You may be able to use substr and length to accomplish this task much faster: 

chomp $key; # don't care about trailing newline, if any.
foreach my $combine (keys %$self) {
  if (substr($key, 0, length $combine) eq $combine) {
    print "Found (prefix $combine): ", substr ($key, length $combine),
+ "\n";
  }
  if (substr($key, -length $combine) eq $combine) {
    print "Found (suffix $combine): ",
      substr ($key, 0, length($key) - length $combine), "\n";
  }
}

[download]

This should avoid the overhead of compiling a regex, and the overhead of index (or rindex) searching in more places in the string then are needed.

It will of course not work if you want regex-type searching, of the keys of %$self.

I think that unless you could have your keys stored already ordered, it is likely that sorting overhead would outway any advantage gained through a binary search, etc.

In reply to Re: Fast sublist generation by wog
in thread Fast sublist generation by PetaMem

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.