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Groups > comp.compilers > #2971

Why is flex pattern-matching of NULs slow?

From Roger L Costello <costello@mitre.org>
Newsgroups comp.compilers
Subject Why is flex pattern-matching of NULs slow?
Date 2022-04-08 11:06 +0000
Organization Compilers Central
Message-ID <22-04-001@comp.compilers> (permalink)

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Hi Folks,

The Flex manual says this:

    Pattern-matching of NULs is substantially slower
    than matching other characters.

Why is that?

/Roger
[My recollection is that zero is used as a flag value in internal
tables and there is some slow kludge to say that this is a nul not the
flag, but perhaps someone who has looked at the code more recently
will remember the details. -John]

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Why is flex pattern-matching of NULs slow? Roger L Costello <costello@mitre.org> - 2022-04-08 11:06 +0000
  Why is flex pattern-matching of NULs slow? Christopher F Clark <christopher.f.clark@compiler-resources.com> - 2022-04-09 21:40 +0300

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