Discussion:
history of use of Regular Expressions in computer code
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Dallas
2020-06-06 15:43:59 UTC
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When did we start using Regular Expressions in computer code?
John Levine
2020-06-06 18:48:10 UTC
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Post by Dallas
When did we start using Regular Expressions in computer code?
In 1968, when Ken Thompson published this article in the CACM:

https://dl.acm.org/doi/10.1145/363347.363387

Kleene described regular expressions as a mathematical concept in the
1950s but Thompson's paper showed how he used them as search patterns
in the qed text editor and compiled them to 7094 machine code NFAs to
make the searching fast.

Later the same year a group at MIT published a paper about using REs
to create the lexer step in the AED compiler, but I think Thompson's
paper was more influential.

https://dl.acm.org/doi/10.1145/364175.364185

Both of those turned the RE into an NFA. The mathematical proof that
any NFA can be turned into a DFA was published in 1959 but as far as I
know the first DFA search was published by Aho and Corasick in 1975:

https://dl.acm.org/doi/10.1145/360825.360855
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