June 2026 - pro - mailman3.common-lisp.net

Re: Question about CL-PPCRE
by Marco Antoniotti 24 Jun '26

24 Jun '26

Thanks Martin. That's it. Workarounds? Shall I just roll out my own replacement function? Note that in my case I really just need (replace-string-in <source string> <replacement indicator string> <replacement>) MA On Wed, Jun 24, 2026 at 12:09 PM Martin Simmons <martin(a)lispworks.com> wrote: > >>>>> On Tue, 23 Jun 2026 20:47:32 +0200, Marco Antoniotti (as marco dot > antoniotti at unimib dot it) said: > > > > Hi > > > > I am sure I missed something in the CL-PPCRE documentation, but here it > is. > > > > I am fooling around with a C tokenizer and I am running into the > following > > problem. > > > > The string esre contains the "escape sequences" for C (and Perl, etc etc) > > > > CL Prompt > esre > > "(\\\\(['\\\"\\?\\\\abfnrtv]|[0-7]{1,3}|x[a-fA-F0-9]+))" > > > > If I use CL-PPCRE:REPLACE-ALL I get the following (I tried to boil it > down): > > > > CL Prompt > (regex-replace-all "\\$<ES>" "/$<ES>/" esre) > > "/(\\(['\\\"\\?\\abfnrtv]|[0-7]{1,3}|x[a-fA-F0-9]+))/" > > T > > > > Apart from the bounding slashes, I would have expected the result of > > CL-PPCRE:REPLACE-ALL not to return a shorter string. > > > > What exactly (backslash escaping for sure) am I missing? > > It looks like an undocumented feature of the replacement string: \\ is > converted to a single backslash by CL-PPCRE::BUILD-REPLACEMENT-TEMPLATE. > That > means it will always return a shorter string when \\ is present in the > replacement string and if you want \\ in the output then you'll need to use > \\\\ (i.e. 8 backslashes in the Lisp syntax of that string!). > > Also, to make it more confusing, if \ is followed by anything other than \ > & ` > ' digits or {digits} then it is also treated as a single backslash. i.e. > \a > is \a. > > -- > Martin Simmons > LispWorks Ltd > http://www.lispworks.com/ > > _______________________________________________ > Lisp Hug - the mailing list for LispWorks users > lisp-hug(a)lispworks.com > http://www.lispworks.com/support/lisp-hug.html > -- Marco Antoniotti, Professor, Director tel. +39 - 02 64 48 79 01 DISCo, University of Milan-Bicocca U14 2043 http://dcb.disco.unimib.it Viale Sarca 336 I-20126 Milan (MI) ITALY REGAINS: https://regains.disco.unimib.it/

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Question about CL-PPCRE
by Marco Antoniotti 24 Jun '26

24 Jun '26

Hi I am sure I missed something in the CL-PPCRE documentation, but here it is. I am fooling around with a C tokenizer and I am running into the following problem. The string *esre* contains the "escape sequences" for C (and Perl, etc etc) CL Prompt > *esre* "(\\\\(['\\\"\\?\\\\abfnrtv]|[0-7]{1,3}|x[a-fA-F0-9]+))" If I use CL-PPCRE:REPLACE-ALL I get the following (I tried to boil it down): CL Prompt > *(regex-replace-all "\\$<ES>" "/$<ES>/" esre)* "/(\\(['\\\"\\?\\abfnrtv]|[0-7]{1,3}|x[a-fA-F0-9]+))/" T Apart from the bounding slashes, I would have expected the result of CL-PPCRE:REPLACE-ALL not to return a shorter string. What exactly (backslash escaping for sure) am I missing? Thanks. -- MA

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CL-INTERPOL and CL-PPCRE
by Marco Antoniotti 17 Jun '26

17 Jun '26

Hi I would like to munge regex strings to interpolate substrings in them (I know you can do that in CL-PPCRE using the SEXP based regexps). Something equivalent *(defvar L "[A-Za-z]")* *(scan #?"|${L}+|" " |foobar|...")* But I would like to build the interpolated string dynamically, i.e., *before* I create the *L* variable. In other words, I would like to interpolate at the latest possible time. I know I am doing something wrong. Thanks -- Marco

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