Tools/idle/FormatParagraph.py

   1 # Extension to format a paragraph
   2
   3 # Does basic, standard text formatting, and also understands Python
   4 # comment blocks.  Thus, for editing Python source code, this
   5 # extension is really only suitable for reformatting these comment
   6 # blocks or triple-quoted strings.
   7
   8 # Known problems with comment reformatting:
   9 # * If there is a selection marked, and the first line of the
  10 #   selection is not complete, the block will probably not be detected
  11 #   as comments, and will have the normal "text formatting" rules
  12 #   applied.
  13 # * If a comment block has leading whitespace that mixes tabs and
  14 #   spaces, they will not be considered part of the same block.
  15 # * Fancy comments, like this bulleted list, arent handled :-)
  16
  17 import re
  18
  19 class FormatParagraph:
  20
  21     menudefs = [
  22         ('edit', [
  23             ('Format Paragraph', '<<format-paragraph>>'),
  24          ])
  25     ]
  26
  27     keydefs = {
  28         '<<format-paragraph>>': ['<Alt-q>'],
  29     }
  30
  31     unix_keydefs = {
  32         '<<format-paragraph>>': ['<Meta-q>'],
  33     }
  34
  35     def __init__(self, editwin):
  36         self.editwin = editwin
  37
  38     def close(self):
  39         self.editwin = None
  40
  41     def format_paragraph_event(self, event):
  42         text = self.editwin.text
  43         first, last = self.editwin.get_selection_indices()
  44         if first and last:
  45             data = text.get(first, last)
  46             comment_header = ''
  47         else:
  48             first, last, comment_header, data = \
  49                     find_paragraph(text, text.index("insert"))
  50         if comment_header:
  51             # Reformat the comment lines - convert to text sans header.
  52             lines = data.split("\n")
  53             lines = map(lambda st, l=len(comment_header): st[l:], lines)
  54             data = "\n".join(lines)
  55             # Reformat to 70 chars or a 20 char width, whichever is greater.
  56             format_width = max(70-len(comment_header), 20)
  57             newdata = reformat_paragraph(data, format_width)
  58             # re-split and re-insert the comment header.
  59             newdata = newdata.split("\n")
  60             # If the block ends in a \n, we dont want the comment
  61             # prefix inserted after it. (Im not sure it makes sense to
  62             # reformat a comment block that isnt made of complete
  63             # lines, but whatever!)  Can't think of a clean soltution,
  64             # so we hack away
  65             block_suffix = ""
  66             if not newdata[-1]:
  67                 block_suffix = "\n"
  68                 newdata = newdata[:-1]
  69             builder = lambda item, prefix=comment_header: prefix+item
  70             newdata = '\n'.join(map(builder, newdata)) + block_suffix
  71         else:
  72             # Just a normal text format
  73             newdata = reformat_paragraph(data)
  74         text.tag_remove("sel", "1.0", "end")
  75         if newdata != data:
  76             text.mark_set("insert", first)
  77             text.undo_block_start()
  78             text.delete(first, last)
  79             text.insert(first, newdata)
  80             text.undo_block_stop()
  81         else:
  82             text.mark_set("insert", last)
  83         text.see("insert")
  84
  85 def find_paragraph(text, mark):
  86     lineno, col = map(int, mark.split("."))
  87     line = text.get("%d.0" % lineno, "%d.0 lineend" % lineno)
  88     while text.compare("%d.0" % lineno, "<", "end") and is_all_white(line):
  89         lineno = lineno + 1
  90         line = text.get("%d.0" % lineno, "%d.0 lineend" % lineno)
  91     first_lineno = lineno
  92     comment_header = get_comment_header(line)
  93     comment_header_len = len(comment_header)
  94     while get_comment_header(line)==comment_header and \
  95               not is_all_white(line[comment_header_len:]):
  96         lineno = lineno + 1
  97         line = text.get("%d.0" % lineno, "%d.0 lineend" % lineno)
  98     last = "%d.0" % lineno
  99     # Search back to beginning of paragraph
 100     lineno = first_lineno - 1
 101     line = text.get("%d.0" % lineno, "%d.0 lineend" % lineno)
 102     while lineno > 0 and \
 103               get_comment_header(line)==comment_header and \
 104               not is_all_white(line[comment_header_len:]):
 105         lineno = lineno - 1
 106         line = text.get("%d.0" % lineno, "%d.0 lineend" % lineno)
 107     first = "%d.0" % (lineno+1)
 108     return first, last, comment_header, text.get(first, last)
 109
 110 def reformat_paragraph(data, limit=70):
 111     lines = data.split("\n")
 112     i = 0
 113     n = len(lines)
 114     while i < n and is_all_white(lines[i]):
 115         i = i+1
 116     if i >= n:
 117         return data
 118     indent1 = get_indent(lines[i])
 119     if i+1 < n and not is_all_white(lines[i+1]):
 120         indent2 = get_indent(lines[i+1])
 121     else:
 122         indent2 = indent1
 123     new = lines[:i]
 124     partial = indent1
 125     while i < n and not is_all_white(lines[i]):
 126         # XXX Should take double space after period (etc.) into account
 127         words = re.split("(\s+)", lines[i])
 128         for j in range(0, len(words), 2):
 129             word = words[j]
 130             if not word:
 131                 continue # Can happen when line ends in whitespace
 132             if len((partial + word).expandtabs()) > limit and \
 133                partial != indent1:
 134                 new.append(partial.rstrip())
 135                 partial = indent2
 136             partial = partial + word + " "
 137             if j+1 < len(words) and words[j+1] != " ":
 138                 partial = partial + " "
 139         i = i+1
 140     new.append(partial.rstrip())
 141     # XXX Should reformat remaining paragraphs as well
 142     new.extend(lines[i:])
 143     return "\n".join(new)
 144
 145 def is_all_white(line):
 146     return re.match(r"^\s*$", line) is not None
 147
 148 def get_indent(line):
 149     return re.match(r"^(\s*)", line).group()
 150
 151 def get_comment_header(line):
 152     m = re.match(r"^(\s*#*)", line)
 153     if m is None: return ""
 154     return m.group(1)