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bpo-32969: Expose some missing constants in zlib and fix the doc (GH-5988) 

(cherry picked from commit bc3f2289b9)

Co-authored-by: Xiang Zhang <angwerzx@126.com>
This commit is contained in:
Miss Islington (bot) 2018-03-06 21:26:19 -08:00 committed by GitHub
parent 112f799666
commit c4d77a6611
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4 changed files with 44 additions and 23 deletions
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41
Doc/library/zlib.rst
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@ -51,9 +51,9 @@ The available exception and functions in this module are:
Compresses the bytes in *data*, returning a bytes object containing compressed data.
*level* is an integer from ``0`` to ``9`` or ``-1`` controlling the level of compression;
``1`` is fastest and produces the least compression, ``9`` is slowest and
produces the most. ``0`` is no compression. The default value is ``-1``
(Z_DEFAULT_COMPRESSION). Z_DEFAULT_COMPRESSION represents a default
``1`` (Z_BEST_SPEED) is fastest and produces the least compression, ``9`` (Z_BEST_COMPRESSION)
is slowest and produces the most. ``0`` (Z_NO_COMPRESSION) is no compression.
The default value is ``-1`` (Z_DEFAULT_COMPRESSION). Z_DEFAULT_COMPRESSION represents a default
compromise between speed and compression (currently equivalent to level 6).
Raises the :exc:`error` exception if any error occurs.
@ -61,23 +61,25 @@ The available exception and functions in this module are:
*level* can now be used as a keyword parameter.
.. function:: compressobj(level=-1, method=DEFLATED, wbits=15, memLevel=8, strategy=Z_DEFAULT_STRATEGY[, zdict])
.. function:: compressobj(level=-1, method=DEFLATED, wbits=MAX_WBITS, memLevel=DEF_MEM_LEVEL, strategy=Z_DEFAULT_STRATEGY[, zdict])
Returns a compression object, to be used for compressing data streams that won't
fit into memory at once.
*level* is the compression level -- an integer from ``0`` to ``9`` or ``-1``.
A value of ``1`` is fastest and produces the least compression, while a value of
``9`` is slowest and produces the most. ``0`` is no compression. The default
value is ``-1`` (Z_DEFAULT_COMPRESSION). Z_DEFAULT_COMPRESSION represents a default
compromise between speed and compression (currently equivalent to level 6).
A value of ``1`` (Z_BEST_SPEED) is fastest and produces the least compression,
while a value of ``9`` (Z_BEST_COMPRESSION) is slowest and produces the most.
``0`` (Z_NO_COMPRESSION) is no compression. The default value is ``-1`` (Z_DEFAULT_COMPRESSION).
Z_DEFAULT_COMPRESSION represents a default compromise between speed and compression
(currently equivalent to level 6).
*method* is the compression algorithm. Currently, the only supported value is
``DEFLATED``.
:const:`DEFLATED`.
The *wbits* argument controls the size of the history buffer (or the
"window size") used when compressing data, and whether a header and
trailer is included in the output. It can take several ranges of values:
trailer is included in the output. It can take several ranges of values,
defaulting to ``15`` (MAX_WBITS):
* +9 to +15: The base-two logarithm of the window size, which
therefore ranges between 512 and 32768. Larger values produce
@ -97,7 +99,8 @@ The available exception and functions in this module are:
Higher values use more memory, but are faster and produce smaller output.
*strategy* is used to tune the compression algorithm. Possible values are
``Z_DEFAULT_STRATEGY``, ``Z_FILTERED``, and ``Z_HUFFMAN_ONLY``.
:const:`Z_DEFAULT_STRATEGY`, :const:`Z_FILTERED`, :const:`Z_HUFFMAN_ONLY`,
:const:`Z_RLE` (zlib 1.2.0.1) and :const:`Z_FIXED` (zlib 1.2.2.2).
*zdict* is a predefined compression dictionary. This is a sequence of bytes
(such as a :class:`bytes` object) containing subsequences that are expected
@ -175,7 +178,7 @@ The available exception and functions in this module are:
.. versionchanged:: 3.6
*wbits* and *bufsize* can be used as keyword arguments.
.. function:: decompressobj(wbits=15[, zdict])
.. function:: decompressobj(wbits=MAX_WBITS[, zdict])
Returns a decompression object, to be used for decompressing data streams that
won't fit into memory at once.
@ -213,13 +216,13 @@ Compression objects support the following methods:
All pending input is processed, and a bytes object containing the remaining compressed
output is returned. *mode* can be selected from the constants
:const:`Z_SYNC_FLUSH`, :const:`Z_FULL_FLUSH`, or :const:`Z_FINISH`,
defaulting to :const:`Z_FINISH`. :const:`Z_SYNC_FLUSH` and
:const:`Z_FULL_FLUSH` allow compressing further bytestrings of data, while
:const:`Z_FINISH` finishes the compressed stream and prevents compressing any
more data. After calling :meth:`flush` with *mode* set to :const:`Z_FINISH`,
the :meth:`compress` method cannot be called again; the only realistic action is
to delete the object.
:const:`Z_NO_FLUSH`, :const:`Z_PARTIAL_FLUSH`, :const:`Z_SYNC_FLUSH`,
:const:`Z_FULL_FLUSH`, :const:`Z_BLOCK` (zlib 1.2.3.4), or :const:`Z_FINISH`,
defaulting to :const:`Z_FINISH`. Except :const:`Z_FINISH`, all constants
allow compressing further bytestrings of data, while :const:`Z_FINISH` finishes the
compressed stream and prevents compressing any more data. After calling :meth:`flush`
with *mode* set to :const:`Z_FINISH`, the :meth:`compress` method cannot be called again;
the only realistic action is to delete the object.
.. method:: Compress.copy()

