1 files changed, 104 insertions, 0 deletions
diff --git a/incdec.bash b/incdec.bash
new file mode 100644
index 0000000..98ba10b
--- /dev/null
+++ b/incdec.bash
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+# Copyright (c) 2021  Teddy Wing
+#
+# This file is part of Incdec.
+#
+# Incdec is free software: you can redistribute it and/or modify it
+# under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# Incdec is distributed in the hope that it will be useful, but
+# WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+# General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with Incdec. If not, see <https://www.gnu.org/licenses/>.
+
+
+# Increment or decrement a number on the current line.
+function __readline_incdec {
+	local increment_by="$1"
+	local backward="$2"
+
+	line=$(perl -s -e '
+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 =~ /(-?\d+)/g) {
+		if ($is_backward) {
+			# Set start position to the current match start. This gives us the
+			# correct start position when incrementing the last number in a
+			# line.
+			$start_position = $-[0];
+
+			# If point is not at the end, set start position to the number
+			# closest to the point position.
+			if ($point_position < $-[0]) {
+				$start_position = $previous_match_start;
+
+				last;
+			}
+
+			$previous_match_start = $-[0];
+		}
+		else {
+			if ($point_position < $+[0]) {
+				$start_position = $-[0];
+
+				last;
+			}
+		}
+	}
+
+	pos($line) = $start_position;
+	$line =~ s/\G([^-\d]*)(-?\d+)/$1 . ($2 + $increment_by)/e;
+
+	return $line;
+}
+
+my $output = incdec($line, $increment_by, $point_position, $backward);
+print $output;
+' \
+		-- \
+		-line="$READLINE_LINE" \
+		-increment_by="$increment_by" \
+		-point_position="$READLINE_POINT" \
+		-backward="$backward"
+	)
+
+	READLINE_LINE="$line"
+}
+
+# Increment the nearest number to the left of point by 1.
+function __readline_incdec_increment {
+	local old_line_length="${#READLINE_LINE}"
+
+	__readline_incdec 1 1
+
+	local new_line_length="${#READLINE_LINE}"
+
+	# If a negative sign was removed, keep point where it was.
+	if [ "$old_line_length" -gt "$new_line_length" ]; then
+		READLINE_POINT="$(($READLINE_POINT - 1))"
+	fi
+}
+
+# Decrement the nearest number to the left of point by 1.
+function __readline_incdec_decrement {
+	local old_line_length="${#READLINE_LINE}"
+
+	__readline_incdec -1 1
+
+	local new_line_length="${#READLINE_LINE}"
+
+	# If a negative sign was added, keep point where it was.
+	if [ "$old_line_length" -lt "$new_line_length" ]; then
+		READLINE_POINT="$(($READLINE_POINT + 1))"
+	fi
+}