| /* |
| * 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. |
| */ |
| |
| package org.apache.nifi.serialization.record; |
| |
| import java.io.IOException; |
| |
| public interface RecordSet { |
| |
| /** |
| * @return the {@link RecordSchema} that applies to the records in this RecordSet |
| */ |
| RecordSchema getSchema() throws IOException; |
| |
| /** |
| * @return the next {@link Record} in the set or <code>null</code> if there are no more records |
| */ |
| Record next() throws IOException; |
| |
| /** |
| * Returns a new Record Set that will return no more than {@code maxRecords} records from this |
| * RecordSet. Any Records that are pulled from this newly created RecordSet will also advance |
| * the cursor in this Record Set and vice versa. |
| * |
| * @param maxRecords the maximum number of records to return from the new RecordSet |
| * @return a view of this RecordSet that limits the number of records returned |
| */ |
| default RecordSet limit(final int maxRecords) { |
| if (maxRecords < 0) { |
| throw new IllegalArgumentException("Cannot limit number of records to " + maxRecords + ". Limit must be a non-negative integer"); |
| } |
| |
| final RecordSet original = this; |
| return new RecordSet() { |
| private int count = 0; |
| |
| @Override |
| public RecordSchema getSchema() throws IOException { |
| return original.getSchema(); |
| } |
| |
| @Override |
| public Record next() throws IOException { |
| if (count >= maxRecords) { |
| return null; |
| } |
| |
| final Record record = original.next(); |
| if (record != null) { |
| count++; |
| } |
| |
| return record; |
| } |
| }; |
| } |
| |
| public static RecordSet of(final RecordSchema schema, final Record... records) { |
| return new RecordSet() { |
| private int index = 0; |
| |
| @Override |
| public RecordSchema getSchema() { |
| return schema; |
| } |
| |
| @Override |
| public Record next() { |
| if (index >= records.length) { |
| return null; |
| } |
| |
| return records[index++]; |
| } |
| }; |
| } |
| } |