3
Lib/test/test_zlib.py
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@ -434,7 +434,8 @@ class CompressObjectTestCase(BaseCompressTestCase, unittest.TestCase):
def test_flushes(self):
# Test flush() with the various options, using all the
# different levels in order to provide more variations.
sync_opt = ['Z_NO_FLUSH', 'Z_SYNC_FLUSH', 'Z_FULL_FLUSH']
sync_opt = ['Z_NO_FLUSH', 'Z_SYNC_FLUSH', 'Z_FULL_FLUSH',
'Z_PARTIAL_FLUSH', 'Z_BLOCK']
sync_opt = [getattr(zlib, opt) for opt in sync_opt
if hasattr(zlib, opt)]
data = HAMLET_SCENE * 8

2
Misc/NEWS.d/next/Library/2018-03-06-00-19-41.bpo-32969.rGTKa0.rst Normal file
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@ -0,0 +1,2 @@
Expose several missing constants in zlib and fix corresponding
documentation.

21
Modules/zlibmodule.c
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@ -1361,18 +1361,33 @@ PyInit_zlib(void)
PyModule_AddIntMacro(m, DEFLATED);
PyModule_AddIntMacro(m, DEF_MEM_LEVEL);
PyModule_AddIntMacro(m, DEF_BUF_SIZE);
// compression levels
PyModule_AddIntMacro(m, Z_NO_COMPRESSION);
PyModule_AddIntMacro(m, Z_BEST_SPEED);
PyModule_AddIntMacro(m, Z_BEST_COMPRESSION);
PyModule_AddIntMacro(m, Z_DEFAULT_COMPRESSION);
// compression strategies
PyModule_AddIntMacro(m, Z_FILTERED);
PyModule_AddIntMacro(m, Z_HUFFMAN_ONLY);
#ifdef Z_RLE // 1.2.0.1
PyModule_AddIntMacro(m, Z_RLE);
#endif
#ifdef Z_FIXED // 1.2.2.2
PyModule_AddIntMacro(m, Z_FIXED);
#endif
PyModule_AddIntMacro(m, Z_DEFAULT_STRATEGY);
PyModule_AddIntMacro(m, Z_FINISH);
// allowed flush values
PyModule_AddIntMacro(m, Z_NO_FLUSH);
PyModule_AddIntMacro(m, Z_PARTIAL_FLUSH);
PyModule_AddIntMacro(m, Z_SYNC_FLUSH);
PyModule_AddIntMacro(m, Z_FULL_FLUSH);
PyModule_AddIntMacro(m, Z_FINISH);
#ifdef Z_BLOCK // 1.2.0.5 for inflate, 1.2.3.4 for deflate
PyModule_AddIntMacro(m, Z_BLOCK);
#endif
#ifdef Z_TREES // 1.2.3.4, only for inflate
PyModule_AddIntMacro(m, Z_TREES);
#endif
ver = PyUnicode_FromString(ZLIB_VERSION);
if (ver != NULL)
PyModule_AddObject(m, "ZLIB_VERSION", ver);