Regular expressions
Regular expressions can be viewed a limited kind of programming language. They are often used for pattern matching, text replacement and general text transformation tasks.
Regular expression engines tend to be very bespoke and non-portable. Throughout the history of UNIX, a shared library for regular expressions remained elusive.
Nevertheless, regular expressions are implemented in multiple programming languages and various tools. Sometimes, this leads to inconsistencies, which are well documented in the sources below.
- 1968: Regular Expression Search Algorithm
- by Ken Thompson
- IBM 7094 cheatsheet
- 1987: Structural Regular Expressions
- by Rob Pike
- 2007: Implementing Regular Expressions (lecture)
- by Russ Cox