sub parse_foo {
    my ($text) = @_;
    my $name;
    {
        last if $text =~ /\G \s* \Z/gcmsx;

        if     ($text =~ /\G \s* ^ \s* begfoo \s+ (\S+?) \s* \( \s* (.*?) \s* \) \s* ;/gcmsx) { $name = $1 }
        elsif  ($text =~ /\G \s* ^ \s* endfoo            /gcmsx) { }
        elsif  ($text =~ /\G \s* ^ \s* \S+ \s+  .*? \s* ;/gcmsx) { }
        else { die "ERROR: unknown syntax\n" }

        redo;
    }
    print "LAST FOO: $name\n";
}

##</code><code>##

  last if $text =~ /\G \s* \Z/gcmsx;
  # spent   181ms making 866465 calls to main::CORE:match, avg 208ns/call
  if     ($text =~ /\G \s* ^ \s* begfoo \s+ (\S+?) \s* \( \s* (.*?) \s* \) \s* ;/gcmsx) { $name = $1 }
  # spent  3.74s making 2547279 calls to main::CORE:match, avg 1µs/call

##</code><code>##

  last if $text =~ /\G \s* \Z/gcmsx;
  # spent  289ms making 866465 calls to main::CORE:match, avg 334ns/call
  if     ($text =~ /\G \s* ^ \s* begfoo \s+ (\S+?) \s* \( \s* (.*?) \s* \) \s* ;/gcmsx) { $name = $1 }
  # spent   103s making 2547279 calls to main::CORE:match, avg 41µs/call