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bpo-24665: double-width CJK chars support for textwrap #89

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bpo-24665: double-width CJK chars support for textwrap #89

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6ea78e3
bpo-24665: double-width CJK chars support for textwrap
fgallaire Feb 14, 2017
aa94f26
Fix TextWrapper positionnal arguments
fgallaire Feb 14, 2017
0264d9d
Fix one import per line
fgallaire Feb 14, 2017
d630821
Rename self.len() in self._width()
fgallaire Feb 14, 2017
bfdfb22
Rename CJK functions with _
fgallaire Feb 14, 2017
8337ce5
Improve cjk_slices() complexity from O(n^2) to O(n) (Thanks to INADA …
fgallaire Feb 14, 2017
cb9812b
Add Doc for new CJK option and functions
fgallaire Feb 15, 2017
54de7aa
Fix Python build problems
fgallaire Feb 15, 2017
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Rename CJK functions with _
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@fgallaire
fgallaire committed Feb 15, 2017
commit bfdfb22b7e4c33590a5aaaf82288cd7cf83c06bc
18 changes: 9 additions & 9 deletions Lib/textwrap.py
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Original file line number Diff line number Diff line change
Expand Up @@ -10,7 +10,7 @@
import unicodedata

__all__ = ['TextWrapper', 'wrap', 'fill', 'dedent', 'indent', 'shorten',
'cjkwide', 'cjklen', 'cjkslices']
'cjk_wide', 'cjk_len', 'cjk_slices']

# Hardcode the recognized whitespace characters to the US-ASCII
# whitespace characters. The main reason for doing this is that
Expand Down Expand Up @@ -146,7 +146,7 @@ def __init__(self,
self.placeholder = placeholder
self.cjk = cjk

self._width = cjklen if self.cjk else len
self._width = cjk_len if self.cjk else len

# -- Private methods -----------------------------------------------
# (possibly useful for subclasses to override)
Expand Down Expand Up @@ -224,7 +224,7 @@ def _handle_long_word(self, reversed_chunks, cur_line, cur_len, width):
# of the next chunk onto the current line as will fit.
if self.break_long_words:
if self.cjk:
chunk_start, chunk_end = cjkslices(reversed_chunks[-1], space_left)
chunk_start, chunk_end = cjk_slices(reversed_chunks[-1], space_left)
cur_line.append(chunk_start)
reversed_chunks[-1] = chunk_end
else:
Expand Down Expand Up @@ -424,31 +424,31 @@ def shorten(text, width, cjk=False, **kwargs):

# -- CJK support ------------------------------------------------------

def cjkwide(char):
def cjk_wide(char):
"""Return True if char is Fullwidth or Wide, False otherwise.
Fullwidth and Wide CJK chars are double-width.
"""
return unicodedata.east_asian_width(char) in ('F', 'W')

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Please, @duboviy or @Haypo, could you explain to me why/how a tuple could be slower than a frozenset.



def cjklen(text):
def cjk_len(text):
"""Return the real width of text (its len if not a string).
"""
if not isinstance(text, str):
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Strange case handling, maybe we should expect only string type text argument in this function...

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@fgallaire fgallaire Mar 12, 2017 •
edited
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Again: it's for an handy replacement of the built-in len():
from textwrap import cjk_len as len

return len(text)
return sum(2 if cjkwide(char) else 1 for char in text)
return sum(2 if cjk_wide(char) else 1 for char in text)


def cjkslices(text, index):
def cjk_slices(text, index):
"""Return the two slices of text cut to the index.
"""
if not isinstance(text, str):
return text[:index], text[index:]
if cjklen(text) <= index:
if cjk_len(text) <= index:
return text, ''
i = 1
# <= and i-1 to catch the last double length char of odd line
while cjklen(text[:i]) <= index:
while cjk_len(text[:i]) <= index:
i = i + 1
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I don't like this O(n^2) algorithm.

w = 0
for i, c in enumerate(text):
    w += cjkwide(c) + 1
    if w > index:
        break

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Very relevant point.

return text[:i-1], text[i-1:]

Expand Down
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