lib.CopyContext: Add module

Add a CopyContext class. At this point it mostly acts as a context
manager for two FileContext instances, and copying data is the
canonical case to use it, hence the name.

Signed-off-by: Jan Lindemann <jan@janware.com>

src/python/jw/pkg/lib/CopyContext.py

@@ -0,0 +1,41 @@
+# -*- coding: utf-8 -*-
+
+from typing import Self
+
+from .FileContext import FileContext
+
+class CopyContext:
+
+    def __init__(self, src_uri: str, dst_uri: str, chroot=False) -> None:
+        self.__src_uri = src_uri
+        self.__dst_uri = dst_uri
+        self.__chroot = chroot
+
+    async def __aenter__(self) -> Self:
+        self.__src = FileContext.create(self.__src_uri, chroot=self.__chroot)
+        await self.__src.open()
+        self.__dst = FileContext.create(self.__dst_uri, chroot=self.__chroot)
+        await self.__dst.open()
+        return self
+
+    async def __aexit__(self, exc_type, exc, tb):
+        if self.__src is not None:
+            await self.__src.close()
+            self.__src = None
+        if self.__dst is not None:
+            await self.__dst.close()
+            self.__dst = None
+
+    @property
+    def src(self) -> FileContext:
+        return self.__src
+
+    @property
+    def dst(self) -> FileContext:
+        return self.__dst
+
+    async def _run(self) -> None:
+        await self._run()
+
+    async def run(self) -> None:
+        await self._run()