terms(String field) throws IOException;
/** Returns the number of fields or -1 if the number of
* distinct field names is unknown. If >= 0,
* {@link #iterator} will return as many field names. */
public abstract int size();
/** Returns the number of terms for all fields, or -1 if this
* measure isn't stored by the codec. Note that, just like
* other term measures, this measure does not take deleted
* documents into account.
* @deprecated iterate fields and add their size() instead.
* this method is only provided as a transition mechanism
* to access this statistic for 3.x indexes, which do not
* have this statistic per-field.
* @see Terms#size() */
@Deprecated
public long getUniqueTermCount() throws IOException {
long numTerms = 0;
for (String field : this) {
Terms terms = terms(field);
if (terms != null) {
final long termCount = terms.size();
if (termCount == -1) {
return -1;
}
numTerms += termCount;
}
}
return numTerms;
}
/** Zero-length {@code Fields} array. */
public final static Fields[] EMPTY_ARRAY = new Fields[0];
}