incdec.bash: Set up point moving after start position

This doesn't work yet as it turns out it requires a change to the
`incdec()` Perl subroutine.

We want to move point when switching between positive and negative
numbers (adding or removing a hypen negative sign), but only if point is
on or after the start of the number being incremented. If point is
before that, it looks like it's moving.

Read the start index from the `incdec()` subroutine and prefix it to the
output line in the format: "${start_position}#${output_line}". We can
then use the "#" to split the two values and extract them in the Bash
functions.

Needed to move setting `$READLINE_LINE` to the increment and decrement
Bash functions because I now run `__readline_incdec` in a subshell,
meaning the current line can't be manipulated with that variable in that
function.

In the increment and decrement Bash functions, we now check if the start
position of the incremented number is less than or equal to
`$READLINE_POINT` before trying to move point.

3 files changed, 57 insertions, 16 deletions

diff --git a/incdec.bash b/incdec.bash
index 029d4ea..7144282 100644
--- a/incdec.bash
+++ b/incdec.bash
@@ -23,7 +23,7 @@ function __readline_incdec {
 	local increment_by="$1"
 	local backward="$2"
 
-	line=$(perl -s -e '
+	result="$(perl -s -e '
 sub incdec {
 	my ($line, $increment_by, $point_position, $is_backward) = @_;
 
@@ -76,28 +76,38 @@ my ($output, $start_position) = incdec(
 	$point_position,
 	$backward
 );
-print $output;
+print "$start_position\#$output";
 ' \
 		-- \
 		-line="$READLINE_LINE" \
 		-increment_by="$increment_by" \
 		-point_position="$READLINE_POINT" \
 		-backward="$backward"
-	)
+	)"
 
-	READLINE_LINE="$line"
+	echo "$result"
 }
 
 # Increment the nearest number to the left of point by 1.
 function __readline_incdec_increment {
 	local old_line_length="${#READLINE_LINE}"
 
-	__readline_incdec 1 1
+	result="$(__readline_incdec 1 1)"
+
+	line="${result#*#}"
+	READLINE_LINE="$line"
 
 	local new_line_length="${#READLINE_LINE}"
 
+	local start_position="${result%#*}"
+	echo "$start_position .. $READLINE_POINT"
+
 	# If a negative sign was removed, keep point where it was.
-	if [ "$old_line_length" -gt "$new_line_length" ]; then
+	if [ \
+		"$old_line_length" -gt "$new_line_length" \
+		-a \
+		"$start_position" -le "$READLINE_POINT" \
+	]; then
 		READLINE_POINT="$(($READLINE_POINT - 1))"
 	fi
 }
@@ -106,12 +116,23 @@ function __readline_incdec_increment {
 function __readline_incdec_decrement {
 	local old_line_length="${#READLINE_LINE}"
 
-	__readline_incdec -1 1
+	result="$(__readline_incdec -1 1)"
+
+	line="${result#*#}"
+	READLINE_LINE="$line"
 
 	local new_line_length="${#READLINE_LINE}"
 
+	local start_position="${result%#*}"
+	echo "$start_position .. $READLINE_POINT"
+
+	# TODO: Point should only move when it's over the number. No, actually when it's >= the start of the number.
 	# If a negative sign was added, keep point where it was.
-	if [ "$old_line_length" -lt "$new_line_length" ]; then
+	if [ \
+		"$old_line_length" -lt "$new_line_length" \
+		-a \
+		"$start_position" -le "$READLINE_POINT" \
+	]; then
 		READLINE_POINT="$(($READLINE_POINT + 1))"
 	fi
 }
diff --git a/incdec.m4.bash b/incdec.m4.bash
index ff6bb57..61e7f47 100644
--- a/incdec.m4.bash
+++ b/incdec.m4.bash
@@ -23,7 +23,7 @@ function __readline_incdec {
 	local increment_by="$1"
 	local backward="$2"
 
-	line=$(perl -s -e '
+	result="$(perl -s -e '
 INCLUDE_INCDEC_PL
 ' \
 		-- \
@@ -31,21 +31,31 @@ INCLUDE_INCDEC_PL
 		-increment_by="$increment_by" \
 		-point_position="$READLINE_POINT" \
 		-backward="$backward"
-	)
+	)"
 
-	READLINE_LINE="$line"
+	echo "$result"
 }
 
 # Increment the nearest number to the left of point by 1.
 function __readline_incdec_increment {
 	local old_line_length="${#READLINE_LINE}"
 
-	__readline_incdec 1 1
+	result="$(__readline_incdec 1 1)"
+
+	line="${result#*#}"
+	READLINE_LINE="$line"
 
 	local new_line_length="${#READLINE_LINE}"
 
+	local start_position="${result%#*}"
+	echo "$start_position .. $READLINE_POINT"
+
 	# If a negative sign was removed, keep point where it was.
-	if [ "$old_line_length" -gt "$new_line_length" ]; then
+	if [ \
+		"$old_line_length" -gt "$new_line_length" \
+		-a \
+		"$start_position" -le "$READLINE_POINT" \
+	]; then
 		READLINE_POINT="$(($READLINE_POINT - 1))"
 	fi
 }
@@ -54,13 +64,23 @@ function __readline_incdec_increment {
 function __readline_incdec_decrement {
 	local old_line_length="${#READLINE_LINE}"
 
-	__readline_incdec -1 1
+	result="$(__readline_incdec -1 1)"
+
+	line="${result#*#}"
+	READLINE_LINE="$line"
 
 	local new_line_length="${#READLINE_LINE}"
 
+	local start_position="${result%#*}"
+	echo "$start_position .. $READLINE_POINT"
+
 	# TODO: Point should only move when it's over the number. No, actually when it's >= the start of the number.
 	# If a negative sign was added, keep point where it was.
-	if [ "$old_line_length" -lt "$new_line_length" ]; then
+	if [ \
+		"$old_line_length" -lt "$new_line_length" \
+		-a \
+		"$start_position" -le "$READLINE_POINT" \
+	]; then
 		READLINE_POINT="$(($READLINE_POINT + 1))"
 	fi
 }
diff --git a/incdec.m4.pl b/incdec.m4.pl
index b5d3c72..cd31dc5 100644
--- a/incdec.m4.pl
+++ b/incdec.m4.pl
@@ -6,4 +6,4 @@ my ($output, $start_position) = incdec(
 	$point_position,
 	$backward
 );
-print $output;
+print "$start_position\#$output";