mirror of https://github.com/python/cpython.git
gh-125063: marshal: Add version 5, improve documentation (GH-126829)
* Document that slices can be marshalled * Deduplicate and organize the list of supported types in docs * Organize the type code list in marshal.c, to make it more obvious that this is a versioned format * Back-fill some historical info Co-authored-by: Michael Droettboom <mdboom@gmail.com>
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Petr Viktorin
GitHub
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@ -13,11 +13,12 @@ binary mode.
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Numeric values are stored with the least significant byte first.
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The module supports two versions of the data format: version 0 is the
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historical version, version 1 shares interned strings in the file, and upon
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unmarshalling. Version 2 uses a binary format for floating-point numbers.
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``Py_MARSHAL_VERSION`` indicates the current file format (currently 2).
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The module supports several versions of the data format; see
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the :py:mod:`Python module documentation <marshal>` for details.
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.. c:macro:: Py_MARSHAL_VERSION
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The current format version. See :py:data:`marshal.version`.
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.. c:function:: void PyMarshal_WriteLongToFile(long value, FILE *file, int version)
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@ -38,23 +38,39 @@ supports a substantially wider range of objects than marshal.
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maliciously constructed data. Never unmarshal data received from an
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untrusted or unauthenticated source.
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There are functions that read/write files as well as functions operating on
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bytes-like objects.
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.. index:: object; code, code object
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Not all Python object types are supported; in general, only objects whose value
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is independent from a particular invocation of Python can be written and read by
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this module. The following types are supported: booleans, integers, floating-point
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numbers, complex numbers, strings, bytes, bytearrays, tuples, lists, sets,
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frozensets, dictionaries, and code objects (if *allow_code* is true),
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where it should be understood that
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tuples, lists, sets, frozensets and dictionaries are only supported as long as
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the values contained therein are themselves supported. The
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singletons :const:`None`, :const:`Ellipsis` and :exc:`StopIteration` can also be
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marshalled and unmarshalled.
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For format *version* lower than 3, recursive lists, sets and dictionaries cannot
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be written (see below).
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this module. The following types are supported:
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* Numeric types: :class:`int`, :class:`bool`, :class:`float`, :class:`complex`.
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* Strings (:class:`str`) and :class:`bytes`.
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:term:`Bytes-like objects <bytes-like object>` like :class:`bytearray` are
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marshalled as :class:`!bytes`.
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* Containers: :class:`tuple`, :class:`list`, :class:`set`, :class:`frozenset`,
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and (since :data:`version` 5), :class:`slice`.
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It should be understood that these are supported only if the values contained
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therein are themselves supported.
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Recursive containers are supported since :data:`version` 3.
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* The singletons :const:`None`, :const:`Ellipsis` and :exc:`StopIteration`.
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* :class:`code` objects, if *allow_code* is true. See note above about
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version dependence.
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.. versionchanged:: 3.4
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* Added format version 3, which supports marshalling recursive lists, sets
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and dictionaries.
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* Added format version 4, which supports efficient representations
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of short strings.
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.. versionchanged:: next
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Added format version 5, which allows marshalling slices.
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There are functions that read/write files as well as functions operating on
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bytes-like objects.
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The module defines these functions:
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@ -140,11 +156,24 @@ In addition, the following constants are defined:
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.. data:: version
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Indicates the format that the module uses. Version 0 is the historical
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format, version 1 shares interned strings and version 2 uses a binary format
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for floating-point numbers.
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Version 3 adds support for object instancing and recursion.
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The current version is 4.
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Indicates the format that the module uses.
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Version 0 is the historical first version; subsequent versions
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add new features.
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Generally, a new version becomes the default when it is introduced.
