|regular expression search algorithm firstname.lastname@example.org (1993-03-18)|
|Reg. expr. character class compression email@example.com (1993-03-18)|
|Reg. expr. character class compression firstname.lastname@example.org (1993-03-21)|
|From:||email@example.com (Dennis Ritchie)|
|Date:||Sun, 21 Mar 1993 06:19:52 GMT|
Keep in mind that during the next few years the potential size of the
character set and hence of a character class is likely to increase from
about 256 to about 65536. Converting the Plan 9 regular expression stuff
to Unicode wasn't trivial. (But I didn't do the work and don't know what
techniques were used.)
Another note: the regular expression algorithm described by Thompson was
patented; the patent must have issued around 1973. AT&T never prosecuted
it, and it has probably expired; I mention it as a curiosity, and as an
illustration that software patents are not especially new.
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