[tracker/wip/sam/resource] libtracker-sparql: Implement more of tracker-namespace-manager

[Sam Thursfield <sthursfield src gnome org>]

commit 520559655e666d0bfda01b7c13de580ef98a7b93
Author: Sam Thursfield <ssssam gmail com>
Date:   Sat Apr 9 01:21:19 2016 +0100

    libtracker-sparql: Implement more of tracker-namespace-manager
    
    It can now expand the default prefixes ('rdf:', etc).

 src/libtracker-sparql/tracker-namespace-manager.c |  148 +++++++++++++++++++--
 src/libtracker-sparql/tracker-namespace-manager.h |    4 +-
 2 files changed, 136 insertions(+), 16 deletions(-)
---
diff --git a/src/libtracker-sparql/tracker-namespace-manager.c 
b/src/libtracker-sparql/tracker-namespace-manager.c
index 4755253..21fbbd7 100644
--- a/src/libtracker-sparql/tracker-namespace-manager.c
+++ b/src/libtracker-sparql/tracker-namespace-manager.c
@@ -25,13 +25,17 @@
 #include <glib.h>
 
 #include "tracker-namespace-manager.h"
+#include "tracker-ontologies.h"
+
+#define MAX_PREFIX_LENGTH 100
 
 struct _TrackerNamespaceManager {
-       GObject *parent;
+       GObject parent;
 };
 
 typedef struct {
-       char *foo;
+       GHashTable *prefix_to_namespace;
+       GHashTable *namespace_to_prefix;
 } TrackerNamespaceManagerPrivate;
 
 G_DEFINE_TYPE_WITH_PRIVATE (TrackerNamespaceManager, tracker_namespace_manager, G_TYPE_OBJECT);
@@ -48,9 +52,12 @@ G_DEFINE_TYPE_WITH_PRIVATE (TrackerNamespaceManager, tracker_namespace_manager,
  * #TrackerNamespaceManager keeps track of namespaces. It allows you to assign
  * short prefixes for them to avoid typing full URLs all the time.
  *
+ * The syntax used is that of Compact URIs (CURIEs) as defined here:
+ * <https://www.w3.org/TR/2010/NOTE-curie-20101216/>
+ *
  * Usually you'll want to use the default namespace manager, as returned by
- * tracker_namespace_manager_get_default(). This knows about all the namespaces
- * built in to Tracker.
+ * tracker_namespace_manager_get_default(). This has a set of well-known
+ * prefixes predefined.
  * </para>
  */
 
@@ -68,6 +75,9 @@ static void
 tracker_namespace_manager_init (TrackerNamespaceManager *self)
 {
        TrackerNamespaceManagerPrivate *priv = GET_PRIVATE (self);
+
+       priv->prefix_to_namespace = g_hash_table_new_full (g_str_hash, g_str_equal, g_free, g_free);
+       priv->namespace_to_prefix = g_hash_table_new_full (g_str_hash, g_str_equal, g_free, g_free);
 }
 
 static void
@@ -77,6 +87,9 @@ finalize (GObject *object)
 
        priv = GET_PRIVATE (TRACKER_NAMESPACE_MANAGER (object));
 
+       g_hash_table_unref (priv->prefix_to_namespace);
+       g_hash_table_unref (priv->namespace_to_prefix);
+
        (G_OBJECT_CLASS (tracker_namespace_manager_parent_class)->finalize) (object);
 }
 
@@ -88,26 +101,133 @@ tracker_namespace_manager_new ()
        namespace_manager = g_object_new (TRACKER_TYPE_NAMESPACE_MANAGER, NULL);
 }
 
