Regular Expression Software (Mark Hopkins)
Thu, 17 Feb 1994 09:19:30 GMT

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Regular Expression Software (1994-02-17)
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Newsgroups: comp.compilers
From: (Mark Hopkins)
Keywords: tools, DFA, lex
Organization: Compilers Central
Date: Thu, 17 Feb 1994 09:19:30 GMT

      Source and documentation for:

                      regular expression -> finite automata conversion,
                      regular language accquisition,
              and a grep-like filter using extended regular expression notation

are all available. The grep-like filter literally stands out on its own.
With the inclusion of the Interleave Product (A^B, e.g. ab^c = cab+acb+abc)
you have a notation so powerful that it can even process anagrams. For
example, running

            rex -i "<(n^a^p^o^l^e^o^n)>" /usr/dict/words

will find any anagram of Napoleon from the dictionary (the -i option makes
the search case-insensitive).

      All the methods used are a revival of the ancient Brzozowski methods,
heavily algebraic in nature, but which somehow fell into disuse before
the Modern Era (> 1964).

      Source can be obtained by contacting me at
(or perhaps someone will be willing to devote some space at a FTP site?).

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