[tracker/wip/carlosg/hotdoc: 32/53] docs: Add documentation generation in markdown format

[Carlos Garnacho <carlosg src gnome org>]

commit 22c2295e9fe8e806f2b9bae6b38d0f53ad0cd0f0
Author: Carlos Garnacho <carlosg gnome org>
Date:   Wed Jun 2 11:27:43 2021 +0200

    docs: Add documentation generation in markdown format
    
    This is implemented as separate code that does markdown formatting,
    there's probably some opportunities for subclassing and text
    templating, but it can be made prettier later on.

 docs/reference/ontology/meson.build |   1 +
 docs/tools/meson.build              |   1 +
 docs/tools/tracker-docgen-md.c      | 577 ++++++++++++++++++++++++++++++++++++
 docs/tools/tracker-docgen-md.h      |  36 +++
 docs/tools/tracker-main.c           |  22 +-
 5 files changed, 636 insertions(+), 1 deletion(-)
---
diff --git a/docs/reference/ontology/meson.build b/docs/reference/ontology/meson.build
index b85e1bcfc..5f3c87ac5 100644
--- a/docs/reference/ontology/meson.build
+++ b/docs/reference/ontology/meson.build
@@ -5,6 +5,7 @@ version_xml = configure_file(input: 'version.xml.in',
 generated = custom_target('ontology-doc-generated',
     output: 'gen-doc.stamp',
     command: [tracker_docgen,
+              '--xml',
               '-d', join_paths(source_root, 'src/ontologies/nepomuk'),
               '-o', join_paths(meson.current_build_dir(), 'xml/'),
               '-e', meson.current_source_dir()],
diff --git a/docs/tools/meson.build b/docs/tools/meson.build
index f7636d75c..5bb96c1da 100644
--- a/docs/tools/meson.build
+++ b/docs/tools/meson.build
@@ -3,6 +3,7 @@
 doctool_gresources = gnome.compile_resources('tracker_doctool_gresources', 'dsc-ontology.gresource.xml')
 
