Source Code for Module Ganga.Utility.external.textwrap

  1  """Text wrapping and filling. 
  2  """ 
  3   
  4  # Copyright (C) 1999-2001 Gregory P. Ward. 
  5  # Copyright (C) 2002, 2003 Python Software Foundation. 
  6  # Written by Greg Ward <gward@python.net> 
  7   
  8  __revision__ = "$Id: textwrap.py,v 1.1 2008-07-17 16:41:02 moscicki Exp $" 
  9   
 10  import string, re 
 11   
 12  # Do the right thing with boolean values for all known Python versions 
 13  # (so this module can be copied to projects that don't depend on Python 
 14  # 2.3, e.g. Optik and Docutils). 
 15  try: 
 16      True, False 
 17  except NameError: 
 18      (True, False) = (1, 0) 
 19   
 20  __all__ = ['TextWrapper', 'wrap', 'fill'] 
 21   
 22  # Hardcode the recognized whitespace characters to the US-ASCII 
 23  # whitespace characters.  The main reason for doing this is that in 
 24  # ISO-8859-1, 0xa0 is non-breaking whitespace, so in certain locales 
 25  # that character winds up in string.whitespace.  Respecting 
 26  # string.whitespace in those cases would 1) make textwrap treat 0xa0 the 
 27  # same as any other whitespace char, which is clearly wrong (it's a 
 28  # *non-breaking* space), 2) possibly cause problems with Unicode, 
 29  # since 0xa0 is not in range(128). 
 30  _whitespace = '\t\n\x0b\x0c\r ' 
 31   
 32 -class TextWrapper: 
 33      """ 
 34      Object for wrapping/filling text.  The public interface consists of 
 35      the wrap() and fill() methods; the other methods are just there for 
 36      subclasses to override in order to tweak the default behaviour. 
 37      If you want to completely replace the main wrapping algorithm, 
 38      you'll probably have to override _wrap_chunks(). 
 39   
 40      Several instance attributes control various aspects of wrapping: 
 41        width (default: 70) 
 42          the maximum width of wrapped lines (unless break_long_words 
 43          is false) 
 44        initial_indent (default: "") 
 45          string that will be prepended to the first line of wrapped 
 46          output.  Counts towards the line's width. 
 47        subsequent_indent (default: "") 
 48          string that will be prepended to all lines save the first 
 49          of wrapped output; also counts towards each line's width. 
 50        expand_tabs (default: true) 
 51          Expand tabs in input text to spaces before further processing. 
 52          Each tab will become 1 .. 8 spaces, depending on its position in 
 53          its line.  If false, each tab is treated as a single character. 
 54        replace_whitespace (default: true) 
 55          Replace all whitespace characters in the input text by spaces 
 56          after tab expansion.  Note that if expand_tabs is false and 
 57          replace_whitespace is true, every tab will be converted to a 
 58          single space! 
 59        fix_sentence_endings (default: false) 
 60          Ensure that sentence-ending punctuation is always followed 
 61          by two spaces.  Off by default because the algorithm is 
 62          (unavoidably) imperfect. 
 63        break_long_words (default: true) 
 64          Break words longer than 'width'.  If false, those words will not 
 65          be broken, and some lines might be longer than 'width'. 
 66      """ 
 67   
 68      whitespace_trans = string.maketrans(_whitespace, ' ' * len(_whitespace)) 
 69   
 70      unicode_whitespace_trans = {} 
 71      uspace = ord(u' ') 
 72      for x in map(ord, _whitespace): 
 73          unicode_whitespace_trans[x] = uspace 
 74   
 75      # This funky little regex is just the trick for splitting 
 76      # text up into word-wrappable chunks.  E.g. 
 77      #   "Hello there -- you goof-ball, use the -b option!" 
 78      # splits into 
 79      #   Hello/ /there/ /--/ /you/ /goof-/ball,/ /use/ /the/ /-b/ /option! 
 80      # (after stripping out empty strings). 
 81      wordsep_re = re.compile(r'(\s+|'                  # any whitespace 
 82                              r'-*\w{2,}-(?=\w{2,})|'   # hyphenated words 
 83                              r'(?<=[\w\!\"\'\&\.\,\?])-{2,}(?=\w))')   # em-dash 
 84   
 85      # XXX will there be a locale-or-charset-aware version of 
 86      # string.lowercase in 2.3? 
 87      sentence_end_re = re.compile(r'[%s]'              # lowercase letter 
 88                                   r'[\.\!\?]'          # sentence-ending punct. 
