1 | from __future__ import print_function # for OPy compiler
|
2 | """Text wrapping and filling.
|
3 | """
|
4 |
|
5 | # Copyright (C) 1999-2001 Gregory P. Ward.
|
6 | # Copyright (C) 2002, 2003 Python Software Foundation.
|
7 | # Written by Greg Ward <gward@python.net>
|
8 |
|
9 | __revision__ = "$Id$"
|
10 |
|
11 | import string, re
|
12 |
|
13 | try:
|
14 | _unicode = unicode
|
15 | except NameError:
|
16 | # If Python is built without Unicode support, the unicode type
|
17 | # will not exist. Fake one.
|
18 | class _unicode(object):
|
19 | pass
|
20 |
|
21 | # Do the right thing with boolean values for all known Python versions
|
22 | # (so this module can be copied to projects that don't depend on Python
|
23 | # 2.3, e.g. Optik and Docutils) by uncommenting the block of code below.
|
24 | #try:
|
25 | # True, False
|
26 | #except NameError:
|
27 | # (True, False) = (1, 0)
|
28 |
|
29 | __all__ = ['TextWrapper', 'wrap', 'fill', 'dedent']
|
30 |
|
31 | # Hardcode the recognized whitespace characters to the US-ASCII
|
32 | # whitespace characters. The main reason for doing this is that in
|
33 | # ISO-8859-1, 0xa0 is non-breaking whitespace, so in certain locales
|
34 | # that character winds up in string.whitespace. Respecting
|
35 | # string.whitespace in those cases would 1) make textwrap treat 0xa0 the
|
36 | # same as any other whitespace char, which is clearly wrong (it's a
|
37 | # *non-breaking* space), 2) possibly cause problems with Unicode,
|
38 | # since 0xa0 is not in range(128).
|
39 | _whitespace = '\t\n\x0b\x0c\r '
|
40 |
|
41 | class TextWrapper:
|
42 | """
|
43 | Object for wrapping/filling text. The public interface consists of
|
44 | the wrap() and fill() methods; the other methods are just there for
|
45 | subclasses to override in order to tweak the default behaviour.
|
46 | If you want to completely replace the main wrapping algorithm,
|
47 | you'll probably have to override _wrap_chunks().
|
48 |
|
49 | Several instance attributes control various aspects of wrapping:
|
50 | width (default: 70)
|
51 | the maximum width of wrapped lines (unless break_long_words
|
52 | is false)
|
53 | initial_indent (default: "")
|
54 | string that will be prepended to the first line of wrapped
|
55 | output. Counts towards the line's width.
|
56 | subsequent_indent (default: "")
|
57 | string that will be prepended to all lines save the first
|
58 | of wrapped output; also counts towards each line's width.
|
59 | expand_tabs (default: true)
|
60 | Expand tabs in input text to spaces before further processing.
|
61 | Each tab will become 1 .. 8 spaces, depending on its position in
|
62 | its line. If false, each tab is treated as a single character.
|
63 | replace_whitespace (default: true)
|
64 | Replace all whitespace characters in the input text by spaces
|
65 | after tab expansion. Note that if expand_tabs is false and
|
66 | replace_whitespace is true, every tab will be converted to a
|
67 | single space!
|
68 | fix_sentence_endings (default: false)
|
69 | Ensure that sentence-ending punctuation is always followed
|
70 | by two spaces. Off by default because the algorithm is
|
71 | (unavoidably) imperfect.
|
72 | break_long_words (default: true)
|
73 | Break words longer than 'width'. If false, those words will not
|
74 | be broken, and some lines might be longer than 'width'.
|
75 | break_on_hyphens (default: true)
|
76 | Allow breaking hyphenated words. If true, wrapping will occur
|
77 | preferably on whitespaces and right after hyphens part of
|
78 | compound words.
|
79 | drop_whitespace (default: true)
|
80 | Drop leading and trailing whitespace from lines.