 doctool_files = [
+    'tracker-docgen-md.c',
     'tracker-docgen-xml.c',
     'tracker-main.c',
     'tracker-ontology-model.c',
diff --git a/docs/tools/tracker-docgen-md.c b/docs/tools/tracker-docgen-md.c
new file mode 100644
index 000000000..070fc9e59
--- /dev/null
+++ b/docs/tools/tracker-docgen-md.c
@@ -0,0 +1,577 @@
+/*
+ * Copyright (C) 2021, Red Hat Inc.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+ * 02110-1301, USA.
+ *
+ * Authors: Carlos Garnacho <carlosg gnome org>
+ */
+
+#include <glib/gprintf.h>
+#include <gio/gio.h>
+
+#include "tracker-docgen-md.h"
+#include "tracker-utils.h"
+
+typedef struct {
+       TrackerOntologyModel *model;
+       TrackerOntologyDescription *description;
+       FILE *output;
+} CallbackInfo;
+
+static gchar *
+link_from_shortname (const gchar *shortname)
+{
+       const gchar *sep;
+       gchar *link, *prefix;
+
+       sep = strstr (shortname, ":");
+       g_assert (sep != NULL);
+
+       prefix = g_strndup (shortname, sep - shortname);
+       link = g_strdup_printf ("%s-ontology.html#%s", prefix, shortname);
+       g_free (prefix);
+
+       return link;
+}
+
+static void
+print_predefined_instances (FILE                 *f,
+                            TrackerOntologyClass *klass,
+                            TrackerOntologyModel *model)
+{
+       const gchar *id;
+       GList *l;
+
+       if (!klass->instances)
+               return;
+
+       id = klass->shortname;
+
+       g_fprintf (f, "#### <a name=\"%s.predefined-instances\"></a>Predefined instances\n\n", id);
+       g_fprintf (f, "%s has the following predefined instances:\n\n", klass->shortname);
+
+       for (l = klass->instances; l; l = l->next) {
+               g_fprintf (f, "- %s\n", (gchar*) l->data);
+       }
+
+       g_fprintf (f, "\n");
+}
+
+static void
+print_class_hierarchy (FILE                 *f,
+                       TrackerOntologyClass *klass,
+                       TrackerOntologyModel *model)
+{
+       GPtrArray *strings;
+       const gchar *id;
+       guint i;
+
+       strings = class_get_parent_hierarchy_strings (klass, model);
+
+       if (!strings)
+               return;
+
+       id = klass->shortname;
+
+       g_fprintf (f, "#### <a name=\"%s.hierarchy\"></a>Class hierarchy\n\n", id);
+       g_fprintf (f, "```\n");
+       //g_fprintf (f, " <code>\n");
+
+       for (i = 0; i < strings->len; i++) {
+               HierarchyString *str = g_ptr_array_index (strings, i);
+
+               g_fprintf (f, "%s%s%s\n",
+                          str->before->str,
+                          str->class->shortname,
+                          str->after->str);
+       }
+
+       g_fprintf (f, "```\n\n");
+       g_ptr_array_unref (strings);
+}
+
+static void
+print_flag (FILE        *f,
+            const gchar *flag_property_link,
+            const gchar *icon_name,
+            const gchar *flag_description)
+{
+       g_fprintf (f, "[![%s](%s \"%s\")](%s)",
+                  flag_description, icon_name, flag_description, flag_property_link);
+}
+
+static void
+print_property_table (FILE                 *f,
+                      TrackerOntologyModel *model,
+                      const char           *id,
+                      GList                *properties)
+{
+       GList *l, *m;
+       g_autoptr(GList) properties_sorted = NULL;
+
+       if (!properties)
+               return;
+
+       properties_sorted = g_list_sort (g_list_copy (properties), (GCompareFunc) strcmp);
+
+       g_fprintf (f, "#### <a name=\"%s.properties\"></a>Properties\n\n", id);
+
+       g_fprintf (f, "|Name|Type|Notes|Description|\n");
+       g_fprintf (f, "| --- | --- | --- | --- |\n");
+
+       for (l = properties_sorted; l; l = l->next) {
+               TrackerOntologyProperty *prop;
+               TrackerOntologyClass *range;
+               const gchar *shortname = NULL, *basename = NULL, *type_name = NULL, *type_class_id = NULL, 
*prop_id = NULL;
+               gchar *link;
+
+               prop = tracker_ontology_model_get_property (model, l->data);
+               range = tracker_ontology_model_get_class (model, prop->range->data);
+
+               prop_id = shortname = prop->shortname;
+               basename = prop->basename;
+               type_name = range->basename;
+               type_class_id = range->shortname;
+
+               /* Property name column */
+               g_fprintf (f, "| <a name=\"%s\"></a>%s ", prop_id, basename);
+
+               /* Type column */
+               link = link_from_shortname (type_class_id);
+               g_fprintf (f, "| [%s](%s) ", type_name, link);
+               g_free (link);
+
+               /* Flags column */
+               g_fprintf (f, "| ");
+
+               if (prop->deprecated) {
+                       print_flag (f, "nrl-ontology.html#nrl:deprecated", "icon-deprecated.svg",
+                                   "This property is deprecated.");
+               }
+
+               if (prop->superproperties) {
+                       for (m = prop->superproperties; m; m = m->next) {
+                               const gchar *shortname = NULL;
+                               g_autofree gchar *message = NULL, *link = NULL;
+                               TrackerOntologyProperty *superprop;
+
+                               superprop = tracker_ontology_model_get_property (model, m->data);
