$str  = "  '==\\'==' '==5=='  '\\'\\'' '\\'3' '\\'' '1'  '' ";

my $pos = 0;
my $len = length $str;
my $last = '';
my $char;
while ( $pos < $len ) {
   $char = substr $str, $pos, 1;
   push @pos, $pos if $char eq "'" and $last ne "\\";
   $pos++;
   $last = $char;
}

for ( my $i= 0; $i <@pos; $i +=2 ) {
    my $begin = $pos[$i]+1;
    my $end   = $pos[$i+1];
    my $str   = substr $str, $begin, ($end -$begin);
    print "$begin $end |$str|\n";
}