1 files changed, 49 insertions, 0 deletions
diff --git a/mesonbuild/cargo/toml.py b/mesonbuild/cargo/toml.py
new file mode 100644
index 0000000..601510e
--- /dev/null
+++ b/mesonbuild/cargo/toml.py
@@ -0,0 +1,49 @@
+from __future__ import annotations
+
+import importlib
+import shutil
+import json
+import typing as T
+
+from ..mesonlib import MesonException, Popen_safe
+if T.TYPE_CHECKING:
+    from types import ModuleType
+
+
+# tomllib is present in python 3.11, before that it is a pypi module called tomli,
+# we try to import tomllib, then tomli,
+tomllib: T.Optional[ModuleType] = None
+toml2json: T.Optional[str] = None
+for t in ['tomllib', 'tomli']:
+    try:
+        tomllib = importlib.import_module(t)
+        break
+    except ImportError:
+        pass
+else:
+    # TODO: it would be better to use an Executable here, which could be looked
+    # up in the cross file or provided by a wrap. However, that will have to be
+    # passed in externally, since we don't have (and I don't think we should),
+    # have access to the `Environment` for that in this module.
+    toml2json = shutil.which('toml2json')
+
+class TomlImplementationMissing(MesonException):
+    pass
+
+
+def load_toml(filename: str) -> T.Dict[str, object]:
+    if tomllib:
+        with open(filename, 'rb') as f:
+            raw = tomllib.load(f)
+    else:
+        if toml2json is None:
+            raise TomlImplementationMissing('Could not find an implementation of tomllib, nor toml2json')
+
+        p, out, err = Popen_safe([toml2json, filename])
+        if p.returncode != 0:
+            raise MesonException('toml2json failed to decode output\n', err)
+
+        raw = json.loads(out)
+
+    # tomllib.load() returns T.Dict[str, T.Any] but not other implementations.
+    return T.cast('T.Dict[str, object]', raw)