+                               shortname = superprop->shortname;
+                               link = link_from_shortname (shortname);
+
+                               message = g_strdup_printf ("This property extends %s", shortname);
+
+                               print_flag (f, link, "icon-superproperty.svg", message);
+                       }
+               }
+
+               if (prop->max_cardinality != NULL && atoi (prop->max_cardinality) == 1) {
+                       /* Single valued properties are most common, so we don't display this. */
+               } else {
+                       g_autofree gchar *message = NULL;
+
+                       if (prop->max_cardinality != NULL && atoi (prop->max_cardinality) > 0) {
+                               message = g_strdup_printf ("This property can have a maximum of %i values", 
*prop->max_cardinality);
+                       } else {
+                               message = g_strdup_printf ("This property can have multiple values.");
+                       }
+                       print_flag (f, "nrl-ontology.html#nrl:maxCardinality", "icon-multivalue.svg", 
message);
+               }
+
+               if (prop->fulltextIndexed) {
+                       print_flag (f, "nrl-ontology.html#nrl:fulltextIndexed", "icon-fulltextindexed.svg",
+                                   "This property is full-text-indexed, and can be looked up through 
`fts:match`");
+               }
+
+               /* Description column */
+               if (prop->description) {
+                       g_fprintf (f, "| %s", prop->description);
+               }
+               g_fprintf (f, "|\n");
+       }
+
+       g_fprintf (f, "\n");
+}
+
+static void
+print_ontology_class (TrackerOntologyModel *model,
+                      TrackerOntologyClass *klass,
+                      FILE                 *f)
+{
+       const gchar *name = NULL, *id = NULL;
+
+       g_return_if_fail (f != NULL);
+
+       name = klass->basename;
+       id = klass->shortname;
+
+       /* Anchor for external links. */
+       g_fprintf (f, "### <a name=\"%s\"></a>%s\n\n", id, name);
+
+       if (klass->description || klass->deprecated || klass->notify) {
+               g_fprintf (f, "##### Description\n\n");
+
+               if (klass->description) {
+                       g_fprintf (f, "%s\n\n", klass->description);
+               }
+
+               if (klass->deprecated) {
+                       g_fprintf (f, "**Note:** ");
+                       print_flag (f, "nrl-ontology.html#nrl:deprecated", "icon-deprecated.svg", "Deprecated 
icon");
+                       g_fprintf (f, "\n\n");
+               }
+
+               if (klass->notify) {
+                       g_fprintf (f, "**Note:** ");
+                       print_flag (f, "nrl-ontology.html#nrl:notify", "icon-notify.svg", "Notify icon");
+                       g_fprintf (f, "This class emits notifications about changes, and can "
+                                    "be monitored using `TrackerNotifier`.");
+                       g_fprintf (f, "\n\n");
+               }
+       }
+
+       if (klass->specification) {
+               g_fprintf (f, "### Specification\n");
+               g_fprintf (f, "<%s>\n", klass->specification);
+       }
+
+       print_class_hierarchy (f, klass, model);
+       print_predefined_instances (f, klass, model);
+
+       print_property_table (f, model, id, klass->in_domain_of);
+}
+
+static void
+print_ontology_extra_properties (TrackerOntologyModel *model,
+                                 const char           *ontology_prefix,
+                                 const char           *classname,
+                                 GList                *properties_for_class,
+                                 FILE                 *f)
+{
+       TrackerOntologyClass *klass;
+       const gchar *short_classname = NULL, *class_id = NULL;
+       gchar *section_id = NULL;
+
+       g_return_if_fail (f != NULL);
+
+       klass = tracker_ontology_model_get_class (model, classname);
+       short_classname = class_id = klass->shortname;
+       section_id = g_strconcat (ontology_prefix, ".", class_id, NULL);
+
+       g_fprintf (f, "### <a name=\"%s\"></a>Additional properties for %s\n", section_id, short_classname);
+
+       g_fprintf (f, "#### Description\n");
+       g_fprintf (f, "Properties this ontology defines which can describe %s resources.\n",
+                  short_classname);
+
+       print_property_table (f, model, section_id, properties_for_class);
+
+       g_free (section_id);
+}
+
+static void
+print_itemized_list (FILE *f, GList *list)
+{
+       GList *it;
+
+       for (it = list; it != NULL; it = it->next) {
+               g_fprintf (f, "- %s\n", (gchar *)it->data);
+       }
+}
+
+static void
+print_people_list (FILE *f,
+                   const gchar *role,
+                   GList *list) 
+{
+        if (!list) {
+                return;
+        }
+
+        g_fprintf (f, "%s\n\n", role);
+        print_itemized_list (f, list);
+        g_fprintf (f, "\n");
+}
+
+static void
+print_link (FILE *f,
+            const gchar *term,
+            const gchar *link_text,
+            const gchar *link)
+{
+        g_fprintf (f,"%s ", term);
+       if (link) {
+                g_fprintf (f, "[%s](%s)\n\n", link_text, link);
+       } else {
