[tracker/wip/carlosg/http-endpoint: 3/12] libtracker-sparql: Add private/abstract TrackerSerializer object

[Carlos Garnacho <carlosg src gnome org>]

commit 62c17e72d9d1f3f3e1e1d19f35cf838ce15df816
Author: Carlos Garnacho <carlosg gnome org>
Date:   Sat Dec 12 15:49:59 2020 +0100

    libtracker-sparql: Add private/abstract TrackerSerializer object
    
    This object is a subclass of GInputStream that takes a SPARQL
    cursor on construction. It is meant to handle serialization of
    SPARQL results into text formats.

 docs/reference/libtracker-sparql/meson.build |   1 +
 src/libtracker-sparql/meson.build            |   1 +
 src/libtracker-sparql/tracker-private.h      |   6 ++
 src/libtracker-sparql/tracker-serializer.c   | 140 +++++++++++++++++++++++++++
 src/libtracker-sparql/tracker-serializer.h   |  45 +++++++++
 5 files changed, 193 insertions(+)
---
diff --git a/docs/reference/libtracker-sparql/meson.build b/docs/reference/libtracker-sparql/meson.build
index 994cb3c31..7b7ce25d5 100644
--- a/docs/reference/libtracker-sparql/meson.build
+++ b/docs/reference/libtracker-sparql/meson.build
@@ -37,6 +37,7 @@ image_files = [
 private_headers = [
     'tracker-notifier-private.h',
     'tracker-private.h',
+    'tracker-serializer.h',
     'direct',
     'bus',
     'remote',
diff --git a/src/libtracker-sparql/meson.build b/src/libtracker-sparql/meson.build
index 7b7191a56..a9f505065 100644
--- a/src/libtracker-sparql/meson.build
+++ b/src/libtracker-sparql/meson.build
@@ -25,6 +25,7 @@ libtracker_sparql_c_sources = files(
     'tracker-notifier.c',
     'tracker-resource.c',
     'tracker-statement.c',
+    'tracker-serializer.c',
     'tracker-uri.c',
     'tracker-utils.c',
     'tracker-version.c',
diff --git a/src/libtracker-sparql/tracker-private.h b/src/libtracker-sparql/tracker-private.h
index 6c696d4a7..40d9828ca 100644
--- a/src/libtracker-sparql/tracker-private.h
+++ b/src/libtracker-sparql/tracker-private.h
@@ -250,6 +250,12 @@ struct _TrackerBatchClass {
                                     GError       **error);
 };
 
