[grilo] Add a serializing function for medias

[Juan A. Suarez Romero <jasuarez src gnome org>]

commit 896c38c83ba27fba79ad73a52fb21f705e5ad481
Author: Juan A. Suarez Romero <jasuarez igalia com>
Date:   Tue May 25 13:20:21 2010 +0200

    Add a serializing function for medias
    
    It returns a string that represent a media.
    
    Lot of times, having a "serialized" version of a media is very useful. For
    instance, one can save this serial in a list, or send it to a non-grilo
    compliant application.
    
    Then, the media can be recovered from the serial.
    
    Serial follows the same scheme as an URI:
    
      <type>://<escaped_source_name>/<escaped_id>
    
    As it can be seen, both "id" and "source" are required in media in order to
    build the serial.
    
    <type> denotes the type of media we are dealing with. Thus, we will have:
    
       GrlMedia      => "grl"
       GrlMediaAudio => "grlaudio"
       GrlMediaVideo => "grlvideo"
       GrlMediaBox   => "grlbox"
       GrlMediaImage => "grlimage"
    
    It is worth to tell that the implementation takes in account future new medias.
    Thus, if in future a GrlMediaFoo type is added, then <type> will be "grlfoo"
    for this new media, without needing changes in code.

 src/data/grl-media.c |   35 +++++++++++++++++++++++++++++++++++
 src/data/grl-media.h |    3 +++
 2 files changed, 38 insertions(+), 0 deletions(-)
---
diff --git a/src/data/grl-media.c b/src/data/grl-media.c
index 50310d1..4a85103 100644
--- a/src/data/grl-media.c
+++ b/src/data/grl-media.c
@@ -103,3 +103,38 @@ grl_media_set_rating (GrlMedia *media, gfloat rating, gfloat max)
 		      GRL_METADATA_KEY_RATING,
 		      normalized_value);
 }
+
+gchar *
+grl_media_serialize (GrlMedia *media)
+{
+  GRegex *type_regex;
+  const gchar *id;
+  const gchar *source;
+  const gchar *type_name;
+  gchar *escaped_id;
+  gchar *escaped_source;
+  gchar *protocol;
+  gchar *serial;
+
+  g_return_val_if_fail (GRL_IS_MEDIA (media), NULL);
+  g_return_val_if_fail ((id = grl_media_get_id (media)), NULL);
+  g_return_val_if_fail ((source = grl_media_get_source (media)), NULL);
+
+  type_name = g_type_name (G_TYPE_FROM_INSTANCE (media));
+
+  /* Convert typename to scheme protocol */
+  type_regex = g_regex_new ("GrlMedia(.*)", 0, 0, NULL);
+  protocol = g_regex_replace (type_regex, type_name, -1, 0, "grl\\L\\1\\E", 0, NULL);
+  g_regex_unref (type_regex);
+
+  /* Build serial string with escaped components */
+  escaped_id = g_uri_escape_string (id, NULL, TRUE);
+  escaped_source = g_uri_escape_string (source, NULL, TRUE);
+
+  serial = g_strconcat (protocol, "://", escaped_source, "/", escaped_id, NULL);
+
+  g_free (escaped_id);
+  g_free (escaped_source);
+
+  return serial;
+}
diff --git a/src/data/grl-media.h b/src/data/grl-media.h
index 627ec35..adcaccd 100644
--- a/src/data/grl-media.h
+++ b/src/data/grl-media.h
@@ -384,8 +384,11 @@ void grl_media_set_rating (GrlMedia *media, gfloat rating, gfloat max);
   grl_data_get_string(GRL_DATA((data)), GRL_METADATA_KEY_LAST_PLAYED)
 
 GType grl_media_get_type (void) G_GNUC_CONST;
+
 GrlMedia *grl_media_new (void);
 
+gchar *grl_media_serialize (GrlMedia *media);
+
 G_END_DECLS
 
 #endif /* _GRL_MEDIA_H_ */