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#!/usr/bin/env python3
"""
Unicode case folding database conversion utility
Parses the database and generates a C++ function which implements the case
folding algorithm. The database entries are of the form:
<code>; <status>; <mapping>; # <name>
<status> can be one of four characters:
C - Common mappings
S - mappings for Simple case folding
F - mappings for Full case folding
T - special case for Turkish I characters
Right now this generates a function which implements simple case folding (C+S
entries).
"""
from __future__ import print_function
import sys
import re
try:
from urllib.request import urlopen
except ImportError:
from urllib2 import urlopen
# This variable will body of the mappings function
body = ""
# Reads file line-by-line, extracts Common and Simple case fold mappings and
# returns a (from_char, to_char, from_name) tuple.
def mappings(f):
previous_from = -1
expr = re.compile(r'^(.*); [CS]; (.*); # (.*)')
for line in f:
m = expr.match(line)
if not m: continue
from_char = int(m.group(1), 16)
to_char = int(m.group(2), 16)
from_name = m.group(3)
if from_char <= previous_from:
raise Exception("Duplicate or unsorted characters in input")
yield from_char, to_char, from_name
previous_from = from_char
# Computes the shift (to_char - from_char) in a mapping.
def shift(mapping):
return mapping[1] - mapping[0]
# Computes the stride (from_char2 - from_char1) of two mappings.
def stride2(mapping1, mapping2):
return mapping2[0] - mapping1[0]
# Computes the stride of a list of mappings. The list should have at least two
# mappings. All mappings in the list are assumed to have the same stride.
def stride(block):
return stride2(block[0], block[1])
# b is a list of mappings. All the mappings are assumed to have the same
# shift and the stride between adjecant mappings (if any) is constant.
def dump_block(b):
global body
if len(b) == 1:
# Special case for handling blocks of length 1. We don't even need to
# emit the "if (C < X) return C" check below as all characters in this
# range will be caught by the "C < X" check emitted by the first
# non-trivial block.
body += " // {2}\n if (C == {0:#06x})\n return {1:#06x};\n".format(*b[0])
return
first = b[0][0]
last = first + stride(b) * (len(b)-1)
modulo = first % stride(b)
# All characters before this block map to themselves.
body += " if (C < {0:#06x})\n return C;\n".format(first)
body += " // {0} characters\n".format(len(b))
# Generic pattern: check upper bound (lower bound is checked by the "if"
# above) and modulo of C, return C+shift.
pattern = " if (C <= {0:#06x} && C % {1} == {2})\n return C + {3};\n"
if stride(b) == 2 and shift(b[0]) == 1 and modulo == 0:
# Special case:
# We can elide the modulo-check because the expression "C|1" will map
# the intervening characters to themselves.
pattern = " if (C <= {0:#06x})\n return C | 1;\n"
elif stride(b) == 1:
# Another special case: X % 1 is always zero, so don't emit the
# modulo-check.
pattern = " if (C <= {0:#06x})\n return C + {3};\n"
body += pattern.format(last, stride(b), modulo, shift(b[0]))
current_block = []
f = urlopen(sys.argv[1])
for m in mappings(f):
if len(current_block) == 0:
current_block.append(m)
continue
if shift(current_block[0]) != shift(m):
# Incompatible shift, start a new block.
dump_block(current_block)
current_block = [m]
continue
if len(current_block) == 1 or stride(current_block) == stride2(current_block[-1], m):
current_block.append(m)
continue
# Incompatible stride, start a new block.
dump_block(current_block)
current_block = [m]
f.close()
dump_block(current_block)
print('//===---------- Support/UnicodeCaseFold.cpp -------------------------------===//')
print('//')
print('// This file was generated by utils/unicode-case-fold.py from the Unicode')
print('// case folding database at')
print('// ', sys.argv[1])
print('//')
print('// To regenerate this file, run:')
print('// utils/unicode-case-fold.py \\')
print('// "{}" \\'.format(sys.argv[1]))
print('// > lib/Support/UnicodeCaseFold.cpp')
print('//')
print('//===----------------------------------------------------------------------===//')
print('')
print('#include "llvm/Support/Unicode.h"')
print('')
print("int llvm::sys::unicode::foldCharSimple(int C) {")
print(body)
print(" return C;")
print("}")
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