ptgdp: Implement barebones preprocessor commands

Now to put them to use

ptgdp

@@ -50,6 +50,12 @@ notify() {
 		"$1" \
 		"$2" > /dev/null 2>&1
 }
+execpreprocessor() {
+	# Execute a preprocessor line
+	# $1: The line, either stripped or not of the leading #:
+	line="${1#\#:}"
+	log "pp: $line"
+}
 checkforsong() {
 	# $1: A song name to validate
 	[ -z "$1" ] && return 1
@@ -209,6 +215,11 @@ validateline() {
 	# Strictly speaking, this removes all whitespace from the line
 	# While not *exactly* what I'm looking for, it's sufficient for trimming whitespace lines
 	local linenows=${1//[[:space:]]}
+	# Preprocessor commands
+	if ! [ "${1#\#:}" = "$1" ]; then
+		return 100
+	fi
+	# Comments and whitespace-only lines
 	if ! [ "${1#\#}" = "$1" ] || [ -z "$linenows" ]; then
 		return 1
 	fi
@@ -355,8 +366,9 @@ playlist() {
 	done < "$1"
 	log "Parsed playlist \"$1\" with $maxlines songs"
 	while read line; do
-		[ -z "$line" ] && continue
+		validateline "$line"
-		validateline "$line" || continue
+		case $? in
+			0)
 				rm "$_tmpfile"* > /dev/null 2>&1
 				# Do the do
 				queuesong "$line"
@@ -373,6 +385,14 @@ playlist() {
 						dlfailure+=1
 						;;
 				esac
+				;;
+			100)
+				execpreprocessor "$line"
+				;;
+			*)
+				continue
+				;;
+		esac
 	done < <(if [ -n "$_optshuffle" ]; then shuf "$1"; else cat "$1"; fi)
 	if [ "$dlexist" = "0" ] && [ "$dlsuccess" = "0" ] && [ -z "$_optdryrun" ]; then
 		notify "Failed to download playlist" \