libtracker-data: Implement BASE

It is meant to affect all relative IRIs being parsed.

3 files changed, 147 insertions, 4 deletions

diff --git a/src/libtracker-common/tracker-utils.c b/src/libtracker-common/tracker-utils.c
index f6fb89348..530bb4a70 100644
--- a/src/libtracker-common/tracker-utils.c
+++ b/src/libtracker-common/tracker-utils.c
@@ -323,3 +323,119 @@ tracker_unescape_unichars (const gchar  *str,
 
 	return g_string_free (copy, FALSE);
 }
+
+gboolean
+parse_abs_uri (const gchar  *uri,
+               gchar       **base,
+               const gchar **rel_path)
+{
+	const gchar *loc, *end;
+
+	end = &uri[strlen (uri)];
+	loc = uri;
+
+	if (!g_ascii_isalpha (loc[0]))
+		return FALSE;
+
+	while (loc != end) {
+		if (loc[0] == ':')
+			break;
+		if (!g_ascii_isalpha (loc[0]) &&
+		    loc[0] != '+' && loc[0] != '-' && loc[0] != '.')
+			return FALSE;
+		loc++;
+	}
+
+	if (loc == uri)
+		return FALSE;
+
+	if (strncmp (loc, "://", 3) == 0) {
+		/* Include authority in base */
+		loc += 3;
+		loc = strchr (loc, '/');
+		if (!loc)
+			loc = end;
+	}
+
+	*base = g_strndup (uri, loc - uri);
+	*rel_path = loc + 1;
+
+	return TRUE;
+}
+
+GPtrArray *
+remove_dot_segments (gchar **uri_elems)
+{
+	GPtrArray *array;
+	gint i;
+
+	array = g_ptr_array_new ();
+
+	for (i = 0; uri_elems[i] != NULL; i++) {
+		if (g_strcmp0 (uri_elems[i], ".") == 0) {
+			continue;
+		} else if (g_strcmp0 (uri_elems[i], "..") == 0) {
+			if (array->len > 0)
+				g_ptr_array_remove_index (array, array->len - 1);
+			continue;
+		} else if (*uri_elems[i] != '\0') {
+			/* NB: Not a copy */
+			g_ptr_array_add (array, uri_elems[i]);
+		}
+	}
+
+	return array;
+}
+
+gchar *
+tracker_resolve_relative_uri (const gchar  *base,
+                              const gchar  *rel_uri)
+{
+	gchar **base_split, **rel_split, *host;
+	GPtrArray *base_norm, *rel_norm;
+	GString *str;
+	gint i;
+
+	/* Relative IRIs are combined with base IRIs with a simplified version
+	 * of the algorithm described at RFC3986, Section 5.2. We don't care
+	 * about query and fragment parts of an URI, and some simplifications
+	 * are taken on base uri parsing and relative uri validation.
+	 */
+	rel_split = g_strsplit (rel_uri, "/", -1);
+
+	/* Rel uri is a full uri? */
+	if (strchr (rel_split[0], ':')) {
+		g_strfreev (rel_split);
+		return g_strdup (rel_uri);
+	}
+
+	if (!parse_abs_uri (base, &host, &base)) {
+		g_strfreev (rel_split);
+		return g_strdup (rel_uri);
+	}
+
+	base_split = g_strsplit (base, "/", -1);
+
+	base_norm = remove_dot_segments (base_split);
+	rel_norm = remove_dot_segments (rel_split);
+
+	for (i = 0; i < rel_norm->len; i++) {
+		g_ptr_array_add (base_norm,
+		                 g_ptr_array_index (rel_norm, i));
+	}
+
+	str = g_string_new (host);
+	for (i = 0; i < base_norm->len; i++) {
+		g_string_append_c (str, '/');
+		g_string_append (str,
+		                 g_ptr_array_index (base_norm, i));
+	}
+
+	g_ptr_array_unref (base_norm);
+	g_ptr_array_unref (rel_norm);
+	g_strfreev (base_split);
+	g_strfreev (rel_split);
+	g_free (host);
+
+	return g_string_free (str, FALSE);
+}
diff --git a/src/libtracker-common/tracker-utils.h b/src/libtracker-common/tracker-utils.h
index 2cb78e5ba..c12c9ccae 100644
--- a/src/libtracker-common/tracker-utils.h
+++ b/src/libtracker-common/tracker-utils.h
@@ -47,6 +47,8 @@ gchar *  tracker_utf8_truncate              (const gchar  *str,
                                              gsize         max_size);
 gchar *  tracker_unescape_unichars          (const gchar  *str,
 					     gssize        len);
+gchar *  tracker_resolve_relative_uri       (const gchar  *base,
+                                             const gchar  *rel_uri);
 