+/**
+ * tracker_namespace_manager_add_prefix:
+ * @self: a #TrackerNamespaceManager
+ * @prefix: a short, unique prefix to identify @namespace
+ * @namespace: the URL of the given namespace
+ *
+ * Adds @prefix as the recognised abbreviaton of @namespace.
+ *
+ * Only one prefix is allowed for a given namespace, and all prefixes must
+ * be unique.
+ *
+ * Since: 1.10
+ */
+void
+tracker_namespace_manager_add_prefix (TrackerNamespaceManager *self,
+                                      const char *prefix,
+                                      const char *namespace)
+{
+       TrackerNamespaceManagerPrivate *priv;
+       const char *str;
+
+       priv = GET_PRIVATE (TRACKER_NAMESPACE_MANAGER (self));
+
+       if (strlen (prefix) > MAX_PREFIX_LENGTH) {
+               g_error ("Prefix is too long: max %i characters.", MAX_PREFIX_LENGTH);
+               return;
+       }
+
+       str = g_hash_table_lookup (priv->prefix_to_namespace, prefix);
+       if (str) {
+               g_error ("Prefix %s already points to %s", prefix, str);
+               return;
+       }
+
+       str = g_hash_table_lookup (priv->namespace_to_prefix, namespace);
+       if (str) {
+               g_error ("Namespace %s already has prefix %s", namespace, str);
+               return;
+       }
+
+       g_hash_table_insert (priv->prefix_to_namespace, g_strdup (prefix), g_strdup (namespace));
+       g_hash_table_insert (priv->namespace_to_prefix, g_strdup (namespace), g_strdup (prefix));
+}
+
+/**
+ * tracker_namespace_manager_expand_uri:
+ * @self: a #TrackerNamespaceManager
+ * @compact_uri: a URI or compact URI
+ *
+ * If @compact_uri begins with one of the prefixes known to this
+ * #TrackerNamespaceManager, then the return value will be the
+ * expanded URI. Otherwise, a copy of @compact_uri will be returned.
+ *
+ * Returns: a newly-allocated string
+ *
+ * Since: 1.10
+ */
+char *
+tracker_namespace_manager_expand_uri (TrackerNamespaceManager *self,
+                                      const char *compact_uri)
+{
+       TrackerNamespaceManagerPrivate *priv = GET_PRIVATE (self);
+
+       char prefix[MAX_PREFIX_LENGTH + 1];
+       char *colon;
+       char *namespace = NULL;
+
+       colon = strchr (compact_uri, ':');
+       if (colon != NULL) {
+               int colon_pos = colon - compact_uri;
+               if (colon_pos < MAX_PREFIX_LENGTH) {
+                       strncpy (prefix, compact_uri, colon_pos - 1);
+
+                       namespace = g_hash_table_lookup (priv->prefix_to_namespace, prefix);
+               }
+       }
+
+       if (namespace) {
+               return g_strconcat (namespace, colon, NULL);
+       } else {
+               return g_strdup (compact_uri);
+       }
+}
+
+/**
+ * tracker_namespace_manager_get_default:
+ *
+ * Returns the global #TrackerNamespaceManager that contains a set of well-known
+ * namespaces and prefixes, such as rdf:, rdfs:, nie:, tracker:, etc.
+ *
+ * Note that the list of prefixes and namespaces is hardcoded in
+ * libtracker-sparql. It may not correspond with the installed set of
+ * ontologies, if they have been modified since they were installed.
+ *
+ * Returns: a global, shared #TrackerNamespaceManager instance
+ *
+ * Since: 1.10
+ */
 TrackerNamespaceManager *
 tracker_namespace_manager_get_default ()
 {
-       static TrackerNamespaceManager * volatile default_namespace_manager__volatile;
+       static TrackerNamespaceManager * volatile default_namespace_manager__volatile = NULL;
 
        if (g_once_init_enter (&default_namespace_manager__volatile)) {
                TrackerNamespaceManager *manager = tracker_namespace_manager_new();
 
-               /* FIXME: populate namespaces from tracker-ontology.h */
+               tracker_namespace_manager_add_prefix (manager, "rdf", TRACKER_PREFIX_RDF);
+               tracker_namespace_manager_add_prefix (manager, "rdfs", TRACKER_PREFIX_RDFS);
+               tracker_namespace_manager_add_prefix (manager, "xsd", TRACKER_PREFIX_XSD);
+               tracker_namespace_manager_add_prefix (manager, "tracker", TRACKER_PREFIX_TRACKER);
+               tracker_namespace_manager_add_prefix (manager, "dc", TRACKER_PREFIX_DC);
+
+               tracker_namespace_manager_add_prefix (manager, "nrl", TRACKER_PREFIX_NRL);
+               tracker_namespace_manager_add_prefix (manager, "nmo", TRACKER_PREFIX_NMO);
+               tracker_namespace_manager_add_prefix (manager, "nie", TRACKER_PREFIX_NIE);
+               tracker_namespace_manager_add_prefix (manager, "nco", TRACKER_PREFIX_NCO);
+               tracker_namespace_manager_add_prefix (manager, "nao", TRACKER_PREFIX_NAO);
+               tracker_namespace_manager_add_prefix (manager, "nid3", TRACKER_PREFIX_NID3);
+               tracker_namespace_manager_add_prefix (manager, "nfo", TRACKER_PREFIX_NFO);
+
+               tracker_namespace_manager_add_prefix (manager, "slo", TRACKER_PREFIX_SLO);
+               tracker_namespace_manager_add_prefix (manager, "nmm", TRACKER_PREFIX_NMM);
+               tracker_namespace_manager_add_prefix (manager, "mlo", TRACKER_PREFIX_MLO);
+               tracker_namespace_manager_add_prefix (manager, "mfo", TRACKER_PREFIX_MFO);
 
                g_once_init_leave (&default_namespace_manager__volatile, manager);
        }
 
        return default_namespace_manager__volatile;
 }
-
-char *
-tracker_namespace_manager_expand_uri (TrackerNamespaceManager *self,
-                                      const char *short_uri)
-{
-       /* FIXME: stub */
-       return g_strdup (short_uri);
-}
diff --git a/src/libtracker-sparql/tracker-namespace-manager.h 
b/src/libtracker-sparql/tracker-namespace-manager.h
index 02b6876..00333bc 100644
--- a/src/libtracker-sparql/tracker-namespace-manager.h
+++ b/src/libtracker-sparql/tracker-namespace-manager.h
@@ -31,9 +31,9 @@ G_BEGIN_DECLS
 #define TRACKER_TYPE_NAMESPACE_MANAGER (tracker_namespace_manager_get_type())
 G_DECLARE_FINAL_TYPE (TrackerNamespaceManager, tracker_namespace_manager, TRACKER, NAMESPACE_MANAGER, 
GObject);
 
-TrackerNamespaceManager *tracker_namespace_manager_get_default (void);
+char *tracker_namespace_manager_expand_uri (TrackerNamespaceManager *self, const char *compact_uri);
 
-char *tracker_namespace_manager_expand_uri (TrackerNamespaceManager *self, const char *short_uri);
+TrackerNamespaceManager *tracker_namespace_manager_get_default (void);
 
 G_END_DECLS