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diff mercurial/thirdparty/cbor/cbor2/compat.py @ 37126:4bd73a955ab0

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thirdparty: vendor cbor2 python library CBOR stands for Concise Binary Object Representation, which is a data format which is very compact and extensible. This patch moves the python library which can serilaize and deserialize python objects to/from cbor formats. The library is taken from https://github.com/agronholm/cbor2/ from commit 84181540f6eb650437e3f73cd104a65661fe8e67. Unrequired files from the cbor library - docs/, tests/, setup.py, setup.cfg, and tox.ini - have not been vendored. There is another python library for cbor at https://github.com/brianolson/cbor_py/ which is used in evolve extension and was imported in initial version of this series. That library though contains C code and is bit faster, but has known bugs around serializing nested structures, is unmaintained, raises an Exception object instead of a more dedicated Error type. So, it's better to use a bug free and actively maintained library. This library is not yet used and will be used in later commits. # no-check-commit because we are importing a third library module Differential Revision: https://phab.mercurial-scm.org/D2750
author Pulkit Goyal <7895pulkit@gmail.com>
date Mon, 26 Mar 2018 08:33:57 -0700
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--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mercurial/thirdparty/cbor/cbor2/compat.py	Mon Mar 26 08:33:57 2018 -0700
@@ -0,0 +1,101 @@
+from math import ldexp
+import struct
+import sys
+
+
+if sys.version_info.major < 3:
+    from datetime import tzinfo, timedelta
+
+    class timezone(tzinfo):
+        def __init__(self, offset):
+            self.offset = offset
+
+        def utcoffset(self, dt):
+            return self.offset
+
+        def dst(self, dt):
+            return timedelta(0)
+
+        def tzname(self, dt):
+            return 'UTC+00:00'
+
+    def as_unicode(string):
+        return string.decode('utf-8')
+
+    def iteritems(self):
+        return self.iteritems()
+
+    def bytes_from_list(values):
+        return bytes(bytearray(values))
+
+    byte_as_integer = ord
+    timezone.utc = timezone(timedelta(0))
+    xrange = xrange  # noqa: F821
+    long = long  # noqa: F821
+    unicode = unicode  # noqa: F821
+else:
+    from datetime import timezone
+
+    def byte_as_integer(bytestr):
+        return bytestr[0]
+
+    def as_unicode(string):
+        return string
+
+    def iteritems(self):
+        return self.items()
+
+    xrange = range
+    long = int
+    unicode = str
+    bytes_from_list = bytes
+
+
+if sys.version_info.major >= 3 and sys.version_info.minor >= 6:
+    # Python 3.6 added 16 bit floating point to struct
+
+    def pack_float16(value):
+        try:
+            return struct.pack('>Be', 0xf9, value)
+        except OverflowError:
+            return False
+
+    def unpack_float16(payload):
+        return struct.unpack('>e', payload)[0]
+else:
+    def pack_float16(value):
+        # Based on node-cbor by hildjj
+        # which was based in turn on Carsten Borman's cn-cbor
+        u32 = struct.pack('>f', value)
+        u = struct.unpack('>I', u32)[0]
+
+        if u & 0x1FFF != 0:
+            return False
+
+        s16 = (u >> 16) & 0x8000
+        exponent = (u >> 23) & 0xff
+        mantissa = u & 0x7fffff
+
+        if 113 <= exponent <= 142:
+            s16 += ((exponent - 112) << 10) + (mantissa >> 13)
+        elif 103 <= exponent < 113:
+            if mantissa & ((1 << (126 - exponent)) - 1):
+                return False
+
+            s16 += ((mantissa + 0x800000) >> (126 - exponent))
+        else:
+            return False
+
+        return struct.pack('>BH', 0xf9, s16)
+
+    def unpack_float16(payload):
+        # Code adapted from RFC 7049, appendix D
+        def decode_single(single):
+            return struct.unpack("!f", struct.pack("!I", single))[0]
+
+        payload = struct.unpack('>H', payload)[0]
+        value = (payload & 0x7fff) << 13 | (payload & 0x8000) << 16
+        if payload & 0x7c00 != 0x7c00:
+            return ldexp(decode_single(value), 112)
+
+        return decode_single(value | 0x7f800000)