On 03/12/2015 04:36 PM, Matěj Týč wrote: > Hello, > I am doing some m4sugar programming and I found the m4_pattern_forbid > insufficient. > As we all know, there are many kinds of regular expression in different > programs and even on different OSs (grep, vim, Python, linux sed, osx > sed, ...). So my question is - where should I look to learn what kind of > regular expression I can specify to that macro? It is an extended regular expression according to what perl understands (which is similar to what 'grep -E' understands). > > Interestingly, I took a look at the autoconf/m4sugar/m4sugar.m4:2005 to > learn the definition and I was surprised by what I have found there: > > # m4_pattern_forbid(ERE, [WHY]) > # ----------------------------- > # Declare that no token matching the forbidden extended regular > # expression ERE should be seen in the output unless... > m4_define([m4_pattern_forbid], []) > > I was unable to find the true macro's definition anywhere, so here is > the second question: How (and where) is m4_pattern_forbid defined? That's exactly where it is defined in m4. What you are really looking for is the code that traces all no-op uses of that definition and then greps the output for those forbidden patterns. For that, look at bin/autom4te.in, for 'sub warn_forbidden'. It is one of several m4sugar constructs that is done by the autom4te perl wrapper that invokes m4 and post-processes the output, rather than directly by m4. Would you like to propose a documentation patch to make it clear that the flavor of regex in use by this macro is what perl understands? -- Eric Blake eblake redhat com +1-919-301-3266 Libvirt virtualization library http://libvirt.org
Attachment:
signature.asc
Description: OpenPGP digital signature
_______________________________________________ Autoconf mailing list Autoconf@xxxxxxx https://lists.gnu.org/mailman/listinfo/autoconf
