#!/usr/bin/perl --
use strict; use warnings; use Data::Dump;

my $root = 
[
  [
    [
      [
        [[["a", "b"], "c"], ["d", "e"]],
        [[["f", "g"], "h"], [["i", "j"], ["k", ["l", "m"]]]],
#~         [[["a", "b"], "cc"], ["dd", "ee"]],
#~         [[["a", "b"], "ccc"], ["ddd", "eee"]],
      ],
      ["n", [[["o", "p"], "q"], ["r", "s"]]],
    ],
    ["t", ["u", "v"]],
  ],
  [["w", ["x", "y"]], "z"],
];

my $leftstart = 1000;
my @lines;
my @rows;
my $leftestmost = 0;
my $rightestmost = 0;
Fudgy( $root, 0, 0, sub {
    my($node, $x,$y,$px,$py, $leftoright ) = @_;
    $leftestmost  = $x if $x < 0 and $leftestmost  > $x;
    $rightestmost = $x if $x > 0 and $rightestmost < $x;
    
    my $text = $node;
    if( ref $node ){
        my( $left, $right ) =  @$node;
        $text = '';
        $text .= '/' if $left;
        $text .= '\\' if $right;
    }
    
    
    my $xpd = abs(abs($px)-abs($x));
    
    
    $x = $leftstart + $x;
    push @{ $rows[ $y ] } ,  [ $x, $text , $px, $py ,  $xpd ];
    my $lll = $lines[ $y ]; $lll  ||= ' ' x ( 2 * $leftstart );;
    substr $lll, $x, length($text), $text;
    $lines[ $y ] = $lll;
    
    if( $y > 0 ){
        my $off   = $x + 1;
        my $rep   = '_' x ( $xpd - 1 );
        my $lline = $lines[ $y - 1];
        
        if( $leftoright > 0 ){
            $off -= length( $rep );
        }
        
        substr $lline, $off, length($rep),$rep;
        $lines[ $y -1 ] = $lline;
    }
    
} );

dd \@rows;
s/\s+$// for @lines;
$leftestmost = $leftstart + $leftestmost ;
s/^\s{$leftestmost}// for @lines;
print join "\n", @lines;



sub Fudgy {
    my( $node , $x, $y, $subref ) = @_;
    
    return if not @$node;
    
    my( $left, $right ) = @$node;
    
    $subref->( $node, $x, $y , $x, $y );
    
    $left  and draw_left(  $left, $x , $y , $subref );
    $right and draw_right($right, $x , $y , $subref );
}
sub draw_left {
    my( $node , $px, $py, $subref ) = @_;
    my $count = 0;
    my( $left, $right ) = eval { @$node };
    $right and $count = 1 + descendents_count( $right );
    my $x = $px - $count - 1;
    my $y = $py + 1;
    $subref->( $node, $x, $y, $px, $py , -1 );
    $left  and draw_left( $left , $x, $y, $subref );
    $right and draw_right( $right, $x, $y, $subref );
}
sub children_count {
    return 1 if not ref $_[0];
    return int @{ $_[0] };
}
sub descendents_count {
    my( $node  ) = @_;
    my( $left, $right ) = eval { @$node };
    my $count = 0;
    $left  and $count += 1 + descendents_count( $left );
    $right and $count += 1 + descendents_count( $right );
    return $count;
}
sub draw_right {
    my( $node , $px, $py, $subref ) = @_;
    my $count = 0;
    my( $left, $right ) = eval { @$node };
    $right and $count = 1 + descendents_count( $left );
    my $x = $px + $count + 1;
    my $y = $py + 1;
    $subref->( $node, $x, $y, $px, $py , +1 );
    $left  and draw_left( $left , $x, $y, $subref );
    $right and draw_right( $right, $x, $y, $subref );
}


__END__
__END__
__END__
__END__