 89                                   r'[\"\']?'           # optional end-of-quote 
 90                                   % string.lowercase) 
 91   
 92   
 93 -    def __init__(self, 
 94                   width=70, 
 95                   initial_indent="", 
 96                   subsequent_indent="", 
 97                   expand_tabs=True, 
 98                   replace_whitespace=True, 
 99                   fix_sentence_endings=False, 
100                   break_long_words=True): 
101          self.width = width 
102          self.initial_indent = initial_indent 
103          self.subsequent_indent = subsequent_indent 
104          self.expand_tabs = expand_tabs 
105          self.replace_whitespace = replace_whitespace 
106          self.fix_sentence_endings = fix_sentence_endings 
107          self.break_long_words = break_long_words 
108   
109   
110      # -- Private methods ----------------------------------------------- 
111      # (possibly useful for subclasses to override) 
112   
113 -    def _munge_whitespace(self, text): 
114          """_munge_whitespace(text : string) -> string 
115   
116          Munge whitespace in text: expand tabs and convert all other 
117          whitespace characters to spaces.  Eg. " foo\tbar\n\nbaz" 
118          becomes " foo    bar  baz". 
119          """ 
120          if self.expand_tabs: 
121              text = text.expandtabs() 
122          if self.replace_whitespace: 
123              if isinstance(text, str): 
124                  text = text.translate(self.whitespace_trans) 
125              elif isinstance(text, unicode): 
126                  text = text.translate(self.unicode_whitespace_trans) 
127          return text 
128   
129   
130 -    def _split(self, text): 
131          """_split(text : string) -> [string] 
132   
133          Split the text to wrap into indivisible chunks.  Chunks are 
134          not quite the same as words; see wrap_chunks() for full 
135          details.  As an example, the text 
136            Look, goof-ball -- use the -b option! 
137          breaks into the following chunks: 
138            'Look,', ' ', 'goof-', 'ball', ' ', '--', ' ', 
139            'use', ' ', 'the', ' ', '-b', ' ', 'option!' 
140          """ 
141          chunks = self.wordsep_re.split(text) 
142          chunks = filter(None, chunks) 
143          return chunks 
144   
145 -    def _fix_sentence_endings(self, chunks): 
146          """_fix_sentence_endings(chunks : [string]) 
147   
148          Correct for sentence endings buried in 'chunks'.  Eg. when the 
149          original text contains "... foo.\nBar ...", munge_whitespace() 
150          and split() will convert that to [..., "foo.", " ", "Bar", ...] 
151          which has one too few spaces; this method simply changes the one 
152          space to two. 
153          """ 
154          i = 0 
155          pat = self.sentence_end_re 
156          while i < len(chunks)-1: 
157              if chunks[i+1] == " " and pat.search(chunks[i]): 
158                  chunks[i+1] = "  " 
159                  i += 2 
160              else: 
161                  i += 1 
162   
163 -    def _handle_long_word(self, chunks, cur_line, cur_len, width): 
164          """_handle_long_word(chunks : [string], 
165                               cur_line : [string], 
166                               cur_len : int, width : int) 
167   
168          Handle a chunk of text (most likely a word, not whitespace) that 
169          is too long to fit in any line. 
170          """ 
171          space_left = max(width - cur_len, 1) 
172   
173          # If we're allowed to break long words, then do so: put as much 
174          # of the next chunk onto the current line as will fit. 
175          if self.break_long_words: 
176              cur_line.append(chunks[0][0:space_left]) 
177              chunks[0] = chunks[0][space_left:] 
178   
179          # Otherwise, we have to preserve the long word intact.  Only add 
180          # it to the current line if there's nothing already there -- 
181          # that minimizes how much we violate the width constraint. 
182          elif not cur_line: 
183              cur_line.append(chunks.pop(0)) 
184   
185          # If we're not allowed to break long words, and there's already 
186          # text on the current line, do nothing.  Next time through the 
187          # main loop of _wrap_chunks(), we'll wind up here again, but 
188          # cur_len will be zero, so the next line will be entirely 
189          # devoted to the long word that we can't handle right now. 
190   
191 -    def _wrap_chunks(self, chunks): 
192          """_wrap_chunks(chunks : [string]) -> [string] 
193   
194          Wrap a sequence of text chunks and return a list of lines of 
195          length 'self.width' or less.  (If 'break_long_words' is false, 
196          some lines may be longer than this.)  Chunks correspond roughly 
197          to words and the whitespace between them: each chunk is 
198          indivisible (modulo 'break_long_words'), but a line break can 
199          come between any two chunks.  Chunks should not have internal 
200          whitespace; ie. a chunk is either all whitespace or a "word". 
201          Whitespace chunks will be removed from the beginning and end of 
202          lines, but apart from that whitespace is preserved. 
203          """ 
204          lines = [] 
205          if self.width <= 0: 
206              raise ValueError("invalid width %r (must be > 0)" % self.width) 
207   
208          while chunks: 
209   
210              # Start the list of chunks that will make up the current line. 
211              # cur_len is just the length of all the chunks in cur_line. 
212              cur_line = [] 
213              cur_len = 0 
214   
215              # Figure out which static string will prefix this line. 
