content: // Protocol Buffers - Google's data interchange format
  // Copyright 2008 Google Inc.  All rights reserved.
  // https://developers.google.com/protocol-buffers/
  //
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  // modification, are permitted provided that the following conditions are
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  //
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  // notice, this list of conditions and the following disclaimer.
  //     * Redistributions in binary form must reproduce the above
  // copyright notice, this list of conditions and the following disclaimer
  // in the documentation and/or other materials provided with the
  // distribution.
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  // contributors may be used to endorse or promote products derived from
  // this software without specific prior written permission.
  //
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  // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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  package com.google.protobuf;
  
  import java.util.Collection;
  import java.util.List;
  
  /**
   * An interface extending {@code List<String>} that also provides access to the items of the list as
   * UTF8-encoded ByteString or byte[] objects. This is used by the protocol buffer implementation to
   * support lazily converting bytes parsed over the wire to String objects until needed and also
   * increases the efficiency of serialization if the String was never requested as the ByteString or
   * byte[] is already cached. The ByteString methods are used in immutable API only and byte[]
   * methods used in mutable API only for they use different representations for string/bytes fields.
   *
   * @author jonp@google.com (Jon Perlow)
   */
  public interface LazyStringList extends ProtocolStringList {
  
    /**
     * Returns the element at the specified position in this list as a ByteString.
     *
     * @param index index of the element to return
     * @return the element at the specified position in this list
     * @throws IndexOutOfBoundsException if the index is out of range ({@code index < 0 || index >=
     *     size()})
     */
    ByteString getByteString(int index);
  
    /**
     * Returns the element at the specified position in this list as an Object that will either be a
     * String or a ByteString.
     *
     * @param index index of the element to return
     * @return the element at the specified position in this list
     * @throws IndexOutOfBoundsException if the index is out of range ({@code index < 0 || index >=
     *     size()})
     */
    Object getRaw(int index);
  
    /**
     * Returns the element at the specified position in this list as byte[].
     *
     * @param index index of the element to return
     * @return the element at the specified position in this list
     * @throws IndexOutOfBoundsException if the index is out of range ({@code index < 0 || index >=
     *     size()})
     */
    byte[] getByteArray(int index);
  
    /**
     * Appends the specified element to the end of this list (optional operation).
     *
     * @param element element to be appended to this list
     * @throws UnsupportedOperationException if the <tt>add</tt> operation is not supported by this
     *     list
     */
    void add(ByteString element);
  
    /**
     * Appends the specified element to the end of this list (optional operation).
     *
     * @param element element to be appended to this list
     * @throws UnsupportedOperationException if the <tt>add</tt> operation is not supported by this
     *     list
     */
    void add(byte[] element);
  
    /**
     * Replaces the element at the specified position in this list with the specified element
     * (optional operation).
     *
     * @param index index of the element to replace
     * @param element the element to be stored at the specified position
     * @throws UnsupportedOperationException if the <tt>set</tt> operation is not supported by this
     *     list IndexOutOfBoundsException if the index is out of range ({@code index < 0 || index >=
     *     size()})
     */
    void set(int index, ByteString element);
  
    /**
     * Replaces the element at the specified position in this list with the specified element
     * (optional operation).
     *
     * @param index index of the element to replace
     * @param element the element to be stored at the specified position
     * @throws UnsupportedOperationException if the <tt>set</tt> operation is not supported by this
     *     list IndexOutOfBoundsException if the index is out of range ({@code index < 0 || index >=
     *     size()})
     */
    void set(int index, byte[] element);
  
    /**
     * Appends all elements in the specified ByteString collection to the end of this list.
     *
     * @param c collection whose elements are to be added to this list
     * @return true if this list changed as a result of the call
     * @throws UnsupportedOperationException if the <tt>addAllByteString</tt> operation is not
     *     supported by this list
     */
    boolean addAllByteString(Collection<? extends ByteString> c);
  
    /**
     * Appends all elements in the specified byte[] collection to the end of this list.
     *
     * @param c collection whose elements are to be added to this list
     * @return true if this list changed as a result of the call
     * @throws UnsupportedOperationException if the <tt>addAllByteArray</tt> operation is not
     *     supported by this list
     */
    boolean addAllByteArray(Collection<byte[]> c);
  
    /**
     * Returns an unmodifiable List of the underlying elements, each of which is either a {@code
     * String} or its equivalent UTF-8 encoded {@code ByteString} or byte[]. It is an error for the
     * caller to modify the returned List, and attempting to do so will result in an {@link
     * UnsupportedOperationException}.
     */
    List<?> getUnderlyingElements();
  
    /**
     * Merges all elements from another LazyStringList into this one. This method differs from {@link
     * #addAll(Collection)} on that underlying byte arrays are copied instead of reference shared.
     * Immutable API doesn't need to use this method as byte[] is not used there at all.
     */
    void mergeFrom(LazyStringList other);
  
    /**
     * Returns a mutable view of this list. Changes to the view will be made into the original list.
     * This method is used in mutable API only.
     */
    List<byte[]> asByteArrayList();
  
    /** Returns an unmodifiable view of the list. */
    LazyStringList getUnmodifiableView();
  }
  