1 files changed, 79 insertions, 0 deletions
diff --git a/qutebrowser/qt/machinery.py b/qutebrowser/qt/machinery.py
new file mode 100644
index 000000000..66a35a855
--- /dev/null
+++ b/qutebrowser/qt/machinery.py
@@ -0,0 +1,79 @@
+# vim: ft=python fileencoding=utf-8 sts=4 sw=4 et:
+# FIXME:qt6 (lint)
+# pylint: disable=missing-module-docstring
+# flake8: noqa
+
+import os
+import importlib
+
+
+_WRAPPERS = [
+    "PyQt6",
+    "PyQt5",
+    # Needs more work
+    # "PySide6",
+]
+
+
+class Error(Exception):
+    pass
+
+
+class Unavailable(Error, ImportError):
+
+    """Raised when a module is unavailable with the given wrapper."""
+
+    def __init__(self) -> None:
+        super().__init__(f"Unavailable with {WRAPPER}")
+
+
+class UnknownWrapper(Error):
+    pass
+
+
+def _autoselect_wrapper():
+    for wrapper in _WRAPPERS:
+        try:
+            importlib.import_module(wrapper)
+        except ImportError:
+            # FIXME:qt6 show/log this somewhere?
+            continue
+        return wrapper
+
+    wrappers = ", ".join(_WRAPPERS)
+    raise Error(f"No Qt wrapper found, tried {wrappers}")
+
+
+def _select_wrapper():
+    env_var = "QUTE_QT_WRAPPER"
+    env_wrapper = os.environ.get(env_var)
+    if env_wrapper is None:
+        return _autoselect_wrapper()
+
+    if env_wrapper not in _WRAPPERS:
+        raise Error(f"Unknown wrapper {env_wrapper} set via {env_var}, "
+                    f"allowed: {', '.join(_WRAPPERS)}")
+
+    return env_wrapper
+
+
+WRAPPER = _select_wrapper()
+USE_PYQT5 = WRAPPER == "PyQt5"
+USE_PYQT6 = WRAPPER == "PyQt6"
+USE_PYSIDE6 = WRAPPER == "PySide6"
+assert USE_PYQT5 ^ USE_PYQT6 ^ USE_PYSIDE6
+
+IS_QT5 = USE_PYQT5
+IS_QT6 = USE_PYQT6 or USE_PYSIDE6
+IS_PYQT = USE_PYQT5 or USE_PYQT6
+IS_PYSIDE = USE_PYSIDE6
+assert IS_QT5 ^ IS_QT6
+assert IS_PYQT ^ IS_PYSIDE
+
+
+if USE_PYQT5:
+    PACKAGE = "PyQt5"
+elif USE_PYQT6:
+    PACKAGE = "PyQt6"
+elif USE_PYSIDE6:
+    PACKAGE = "PySide6"