incdec: Move point if negative hyphen is added or removed

Previously, point would stay in the same position, causing it to look
like it moved when incrementing or decrementing between a negative
number and a positive number. This moves point by one to the right when
decrementing to a negative integer, or by one to the left when
incrementing to a positive integer. That makes the point seem like it
hasn't moved and making it look more natural.

For example, now point behaves like this:

    $ test 12 0
              ^
    _decrement_

    $ test 12 -1
               ^

    $ test 12 -1
               ^
    _increment_

    $ test 12 0
              ^

Before, it would do:

    $ test 12 0
              ^
    _decrement_

    $ test 12 -1
              ^

    $ test 12 -1
               ^
    _increment_

    $ test 12 0
               ^

1 files changed, 23 insertions, 1 deletions

diff --git a/incdec b/incdec
index fe4670b..c253028 100644
--- a/incdec
+++ b/incdec
@@ -128,10 +128,32 @@ sub incdec {
 }
 
 function __readline_incdec_increment {
+	local old_line_length="${#READLINE_LINE}"
+
 	__readline_incdec 1 1
+
+	local new_line_length="${#READLINE_LINE}"
+
+	if [ "$old_line_length" -gt "$new_line_length" ]; then
+		READLINE_POINT="$(($READLINE_POINT - 1))"
+	fi
+}
+
+function __readline_incdec_decrement {
+	local old_line_length="${#READLINE_LINE}"
+
+	__readline_incdec -1 1
+
+	local new_line_length="${#READLINE_LINE}"
+
+	if [ "$old_line_length" -lt "$new_line_length" ]; then
+		READLINE_POINT="$(($READLINE_POINT + 1))"
+	# elif [ "$old_line_length" -gt "$new_line_length" ]; then
+	# 	READLINE_POINT="$(($READLINE_POINT - 1))"
+	fi
 }
 
-bind -x '"\C-x-": __readline_incdec -1 1'
+bind -x '"\C-x-": __readline_incdec_decrement'
 bind -x '"\C-x+": __readline_incdec_increment'