SPAN

    Creates a pattern matching the longest string containing only
    characters from the specified string, range, or buffer.

 Syntax

    pattern := SPAN ({string | range | buffer} [, {FORWARD | REVERSE}])

    Parameters

    string               A string containing the characters that VAXTPU is
                         to match in the searched text.

    range                A range containing the characters that VAXTPU is
                         to match in the searched text.

    buffer               A buffer containing the characters that VAXTPU is
                         to match in the searched text.

    FORWARD              A keyword directing VAXTPU to match characters in
                         the forward direction.

    REVERSE              A keyword directing VAXTPU to match characters as
                         follows:  First, match characters in the forward
                         direction until VAXTPU finds a character that is
                         not a member of the set of characters in the
                         specified buffer, range, or string.  Next, return
                         to the first character that SPAN matched and start
                         matching characters in the reverse direction until
                         VAXTPU finds a character not in the specified
                         buffer, range, or string.  You can specify REVERSE
                         only if you are using SPAN in the first element of
                         a pattern being used in a reverse search.  In
                         other contexts, specifying REVERSE has no effect.

                         The behavior enabled by REVERSE allows an
                         alternate form of reverse search.  By default, a
                         reverse search stops as soon as a successful match
                         occurs, even if there might have been a longer
                         successful match in the reverse direction.  By
                         specifying REVERSE with SPAN, you direct VAXTPU
                         not to stop matching in either direction until it
                         has matched as many characters as possible.

 Comments

    SPAN matches one or more characters, each of which must appear in the
    string, range, or buffer passed as the first parameter.  SPAN matches
    as many characters as possible, stopping only if it finds a character
    not present in the string, range, or buffer, or if it reaches the end
    of a line.  SPAN does not cross line boundaries.  To match a pattern
    that may cross one or more line boundaries, use SPANL.

 Examples


    1.  pat1 := SPAN ("1234567890");

        Creates a pattern matching any sequence of numerals and any number
        of contiguous digits on one line.

    2.  pat1 := SPAN ("1234567890", FORWARD);

        This statement has exactly the same effect as Example 1.

    3.  vowel_pattern := SPAN ('aeiouy', REVERSE);

        This statement defines the variable "vowel_pattern" to mean the
        longest string of characters that are all vowels.  If you use the
        following statement:

        the_range := SEARCH (vowel_pattern, REVERSE);

        when the cursor is on the "a" in the word "liaison", then the
        variable "the_range" contains the string "iai".  This is because
        when you use SPAN with REVERSE as the first element of a pattern,
        and then use that pattern in a reverse search, SPAN matches as many
        characters as possible in both the forward and reverse directions.

        If the cursor is on the "a" but you define the variable
        "vowel_pattern" without the REVERSE keyword, like this:

        vowel_pattern := SCAN ('aeiouy');

        and then do a reverse search, "the_range" contains the string "ai",
        showing that the search matched from the starting point forward but
        did not return to the starting point to match backward as well.


 Related Topics

 ANCHOR       ANY       ARB              MATCH      NOTANY     SCAN
 SCANL        SEARCH    SEARCH_QUIETLY   SPANL      UNANCHOR