 G_END_DECLS
 
diff --git a/src/libtracker-data/tracker-sparql.c b/src/libtracker-data/tracker-sparql.c
index a516cb946..c2c336740 100644
--- a/src/libtracker-data/tracker-sparql.c
+++ b/src/libtracker-data/tracker-sparql.c
@@ -30,6 +30,7 @@
 #include "tracker-collation.h"
 #include "tracker-db-interface-sqlite.h"
 #include "tracker-sparql-query.h"
+#include "tracker-utils.h"
 
 #define TRACKER_NS "http://www.tracker-project.org/ontologies/tracker#"
 #define RDF_NS "http://www.w3.org/1999/02/22-rdf-syntax-ns#"
@@ -132,6 +133,7 @@ struct _TrackerSparql
 
 	GPtrArray *anon_graphs;
 	GPtrArray *named_graphs;
+	gchar *base;
 
 	struct {
 		TrackerContext *context;
@@ -190,6 +192,7 @@ tracker_sparql_finalize (GObject *object)
 	g_ptr_array_unref (sparql->anon_graphs);
 	g_ptr_array_unref (sparql->var_names);
 	g_array_unref (sparql->var_types);
+	g_free (sparql->base);
 
 	if (sparql->blank_nodes)
 		g_variant_builder_unref (sparql->blank_nodes);
@@ -249,6 +252,16 @@ tracker_sparql_swap_current_expression_list_separator (TrackerSparql *sparql,
 }
 
 static inline gchar *
+tracker_sparql_expand_base (TrackerSparql *sparql,
+                            const gchar   *term)
+{
+	if (sparql->base)
+		return tracker_resolve_relative_uri (sparql->base, term);
+	else
+		return g_strdup (term);
+}
+
+static inline gchar *
 tracker_sparql_expand_prefix (TrackerSparql *sparql,
                               const gchar   *term)
 {
@@ -678,9 +691,17 @@ _extract_node_string (TrackerParserNode *node,
 			add_start = subtract_end = 3;
 			compress = TRUE;
 			break;
-		case TERMINAL_TYPE_IRIREF:
+		case TERMINAL_TYPE_IRIREF: {
+			gchar *unexpanded;
+
 			add_start = subtract_end = 1;
+			unexpanded = g_strndup (terminal_start + add_start,
+			                        terminal_end - terminal_start -
+			                        add_start - subtract_end);
+			str = tracker_sparql_expand_base (sparql, unexpanded);
+			g_free (unexpanded);
 			break;
+		}
 		case TERMINAL_TYPE_BLANK_NODE_LABEL:
 			add_start = 2;
 			break;
@@ -1812,11 +1833,15 @@ translate_BaseDecl (TrackerSparql  *sparql,
 	/* BaseDecl ::= 'BASE' IRIREF
 	 */
 	_expect (sparql, RULE_TYPE_LITERAL, LITERAL_BASE);
-
-	/* FIXME: BASE is unimplemented, and we never raised an error */
-
 	_expect (sparql, RULE_TYPE_TERMINAL, TERMINAL_TYPE_IRIREF);
 
+	/* Sparql syntax allows for multiple BaseDecl, but it only makes
+	 * sense to keep one. Given that the sparql1.1-query recommendation
+	 * does not define the behavior, just pick the first one.
+	 */
+	if (!sparql->base)
+		sparql->base = _dup_last_string (sparql);
+
 	return TRUE;
 }