There exists GraphViz::Regex which visualises a regex as a graph.

My idea was to visualise what happens to that graph when an input string is run against the regex. And then find unvisited or failed nodes. Sorry, that's a rough sketch. Whatever the way, I don't know how to do that. BUT! there is re_graph.pl which claims to not only visualise a regex but also visualise it when run against some input, see the example parsing perl comments. The author is Steve Oualline. Unfortunately I did not manage to get that example to work.

Update: along the lines of the above rough sketch I found (again I think?) this online regex visualiser https://blog.robertelder.org/regular-expression-visualizer/ which shows that it is visible. Anonymous Monk has a way to conveniently extract all the info from running the regex against some input: Re: Tell or determine whichever Perl regex group fails

bw, bliako

In reply to Re: Tell or determine whichever Perl regex group fails by bliako
in thread Tell or determine whichever Perl regex group fails by Anonymous Monk

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.