1 files changed, 39 insertions, 0 deletions
diff --git a/meson/mesonbuild/interpreterbase/_unholder.py b/meson/mesonbuild/interpreterbase/_unholder.py
new file mode 100644
index 000000000..10c7cfc8f
--- /dev/null
+++ b/meson/mesonbuild/interpreterbase/_unholder.py
@@ -0,0 +1,39 @@
+# 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 .baseobjects import InterpreterObject, MesonInterpreterObject, ObjectHolder, TYPE_var
+from .exceptions import InvalidArguments
+from ..mesonlib import HoldableObject, MesonBugException
+
+import typing as T
+
+def _unholder(obj: T.Union[TYPE_var, InterpreterObject], *, permissive: bool = False) -> TYPE_var:
+    if isinstance(obj, (int, bool, str)):
+        return obj
+    elif isinstance(obj, list):
+        return [_unholder(x, permissive=permissive) for x in obj]
+    elif isinstance(obj, dict):
+        return {k: _unholder(v, permissive=permissive) for k, v in obj.items()}
+    elif isinstance(obj, ObjectHolder):
+        assert isinstance(obj.held_object, HoldableObject)
+        return obj.held_object
+    elif isinstance(obj, MesonInterpreterObject):
+        return obj
+    elif isinstance(obj, HoldableObject) and permissive:
+        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.')