// Protocol Buffers - Google's data interchange format
// Copyright 2008 Google Inc. All rights reserved.
// http://code.google.com/p/protobuf/
//
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// modification, are permitted provided that the following conditions are
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//
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package com.google.protobuf;
import java.util.List;
/**
* An interface extending {@code List<String>} that also provides access to the
* items of the list as UTF8-encoded ByteString 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 is already cached.
* <p>
* This only adds additional methods that are required for the use in the
* protocol buffer code in order to be able successfully round trip byte arrays
* through parsing and serialization without conversion to strings. It's not
* attempting to support the functionality of say {@code List<ByteString>}, hence
* why only these two very specific methods are added.
*
* @author jonp@google.com (Jon Perlow)
*/
public interface LazyStringList extends List<String> {
/**
* 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);
/**
* 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);
/**
* Returns an unmodifiable List of the underlying elements, each of
* which is either a {@code String} or its equivalent UTF-8 encoded
* {@code ByteString}. 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();
}