Regex Library

Definitions

There has arisen some ambiguity in the use of the term Regular Expression. In different contexts, it is used to mean a number of subtly different things.

Some of the different uses of the term include:

• The classical Computer Science definition involving concatenation, selection and repetition over an alphabet;
• Text matching in the unix grep and egrep utilities;
• Search features in any number of text editors;
• Text matching in various versions of Perl.

Even within these groups, the extact definition of a regular expression can differ. Two good examples of this can be seen by comparing, in the first case, the grep and egrep utilities, and in the second, different versions in the evolution of Perl.

Given all these different definitions, what does this Regular Expression library do and where does it fit?

The best match above is to the classical Computer Science definition - what some refer to as pure regular expressions.

So, if your application requires features such as backtracking and substitutions, then this library is not suitable.

On the other hand, if you need the text matching capability of regular expressions and don't require any of the bells and whistles that have been grafted on top of the original, look no further.