Support for certain unicode literals depends on sys.maxunicode #350
Description
It seems that support for unicode literals over code point 0xffff, introduced in cf1c86c, depends on sys.maxunicode. So for example, it'll work with standard Python 3 builds, but won't work with standard Python 2 builds, where sys.maxunicode is 2**16-1 (built with UCS-2).
Here's a simple test program that works on Python 3, but not on a standard Python 2 build:
# coding=utf8
import yaml
s = '''
"😢"
'''
assert yaml.safe_load(s) == '😢'It produces the following error on Python 2:
Traceback (most recent call last):
File "pyyaml_unicode.py", line 8, in <module>
assert yaml.safe_load(s) == '😢'
File "/usr/local/lib/python2.7/site-packages/yaml/__init__.py", line 162, in safe_load
return load(stream, SafeLoader)
File "/usr/local/lib/python2.7/site-packages/yaml/__init__.py", line 112, in load
loader = Loader(stream)
File "/usr/local/lib/python2.7/site-packages/yaml/loader.py", line 34, in __init__
Reader.__init__(self, stream)
File "/usr/local/lib/python2.7/site-packages/yaml/reader.py", line 81, in __init__
self.determine_encoding()
File "/usr/local/lib/python2.7/site-packages/yaml/reader.py", line 137, in determine_encoding
self.update(1)
File "/usr/local/lib/python2.7/site-packages/yaml/reader.py", line 174, in update
self.check_printable(data)
File "/usr/local/lib/python2.7/site-packages/yaml/reader.py", line 149, in check_printable
'unicode', "special characters are not allowed")
yaml.reader.ReaderError: unacceptable character #xd83d: special characters are not allowed
in "<string>", position 2
Is there any reasonable way to support this functionality on Python 2 as well?