1 files changed, 35 insertions, 0 deletions
diff --git a/mesonbuild/interpreterbase/_unholder.py b/mesonbuild/interpreterbase/_unholder.py
new file mode 100644
index 0000000..4f1edc1
--- /dev/null
+++ b/mesonbuild/interpreterbase/_unholder.py
@@ -0,0 +1,35 @@
+# Copyright 2013-2021 The Meson development team
+
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+
+#     http://www.apache.org/licenses/LICENSE-2.0
+
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+from __future__ import annotations
+
+import typing as T
+
+from .baseobjects import InterpreterObject, MesonInterpreterObject, ObjectHolder, HoldableTypes
+from .exceptions import InvalidArguments
+from ..mesonlib import HoldableObject, MesonBugException
+
+if T.TYPE_CHECKING:
+    from .baseobjects import TYPE_var
+
+def _unholder(obj: InterpreterObject) -> TYPE_var:
+    if isinstance(obj, ObjectHolder):
+        assert isinstance(obj.held_object, HoldableTypes)
+        return obj.held_object
+    elif isinstance(obj, MesonInterpreterObject):
+        return obj
+    elif isinstance(obj, HoldableObject):
+        raise MesonBugException(f'Argument {obj} of type {type(obj).__name__} is not held by an ObjectHolder.')
+    elif isinstance(obj, InterpreterObject):
+        raise InvalidArguments(f'Argument {obj} of type {type(obj).__name__} cannot be passed to a method or function')
+    raise MesonBugException(f'Unknown object {obj} of type {type(obj).__name__} in the parameters.')