Utilities.java

package com.senzing.g2.engine;

class Utilities {
  /**
   * Formats a <code>long</code> integer value as hexadecimal with spaces between each group of for
   * hex digits.
   *
   * @param value The value to format.
   * @return The value formatted as a {@link String}.
   */
  public static String hexFormat(long value) {
    StringBuilder sb = new StringBuilder(20);
    long mask = 0xFFFF << 48;
    String prefix = "";

    for (int index = 0; index < 4; index++) {
      long masked = value & mask;
      mask = mask >>> 16;
      masked = masked >>> ((3 - index) * 16);
      sb.append(prefix);
      String hex = Long.toUnsignedString(masked, 16);
      for (int zero = hex.length(); zero < 4; zero++) {
        sb.append("0");
      }
      sb.append(hex);
      prefix = " ";
    }

    return sb.toString();
  }

  /**
   * Escapes the specified {@link String} into a JSON string with the the surrounding double quotes.
   * If the specified {@link String} is <code>null</code> then <code>"null"</code> is returned.
   *
   * @param string The {@link String} to escape for JSON.
   * @return The quoted escaped {@link String} or <code>"null"</code> if the specified parameter is
   *     <code>null</code>.
   */
  public static String jsonEscape(String string) {
    if (string == null) return "null";
    int escapeCount = 0;
    for (int index = 0; index < string.length(); index++) {
      char c = string.charAt(index);
      escapeCount +=
          switch (c) {
            case '\b', '\f', '\n', '\r', '\t', '"', '\\':
              yield 1;
            default:
              yield (c < ' ') ? 6 : 0;
          };
    }
    if (escapeCount == 0) return "\"" + string + "\"";
    StringBuilder sb = new StringBuilder(string.length() + escapeCount + 2);
    sb.append('"');
    for (int index = 0; index < string.length(); index++) {
      char c = string.charAt(index);
      switch (c) {
        case '"', '\\':
          sb.append('\\').append(c);
          break;
        case '\b':
          sb.append("\\b");
          break;
        case '\f':
          sb.append("\\f");
          break;
        case '\n':
          sb.append("\\n");
          break;
        case '\r':
          sb.append("\\r");
          break;
        case '\t':
          sb.append("\\t");
          break;
        default:
          if (c >= ' ') sb.append(c);
          else {
            sb.append("\\u00");
            String hex = Integer.toHexString(c);
            if (hex.length() == 1) {
              sb.append("0"); // one more zero if single-digit hex
            }
            sb.append(hex);
          }
      }
      ;
    }
    sb.append('"');

    // return the escaped string
    return sb.toString();
  }
}