use strict;
use warnings;

my $pattern = qr{(?<!\\)(%[^\s]+)};


my @strings = (
    '%.02f foo',
    'foo %.02f',
    '%f.02f',
    'foo %0.02f bar',
    '\%f.02f',
    'foo \%.02f',
    '\%.02f foo',
    'foo \%.02f bar',
);

foreach my $string (@strings) {
    my @parts = split /$pattern/, $string;
    print "String: $string.  Parts: ", (map {'(' . $_ . ')'} @parts), "\n";
    my $c = 1;
    foreach my $part (@parts) {
        print $c++ % 2 ? "\tComponent: $part\n" : "\tDelimiter: $part\n";
    }
}