216              if lines: 
217                  indent = self.subsequent_indent 
218              else: 
219                  indent = self.initial_indent 
220   
221              # Maximum width for this line. 
222              width = self.width - len(indent) 
223   
224              # First chunk on line is whitespace -- drop it, unless this 
225              # is the very beginning of the text (ie. no lines started yet). 
226              if chunks[0].strip() == '' and lines: 
227                  del chunks[0] 
228   
229              while chunks: 
230                  l = len(chunks[0]) 
231   
232                  # Can at least squeeze this chunk onto the current line. 
233                  if cur_len + l <= width: 
234                      cur_line.append(chunks.pop(0)) 
235                      cur_len += l 
236   
237                  # Nope, this line is full. 
238                  else: 
239                      break 
240   
241              # The current line is full, and the next chunk is too big to 
242              # fit on *any* line (not just this one). 
243              if chunks and len(chunks[0]) > width: 
244                  self._handle_long_word(chunks, cur_line, cur_len, width) 
245   
246              # If the last chunk on this line is all whitespace, drop it. 
247              if cur_line and cur_line[-1].strip() == '': 
248                  del cur_line[-1] 
249   
250              # Convert current line back to a string and store it in list 
251              # of all lines (return value). 
252              if cur_line: 
253                  lines.append(indent + ''.join(cur_line)) 
254   
255          return lines 
256   
257   
258      # -- Public interface ---------------------------------------------- 
259   
260 -    def wrap(self, text): 
261          """wrap(text : string) -> [string] 
262   
263          Reformat the single paragraph in 'text' so it fits in lines of 
264          no more than 'self.width' columns, and return a list of wrapped 
265          lines.  Tabs in 'text' are expanded with string.expandtabs(), 
266          and all other whitespace characters (including newline) are 
267          converted to space. 
268          """ 
269          text = self._munge_whitespace(text) 
270          indent = self.initial_indent 
271          chunks = self._split(text) 
272          if self.fix_sentence_endings: 
273              self._fix_sentence_endings(chunks) 
274          return self._wrap_chunks(chunks) 
275   
276 -    def fill(self, text): 
277          """fill(text : string) -> string 
278   
279          Reformat the single paragraph in 'text' to fit in lines of no 
280          more than 'self.width' columns, and return a new string 
281          containing the entire wrapped paragraph. 
282          """ 
283          return "\n".join(self.wrap(text)) 
284   
285   
286  # -- Convenience interface --------------------------------------------- 
287   
288 -def wrap(text, width=70, **kwargs): 
289      """Wrap a single paragraph of text, returning a list of wrapped lines. 
290   
291      Reformat the single paragraph in 'text' so it fits in lines of no 
292      more than 'width' columns, and return a list of wrapped lines.  By 
293      default, tabs in 'text' are expanded with string.expandtabs(), and 
294      all other whitespace characters (including newline) are converted to 
295      space.  See TextWrapper class for available keyword args to customize 
296      wrapping behaviour. 
297      """ 
298      w = TextWrapper(width=width, **kwargs) 
299      return w.wrap(text) 
300   
301 -def fill(text, width=70, **kwargs): 
302      """Fill a single paragraph of text, returning a new string. 
303   
304      Reformat the single paragraph in 'text' to fit in lines of no more 
305      than 'width' columns, and return a new string containing the entire 
306      wrapped paragraph.  As with wrap(), tabs are expanded and other 
307      whitespace characters converted to space.  See TextWrapper class for 
308      available keyword args to customize wrapping behaviour. 
309      """ 
310      w = TextWrapper(width=width, **kwargs) 
311      return w.fill(text) 
312   
313   
314  # -- Loosely related functionality ------------------------------------- 
315   
316 -def dedent(text): 
317      """dedent(text : string) -> string 
318   
319      Remove any whitespace than can be uniformly removed from the left 
320      of every line in `text`. 
321   
322      This can be used e.g. to make triple-quoted strings line up with 
323      the left edge of screen/whatever, while still presenting it in the 
324      source code in indented form. 
325   
326      For example: 
327   
328          def test(): 
329              # end first line with \ to avoid the empty line! 
330              s = '''\ 
331              hello 
332                world 
333              ''' 
334              print repr(s)          # prints '    hello\n      world\n    ' 
335              print repr(dedent(s))  # prints 'hello\n  world\n' 
336      """ 
337      lines = text.expandtabs().split('\n') 
338      margin = None 
339      for line in lines: 
340          content = line.lstrip() 
341          if not content: 
342              continue 
343          indent = len(line) - len(content) 
344          if margin is None: 
345              margin = indent 
346          else: 
347              margin = min(margin, indent) 
348   
349      if margin is not None and margin > 0: 
350          for i in range(len(lines)): 
351              lines[i] = lines[i][margin:] 
352   
353      return '\n'.join(lines) 
354