Add incdec.pl

This was from when I extracted the `incdec` function to a standalone
Perl script to test what was wrong with negative numbers in the second
position.

1 files changed, 56 insertions, 0 deletions

diff --git a/incdec.pl b/incdec.pl
new file mode 100755
index 0000000..e60922e
--- /dev/null
+++ b/incdec.pl
@@ -0,0 +1,56 @@
+#!/usr/bin/env perl -s
+#
+use strict;
+use warnings;
+
+sub incdec {
+	my ($line, $increment_by, $point_position, $is_backward) = @_;
+
+	$point_position ||= 0;
+	$is_backward ||= 0;
+
+	my $start_position = 0;
+	my $previous_match_start = 0;
+	while ($line =~ /\b(-?\d+)\b/g) {
+		if ($is_backward) {
+			if ($point_position < $-[0]) {
+				$start_position = $previous_match_start;
+
+				last;
+			}
+
+			$previous_match_start = $-[0];
+		}
+		else {
+			if ($point_position < $+[0]) {
+				$start_position = $-[0];
+
+				last;
+			}
+		}
+	}
+
+	if ($is_backward && $point_position == length $line) {
+		$start_position = $previous_match_start;
+	}
+
+	pos($line) = $start_position;
+	$line =~ s/\G([^-\d]*)(-?\d+)/$1 . ($2 + $increment_by)/e;
+
+	return $line;
+}
+
+# my $line = 'test 1 0';
+# my ${"increment-by"} = -1;
+# my ${"point-position"} = 8;
+# my $backward = 1;
+
+my $line = 'test 1 -2';
+my $increment_by = -1;
+my $point_position = 9;
+my $backward = 1;
+
+print "$line, $increment_by, $point_position, $backward\n";
+my $output = incdec($line, $increment_by, $point_position, $backward);
+print $output;
+print "\n";