[Python-checkins] cpython: Add fileobj support to gzip.open().

[nadeem.vawda]

http://hg.python.org/cpython/rev/d87ec233d514
changeset:   77352:d87ec233d514
user:        Nadeem Vawda <nadeem.vawda at gmail.com>
date:        Mon Jun 04 23:21:38 2012 +0200
summary:
  Add fileobj support to gzip.open().

files:
  Doc/library/gzip.rst  |  20 +++++++++++---------
  Lib/gzip.py           |  13 ++++++++++++-
  Lib/test/test_gzip.py |  13 +++++++++++++
  Misc/NEWS             |   2 ++
  4 files changed, 38 insertions(+), 10 deletions(-)


diff --git a/Doc/library/gzip.rst b/Doc/library/gzip.rst
--- a/Doc/library/gzip.rst
+++ b/Doc/library/gzip.rst
@@ -14,10 +14,10 @@
 The data compression is provided by the :mod:`zlib` module.
 
 The :mod:`gzip` module provides the :class:`GzipFile` class, as well as the
-:func:`gzip.open`, :func:`compress` and :func:`decompress` convenience
-functions. The :class:`GzipFile` class reads and writes :program:`gzip`\ -format
-files, automatically compressing or decompressing the data so that it looks like
-an ordinary :term:`file object`.
+:func:`.open`, :func:`compress` and :func:`decompress` convenience functions.
+The :class:`GzipFile` class reads and writes :program:`gzip`\ -format files,
+automatically compressing or decompressing the data so that it looks like an
+ordinary :term:`file object`.
 
 Note that additional file formats which can be decompressed by the
 :program:`gzip` and :program:`gunzip` programs, such  as those produced by
@@ -28,9 +28,11 @@
 
 .. function:: open(filename, mode='rb', compresslevel=9, encoding=None, errors=None, newline=None)
 
-   Open *filename* as a gzip-compressed file in binary or text mode.
+   Open a gzip-compressed file in binary or text mode, returning a :term:`file
+   object`.
 
-   Returns a :term:`file object`.
+   The *filename* argument can be an actual filename (a :class:`str` or
+   :class:`bytes` object), or an existing file object to read from or write to.
 
    The *mode* argument can be any of ``'r'``, ``'rb'``, ``'a'``, ``'ab'``,
    ``'w'``, or ``'wb'`` for binary mode, or ``'rt'``, ``'at'``, or ``'wt'`` for
@@ -48,8 +50,8 @@
    handling behavior, and line ending(s).
 
    .. versionchanged:: 3.3
-      Support for text mode was added, along with the *encoding*, *errors* and
-      *newline* arguments.
+      Added support for *filename* being a file object, support for text mode,
+      and the *encoding*, *errors* and *newline* arguments.
 
 
 .. class:: GzipFile(filename=None, mode=None, compresslevel=9, fileobj=None, mtime=None)
@@ -75,7 +77,7 @@
    is the mode of *fileobj* if discernible; otherwise, the default is ``'rb'``.
 
    Note that the file is always opened in binary mode. To open a compressed file
-   in text mode, use :func:`gzip.open` (or wrap your :class:`GzipFile` with an
+   in text mode, use :func:`.open` (or wrap your :class:`GzipFile` with an
    :class:`io.TextIOWrapper`).
 
    The *compresslevel* argument is an integer from ``1`` to ``9`` controlling the
diff --git a/Lib/gzip.py b/Lib/gzip.py
--- a/Lib/gzip.py
+++ b/Lib/gzip.py
@@ -20,6 +20,9 @@
          encoding=None, errors=None, newline=None):
     """Open a gzip-compressed file in binary or text mode.
 
+    The filename argument can be an actual filename (a str or bytes object), or
+    an existing file object to read from or write to.
+
     The mode argument can be "r", "rb", "w", "wb", "a" or "ab" for binary mode,
     or "rt", "wt" or "at" for text mode. The default mode is "rb", and the
     default compresslevel is 9.
@@ -43,7 +46,15 @@
             raise ValueError("Argument 'errors' not supported in binary mode")
         if newline is not None:
             raise ValueError("Argument 'newline' not supported in binary mode")
-    binary_file = GzipFile(filename, mode.replace("t", ""), compresslevel)
+
+    gz_mode = mode.replace("t", "")
+    if isinstance(filename, (str, bytes)):
+        binary_file = GzipFile(filename, gz_mode, compresslevel)
+    elif hasattr(filename, "read") or hasattr(filename, "write"):
+        binary_file = GzipFile(None, gz_mode, compresslevel, filename)
+    else:
+        raise TypeError("filename must be a str or bytes object, or a file")
+
     if "t" in mode:
         return io.TextIOWrapper(binary_file, encoding, errors, newline)
     else:
diff --git a/Lib/test/test_gzip.py b/Lib/test/test_gzip.py
--- a/Lib/test/test_gzip.py
+++ b/Lib/test/test_gzip.py
@@ -424,8 +424,21 @@
             file_data = gzip.decompress(f.read()).decode("ascii")
             self.assertEqual(file_data, uncompressed_raw * 2)
 
+    def test_fileobj(self):
+        uncompressed_bytes = data1 * 50
+        uncompressed_str = uncompressed_bytes.decode("ascii")
+        compressed = gzip.compress(uncompressed_bytes)
+        with gzip.open(io.BytesIO(compressed), "r") as f:
+            self.assertEqual(f.read(), uncompressed_bytes)
+        with gzip.open(io.BytesIO(compressed), "rb") as f:
+            self.assertEqual(f.read(), uncompressed_bytes)
+        with gzip.open(io.BytesIO(compressed), "rt") as f:
+            self.assertEqual(f.read(), uncompressed_str)
+
     def test_bad_params(self):
         # Test invalid parameter combinations.
+        with self.assertRaises(TypeError):
+            gzip.open(123.456)
         with self.assertRaises(ValueError):
             gzip.open(self.filename, "wbt")
         with self.assertRaises(ValueError):
diff --git a/Misc/NEWS b/Misc/NEWS
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -15,6 +15,8 @@
 Library
 -------
 
+- gzip.open() now accepts file objects as well as filenames.
+
 - Issue #14992: os.makedirs(path, exist_ok=True) would raise an OSError
   when the path existed and had the S_ISGID mode bit set when it was
   not explicitly asked for.  This is no longer an exception as mkdir

-- 
Repository URL: http://hg.python.org/cpython