lang: ast: implement cascade operator parsing

lang/ast/ctx.c

@@ -94,6 +94,27 @@ struct parser_state *parser_get_state_generic(struct ivy_parser *parser)
 	return state;
 }
 
+struct parser_state *parser_get_parent_state_generic(struct ivy_parser *parser, enum ivy_ast_node_type type)
+{
+	b_queue_entry *entry = b_queue_last(&parser->p_state);
+	if (!entry) {
+		return NULL;
+	}
+
+	entry = b_queue_prev(entry);
+	if (!entry) {
+		return NULL;
+	}
+
+	struct parser_state *state = b_unbox(struct parser_state, entry, s_entry);
+
+	if (state->s_node->n_type != type) {
+		return NULL;
+	}
+
+	return state;
+}
+
 struct parser_state *parser_push_state(
 	struct ivy_parser *parser, enum ivy_ast_node_type type)
 {