code: /*
   * Copyright 2012-2018 Chronicle Map Contributors
   *
   * Licensed 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 net.openhft.chronicle.hash.serialization.impl;
  
  import net.openhft.chronicle.bytes.Bytes;
  import net.openhft.chronicle.hash.serialization.BytesReader;
  import net.openhft.chronicle.hash.serialization.ListMarshaller;
  import net.openhft.chronicle.hash.serialization.SetMarshaller;
  import net.openhft.chronicle.hash.serialization.StatefulCopyable;
  import net.openhft.chronicle.wire.WireIn;
  import net.openhft.chronicle.wire.WireOut;
  import org.jetbrains.annotations.NotNull;
  import org.jetbrains.annotations.Nullable;
  
  /**
   * {@link BytesReader} implementation for String, for the primary ChronicleMap's key or value type
   * {@link StringSizedReader} + {@link StringUtf8DataAccess} are more efficient (because don't
   * store the size twice), so this reader is useful in conjunction with {@link ListMarshaller} or
   * {@link SetMarshaller}.
   *
   * @see CharSequenceBytesWriter
   */
  public class StringBytesReader implements BytesReader<String>, StatefulCopyable<StringBytesReader> {
  
      /**
       * Cache field
       */
      private transient StringBuilder sb;
  
      public StringBytesReader() {
          initTransients();
      }
  
      private void initTransients() {
          sb = new StringBuilder();
      }
  
      @NotNull
      @Override
      public String read(Bytes in, @Nullable String using) {
          if (in.readUtf8(sb)) {
              return sb.toString();
          } else {
              throw new NullPointerException("BytesReader couldn't read null");
          }
      }
  
      @Override
      public StringBytesReader copy() {
          return new StringBytesReader();
      }
  
      @Override
      public void readMarshallable(@NotNull WireIn wireIn) {
          // no fields to read
          initTransients();
      }
  
      @Override
      public void writeMarshallable(@NotNull WireOut wireOut) {
          // no fields to write
      }
  }
  