Package org.evolvis.tartools.rfc822

Class FQDN

  • public class FQDN
extends Object

    Represents an FQDN (“domain” production) for use in eMail.

    The main entry point is the isDomain(String) method. The parser does not trim surrounding whitespace by itself.

    Author:
    mirabilos (t.glaser@tarent.de)

    • Constructor Summary

      Constructors 
      Modifier Constructor Description
      protected FQDN​(String input)
      Private constructor.

    • Method Summary

      All Methods Static Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      protected int accept()
      Advances the current position to the next character.
      protected int bra​(int deltapos)
      Jumps to a specified input character position, relative jump.
      protected int cur()
      Returns the wide character at the current position.
      boolean isDomain()
      Checks if a supposed hostname is a valid Fully-Qualified Domain Name.
      static boolean isDomain​(String hostname)
      Checks if a supposed hostname is a valid Fully-Qualified Domain Name.
      protected int jmp​(int pos)
      Jumps to a specified input character position, absolute jump.
      protected static <T extends org.evolvis.tartools.rfc822.Parser>
      T      		 of​(Class<T> cls, String input)
      Constructs a parser.
      static FQDN of​(String hostname)
      Creates and initialises a new parser for Fully-Qualified Domain Names.
      protected int peek()
      Returns the wide character after the one at the current position.
      protected int pos()
      Returns the current input character position.
      protected String s()
      Returns the input string, for use with substring comparisons.
      protected int skip​(Function<Integer,​Boolean> matcher)
      Advances the current position using a regular matcher.
      protected int skipPeek​(BiFunction<Integer,​Integer,​Boolean> matcher)
      Advances the current position using a peeking matcher.

    • Constructor Detail

      • FQDN

        protected FQDN​(String input)
        Private constructor. Use the factory method of(String) instead.
        Parameters:
        input - string to analyse

    • Method Detail

      • of

        public static FQDN of​(String hostname)
        Creates and initialises a new parser for Fully-Qualified Domain Names.
        Parameters:
        hostname - to parse
        Returns:
        null if hostname was null or longer than 254 characters, the new parser instance otherwise

      • isDomain

        public boolean isDomain()

        Checks if a supposed hostname is a valid Fully-Qualified Domain Name.

        Valid FQDNs are up to 254 octets in length, comprised only of labels (letters, digits and hyphen-minus, but not beginning or ending with a hyphen-minus) up to 63 octets long, separated by dots (‘.’).

        Strictly speaking an FQDN could be 255 octets in length, but these may cause problems with DNS and will not work in SMTP anyway.

        Returns:
        true if the hostname passed during construction is valid, else false

      • isDomain

        public static boolean isDomain​(String hostname)

        Checks if a supposed hostname is a valid Fully-Qualified Domain Name.

        Valid FQDNs are up to 254 octets in length, comprised only of labels (letters, digits and hyphen-minus, but not beginning or ending with a hyphen-minus) up to 63 octets long, separated by dots (‘.’).

        Strictly speaking an FQDN could be 255 octets in length, but these may cause problems with DNS and will not work in SMTP anyway.

        Parameters:
        hostname - to check
        Returns:
        true if hostname is valid, false otherwise

      • of

        protected static <T extends org.evolvis.tartools.rfc822.Parser> T of​(Class<T> cls,
                                                                     String input)

        Constructs a parser. Intended to be used by subclasses from static factory methods *only*; see Path.of(String) for an example.

        Type Parameters:
        T - subclass of Parser to construct
        Parameters:
        cls - subclass of Parser to construct
        input - user-provided String to parse
        Returns:
        null if input was null or too large, the new parser subclass instance otherwise

      • jmp

        protected final int jmp​(int pos)
        Jumps to a specified input character position, absolute jump.
        Parameters:
        pos - to jump to
        Returns:
        the codepoint at that position
        Throws:
        IndexOutOfBoundsException - if pos is not in or just past the input

      • bra

        protected final int bra​(int deltapos)
        Jumps to a specified input character position, relative jump.
        Parameters:
        deltapos - to add to the current position
        Returns:
        the codepoint at that position
        Throws:
        IndexOutOfBoundsException - if pos is not in or just past the input

      • pos

        protected final int pos()
        Returns the current input character position. Useful for saving and restoring (with jmp(int)) and for error messages.
        Returns:
        position

      • s

        protected final String s()
        Returns the input string, for use with substring comparisons. (This is safe because Java™ strings are immutable.)
        Returns:
        String input

      • cur

        protected final int cur()
        Returns the wide character at the current position.
        Returns:
        UCS-4 codepoint, or -1 if end of input is reached

      • peek

        protected final int peek()
        Returns the wide character after the one at the current position.
        Returns:
        UCS-4 codepoint, or -1 if end of input is reached

      • accept

        protected final int accept()
        Advances the current position to the next character.
        Returns:
        codepoint of the next character, or -1 if end of input is reached
        Throws:
        IndexOutOfBoundsException - if end of input was already reached

      • skipPeek

        protected final int skipPeek​(BiFunction<Integer,​Integer,​Boolean> matcher)
        Advances the current position using a peeking matcher. Continues as long as the matcher returns true and end of input is not yet reached.
        Parameters:
        matcher - gets called with cur() and peek() as arguments
        Returns:
        codepoint of the first character where the matcher returned false, or -1 if end of input is reached
        See Also:
        skip(Function)

      • skip

        protected final int skip​(Function<Integer,​Boolean> matcher)
        Advances the current position using a regular matcher. Continues as long as the matcher returns true and end of input is not yet reached.
        Parameters:
        matcher - gets called with just cur() as argument
        Returns:
        codepoint of the first character where the matcher returned false, or -1 if end of input is reached
        See Also:
        skipPeek(BiFunction)