[rygel] server: Allow MediaServerPlugins to override search capabilities

[Jens Georg <jensgeorg src gnome org>]

commit 0a312d63b65bb9cb637b9f054e7f48180676c225
Author: Jussi Kukkonen <jussi kukkonen intel com>
Date:   Tue Nov 19 12:06:50 2013 +0200

    server: Allow MediaServerPlugins to override search capabilities
    
    Use a virtual MediaServerPlugin.search_caps property instead of hard
    coding the value in ContentDirectory. This way plugin implementations
    can represent their search capabilities correctly.
    
    The default value is still the same: no change needed in plugins.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=712660

 src/librygel-server/rygel-content-directory.vala   |   16 +++++--------
 src/librygel-server/rygel-media-server-plugin.vala |   24 ++++++++++++++++++++
 2 files changed, 30 insertions(+), 10 deletions(-)
---
diff --git a/src/librygel-server/rygel-content-directory.vala 
b/src/librygel-server/rygel-content-directory.vala
index cdc115a..e87f480 100644
--- a/src/librygel-server/rygel-content-directory.vala
+++ b/src/librygel-server/rygel-content-directory.vala
@@ -85,8 +85,6 @@ public class Rygel.ContentDirectory: Service {
 
     private string service_reset_token;
 
-    private string search_caps;
-
     public override void constructed () {
         base.constructed ();
 
@@ -118,12 +116,6 @@ public class Rygel.ContentDirectory: Service {
 
         this.last_change = new LastChange ();
 
-        this.search_caps = RelationalExpression.CAPS;
-
-        if (PluginCapabilities.TRACK_CHANGES in plugin.capabilities) {
-            this.search_caps += ",upnp:objectUpdateID,upnp:containerUpdateID";
-        }
-
         this.feature_list =
             "<?xml version=\"1.0\" encoding=\"UTF-8\"?>" +
             "<Features xmlns=\"urn:schemas-upnp-org:av:avs\" " +
@@ -354,8 +346,10 @@ public class Rygel.ContentDirectory: Service {
             return;
         }
 
+        var plugin = this.root_device.resource_factory as MediaServerPlugin;
+
         /* Set action return arguments */
-        action.set ("SearchCaps", typeof (string), this.search_caps);
+        action.set ("SearchCaps", typeof (string), plugin.search_caps);
 
         action.return ();
     }
@@ -364,9 +358,11 @@ public class Rygel.ContentDirectory: Service {
     private void query_search_capabilities (Service        content_dir,
                                             string         variable,
                                             ref GLib.Value value) {
+        var plugin = this.root_device.resource_factory as MediaServerPlugin;
+
         /* Set action return arguments */
         value.init (typeof (string));
-        value.set_string (this.search_caps);
+        value.set_string (plugin.search_caps);
     }
 
     /* action GetSortCapabilities implementation */
diff --git a/src/librygel-server/rygel-media-server-plugin.vala 
b/src/librygel-server/rygel-media-server-plugin.vala
index 3670bd6..fd0aa13 100644
--- a/src/librygel-server/rygel-media-server-plugin.vala
+++ b/src/librygel-server/rygel-media-server-plugin.vala
@@ -40,6 +40,30 @@ public abstract class Rygel.MediaServerPlugin : Rygel.Plugin {
 
     public MediaContainer root_container { get; construct; }
 
+    private string _search_caps;
+
+    /**
+     * The SearchCapabilities this MediaServer plugin supports.
+     *
+     * Implementations can override this to match their capabilities. If they do,
+     * they should take care to include the change tracking capabilities
+     * (upnp:objectUpdateID, upnp:containerUpdateID) based on
+     * PluginCapabilities.TRACK_CHANGES.
+     */
+    public virtual string search_caps {
+        get {
+            if (this._search_caps == null) {
+                this._search_caps = RelationalExpression.CAPS;
+
+                if (PluginCapabilities.TRACK_CHANGES in this.capabilities) {
+                    this._search_caps += ",upnp:objectUpdateID,upnp:containerUpdateID";
+                }
+            }
+
+            return this._search_caps;
+        }
+    }
+
     private GLib.List<DLNAProfile> _upload_profiles;
 
     /**