+               g_fprintf (f, "*Not available*\n\n");
+       }
+}
+
+static void
+print_md_header (FILE *f, TrackerOntologyDescription *desc)
+{
+       g_fprintf (f, "Title: %s\n\n", desc->title);
+       g_fprintf (f, "%s\n\n", desc->description);
+}
+
+static void
+print_md_footer (FILE *f, TrackerOntologyDescription *desc)
+{
+       g_fprintf (f, "## Credits and Copyright\n\n");
+       print_people_list (f, "Authors:", desc->authors);
+       print_people_list (f, "Editors:", desc->editors);
+       print_people_list (f, "Contributors:", desc->contributors);
+
+       print_link (f, "Upstream:", "Upstream version", desc->upstream);
+       print_link (f, "ChangeLog:", "Tracker changes", desc->gitlog);
+
+       if (desc->copyright) {
+               g_fprintf (f, "Copyright:\n");
+               g_fprintf (f, "%s\n", desc->copyright);
+       }
+}
+
+/* By default we list properties under their respective class.
+ *
+ * Ontologies can contain properties whose class is in a different
+ * ontology, and we treat these specially as 'extra properties'.
+ *
+ * This functions returns a hash table mapping class name to the
+ * extra properties provided for that class.
+ */
+static GHashTable *
+get_extra_properties (TrackerOntologyModel *model,
+                      GList                *classes,
+                      GList                *properties)
+{
+       GList *l, *c;
+       GHashTable *extra_properties;
+       GHashTableIter iter;
+       gchar *classname;
+       GList *properties_for_class;
+
+       extra_properties = g_hash_table_new_full (g_str_hash, g_str_equal, g_free, NULL);
+
+       for (l = properties; l; l = l->next) {
+               TrackerOntologyProperty *prop;
+               gboolean has_domain_in_this_ontology = FALSE;
+
+               prop = tracker_ontology_model_get_property (model, l->data);
+
+               for (c = prop->domain; c; c = c->next) {
+                       TrackerOntologyClass *klass;
+                       gchar *prefix;
+                       const gchar *sep;
+
+                       klass = tracker_ontology_model_get_class (model, c->data);
+                       sep = strstr (klass->shortname, ":");
+
+                       if (sep) {
+                               prefix = g_strndup (klass->shortname, sep - klass->shortname);
+                               has_domain_in_this_ontology = g_str_has_prefix (prop->shortname, prefix);
+                               g_free (prefix);
+                       }
+               }
+
+               if (!has_domain_in_this_ontology) {
+                       for (c = prop->domain; c; c = c->next) {
+                               const gchar *classname;
+                               GList *list;
+
+                               classname = c->data;
+                               list = g_hash_table_lookup (extra_properties, classname);
+                               list = g_list_append (list, prop->propertyname);
+                               g_hash_table_insert (extra_properties, g_strdup (classname), list);
+                       }
+               }
+       }
+
+       g_hash_table_iter_init (&iter, extra_properties);
+       while (g_hash_table_iter_next (&iter, (gpointer *)&classname, (gpointer *)&properties_for_class)) {
+               properties_for_class = g_list_sort (properties_for_class, (GCompareFunc) strcmp);
+               g_hash_table_iter_replace (&iter, properties_for_class);
+       }
+
+       return extra_properties;
+}
+
+static void
+print_synopsis (FILE                       *f,
+                TrackerOntologyDescription *desc)
+{
+       g_fprintf (f, "```turtle\n");
+       g_fprintf (f, "@prefix %s: <%s>\n", desc->localPrefix, desc->baseUrl);
+       g_fprintf (f, "```\n\n");
+}
+
+static void
+print_toc_classes (FILE                 *f,
+                   TrackerOntologyModel *model,
+                   const char           *id,
+                   GList                *classes)
+{
+       GList *l;
+
+       if (!classes)
+               return;
+
+       g_fprintf (f, "## <a name=\"%s.classes\"></a>Classes\n\n", id);
+
+       for (l = classes; l; l = l->next) {
+               TrackerOntologyClass *klass;
+               const char *basename = NULL, *id = NULL;
+
+               klass = tracker_ontology_model_get_class (model, l->data);
+               basename = klass->basename;
+               id = klass->shortname;
+
+               if (l != classes) {
+                       g_fprintf (f, ", ");
+               }
+               g_fprintf (f, "[%s](#%s)", basename, id);
+       }
+
+       g_fprintf (f, "\n\n");
+}
+
+static void
+print_toc_extra_properties (FILE                 *f,
+                            TrackerOntologyModel *model,
+                            const char           *id,
+                            GHashTable           *extra_properties)
+{
+       GList *props_for_class, *c, *l;
+       g_autoptr(GList) classes = NULL;
+       gboolean print_comma = FALSE;
+
+       if (g_hash_table_size (extra_properties) == 0)
+               return;
+
+       g_fprintf (f, "## <a name=\"%s.extra_properties\"></a>Additional Properties\n", id);
+
+       classes = g_hash_table_get_keys (extra_properties);
+       classes = g_list_sort (classes, (GCompareFunc)strcmp);
+       for (c = classes; c; c = c->next) {
+               gchar *classname;
+
