Documentation of the module re

by Peter Verhas

Table of Contents


1. Introduction


2. The module RE

This module implements some simple regular expression handling functions. They can be used to match some strings against regular expressions and to use matched sub strings to format replace strings. This module provides functions that are similar to the Perl language operators m// and s///.


3. Match a string against a regular expression

re::match(string,regexp [, replace])
re::m(string,regexp [, replace])

This function is the main regular expression match function. The first argument is the string that is to be matched against the regular expression. The second argument is the regular expression. If the string matches the regular expression the return value of the function is true, otherwise false. The regular expressions may contain parentheses inside it. If it does the substrings matching the regular expression part between the parentheses will be stored in a regular expression dollar array.

The substrings can be accessed via the function re::dollar() dollar.

If there is a replace string defined the return value is either false if the string is not matched by the regular expression; or the replace string itself. The replace string may contain $0, $1, ... $n literal that will be replaced by the actual substrings between the parentheses. This is the same way as Perl does.

$0 is the substring matched by the whole regular expression.

For example:

import re.bas

print "match result=",re::match("ahlma","h(.*)","haho $0 $1 $0 q") print n = re::n() print "number of ()s =",n print for i=0 to n print i,". " print re::dollar(i) print next i

will print
match result=haho hlma lma hlma q
number of ()s =1
0. hlma
1. lma
Note that the short for re::m exists in case you are a Perl knowing programmer, because this function is similar to the Perl operator =~ m/.


4. number of matches

return the number of usable matches substrings


5. Return the i-th sub string


return the i-th matched substring


6. Reset matches


Delete the dollar string array and release all memory that was allocated during the last match. This function is autoamtically invoked between matches.


7. Format a string with replacement sub-strings


Use this function to format a string using the $1, $2, ... $n placeholders to be replaced by the actual strings after a successful pattern matching.


8. Search and replace

This function searches the string for matches of the regular expression and replaces the actual matches with the replace string. This is the same functionality as the =~s/ operator in Perl.

The function fills the dollar array the same way as the function match.

For example

import re.bas

print re::s("almakbat*","a(.)","$1s") print print re::$(0)," ",re::$(1) print

will print

at t

As you can see in this case the value of re::$(0) is the string that was matched by the last replace inside the string.