1 files changed, 48 insertions, 0 deletions
diff --git a/buildstream/_options/optioneltmask.py b/buildstream/_options/optioneltmask.py
new file mode 100644
index 000000000..765c50d10
--- /dev/null
+++ b/buildstream/_options/optioneltmask.py
@@ -0,0 +1,48 @@
+#!/usr/bin/env python3
+#
+#  Copyright (C) 2017 Codethink Limited
+#
+#  This program 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 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, see <http://www.gnu.org/licenses/>.
+#
+#  Authors:
+#        Tristan Van Berkom <tristan.vanberkom@codethink.co.uk>
+
+from .. import utils
+from .option import OPTION_SYMBOLS
+from .optionflags import OptionFlags
+
+
+# OptionEltMask
+#
+# A flags option which automatically only allows element
+# names as values.
+#
+class OptionEltMask(OptionFlags):
+
+    OPTION_TYPE = 'element-mask'
+
+    def load(self, node):
+        # Ask the parent constructor to disallow value definitions,
+        # we define those automatically only.
+        super(OptionEltMask, self).load(node, allow_value_definitions=False)
+
+    # Here we want all valid elements as possible values,
+    # but we'll settle for just the relative filenames
+    # of files ending with ".bst" in the project element directory
+    def load_valid_values(self, node):
+        values = []
+        for filename in utils.list_relative_paths(self.pool.element_path):
+            if filename.endswith('.bst'):
+                values.append(filename)
+        return values