Re: Multi-Line Definitions

[Eric Blake]

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According to Ralf Wildenhues on 9/29/2007 11:23 AM:
>>      Enhance previous patch's handling of raw newlines.
>>      * lib/autoconf/general.m4 (_AC_RAW_NEWLINE_RE): New macro.
>>      (AC_DEFINE, AC_DEFINE_UNQUOTED): Die on raw newlines in value.
> 
> Won't this slow down `autoconf' by much?

Well, autoconf does use a lot of regex operations already.  On autoconf
itself, 'autoconf -t m4_bpatsubst -t m4_bregexp -d', followed by 'grep
"^AT_m4_b" $TMPDIR/am4t*/traces.m4 |wc' shows more than 10000 regular
expression matches.

Maybe m4 should be taught to cache the most recent few regular
expressions, as the same patterns are used rather frequently.  For
example, "grep '\[\[`\$\]\])$' trace' shows that there were 311 repeats of
the regex [[`$]].

You've given me a good idea - I'll try instrumenting a version of m4 and
coming up with a good list of the most popular regex patterns in use by
autoconf (autoconf -t has limitations, since regex patterns tend to mess
up the quoting of the trace file).

- --
Don't work too hard, make some time for fun as well!

Eric Blake             address@hidden
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