[gtksourceview] stylescheme: add support for <metadata>

[Christian Hergert <chergert src gnome org>]

commit 47d516debc6884604e197f3f6279c81fa0c2f182
Author: Christian Hergert <chergert redhat com>
Date:   Wed Dec 1 13:44:58 2021 -0800

    stylescheme: add support for <metadata>
    
    Language syntax files allow for <metadata> with <property> elements
    within them. This can be handy to add additional non-critical information
    to the style scheme which can be parsed by applications.
    
    In particular, we'd like to use this to associate possible related
    variants and other information in a somewhat flexible manner.
    
    A new gtk_source_style_scheme_get_metadata() function has been added
    similar to the equivalent in GtkSourceLanguage.
    
    Related #220

 docs/reference/gtksourceview-5.0-sections.txt |  1 +
 gtksourceview/gtksourcestylescheme.c          | 82 +++++++++++++++++++++------
 gtksourceview/gtksourcestylescheme.h          |  3 +
 3 files changed, 69 insertions(+), 17 deletions(-)
---
diff --git a/docs/reference/gtksourceview-5.0-sections.txt b/docs/reference/gtksourceview-5.0-sections.txt
index b552943b..9d163258 100644
--- a/docs/reference/gtksourceview-5.0-sections.txt
+++ b/docs/reference/gtksourceview-5.0-sections.txt
@@ -925,6 +925,7 @@ gtk_source_style_scheme_get_name
 gtk_source_style_scheme_get_description
 gtk_source_style_scheme_get_authors
 gtk_source_style_scheme_get_filename
+gtk_source_style_scheme_get_metadata
 gtk_source_style_scheme_get_style
 <SUBSECTION Standard>
 GtkSourceStyleSchemeClass
diff --git a/gtksourceview/gtksourcestylescheme.c b/gtksourceview/gtksourcestylescheme.c
index 5b931a53..91437fd3 100644
--- a/gtksourceview/gtksourcestylescheme.c
+++ b/gtksourceview/gtksourcestylescheme.c
@@ -94,6 +94,7 @@ struct _GtkSourceStyleScheme
        GHashTable *defined_styles;
        GHashTable *style_cache;
        GHashTable *named_colors;
+       GHashTable *metadata;
 
        GtkCssProvider *css_provider;
 };
@@ -105,23 +106,10 @@ gtk_source_style_scheme_dispose (GObject *object)
 {
        GtkSourceStyleScheme *scheme = GTK_SOURCE_STYLE_SCHEME (object);
 
-       if (scheme->named_colors != NULL)
-       {
-               g_hash_table_unref (scheme->named_colors);
-               scheme->named_colors = NULL;
-       }
-
-       if (scheme->style_cache != NULL)
-       {
-               g_hash_table_unref (scheme->style_cache);
-               scheme->style_cache = NULL;
-       }
-
-       if (scheme->defined_styles != NULL)
-       {
-               g_hash_table_unref (scheme->defined_styles);
-               scheme->defined_styles = NULL;
-       }
+       g_clear_pointer (&scheme->named_colors, g_hash_table_unref);
+       g_clear_pointer (&scheme->style_cache, g_hash_table_unref);
+       g_clear_pointer (&scheme->defined_styles, g_hash_table_unref);
+       g_clear_pointer (&scheme->metadata, g_hash_table_unref);
 
        g_clear_object (&scheme->parent);
        g_clear_object (&scheme->css_provider);
@@ -1256,6 +1244,38 @@ parse_style_scheme_child (GtkSourceStyleScheme  *scheme,
                scheme->description = g_strdup (_((char*) tmp));
                xmlFree (tmp);
        }
+       else if (strcmp ((char*) node->name, "metadata") == 0)
+       {
+               for (xmlNode *child = node->children; child != NULL; child = child->next)
+               {
+                       if (strcmp ((char*) child->name, "property") == 0)
+                       {
+                               xmlChar *name;
+                               xmlChar *content;
+
+                               name = xmlGetProp (child, BAD_CAST "name");
+                               content = xmlNodeGetContent (child);
+
+                               if (name != NULL && content != NULL)
+                               {
+                                       if (scheme->metadata == NULL)
+                                       {
+                                               scheme->metadata = g_hash_table_new_full (g_str_hash,
+                                                                                         g_str_equal,
+                                                                                         g_free,
+                                                                                         g_free);
+                                       }
+
+                                       g_hash_table_insert (scheme->metadata,
+                                                            g_strdup ((char *)name),
+                                                            g_strdup ((char *)content));
+                               }
+
+                               xmlFree (name);
+                               xmlFree (content);
+                       }
+               }
+       }
        else
        {
                g_set_error (error, ERROR_QUARK, 0, "unknown node '%s'", node->name);
@@ -1482,3 +1502,31 @@ _gtk_source_style_scheme_get_default (void)
        return gtk_source_style_scheme_manager_get_scheme (manager,
                                                           DEFAULT_STYLE_SCHEME);
 }
+
+/**
+ * gtk_source_style_scheme_get_metadata:
+ * @scheme: a #GtkSourceStyleScheme.
+ * @name: metadata property name.
+ *
+ * Gets a metadata property from the style scheme.
+ *
+ * Returns: (nullable) (transfer none): value of property @name stored in
+ *   the metadata of @scheme or %NULL if @scheme does not contain the
+ *   specified metadata property.
+ *
+ * Since: 5.4
+ */
+const char *
+gtk_source_style_scheme_get_metadata (GtkSourceStyleScheme *scheme,
+                                      const char           *name)
+{
+       g_return_val_if_fail (GTK_SOURCE_IS_STYLE_SCHEME (scheme), NULL);
+       g_return_val_if_fail (name != NULL, NULL);
+
+       if (scheme->metadata == NULL)
+       {
+               return NULL;
+       }
+
+       return g_hash_table_lookup (scheme->metadata, name);
+}
diff --git a/gtksourceview/gtksourcestylescheme.h b/gtksourceview/gtksourcestylescheme.h
index 4541ec79..47234c2a 100644
--- a/gtksourceview/gtksourcestylescheme.h
+++ b/gtksourceview/gtksourcestylescheme.h
@@ -47,5 +47,8 @@ const gchar         *gtk_source_style_scheme_get_filename    (GtkSourceStyleSche
 GTK_SOURCE_AVAILABLE_IN_ALL
 GtkSourceStyle      *gtk_source_style_scheme_get_style       (GtkSourceStyleScheme *scheme,
                                                               const gchar          *style_id);
+GTK_SOURCE_AVAILABLE_IN_5_4
+const char          *gtk_source_style_scheme_get_metadata    (GtkSourceStyleScheme *scheme,
+                                                              const char           *name);
 
 G_END_DECLS