+               classname = c->data;
+               props_for_class = g_hash_table_lookup (extra_properties, classname);
+               for (l = props_for_class; l; l = l->next) {
+                       TrackerOntologyProperty *prop;
+                       const char *basename = NULL, *prop_id = NULL;
+
+                       prop = tracker_ontology_model_get_property (model, l->data);
+                       basename = prop->basename;
+                       prop_id = prop->shortname;
+
+                       if (print_comma) {
+                               g_fprintf (f, ", ");
+                       } else {
+                               print_comma = TRUE;
+                       }
+
+                       g_fprintf (f, "[%s](#%s)", basename, prop_id);
+               }
+       }
+
+       g_fprintf (f, "\n\n");
+}
+
+/* Generate docbook markdown document for one ontology. */
+void
+ttl_md_print (TrackerOntologyDescription *description,
+              TrackerOntologyModel       *model,
+              const gchar                *prefix,
+              GFile                      *output_location,
+              const gchar                *description_dir)
+{
+       gchar *upper_name, *path, *introduction, *basename, *filename;
+       g_autoptr(GList) classes = NULL, properties = NULL, extra_classes = NULL;
+       g_autoptr(GHashTable) extra_properties = NULL;
+       GFile *file;
+       GList *l;
+       FILE *f;
+
+       filename = g_strdup_printf ("%s-ontology.md", description->localPrefix);
+       file = g_file_get_child (output_location, filename);
+       g_free (filename);
+
+       path = g_file_get_path (file);
+       f = fopen (path, "w");
+       g_assert (f != NULL);
+       g_free (path);
+
+       upper_name = g_ascii_strup (description->localPrefix, -1);
+       classes = tracker_ontology_model_list_classes (model, prefix);
+       properties = tracker_ontology_model_list_properties (model, prefix);
+       extra_properties = get_extra_properties (model, classes, properties);
+
+       print_md_header (f, description);
+
+       print_synopsis (f, description);
+       print_toc_classes (f, model, description->localPrefix, classes);
+       print_toc_extra_properties (f, model, description->localPrefix, extra_properties);
+
+       basename = g_strdup_printf ("%s-introduction.md", description->localPrefix);
+       introduction = g_build_filename (description_dir, basename, NULL);
+       g_free (basename);
+
+       if (g_file_test (introduction, G_FILE_TEST_EXISTS)) {
+               GMappedFile *mapped_file;
+
+               mapped_file = g_mapped_file_new (introduction, FALSE, NULL);
+               fwrite (g_mapped_file_get_contents (mapped_file),
+                       g_mapped_file_get_length (mapped_file),
+                       1, f);
+               g_mapped_file_unref (mapped_file);
+       }
+
+       if (classes != NULL) {
+               g_fprintf (f, "## <a name=\"%s-classes\"></a>Class Details\n\n", description->localPrefix);
+
+               for (l = classes; l; l = l->next) {
+                       TrackerOntologyClass *klass;
+
+                       klass = tracker_ontology_model_get_class (model, l->data);
+                       print_ontology_class (model, klass, f);
+               }
+       }
+
+       if (g_hash_table_size (extra_properties) > 0) {
+               g_fprintf (f, "## <a name=\"%s-extra-properties\"></a>Property Details\n\n", 
description->localPrefix);
+
+               extra_classes = g_hash_table_get_keys (extra_properties);
+               extra_classes = g_list_sort (extra_classes, (GCompareFunc)strcmp);
+               for (l = extra_classes; l; l = l->next) {
+                       gchar *classname;
+                       GList *properties_for_class;
+
+                       classname = l->data;
+
+                       properties_for_class = g_hash_table_lookup (extra_properties, classname);
+                       if (properties_for_class) {
+                               print_ontology_extra_properties (model, description->localPrefix, classname, 
properties_for_class, f);
+                       }
+               }
+       }
+
+       print_md_footer (f, description);
+
+       g_free (upper_name);
+       g_free (introduction);
+       g_object_unref (file);
+       fclose (f);
+}
diff --git a/docs/tools/tracker-docgen-md.h b/docs/tools/tracker-docgen-md.h
new file mode 100644
index 000000000..0123ea743
--- /dev/null
+++ b/docs/tools/tracker-docgen-md.h
@@ -0,0 +1,36 @@
+/*
+ * Copyright (C) 2009, Nokia <ivan frade nokia com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+ * 02110-1301, USA.
+ */
+
+#ifndef TRACKER_DOCGEN_MD_H
+#define TRACKER_DOCGEN_MD_H
+
+#include <gio/gio.h>
+#include "tracker-ontology-model.h"
+
+G_BEGIN_DECLS
+
+void ttl_md_print (TrackerOntologyDescription *description,
+                   TrackerOntologyModel       *model,
+                   const gchar                *prefix,
+                   GFile                      *output_location,
+                   const gchar                *description_dir);
+
+G_END_DECLS
+
+#endif /* TRACKER_DOCGEN_MD_H */
diff --git a/docs/tools/tracker-main.c b/docs/tools/tracker-main.c
index fcdfed8a8..c86e6090b 100644
--- a/docs/tools/tracker-main.c
+++ b/docs/tools/tracker-main.c
@@ -22,12 +22,15 @@
 #include <string.h>
 #include <stdio.h>
 