|
81 | """
|
82 |
|
83 | whitespace_trans = string.maketrans(_whitespace, ' ' * len(_whitespace))
|
84 |
|
85 | unicode_whitespace_trans = {}
|
86 | uspace = ord(u' ')
|
87 | for x in map(ord, _whitespace):
|
88 | unicode_whitespace_trans[x] = uspace
|
89 |
|
90 | # This funky little regex is just the trick for splitting
|
91 | # text up into word-wrappable chunks. E.g.
|
92 | # "Hello there -- you goof-ball, use the -b option!"
|
93 | # splits into
|
94 | # Hello/ /there/ /--/ /you/ /goof-/ball,/ /use/ /the/ /-b/ /option!
|
95 | # (after stripping out empty strings).
|
96 | wordsep_re = re.compile(
|
97 | r'(\s+|' # any whitespace
|
98 | r'[^\s\w]*\w+[^0-9\W]-(?=\w+[^0-9\W])|' # hyphenated words
|
99 | r'(?<=[\w\!\"\'\&\.\,\?])-{2,}(?=\w))') # em-dash
|
100 |
|
101 | # This less funky little regex just split on recognized spaces. E.g.
|
102 | # "Hello there -- you goof-ball, use the -b option!"
|
103 | # splits into
|
104 | # Hello/ /there/ /--/ /you/ /goof-ball,/ /use/ /the/ /-b/ /option!/
|
105 | wordsep_simple_re = re.compile(r'(\s+)')
|
106 |
|
107 | # XXX this is not locale- or charset-aware -- string.lowercase
|
108 | # is US-ASCII only (and therefore English-only)
|
109 | sentence_end_re = re.compile(r'[%s]' # lowercase letter
|
110 | r'[\.\!\?]' # sentence-ending punct.
|
111 | r'[\"\']?' # optional end-of-quote
|
112 | r'\Z' # end of chunk
|
113 | % string.lowercase)
|
114 |
|
115 |
|
116 | def __init__(self,
|
117 | width=70,
|
118 | initial_indent="",
|
119 | subsequent_indent="",
|
120 | expand_tabs=True,
|
121 | replace_whitespace=True,
|
122 | fix_sentence_endings=False,
|
123 | break_long_words=True,
|
124 | drop_whitespace=True,
|
125 | break_on_hyphens=True):
|
126 | self.width = width
|
127 | self.initial_indent = initial_indent
|
128 | self.subsequent_indent = subsequent_indent
|
129 | self.expand_tabs = expand_tabs
|
130 | self.replace_whitespace = replace_whitespace
|
131 | self.fix_sentence_endings = fix_sentence_endings
|
132 | self.break_long_words = break_long_words
|
133 | self.drop_whitespace = drop_whitespace
|
134 | self.break_on_hyphens = break_on_hyphens
|
135 |
|
136 | # recompile the regexes for Unicode mode -- done in this clumsy way for
|
137 | # backwards compatibility because it's rather common to monkey-patch
|
138 | # the TextWrapper class' wordsep_re attribute.
|
139 | self.wordsep_re_uni = re.compile(self.wordsep_re.pattern, re.U)
|
140 | self.wordsep_simple_re_uni = re.compile(
|
141 | self.wordsep_simple_re.pattern, re.U)
|
142 |
|
143 |
|
144 | # -- Private methods -----------------------------------------------
|
145 | # (possibly useful for subclasses to override)
|
146 |
|
147 | def _munge_whitespace(self, text):
|
148 | """_munge_whitespace(text : string) -> string
|
149 |
|
150 | Munge whitespace in text: expand tabs and convert all other
|
151 | whitespace characters to spaces. Eg. " foo\\tbar\\n\\nbaz"
|
152 | becomes " foo bar baz".
