vala: Add InvalidExpression as replacement for erroneous nodes instead

This type is meant to be used where a successful parsing or transforming
cannot be achieved and the usage of "null" is not possible.

2 files changed, 39 insertions, 0 deletions

diff --git a/vala/Makefile.am b/vala/Makefile.am
index 78e4c9390..c833939a3 100644
--- a/vala/Makefile.am
+++ b/vala/Makefile.am
@@ -102,6 +102,7 @@ libvala_la_VALASOURCES = \
 	valaintegertype.vala \
 	valainterface.vala \
 	valainterfacetype.vala \
+	valainvalidexpression.vala \
 	valainvalidtype.vala \
 	valalambdaexpression.vala \
 	valaliteral.vala \
diff --git a/vala/valainvalidexpression.vala b/vala/valainvalidexpression.vala
new file mode 100644
index 000000000..dc7d5e4f7
--- /dev/null
+++ b/vala/valainvalidexpression.vala
@@ -0,0 +1,38 @@
+/* valainvalidexpression.vala
+ *
+ * Copyright (C) 2020  Rico Tzschichholz
+ *
+ * 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:
+ * 	Rico Tzschichholz <ricotz@ubuntu.com>
+ */
+
+/**
+ * An invalid expression.
+ */
+public class Vala.InvalidExpression : Expression {
+	public InvalidExpression () {
+		error = true;
+	}
+
+	public override bool is_pure () {
+		return false;
+	}
+
+	public override bool check (CodeContext context) {
+		return false;
+	}
+}