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======= =============== ====================================================
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Version Available since New features
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======= =============== ====================================================
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1 Python 2.4 Sharing interned strings
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------- --------------- ----------------------------------------------------
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2 Python 2.5 Binary representation of floats
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------- --------------- ----------------------------------------------------
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3 Python 3.4 Support for object instancing and recursion
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------- --------------- ----------------------------------------------------
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4 Python 3.4 Efficient representation of short strings
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------- --------------- ----------------------------------------------------
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5 Python 3.14 Support for :class:`slice` objects
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======= =============== ====================================================
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.. rubric:: Footnotes
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@ -154,4 +183,3 @@ In addition, the following constants are defined:
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around in a self-contained form. Strictly speaking, "to marshal" means to
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convert some data from internal to external form (in an RPC buffer for instance)
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and "unmarshalling" for the reverse process.
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@ -13,7 +13,7 @@ PyAPI_FUNC(PyObject *) PyMarshal_ReadObjectFromString(const char *,
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Py_ssize_t);
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PyAPI_FUNC(PyObject *) PyMarshal_WriteObjectToString(PyObject *, int);
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#define Py_MARSHAL_VERSION 4
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#define Py_MARSHAL_VERSION 5
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PyAPI_FUNC(long) PyMarshal_ReadLongFromFile(FILE *);
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PyAPI_FUNC(int) PyMarshal_ReadShortFromFile(FILE *);
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@ -28,6 +28,13 @@ def helper(self, sample, *extra):
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finally:
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os_helper.unlink(os_helper.TESTFN)
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def omit_last_byte(data):
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"""return data[:-1]"""
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# This file's code is used in CompatibilityTestCase,
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# but slices need marshal version 5.
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# Avoid the slice literal.
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return data[slice(0, -1)]
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class IntTestCase(unittest.TestCase, HelperMixin):
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def test_ints(self):
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# Test a range of Python ints larger than the machine word size.
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@ -241,7 +248,8 @@ def test_bug_5888452(self):
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def test_patch_873224(self):
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self.assertRaises(Exception, marshal.loads, b'0')
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self.assertRaises(Exception, marshal.loads, b'f')
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self.assertRaises(Exception, marshal.loads, marshal.dumps(2**65)[:-1])
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self.assertRaises(Exception, marshal.loads,
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omit_last_byte(marshal.dumps(2**65)))
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def test_version_argument(self):
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# Python 2.4.0 crashes for any call to marshal.dumps(x, y)
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@ -594,6 +602,19 @@ def testNoIntern(self):
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s2 = sys.intern(s)
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self.assertNotEqual(id(s2), id(s))
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class SliceTestCase(unittest.TestCase, HelperMixin):
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def test_slice(self):
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for obj in (
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slice(None), slice(1), slice(1, 2), slice(1, 2, 3),
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slice({'set'}, ('tuple', {'with': 'dict'}, ), self.helper.__code__)
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):
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with self.subTest(obj=str(obj)):
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self.helper(obj)
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for version in range(4):
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with self.assertRaises(ValueError):
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marshal.dumps(obj, version)
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@support.cpython_only
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@unittest.skipUnless(_testcapi, 'requires _testcapi')
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class CAPI_TestCase(unittest.TestCase, HelperMixin):
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@ -654,7 +675,7 @@ def test_read_last_object_from_file(self):
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self.assertEqual(r, obj)
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with open(os_helper.TESTFN, 'wb') as f:
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f.write(data[:1])
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f.write(omit_last_byte(data))
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with self.assertRaises(EOFError):
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_testcapi.pymarshal_read_last_object_from_file(os_helper.TESTFN)
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os_helper.unlink(os_helper.TESTFN)
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@ -671,7 +692,7 @@ def test_read_object_from_file(self):
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self.assertEqual(p, len(data))
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with open(os_helper.TESTFN, 'wb') as f:
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f.write(data[:1])
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f.write(omit_last_byte(data))
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with self.assertRaises(EOFError):
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_testcapi.pymarshal_read_object_from_file(os_helper.TESTFN)
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os_helper.unlink(os_helper.TESTFN)
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@ -0,0 +1,2 @@
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:mod:`marshal` now supports :class:`slice` objects. The marshal format
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version was increased to 5.