+typedef struct _TrackerSerializerClass TrackerSerializerClass;
+
+struct _TrackerSerializerClass {
+       GInputStreamClass parent_class;
+};
+
 void tracker_sparql_cursor_set_connection (TrackerSparqlCursor     *cursor,
                                            TrackerSparqlConnection *connection);
 GError * _translate_internal_error (GError *error);
diff --git a/src/libtracker-sparql/tracker-serializer.c b/src/libtracker-sparql/tracker-serializer.c
new file mode 100644
index 000000000..f96b439ab
--- /dev/null
+++ b/src/libtracker-sparql/tracker-serializer.c
@@ -0,0 +1,140 @@
+/*
+ * Copyright (C) 2020, Red Hat, Inc
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
+ * Boston, MA  02110-1301, USA.
+ *
+ * Author: Carlos Garnacho <carlosg gnome org>
+ */
+
+#include "config.h"
+
+#include "tracker-serializer.h"
+
+#include "tracker-private.h"
+
+enum {
+       PROP_0,
+       PROP_CURSOR,
+       N_PROPS
+};
+
+static GParamSpec *props[N_PROPS];
+
+typedef struct _TrackerSerializerPrivate TrackerSerializerPrivate;
+
+struct _TrackerSerializerPrivate
+{
+       TrackerSparqlCursor *cursor;
+};
+
+G_DEFINE_ABSTRACT_TYPE_WITH_PRIVATE (TrackerSerializer, tracker_serializer,
+                                     G_TYPE_INPUT_STREAM)
+
+static void
+tracker_serializer_finalize (GObject *object)
+{
+       TrackerSerializer *serializer = TRACKER_SERIALIZER (object);
+       TrackerSerializerPrivate *priv =
+               tracker_serializer_get_instance_private (serializer);
+
+       g_object_unref (priv->cursor);
+
+       G_OBJECT_CLASS (tracker_serializer_parent_class)->finalize (object);
+}
+static void
+tracker_serializer_set_property (GObject      *object,
+                                 guint         prop_id,
+                                 const GValue *value,
+                                 GParamSpec   *pspec)
+{
+       TrackerSerializer *serializer = TRACKER_SERIALIZER (object);
+       TrackerSerializerPrivate *priv =
+               tracker_serializer_get_instance_private (serializer);
+
+       switch (prop_id) {
+       case PROP_CURSOR:
+               priv->cursor = g_value_get_object (value);
+               break;
+       default:
+               G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
+               break;
+       }
+}
+
+static void
+tracker_serializer_get_property (GObject    *object,
+                                 guint       prop_id,
+                                 GValue     *value,
+                                 GParamSpec *pspec)
+{
+       TrackerSerializer *serializer = TRACKER_SERIALIZER (object);
+       TrackerSerializerPrivate *priv =
+               tracker_serializer_get_instance_private (serializer);
+
+       switch (prop_id) {
+       case PROP_CURSOR:
+               g_value_set_object (value, priv->cursor);
+               break;
+       default:
+               G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
+               break;
+       }
+}
+
+static void
+tracker_serializer_class_init (TrackerSerializerClass *klass)
+{
+       GObjectClass *object_class = G_OBJECT_CLASS (klass);
+
+       object_class->finalize = tracker_serializer_finalize;
+       object_class->set_property = tracker_serializer_set_property;
+       object_class->get_property = tracker_serializer_get_property;
+
+       props[PROP_CURSOR] =
+               g_param_spec_object ("cursor",
+                                    "cursor",
+                                    "cursor",
+                                    TRACKER_TYPE_SPARQL_CURSOR,
+                                    G_PARAM_CONSTRUCT_ONLY |
+                                    G_PARAM_STATIC_STRINGS |
+                                    G_PARAM_READABLE |
+                                    G_PARAM_WRITABLE);
+
+       g_object_class_install_properties (object_class, N_PROPS, props);
+}
+
+static void
+tracker_serializer_init (TrackerSerializer *serializer)
+{
+}
+
+GInputStream *
+tracker_serializer_new (TrackerSparqlCursor     *cursor,
+                        TrackerSerializerFormat  format)
+{
+       return NULL;
+}
+
+TrackerSparqlCursor *
+tracker_serializer_get_cursor (TrackerSerializer *serializer)
+{
+       TrackerSerializerPrivate *priv =
+               tracker_serializer_get_instance_private (serializer);
+
+       g_return_val_if_fail (TRACKER_IS_SERIALIZER (serializer), NULL);
+
+       return priv->cursor;
+}
diff --git a/src/libtracker-sparql/tracker-serializer.h b/src/libtracker-sparql/tracker-serializer.h
new file mode 100644
index 000000000..f948858bb
--- /dev/null
+++ b/src/libtracker-sparql/tracker-serializer.h
@@ -0,0 +1,45 @@
+/*
+ * Copyright (C) 2020, Red Hat, Inc
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
+ * Boston, MA  02110-1301, USA.
+ *
+ * Author: Carlos Garnacho <carlosg gnome org>
+ */
+
+#ifndef TRACKER_SERIALIZER_H
+#define TRACKER_SERIALIZER_H
+
+#include <libtracker-sparql/tracker-sparql.h>
+
+#define TRACKER_TYPE_SERIALIZER (tracker_serializer_get_type())
+
+G_DECLARE_DERIVABLE_TYPE (TrackerSerializer,
+                          tracker_serializer,
+                          TRACKER, SERIALIZER,
+                          GInputStream);
+
+typedef enum
+{
+       TRACKER_SERIALIZER_FORMAT_JSON, /* application/sparql-results+json */
+       TRACKER_SERIALIZER_FORMAT_XML, /* application/sparql-results+xml */
+} TrackerSerializerFormat;
+
+GInputStream * tracker_serializer_new (TrackerSparqlCursor     *cursor,
+                                       TrackerSerializerFormat  format);
+
+TrackerSparqlCursor * tracker_serializer_get_cursor (TrackerSerializer *serializer);
+
+#endif /* TRACKER_SERIALIZER_H */