|
153 | """
|
154 | if self.expand_tabs:
|
155 | text = text.expandtabs()
|
156 | if self.replace_whitespace:
|
157 | if isinstance(text, str):
|
158 | text = text.translate(self.whitespace_trans)
|
159 | elif isinstance(text, _unicode):
|
160 | text = text.translate(self.unicode_whitespace_trans)
|
161 | return text
|
162 |
|
163 |
|
164 | def _split(self, text):
|
165 | """_split(text : string) -> [string]
|
166 |
|
167 | Split the text to wrap into indivisible chunks. Chunks are
|
168 | not quite the same as words; see _wrap_chunks() for full
|
169 | details. As an example, the text
|
170 | Look, goof-ball -- use the -b option!
|
171 | breaks into the following chunks:
|
172 | 'Look,', ' ', 'goof-', 'ball', ' ', '--', ' ',
|
173 | 'use', ' ', 'the', ' ', '-b', ' ', 'option!'
|
174 | if break_on_hyphens is True, or in:
|
175 | 'Look,', ' ', 'goof-ball', ' ', '--', ' ',
|
176 | 'use', ' ', 'the', ' ', '-b', ' ', option!'
|
177 | otherwise.
|
178 | """
|
179 | if isinstance(text, _unicode):
|
180 | if self.break_on_hyphens:
|
181 | pat = self.wordsep_re_uni
|
182 | else:
|
183 | pat = self.wordsep_simple_re_uni
|
184 | else:
|
185 | if self.break_on_hyphens:
|
186 | pat = self.wordsep_re
|
187 | else:
|
188 | pat = self.wordsep_simple_re
|
189 | chunks = pat.split(text)
|
190 | chunks = filter(None, chunks) # remove empty chunks
|
191 | return chunks
|
192 |
|
193 | def _fix_sentence_endings(self, chunks):
|
194 | """_fix_sentence_endings(chunks : [string])
|
195 |
|
196 | Correct for sentence endings buried in 'chunks'. Eg. when the
|
197 | original text contains "... foo.\\nBar ...", munge_whitespace()
|
198 | and split() will convert that to [..., "foo.", " ", "Bar", ...]
|
199 | which has one too few spaces; this method simply changes the one
|
200 | space to two.
|
201 | """
|
202 | i = 0
|
203 | patsearch = self.sentence_end_re.search
|
204 | while i < len(chunks)-1:
|
205 | if chunks[i+1] == " " and patsearch(chunks[i]):
|
206 | chunks[i+1] = " "
|
207 | i += 2
|
208 | else:
|
209 | i += 1
|
210 |
|
211 | def _handle_long_word(self, reversed_chunks, cur_line, cur_len, width):
|
212 | """_handle_long_word(chunks : [string],
|
213 | cur_line : [string],
|
214 | cur_len : int, width : int)
|
215 |
|
216 | Handle a chunk of text (most likely a word, not whitespace) that
|
217 | is too long to fit in any line.
|
218 | """
|
219 | # Figure out when indent is larger than the specified width, and make
|
220 | # sure at least one character is stripped off on every pass
|
221 | if width < 1:
|
222 | space_left = 1
|
223 | else:
|
224 | space_left = width - cur_len
|
225 |
|
226 | # If we're allowed to break long words, then do so: put as much
|
227 | # of the next chunk onto the current line as will fit.
|
228 | if self.break_long_words:
|
229 | cur_line.append(reversed_chunks[-1][:space_left])
|
230 | reversed_chunks[-1] = reversed_chunks[-1][space_left:]
|
231 |
|
232 | # Otherwise, we have to preserve the long word intact. Only add
|
233 | # it to the current line if there's nothing already there --
|
234 | # that minimizes how much we violate the width constraint.
|
235 | elif not cur_line:
|
236 | cur_line.append(reversed_chunks.pop())
|
237 |
|
238 | # If we're not allowed to break long words, and there's already
|
239 | # text on the current line, do nothing. Next time through the
|
240 | # main loop of _wrap_chunks(), we'll wind up here again, but
|
241 | # cur_len will be zero, so the next line will be entirely
|
242 | # devoted to the long word that we can't handle right now.
