content: /*
   * 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.kafka.common.protocol.types;
  
  import org.apache.kafka.common.protocol.Writable;
  
  import java.util.ArrayList;
  import java.util.List;
  import java.util.ListIterator;
  
  /**
   * The RawTaggedFieldWriter is used by Message subclasses to serialize their
   * lists of raw tags.
   */
  public class RawTaggedFieldWriter {
      private static final RawTaggedFieldWriter EMPTY_WRITER =
          new RawTaggedFieldWriter(new ArrayList<>(0));
  
      private final List<RawTaggedField> fields;
      private final ListIterator<RawTaggedField> iter;
      private int prevTag;
  
      public static RawTaggedFieldWriter forFields(List<RawTaggedField> fields) {
          if (fields == null) {
              return EMPTY_WRITER;
          }
          return new RawTaggedFieldWriter(fields);
      }
  
      private RawTaggedFieldWriter(List<RawTaggedField> fields) {
          this.fields = fields;
          this.iter = this.fields.listIterator();
          this.prevTag = -1;
      }
  
      public int numFields() {
          return fields.size();
      }
  
      public void writeRawTags(Writable writable, int nextDefinedTag) {
          while (iter.hasNext()) {
              RawTaggedField field = iter.next();
              int tag = field.tag();
              if (tag >= nextDefinedTag) {
                  if (tag == nextDefinedTag) {
                      // We must not have a raw tag field that duplicates the tag of another field.
                      throw new RuntimeException("Attempted to use tag " + tag + " as an " +
                          "undefined tag.");
                  }
                  iter.previous();
                  return;
              }
              if (tag <= prevTag) {
                  // The raw tag field list must be sorted by tag, and there must not be
                  // any duplicate tags.
                  throw new RuntimeException("Invalid raw tag field list: tag " + tag +
                      " comes after tag " + prevTag + ", but is not higher than it.");
              }
              writable.writeUnsignedVarint(field.tag());
              writable.writeUnsignedVarint(field.data().length);
              writable.writeByteArray(field.data());
              prevTag = tag;
          }
      }
  }
  