db/Selection: add `sort` and `window`

src/command/DatabaseCommands.cxx

@@ -107,12 +107,13 @@ handle_match(Client &client, Request args, Response &r, bool fold_case)
 	}
 	filter.Optimize();
 
-	const DatabaseSelection selection("", true, &filter);
+	DatabaseSelection selection("", true, &filter);
+	selection.window = window;
+	selection.sort = sort;
+	selection.descending = descending;
 
 	db_selection_print(r, client.GetPartition(),
-			   selection, true, false,
-			   sort, descending,
-			   window);
+			   selection, true, false);
 	return CommandResult::OK;
 }
 

src/db/DatabasePrint.cxx

 /*
- * Copyright 2003-2017 The Music Player Daemon Project
+ * Copyright 2003-2018 The Music Player Daemon Project
  * http://www.musicpd.org
  *
  * This program is free software; you can redistribute it and/or modify
@@ -179,9 +179,7 @@ CompareTags(TagType type, bool descending, const Tag &a, const Tag &b) noexcept
 void
 db_selection_print(Response &r, Partition &partition,
 		   const DatabaseSelection &selection,
-		   bool full, bool base,
-		   TagType sort, bool descending,
-		   RangeArg window)
+		   bool full, bool base)
 {
 	const Database &db = partition.GetDatabaseOrThrow();
 
@@ -197,9 +195,11 @@ db_selection_print(Response &r, Partition &partition,
 			    std::ref(r), base, _1, _2)
 		: VisitPlaylist();
 
-	if (sort == TAG_NUM_OF_ITEM_TYPES) {
+	const auto window = selection.window;
+
+	if (selection.sort == TAG_NUM_OF_ITEM_TYPES) {
 		unsigned i = 0;
-		if (!window.IsAll())
+		if (!selection.window.IsAll())
 			s = [s, window, &i](const LightSong &song){
 				if (window.Contains(i++))
 					s(song);
@@ -223,6 +223,9 @@ db_selection_print(Response &r, Partition &partition,
 			db.Visit(selection, d, collect_songs, p);
 		}
 
+		const auto sort = selection.sort;
+		const auto descending = selection.descending;
+
 		if (sort == TagType(SORT_TAG_LAST_MODIFIED))
 			std::stable_sort(songs.begin(), songs.end(),
 					 [descending](const DetachedSong &a, const DetachedSong &b){
@@ -254,16 +257,6 @@ db_selection_print(Response &r, Partition &partition,
 	}
 }
 
-void
-db_selection_print(Response &r, Partition &partition,
-		   const DatabaseSelection &selection,
-		   bool full, bool base)
-{
-	db_selection_print(r, partition, selection, full, base,
-			   TAG_NUM_OF_ITEM_TYPES, false,
-			   RangeArg::All());
-}
-
 static void
 PrintSongURIVisitor(Response &r, const LightSong &song) noexcept
 {

src/db/DatabasePrint.hxx

 /*
- * Copyright 2003-2017 The Music Player Daemon Project
+ * Copyright 2003-2018 The Music Player Daemon Project
  * http://www.musicpd.org
  *
  * This program is free software; you can redistribute it and/or modify
@@ -39,17 +39,6 @@ db_selection_print(Response &r, Partition &partition,
 		   const DatabaseSelection &selection,
 		   bool full, bool base);
 
-/**
- * @param sort the sort tag; TAG_NUM_OF_ITEM_TYPES means don't sort;
- * LOCATE_TAG_MODIFIED_SINCE means sort by file modification time
- */
-void
-db_selection_print(Response &r, Partition &partition,
-		   const DatabaseSelection &selection,
-		   bool full, bool base,
-		   TagType sort, bool descending,
-		   RangeArg window);
-
 void
 PrintSongUris(Response &r, Partition &partition,
 	      const SongFilter *filter);

src/db/Selection.cxx

 /*
- * Copyright 2003-2017 The Music Player Daemon Project
+ * Copyright 2003-2018 The Music Player Daemon Project
  * http://www.musicpd.org
  *
  * This program is free software; you can redistribute it and/or modify

src/db/Selection.hxx

 /*
- * Copyright 2003-2017 The Music Player Daemon Project
+ * Copyright 2003-2018 The Music Player Daemon Project
  * http://www.musicpd.org
  *
  * This program is free software; you can redistribute it and/or modify
@@ -20,6 +20,8 @@
 #ifndef MPD_DATABASE_SELECTION_HXX
 #define MPD_DATABASE_SELECTION_HXX
 
+#include "protocol/RangeArg.hxx"
+#include "tag/Type.h"
 #include "util/Compiler.h"
 
 #include <string>
@@ -36,6 +38,20 @@ struct DatabaseSelection {
 
 	const SongFilter *filter;
 
+	RangeArg window = RangeArg::All();
+
+	/**
+	 * Sort the result by the given tag.  #TAG_NUM_OF_ITEM_TYPES
+	 * means don't sort.  #SORT_TAG_LAST_MODIFIED sorts by
+	 * "Last-Modified" (not technically a tag).
+	 */
+	TagType sort = TAG_NUM_OF_ITEM_TYPES;
+
+	/**
+	 * If #sort is set, this flag can reverse the sort order.
+	 */
+	bool descending = false;
+
 	/**
 	 * Recursively search all sub directories?
 	 */