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@ -121,6 +121,7 @@ compile_and_marshal(const char *name, const char *text)
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return NULL;
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}
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assert(Py_MARSHAL_VERSION >= 5);
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PyObject *marshalled = PyMarshal_WriteObjectToString(code, Py_MARSHAL_VERSION);
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Py_CLEAR(code);
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if (marshalled == NULL) {
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@ -50,41 +50,52 @@ module marshal
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# define MAX_MARSHAL_STACK_DEPTH 2000
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#endif
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/* Supported types */
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#define TYPE_NULL '0'
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#define TYPE_NONE 'N'
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#define TYPE_FALSE 'F'
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#define TYPE_TRUE 'T'
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#define TYPE_STOPITER 'S'
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#define TYPE_ELLIPSIS '.'
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#define TYPE_INT 'i'
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/* TYPE_INT64 is not generated anymore.
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Supported for backward compatibility only. */
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#define TYPE_INT64 'I'
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#define TYPE_FLOAT 'f'
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#define TYPE_BINARY_FLOAT 'g'
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#define TYPE_COMPLEX 'x'
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#define TYPE_BINARY_COMPLEX 'y'
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#define TYPE_LONG 'l'
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#define TYPE_STRING 's'
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#define TYPE_INTERNED 't'
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#define TYPE_REF 'r'
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#define TYPE_TUPLE '('
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#define TYPE_BINARY_FLOAT 'g' // Version 0 uses TYPE_FLOAT instead.
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#define TYPE_BINARY_COMPLEX 'y' // Version 0 uses TYPE_COMPLEX instead.
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#define TYPE_LONG 'l' // See also TYPE_INT.
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#define TYPE_STRING 's' // Bytes. (Name comes from Python 2.)
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#define TYPE_TUPLE '(' // See also TYPE_SMALL_TUPLE.
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#define TYPE_LIST '['
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#define TYPE_DICT '{'
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#define TYPE_CODE 'c'
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#define TYPE_UNICODE 'u'
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#define TYPE_UNKNOWN '?'
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// added in version 2:
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#define TYPE_SET '<'
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#define TYPE_FROZENSET '>'
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// added in version 5:
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#define TYPE_SLICE ':'
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#define FLAG_REF '\x80' /* with a type, add obj to index */
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// Remember to update the version and documentation when adding new types.
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/* Special cases for unicode strings (added in version 4) */
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#define TYPE_INTERNED 't' // Version 1+
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#define TYPE_ASCII 'a'
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#define TYPE_ASCII_INTERNED 'A'
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#define TYPE_SMALL_TUPLE ')'
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#define TYPE_SHORT_ASCII 'z'
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#define TYPE_SHORT_ASCII_INTERNED 'Z'
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/* Special cases for small objects */
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#define TYPE_INT 'i' // All versions. 32-bit encoding.
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#define TYPE_SMALL_TUPLE ')' // Version 4+
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/* Supported for backwards compatibility */
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#define TYPE_COMPLEX 'x' // Generated for version 0 only.
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#define TYPE_FLOAT 'f' // Generated for version 0 only.
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#define TYPE_INT64 'I' // Not generated any more.
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/* References (added in version 3) */
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#define TYPE_REF 'r'
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#define FLAG_REF '\x80' /* with a type, add obj to index */
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// Error codes:
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#define WFERR_OK 0
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#define WFERR_UNMARSHALLABLE 1
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#define WFERR_NESTEDTOODEEP 2
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@ -615,6 +626,11 @@ w_complex_object(PyObject *v, char flag, WFILE *p)
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PyBuffer_Release(&view);
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}
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else if (PySlice_Check(v)) {
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if (p->version < 5) {
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w_byte(TYPE_UNKNOWN, p);
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p->error = WFERR_UNMARSHALLABLE;
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return;
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}
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PySliceObject *slice = (PySliceObject *)v;
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W_TYPE(TYPE_SLICE, p);
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w_object(slice->start, p);
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