Re^2: Can't use an undefined value as a HASH reference

while (my $line = <>) {
  chomp $line;
    
  my $tree = build_subtree($line); 
  
  print Dumper $tree->{children}[0];
  
  print Dumper $tree;
  
  walk_postorder($tree,[\&mark_heads,\&annotate]);
    
  @{$tree->{children}}[0]->{label} =~ s/^\*//; # undo top-level merge
  
  print build_subtree_oneline($tree,1), $/;
}
[download]

I did have to use both prints. They gave output below.

$VAR1 = undef;
$VAR1 = {
          'children' => []
        };
[download]

Not sure where to go from here. But would the $line input be the cause of the problem? The build_subtree($line) subroutine uses it as input.

Also, the correct link to the original script is here: https://github.com/mjpost/dptsg/blob/master/scripts/annotate_spinal_grammar.pl

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Re^3: Can't use an undefined value as a HASH reference by stevieb (Canon) on Aug 25, 2015 at 16:08 UTC
Ok, so now take a step back, and tell us what data you are sending into your script, ie. how you are calling it and with what arguments (post a example snip from the input file). We need to know what is in `$line`. I can't get to the link with the rest of the code, so I'm unsure how `build_subtree` compiles its data, and what it expects to find. Do you have another link, or can you post the full code?	[reply] [d/l] [select]
Re^4: Can't use an undefined value as a HASH reference by Anonymous Monk on Aug 25, 2015 at 16:32 UTC
Thank you'll very much for the pointers. It helped me trace through the problem. It's now resolved. I see `build_tree` was expecting a string that began with parenthesis, like so: "(TOP (S (NP (NP (NNP Pierre) (NNP Vinken))".	[reply] [d/l]
Re^4: Can't use an undefined value as a HASH reference by Anonymous Monk on Aug 25, 2015 at 16:15 UTC
The `build_subtree` subroutine has a sanity test line as follows `if ($line !~ /^$.$\s$/) { print "here: $line\n"; return undef; }` [download] And input `$line` has "1 , 4885".	[reply] [d/l] [select]