[lug] parsing between two lists

[Tkil]

>>>>> "Tkil" == tkil  <tkil at scrye.com> writes:

|    my $first = <FIRST>;
|    my $second = <SECOND>;
|
|    while (defined($first) && defined($second))
|    {
|        if ($first lt $second)
|        {
|            print IN_FIRST $first;
|            $first = <FIRST>;
|        }
|        elsif ($first gt $second)
|        {
|            print IN_SECOND $second;
|            $second = <SECOND>;
|        }
|        else
|        {
|            print IN_COMMON $first;
|            $first = <FIRST>;
|            $second = <SECOND>;
|        }
|    }
|
|    # take care of stragglers
|    if (defined($first))
|    {
|        while ($first = <FIRST>)   { print $first; }
|    }
|    else
|    {
|        while ($second = <SECOND>) { print $second }
|    }

that last bit is probably wrong.  consider:

   first:  a b c d f g
   second: a b c d e

the first four get caught by the "common" case at the top.  after
that, $second is undef, so it drops out.  $first is still defined (to
be "f"), so we drop into the first straggler case.  and there's the
problem: we immediately overwrite $first with the next letter ("g").

huh.  i forgot to send the output to the appropriate filehandles, at
that.  bad tkil, no donut.

so, we want something more like this:

|    # take care of stragglers
|    if (defined($first))
|    {
|        do
|        {
|            print IN_FIRST $first;
|        }    
|        while ($first = <FIRST>);
|    }
|    else
|    {
|        do
|        {
|            print IN_SECOND $second;
|        }    
|        while ($second = <SECOND>);
|    }

mm... this nugget is quite shiny by now, ain't it?

t.