command/queue: move position parameter functions to separate library

meson.build

@@ -267,6 +267,7 @@ sources = [
   'src/protocol/ArgParser.cxx',
   'src/protocol/Result.cxx',
   'src/command/CommandError.cxx',
+  'src/command/PositionArg.cxx',
   'src/command/AllCommands.cxx',
   'src/command/QueueCommands.cxx',
   'src/command/TagCommands.cxx',

src/command/PositionArg.cxx

+/*
+ * Copyright 2003-2021 The Music Player Daemon Project
+ * http://www.musicpd.org
+ *
+ * This program 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 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program 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 this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#include "PositionArg.hxx"
+#include "protocol/Ack.hxx"
+#include "protocol/ArgParser.hxx"
+#include "protocol/RangeArg.hxx"
+#include "queue/Playlist.hxx"
+
+static unsigned
+RequireCurrentPosition(const playlist &p)
+{
+	int position = p.GetCurrentPosition();
+	if (position < 0)
+		throw ProtocolError(ACK_ERROR_PLAYER_SYNC,
+				    "No current song");
+
+	return position;
+}
+
+unsigned
+ParseInsertPosition(const char *s, const playlist &playlist)
+{
+	const auto queue_length = playlist.queue.GetLength();
+
+	if (*s == '+') {
+		/* after the current song */
+
+		const unsigned current = RequireCurrentPosition(playlist);
+		assert(current < queue_length);
+
+		return current + 1 +
+			ParseCommandArgUnsigned(s + 1,
+						queue_length - current - 1);
+	} else if (*s == '-') {
+		/* before the current song */
+
+		const unsigned current = RequireCurrentPosition(playlist);
+		assert(current < queue_length);
+
+		return current - ParseCommandArgUnsigned(s + 1, current);
+	} else
+		/* absolute position */
+		return ParseCommandArgUnsigned(s, queue_length);
+}
+
+unsigned
+ParseMoveDestination(const char *s, const RangeArg range, const playlist &p)
+{
+	assert(!range.IsEmpty());
+	assert(!range.IsOpenEnded());
+
+	const unsigned queue_length = p.queue.GetLength();
+
+	if (*s == '+') {
+		/* after the current song */
+
+		unsigned current = RequireCurrentPosition(p);
+		assert(current < queue_length);
+		if (range.Contains(current))
+			throw ProtocolError(ACK_ERROR_ARG, "Cannot move current song relative to itself");
+
+		if (current >= range.end)
+			current -= range.Count();
+
+		return current + 1 +
+			ParseCommandArgUnsigned(s + 1,
+						queue_length - current - range.Count());
+	} else if (*s == '-') {
+		/* before the current song */
+
+		unsigned current = RequireCurrentPosition(p);
+		assert(current < queue_length);
+		if (range.Contains(current))
+			throw ProtocolError(ACK_ERROR_ARG, "Cannot move current song relative to itself");
+
+		if (current >= range.end)
+			current -= range.Count();
+
+		return current -
+			ParseCommandArgUnsigned(s + 1,
+						queue_length - current - range.Count());
+	} else
+		/* absolute position */
+		return ParseCommandArgUnsigned(s,
+					       queue_length - range.Count());
+}

src/command/PositionArg.hxx

+/*
+ * Copyright 2003-2021 The Music Player Daemon Project
+ * http://www.musicpd.org
+ *
+ * This program 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 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program 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 this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#pragma once
+
+struct playlist;
+struct RangeArg;
+
+/**
+ * Throws #ProtocolError on error.
+ */
+unsigned
+ParseInsertPosition(const char *s, const playlist &playlist);
+
+unsigned
+ParseMoveDestination(const char *s, const RangeArg range, const playlist &p);

src/command/QueueCommands.cxx

@@ -19,6 +19,7 @@
 
 #include "config.h"
 #include "QueueCommands.hxx"
+#include "PositionArg.hxx"
 #include "Request.hxx"
 #include "protocol/RangeArg.hxx"
 #include "db/DatabaseQueue.hxx"
@@ -43,17 +44,6 @@
 
 #include <limits>
 
-static unsigned
-RequireCurrentPosition(const playlist &p)
-{
-	int position = p.GetCurrentPosition();
-	if (position < 0)
-		throw ProtocolError(ACK_ERROR_PLAYER_SYNC,
-				    "No current song");
-
-	return position;
-}
-
 static void
 AddUri(Client &client, const LocatedUri &uri)
 {
@@ -129,30 +119,8 @@ handle_addid(Client &client, Request args, Response &r)
 
 	const auto queue_length = partition.playlist.queue.GetLength();
 
-	if (args.size > 1) {
-		const char *const s = args[1];
-		if (*s == '+') {
-			/* after the current song */
-
-			const unsigned current =
-				RequireCurrentPosition(partition.playlist);
-			assert(current < queue_length);
-
-			to = current + 1 +
-				ParseCommandArgUnsigned(s + 1,
-							queue_length - current - 1);
-		} else if (*s == '-') {
-			/* before the current song */
-
-			const unsigned current =
-				RequireCurrentPosition(partition.playlist);
-			assert(current < queue_length);
-
-			to = current - ParseCommandArgUnsigned(s + 1, current);
-		} else
-			/* absolute position */
-			to = args.ParseUnsigned(1, queue_length);
-	}
+	if (args.size > 1)
+		to = ParseInsertPosition(args[1], partition.playlist);
 
 	const SongLoader loader(client);
 	const unsigned added_position = queue_length;
@@ -363,49 +331,6 @@ handle_prioid(Client &client, Request args, [[maybe_unused]] Response &r)
 	return CommandResult::OK;
 }
 
-static unsigned
-ParseMoveDestination(const char *s, const RangeArg range,
-		     const playlist &p)
-{
-	assert(!range.IsEmpty());
-	assert(!range.IsOpenEnded());
-
-	const unsigned queue_length = p.queue.GetLength();
-
-	if (*s == '+') {
-		/* after the current song */
-
-		unsigned current = RequireCurrentPosition(p);
-		assert(current < queue_length);
-		if (range.Contains(current))
-			throw ProtocolError(ACK_ERROR_ARG, "Cannot move current song relative to itself");
-
-		if (current >= range.end)
-			current -= range.Count();
-
-		return current + 1 +
-			ParseCommandArgUnsigned(s + 1,
-						queue_length - current - range.Count());
-	} else if (*s == '-') {
-		/* before the current song */
-
-		unsigned current = RequireCurrentPosition(p);
-		assert(current < queue_length);
-		if (range.Contains(current))
-			throw ProtocolError(ACK_ERROR_ARG, "Cannot move current song relative to itself");
-
-		if (current >= range.end)
-			current -= range.Count();
-
-		return current -
-			ParseCommandArgUnsigned(s + 1,
-						queue_length - current - range.Count());
-	} else
-		/* absolute position */
-		return ParseCommandArgUnsigned(s,
-					       queue_length - range.Count());
-}
-
 static CommandResult
 handle_move(Partition &partition, RangeArg range, const char *to)
 {