Creating Advanced Reply Expressions

Reply expressions of operator messages can be written as http://java.sun.com/javase/6/docs/api/java/util/regex/package-summary.html, which have a syntax similar to that used by Perl. Regular expressions are used to match a character sequence in a string, here they are used to force valid answers and can be used to create lists of pre-defined answers.

With the use of regular expression, you can force operators to provide a reply that matches a specific pattern, the table below lists some of the characters that have a special meaning in regular expressions.

Note Note

Empty replies are not accepted!

End of the note.

Note Note

Spaces before and after the reply are trimmed. Multiple spaces and/or tabs in a sequence in the reply are replaced with one space. This means that replies consisting of spaces and/or tabs only are not allowed. It is not possible to answer a reply expression like \s or \s+.

End of the note.

Special character	meaning
.	Any one character (equivalent to '?' on Microsoft Windows systems)
*	Used in conjunction with another character, the previous character sequence repeated zero or more times.
+	Used in conjunction with another character, the previous character sequence repeated one or more times.
?	Used in conjunction with another character, the previous character sequence repeated once or not at all.
^	Starts with
\|	The "or" character
$	Ends with
\	The escape character, used as prefix to specify any special character

The following table lists some special patters patterns:

Patterns	Description
\n	A newline character
\d	A digit
\D	Anything but a digit

The following constructs are frequently used:

^a|b|c$ - a combo-box which offers valid answers, "a", "b" or "c"
.* - Any reply accepted (except spaces, null replies).
.+ - Any reply accepted (except spaces; the regular expression disallows null replies).
\d+ - Any number of digits, used to require a job id.