The ASCII character classes are handled with bitmaps.

From the 5.6.1 regcomp.c, the UTF8 classes are handled with RVs. Check out S_regclassutf8(pTHX) with the code 

    if (!SIZE_ONLY) {
        SV *rv = swash_init("utf8", "", listsv, 1, 0);
#ifdef DEBUGGING
        AV *av = newAV();
        av_push(av, rv);
        av_push(av, listsv);
        rv = newRV_noinc((SV*)av);
#else
        SvREFCNT_dec(listsv);
#endif
        n = add_data(1,"s");
        PL_regcomp_rx->data->data[n] = (void*)rv;
        ARG1_SET(ret, flags);
        ARG2_SET(ret, n);
    }

[download]
-Mark

In reply to Re: How are regex character classes implemented? by kvale
in thread How are regex character classes implemented? by John M. Dlugosz

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.