+#include "tracker-docgen-md.h"
 #include "tracker-docgen-xml.h"
 #include "tracker-ontology-model.h"
 
 static gchar *ontology_dir = NULL;
 static gchar *output_dir = NULL;
 static gchar *description_dir = NULL;
+static gboolean xml = FALSE;
+static gboolean markdown = FALSE;
 
 static GOptionEntry   entries[] = {
        { "ontology-dir", 'd', 0, G_OPTION_ARG_FILENAME, &ontology_dir,
@@ -42,6 +45,14 @@ static GOptionEntry   entries[] = {
          "Directory to find ontology descriptions",
          NULL
        },
+       { "xml", 'x', 0, G_OPTION_ARG_NONE, &xml,
+         "Whether to produce docbook XML for gtk-doc",
+         NULL
+       },
+       { "md", 'm', 0, G_OPTION_ARG_NONE, &markdown,
+         "Whether to produce markdown",
+         NULL
+       },
        { NULL }
 };
 
@@ -66,6 +77,12 @@ main (gint argc, gchar **argv)
        g_option_context_add_main_entries (context, entries, NULL);
        g_option_context_parse (context, &argc, &argv, NULL);
 
+       if (!!xml == !!markdown) {
+               g_printerr ("%s\n",
+                           "One of --xml or --md must be provided");
+               return -1;
+       }
+
        if (!ontology_dir || !output_dir) {
                gchar *help;
 
@@ -101,7 +118,10 @@ main (gint argc, gchar **argv)
                if (!description)
                        continue;
 
-               ttl_xml_print (description, model, prefixes[i], output_file, description_dir);
+               if (xml)
+                       ttl_xml_print (description, model, prefixes[i], output_file, description_dir);
+               else if (markdown)
+                       ttl_md_print (description, model, prefixes[i], output_file, description_dir);
        }
 
        g_strfreev (prefixes);