|
243 |
|
244 | def _wrap_chunks(self, chunks):
|
245 | """_wrap_chunks(chunks : [string]) -> [string]
|
246 |
|
247 | Wrap a sequence of text chunks and return a list of lines of
|
248 | length 'self.width' or less. (If 'break_long_words' is false,
|
249 | some lines may be longer than this.) Chunks correspond roughly
|
250 | to words and the whitespace between them: each chunk is
|
251 | indivisible (modulo 'break_long_words'), but a line break can
|
252 | come between any two chunks. Chunks should not have internal
|
253 | whitespace; ie. a chunk is either all whitespace or a "word".
|
254 | Whitespace chunks will be removed from the beginning and end of
|
255 | lines, but apart from that whitespace is preserved.
|
256 | """
|
257 | lines = []
|
258 | if self.width <= 0:
|
259 | raise ValueError("invalid width %r (must be > 0)" % self.width)
|
260 |
|
261 | # Arrange in reverse order so items can be efficiently popped
|
262 | # from a stack of chucks.
|
263 | chunks.reverse()
|
264 |
|
265 | while chunks:
|
266 |
|
267 | # Start the list of chunks that will make up the current line.
|
268 | # cur_len is just the length of all the chunks in cur_line.
|
269 | cur_line = []
|
270 | cur_len = 0
|
271 |
|
272 | # Figure out which static string will prefix this line.
|
273 | if lines:
|
274 | indent = self.subsequent_indent
|
275 | else:
|
276 | indent = self.initial_indent
|
277 |
|
278 | # Maximum width for this line.
|
279 | width = self.width - len(indent)
|
280 |
|
281 | # First chunk on line is whitespace -- drop it, unless this
|
282 | # is the very beginning of the text (ie. no lines started yet).
|
283 | if self.drop_whitespace and chunks[-1].strip() == '' and lines:
|
284 | del chunks[-1]
|
285 |
|
286 | while chunks:
|
287 | l = len(chunks[-1])
|
288 |
|
289 | # Can at least squeeze this chunk onto the current line.
|
290 | if cur_len + l <= width:
|
291 | cur_line.append(chunks.pop())
|
292 | cur_len += l
|
293 |
|
294 | # Nope, this line is full.
|
295 | else:
|
296 | break
|
297 |
|
298 | # The current line is full, and the next chunk is too big to
|
299 | # fit on *any* line (not just this one).
|
300 | if chunks and len(chunks[-1]) > width:
|
301 | self._handle_long_word(chunks, cur_line, cur_len, width)
|
302 |
|
303 | # If the last chunk on this line is all whitespace, drop it.
|
304 | if self.drop_whitespace and cur_line and cur_line[-1].strip() == '':
|
305 | del cur_line[-1]
|
306 |
|
307 | # Convert current line back to a string and store it in list
|
308 | # of all lines (return value).
|
309 | if cur_line:
|
310 | lines.append(indent + ''.join(cur_line))
|
311 |
|
312 | return lines
|
313 |
|
314 |
|
315 | # -- Public interface ----------------------------------------------
|
316 |
|
317 | def wrap(self, text):
|
318 | """wrap(text : string) -> [string]
|
319 |
|
320 | Reformat the single paragraph in 'text' so it fits in lines of
|
321 | no more than 'self.width' columns, and return a list of wrapped
|
322 | lines. Tabs in 'text' are expanded with string.expandtabs(),
|
323 | and all other whitespace characters (including newline) are
|
324 | converted to space.
|
325 | """
|
326 | text = self._munge_whitespace(text)
|
327 | chunks = self._split(text)
|
328 | if self.fix_sentence_endings:
|
329 | self._fix_sentence_endings(chunks)
|
330 | return self._wrap_chunks(chunks)
|
331 |
|
332 | def fill(self, text):
|
333 | """fill(text : string) -> string
|
334 |
|
335 | Reformat the single paragraph in 'text' to fit in lines of no
|
336 | more than 'self.width' columns, and return a new string
|
337 | containing the entire wrapped paragraph.
