TextFormatEscaper.java

// Protocol Buffers - Google's data interchange format
// Copyright 2008 Google Inc.  All rights reserved.
// https://developers.google.com/protocol-buffers/
//
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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 '