Data commit

Task/Tree-datastructures/Perl/tree-datastructures.pl

@@ -0,0 +1,59 @@
+use strict;
+use warnings;
+use feature 'say';
+use JSON;
+use Data::Printer;
+
+my $trees = <<~END;
+    RosettaCode
+      encourages
+        code
+          diversity
+          comparison
+      discourages
+        golfing
+        trolling
+        emphasising execution speed
+    code-golf.io
+      encourages
+        golfing
+      discourages
+        comparison
+    END
+
+my $level = '  ';
+sub nested_to_indent { shift =~ s#^($level*)# ($1 ? length($1)/length $level : 0) . ' ' #egmr }
+sub indent_to_nested { shift =~ s#^(\d+)\s*# $level x $1 #egmr }
+
+say my $indent = nested_to_indent $trees;
+    my $nest   = indent_to_nested $indent;
+
+use Test::More;
+is($trees, $nest, 'Round-trip');
+done_testing();
+
+# Import outline paragraph into native data structure
+sub import {
+    my($trees) = @_;
+    my $level = '  ';
+    my $forest;
+    my $last = -999;
+
+    for my $branch (split /\n/, $trees) {
+        $branch =~ m/(($level*))*/;
+        my $this = $1 ? length($1)/length($level) : 0;
+        $forest .= do {
+            if    ($this gt $last) { '['                   . trim_and_quote($branch) }
+            elsif ($this lt $last) { ']'x($last-$this).',' . trim_and_quote($branch) }
+            else                   {                         trim_and_quote($branch) }
+        };
+        $last = $this;
+    }
+    sub trim_and_quote { shift =~ s/^\s*(.*\S)\s*$/"$1",/r }
+
+    eval $forest . ']' x (1+$last);
+}
+
+my $forest = import $trees;
+say "Native data structure:\n" . np $forest;
+say "\nJSON:\n" . encode_json($forest);