Use constructor method calltip only if available

For D and Python, we try to read the calltip from the constructor method
(e.g. "__init__" for Python) instead of from the class tag itself.
If we don't find a matching constructor method tag, now we continue
looking at the class tag itself. This is useful for global tags where
the constructor signature might be defined on the class tag itself.

src/editor.c

@@ -1843,6 +1843,53 @@ static gint find_start_bracket(ScintillaObject *sci, gint pos)
 }
 
 
+static GPtrArray *get_constructor_tags(GeanyFiletype *ft, TMTag *tag,
+									   const gchar *constructor_method)
+{
+	if (constructor_method && (tag->type == tm_tag_class_t || tag->type == tm_tag_struct_t))
+	{
+		const TMTagType arg_types = tm_tag_function_t | tm_tag_prototype_t |
+			tm_tag_method_t | tm_tag_macro_with_arg_t;
+		const gchar *scope_sep = tm_parser_scope_separator(ft->lang);
+		gchar *scope = EMPTY(tag->scope) ? g_strdup(tag->name) :
+			g_strjoin(scope_sep, tag->scope, tag->name, NULL);
+		GPtrArray *constructor_tags;
+
+		constructor_tags = tm_workspace_find(constructor_method, scope, arg_types, NULL, ft->lang);
+		g_free(scope);
+		if (constructor_tags->len != 0)
+		{	/* found constructor tag, so use it instead of the class tag */
+			return constructor_tags;
+		}
+		else
+		{
+			g_ptr_array_free(constructor_tags, TRUE);
+		}
+	}
+	return NULL;
+}
+
+
+static void update_tag_name_and_scope_for_calltip(const gchar *word, TMTag *tag,
+												  const gchar *constructor_method,
+												  const gchar **tag_name, const gchar **scope)
+{
+	if (tag_name == NULL || scope == NULL)
+		return;
+
+	/* Remove scope and replace name with the current calltip word if the current tag
+	 * is the constructor method of the current calltip word, e.g. for Python:
+	 * "SomeClass.__init__ (self, arg1, ...)" will be changed to "SomeClass (self, arg1, ...)" */
+	if (constructor_method &&
+		utils_str_equal(constructor_method, tag->name) &&
+		!utils_str_equal(word, tag->name))
+	{
+		*tag_name = word;
+		*scope = NULL;
+	}
+}
+
+
 static gchar *find_calltip(const gchar *word, GeanyFiletype *ft)
 {
 	const gchar *constructor_method;
@@ -1865,21 +1912,13 @@ static gchar *find_calltip(const gchar *word, GeanyFiletype *ft)
 
 	/* user typed e.g. 'a = Classname(' in Python so lookup __init__() arguments */
 	constructor_method = tm_parser_get_constructor_method(tag->lang);
-	if (constructor_method && (tag->type == tm_tag_class_t || tag->type == tm_tag_struct_t))
+	if (constructor_method)
 	{
-		const TMTagType arg_types = tm_tag_function_t | tm_tag_prototype_t |
-			tm_tag_method_t | tm_tag_macro_with_arg_t;
-		const gchar *scope_sep = tm_parser_scope_separator(ft->lang);
-		gchar *scope = EMPTY(tag->scope) ? g_strdup(tag->name) :
-			g_strjoin(scope_sep, tag->scope, tag->name, NULL);
-
-		g_ptr_array_free(tags, TRUE);
-		tags = tm_workspace_find(constructor_method, scope, arg_types, NULL, ft->lang);
-		g_free(scope);
-		if (tags->len == 0)
+		GPtrArray *constructor_tags = get_constructor_tags(ft, tag, constructor_method);
+		if (constructor_tags)
 		{
 			g_ptr_array_free(tags, TRUE);
-			return NULL;
+			tags = constructor_tags;
 		}
 	}
 
@@ -1919,9 +1958,13 @@ static gchar *find_calltip(const gchar *word, GeanyFiletype *ft)
 
 		if (str == NULL)
 		{
-			gchar *f = tm_parser_format_function(tag->lang, tag->name,
-				tag->arglist, tag->var_type, tag->scope);
-			str = g_string_new(NULL);
+			const gchar *tag_name = tag->name;
+			const gchar *scope = tag->scope;
+			gchar *f;
+
+			update_tag_name_and_scope_for_calltip(word, tag, constructor_method, &tag_name, &scope);
+			f = tm_parser_format_function(tag->lang, tag_name, tag->arglist, tag->var_type, scope);
+ 			str = g_string_new(NULL);
 			if (calltip.tag_index > 0)
 				g_string_prepend(str, "\001 ");	/* up arrow */
 			g_string_append(str, f);