1 files changed, 57 insertions, 14 deletions

diff --git a/src/song.h b/src/song.h
index 8b97d45d0..119d89ccd 100644
--- a/src/song.h
+++ b/src/song.h
@@ -21,7 +21,9 @@
 #define MPD_SONG_H
 
 #include "util/list.h"
+#include "gcc.h"
 
+#include <assert.h>
 #include <stddef.h>
 #include <stdbool.h>
 #include <sys/time.h>
@@ -41,7 +43,7 @@ struct song {
 	struct list_head siblings;
 
 	struct tag *tag;
-	struct directory *parent;
+	struct Directory *parent;
 	time_t mtime;
 
 	/**
@@ -58,13 +60,21 @@ struct song {
 	char uri[sizeof(int)];
 };
 
+/**
+ * A dummy #directory instance that is used for "detached" song
+ * copies.
+ */
+extern struct Directory detached_root;
+
+G_BEGIN_DECLS
+
 /** allocate a new song with a remote URL */
 struct song *
 song_remote_new(const char *uri);
 
 /** allocate a new song with a local file name */
 struct song *
-song_file_new(const char *path, struct directory *parent);
+song_file_new(const char *path, struct Directory *parent);
 
 /**
  * allocate a new song structure with a local file name and attempt to
@@ -72,7 +82,7 @@ song_file_new(const char *path, struct directory *parent);
  * data, NULL is returned.
  */
 struct song *
-song_file_load(const char *path, struct directory *parent);
+song_file_load(const char *path, struct Directory *parent);
 
 /**
  * Replaces the URI of a song object.  The given song object is
@@ -83,9 +93,52 @@ song_file_load(const char *path, struct directory *parent);
 struct song *
 song_replace_uri(struct song *song, const char *uri);
 
+/**
+ * Creates a "detached" song object.
+ */
+struct song *
+song_detached_new(const char *uri);
+
+/**
+ * Creates a duplicate of the song object.  If the object is in the
+ * database, it creates a "detached" copy of this song, see
+ * song_is_detached().
+ */
+gcc_malloc
+struct song *
+song_dup_detached(const struct song *src);
+
 void
 song_free(struct song *song);
 
+static inline bool
+song_in_database(const struct song *song)
+{
+	return song->parent != NULL;
+}
+
+static inline bool
+song_is_file(const struct song *song)
+{
+	return song_in_database(song) || song->uri[0] == '/';
+}
+
+static inline bool
+song_is_detached(const struct song *song)
+{
+	assert(song != NULL);
+	assert(song_in_database(song));
+
+	return song->parent == &detached_root;
+}
+
+/**
+ * Returns true if both objects refer to the same physical song.
+ */
+gcc_pure
+bool
+song_equals(const struct song *a, const struct song *b);
+
 bool
 song_file_update(struct song *song);
 
@@ -105,16 +158,6 @@ song_get_uri(const struct song *song);
 double
 song_get_duration(const struct song *song);
 
-static inline bool
-song_in_database(const struct song *song)
-{
-	return song->parent != NULL;
-}
-
-static inline bool
-song_is_file(const struct song *song)
-{
-	return song_in_database(song) || song->uri[0] == '/';
-}
+G_END_DECLS
 
 #endif