Class InternetDomainName

corpus/java/training/guava/net/InternetDomainName.java:70–513

An immutable well-formed internet domain name, such as com or foo.co.uk. Only syntactic analysis is performed; no DNS lookups or other network interactions take place. Thus there is no guarantee that the domain actually exists on the internet. One common use of this class is to d

 * @since 5.0
 */
@Beta
@GwtCompatible
public final class InternetDomainName {

  private static final CharMatcher DOTS_MATCHER = CharMatcher.anyOf(".\u3002\uFF0E\uFF61");
  private static final Splitter DOT_SPLITTER = Splitter.on('.');
  private static final Joiner DOT_JOINER = Joiner.on('.');

  /**
   * Value of {@link #publicSuffixIndex} which indicates that no public suffix was found.
   */
  private static final int NO_PUBLIC_SUFFIX_FOUND = -1;

  private static final String DOT_REGEX = "\\.";

  /**
   * Maximum parts (labels) in a domain name. This value arises from the 255-octet limit described
   * in <a href="http://www.ietf.org/rfc/rfc2181.txt">RFC 2181</a> part 11 with the fact that the
   * encoding of each part occupies at least two bytes (dot plus label externally, length byte plus
   * label internally). Thus, if all labels have the minimum size of one byte, 127 of them will fit.
   */
  private static final int MAX_PARTS = 127;

  /**
   * Maximum length of a full domain name, including separators, and leaving room for the root
   * label. See <a href="http://www.ietf.org/rfc/rfc2181.txt">RFC 2181</a> part 11.
   */
  private static final int MAX_LENGTH = 253;

  /**
   * Maximum size of a single part of a domain name. See
   * <a href="http://www.ietf.org/rfc/rfc2181.txt">RFC 2181</a> part 11.
   */
  private static final int MAX_DOMAIN_PART_LENGTH = 63;

  /**
   * The full domain name, converted to lower case.
   */
  private final String name;

  /**
   * The parts of the domain name, converted to lower case.
   */
  private final ImmutableList<String> parts;

  /**
   * The index in the {@link #parts()} list at which the public suffix begins. For example, for the
   * domain name {@code www.google.co.uk}, the value would be 2 (the index of the {@code co} part).
   * The value is negative (specifically, {@link #NO_PUBLIC_SUFFIX_FOUND}) if no public suffix was
   * found.
   */
  private final int publicSuffixIndex;

  /**
   * Constructor used to implement {@link #from(String)}, and from subclasses.
   */
  InternetDomainName(String name) {
    // Normalize: