xcp/accessor.py: openText(): Context manager to read text from addr

Add `Accessor.openText()` as context manager to wrap openAddress() with
`io.TextIOWrapper` (if needed). It yields IO[str] or False, closing the
created TextIOWrapper and the underlying file on leaving the context.

It is intented for use in xcp.repository and any other user requiring
text as string without having to call .decode() on the returned file
object. It also closes the underlying file object on leaving the context.

Signed-off-by: Bernhard Kaindl <bernhard.kaindl@cloud.com>

Author: bernhardkaindl

xcp/accessor.py

@@ -25,17 +25,22 @@
 
 """accessor - provide common interface to access methods"""
 
+# pyre-ignore-all-errors[6,16]
 import ftplib
+import io
 import os
+import sys
 import tempfile
 import errno
+from contextlib import contextmanager
 from typing import cast, TYPE_CHECKING
 
 from six.moves import urllib  # pyright: ignore
 
 from xcp import logger, mount
 
 if TYPE_CHECKING:
+    from collections.abc import Generator
     from typing import IO
     from typing_extensions import Literal
 
@@ -70,6 +75,22 @@ def access(self, name):
 
         return True
 
+    @contextmanager
+    def openText(self, address):
+        # type:(str) -> Generator[IO[str] | Literal[False], None, None]
+        """Context manager to read text from address using 'with'. Yields IO[str] or False"""
+        readbuffer = self.openAddress(address)
+
+        if readbuffer and sys.version_info >= (3, 0):
+            textiowrapper = io.TextIOWrapper(readbuffer, encoding="utf-8")
+            yield textiowrapper
+            textiowrapper.close()
+        else:
+            yield cast(io.TextIOWrapper, readbuffer)
+
+        if readbuffer:
+            readbuffer.close()
+
     def openAddress(self, address):
         # type:(str) -> IO[bytes] | Literal[False]
         """must be overloaded"""