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from __future__ import unicode_literals
import sys
import stringprep
import unicodedata
class StringPrepError(UnicodeError):
pass
def to_unicode(data):
if sys.version_info < (3, 0):
return unicode(data)
else:
return str(data)
def b1_mapping(char):
return '' if stringprep.in_table_c12(char) else None
def c12_mapping(char):
return ' ' if stringprep.in_table_c12(char) else None
def map_input(data, tables=None):
"""
Each character in the input stream MUST be checked against
a mapping table.
"""
result = []
for char in data:
replacement = None
for mapping in tables:
replacement = mapping(char)
if replacement is not None:
break
if replacement is None:
replacement = char
result.append(replacement)
return ''.join(result)
def normalize(data, nfkc=True):
"""
A profile can specify one of two options for Unicode normalization:
- no normalization
- Unicode normalization with form KC
"""
if nfkc:
data = unicodedata.normalize('NFKC', data)
return data
def prohibit_output(data, tables=None):
"""
Before the text can be emitted, it MUST be checked for prohibited
code points.
"""
for char in data:
for check in tables:
if check(char):
raise StringPrepError("Prohibited code point: %s" % char)
def check_bidi(data):
"""
1) The characters in section 5.8 MUST be prohibited.
2) If a string contains any RandALCat character, the string MUST NOT
contain any LCat character.
3) If a string contains any RandALCat character, a RandALCat
character MUST be the first character of the string, and a
RandALCat character MUST be the last character of the string.
"""
has_lcat = False
has_randal = False
for c in data:
if stringprep.in_table_c8(c):
raise StringPrepError("BIDI violation: seciton 6 (1)")
if stringprep.in_table_d1(c):
has_randal = True
elif stringprep.in_table_d2(c):
has_lcat = True
if has_randal and has_lcat:
raise StringPrepError("BIDI violation: section 6 (2)")
first_randal = stringprep.in_table_d1(data[0])
last_randal = stringprep.in_table_d1(data[-1])
if has_randal and not (first_randal and last_randal):
raise StringPrepError("BIDI violation: section 6 (3)")
def create(nfkc=True, bidi=True, mappings=None,
prohibited=None, unassigned=None):
def profile(data, query=False):
try:
data = to_unicode(data)
except UnicodeError:
raise StringPrepError
data = map_input(data, mappings)
data = normalize(data, nfkc)
prohibit_output(data, prohibited)
if bidi:
check_bidi(data)
if query and unassigned:
check_unassigned(data, unassigned)
return data
return profile
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