content: // Protocol Buffers - Google's data interchange format
  // Copyright 2008 Google Inc.  All rights reserved.
  // https://developers.google.com/protocol-buffers/
  //
  // Redistribution and use in source and binary forms, with or without
  // modification, are permitted provided that the following conditions are
  // met:
  //
  //     * Redistributions of source code must retain the above copyright
  // 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.
  //     * Neither the name of Google Inc. nor the names of its
  // contributors may be used to endorse or promote products derived from
  // this software without specific prior written permission.
  //
  // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  
  package com.google.protobuf;
  
  /** Provide text format escaping support for proto2 instances. */
  final class TextFormatEscaper {
    private TextFormatEscaper() {}
  
    private interface ByteSequence {
      int size();
  
      byte byteAt(int offset);
    }
  
    /**
     * Escapes bytes in the format used in protocol buffer text format, which is the same as the
     * format used for C string literals. All bytes that are not printable 7-bit ASCII characters are
     * escaped, as well as backslash, single-quote, and double-quote characters. Characters for which
     * no defined short-hand escape sequence is defined will be escaped using 3-digit octal sequences.
     */
    static String escapeBytes(final ByteSequence input) {
      final StringBuilder builder = new StringBuilder(input.size());
      for (int i = 0; i < input.size(); i++) {
        final byte b = input.byteAt(i);
        switch (b) {
            // Java does not recognize \a or \v, apparently.
          case 0x07:
            builder.append("\\a");
            break;
          case '\b':
            builder.append("\\b");
            break;
          case '\f':
            builder.append("\\f");
            break;
          case '\n':
            builder.append("\\n");
            break;
          case '\r':
            builder.append("\\r");
            break;
          case '\t':
            builder.append("\\t");
            break;
          case 0x0b:
            builder.append("\\v");
            break;
          case '\\':
            builder.append("\\\\");
            break;
          case '\'':
            builder.append("\\\'");
            break;
          case '"':
            builder.append("\\\"");
            break;
          default:
            // Only ASCII characters between 0x20 (space) and 0x7e (tilde) are
            // printable.  Other byte values must be escaped.
            if (b >= 0x20 && b <= 0x7e) {
              builder.append((char) b);
            } else {
              builder.append('\\');
              builder.append((char) ('0' + ((b >>> 6) & 3)));
              builder.append((char) ('0' + ((b >>> 3) & 7)));
              builder.append((char) ('0' + (b & 7)));
            }
            break;
        }
      }
      return builder.toString();
    }
  
    /**
     * Escapes bytes in the format used in protocol buffer text format, which is the same as the
     * format used for C string literals. All bytes that are not printable 7-bit ASCII characters are
     * escaped, as well as backslash, single-quote, and double-quote characters. Characters for which
     * no defined short-hand escape sequence is defined will be escaped using 3-digit octal sequences.
     */
    static String escapeBytes(final ByteString input) {
      return escapeBytes(
          new ByteSequence() {
            @Override
            public int size() {
              return input.size();
            }
  
            @Override
            public byte byteAt(int offset) {
              return input.byteAt(offset);
            }
          });
    }
  
    /** Like {@link #escapeBytes(ByteString)}, but used for byte array. */
    static String escapeBytes(final byte[] input) {
      return escapeBytes(
          new ByteSequence() {
            @Override
            public int size() {
              return input.length;
            }
  
            @Override
            public byte byteAt(int offset) {
              return input[offset];
            }
          });
    }
  
    /**
     * Like {@link #escapeBytes(ByteString)}, but escapes a text string. Non-ASCII characters are
     * first encoded as UTF-8, then each byte is escaped individually as a 3-digit octal escape. Yes,
     * it's weird.
     */
    static String escapeText(final String input) {
      return escapeBytes(ByteString.copyFromUtf8(input));
    }
  
    /** Escape double quotes and backslashes in a String for unicode output of a message. */
    static String escapeDoubleQuotesAndBackslashes(final String input) {
      return input.replace("\\", "\\\\").replace("\"", "\\\"");
    }
  }
  