|
338 | """
|
339 | return "\n".join(self.wrap(text))
|
340 |
|
341 |
|
342 | # -- Convenience interface ---------------------------------------------
|
343 |
|
344 | def wrap(text, width=70, **kwargs):
|
345 | """Wrap a single paragraph of text, returning a list of wrapped lines.
|
346 |
|
347 | Reformat the single paragraph in 'text' so it fits in lines of no
|
348 | more than 'width' columns, and return a list of wrapped lines. By
|
349 | default, tabs in 'text' are expanded with string.expandtabs(), and
|
350 | all other whitespace characters (including newline) are converted to
|
351 | space. See TextWrapper class for available keyword args to customize
|
352 | wrapping behaviour.
|
353 | """
|
354 | w = TextWrapper(width=width, **kwargs)
|
355 | return w.wrap(text)
|
356 |
|
357 | def fill(text, width=70, **kwargs):
|
358 | """Fill a single paragraph of text, returning a new string.
|
359 |
|
360 | Reformat the single paragraph in 'text' to fit in lines of no more
|
361 | than 'width' columns, and return a new string containing the entire
|
362 | wrapped paragraph. As with wrap(), tabs are expanded and other
|
363 | whitespace characters converted to space. See TextWrapper class for
|
364 | available keyword args to customize wrapping behaviour.
|
365 | """
|
366 | w = TextWrapper(width=width, **kwargs)
|
367 | return w.fill(text)
|
368 |
|
369 |
|
370 | # -- Loosely related functionality -------------------------------------
|
371 |
|
372 | _whitespace_only_re = re.compile('^[ \t]+$', re.MULTILINE)
|
373 | _leading_whitespace_re = re.compile('(^[ \t]*)(?:[^ \t\n])', re.MULTILINE)
|
374 |
|
375 | def dedent(text):
|
376 | """Remove any common leading whitespace from every line in `text`.
|
377 |
|
378 | This can be used to make triple-quoted strings line up with the left
|
379 | edge of the display, while still presenting them in the source code
|
380 | in indented form.
|
381 |
|
382 | Note that tabs and spaces are both treated as whitespace, but they
|
383 | are not equal: the lines " hello" and "\\thello" are
|
384 | considered to have no common leading whitespace. (This behaviour is
|
385 | new in Python 2.5; older versions of this module incorrectly
|
386 | expanded tabs before searching for common leading whitespace.)
|
387 | """
|
388 | # Look for the longest leading string of spaces and tabs common to
|
389 | # all lines.
|
390 | margin = None
|
391 | text = _whitespace_only_re.sub('', text)
|
392 | indents = _leading_whitespace_re.findall(text)
|
393 | for indent in indents:
|
394 | if margin is None:
|
395 | margin = indent
|
396 |
|
397 | # Current line more deeply indented than previous winner:
|
398 | # no change (previous winner is still on top).
|
399 | elif indent.startswith(margin):
|
400 | pass
|
401 |
|
402 | # Current line consistent with and no deeper than previous winner:
|
403 | # it's the new winner.
|
404 | elif margin.startswith(indent):
|
405 | margin = indent
|
406 |
|
407 | # Find the largest common whitespace between current line and previous
|
408 | # winner.
|
409 | else:
|
410 | for i, (x, y) in enumerate(zip(margin, indent)):
|
411 | if x != y:
|
412 | margin = margin[:i]
|
413 | break
|
414 | else:
|
415 | margin = margin[:len(indent)]
|
416 |
|
417 | # sanity check (testing/debugging only)
|
418 | if 0 and margin:
|
419 | for line in text.split("\n"):
|
420 | assert not line or line.startswith(margin), \
|
421 | "line = %r, margin = %r" % (line, margin)
|
422 |
|
423 | if margin:
|
424 | text = re.sub(r'(?m)^' + margin, '', text)
|
425 | return text
|
426 |
|
427 | if __name__ == "__main__":
|
428 | #print dedent("\tfoo\n\tbar")
|
429 | #print dedent(" \thello there\n \t how are you?")
|
430 | print(dedent("Hello there.\n This is indented."))
|