/Lib/idlelib/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
 17import re
 18from configHandler import idleConf
 19
 20class FormatParagraph:
 21
 22    menudefs = [
 23        ('format', [   # /s/edit/format   dscherer@cmu.edu
 24            ('Format Paragraph', '<<format-paragraph>>'),
 25         ])
 26    ]
 27
 28    def __init__(self, editwin):
 29        self.editwin = editwin
 30
 31    def close(self):
 32        self.editwin = None
 33
 34    def format_paragraph_event(self, event):
 35        maxformatwidth = int(idleConf.GetOption('main','FormatParagraph','paragraph'))
 36        text = self.editwin.text
 37        first, last = self.editwin.get_selection_indices()
 38        if first and last:
 39            data = text.get(first, last)
 40            comment_header = ''
 41        else:
 42            first, last, comment_header, data = \
 43                    find_paragraph(text, text.index("insert"))
 44        if comment_header:
 45            # Reformat the comment lines - convert to text sans header.
 46            lines = data.split("\n")
 47            lines = map(lambda st, l=len(comment_header): st[l:], lines)
 48            data = "\n".join(lines)
 49            # Reformat to maxformatwidth chars or a 20 char width, whichever is greater.
 50            format_width = max(maxformatwidth - len(comment_header), 20)
 51            newdata = reformat_paragraph(data, format_width)
 52            # re-split and re-insert the comment header.
 53            newdata = newdata.split("\n")
 54            # If the block ends in a \n, we dont want the comment
 55            # prefix inserted after it. (Im not sure it makes sense to
 56            # reformat a comment block that isnt made of complete
 57            # lines, but whatever!)  Can't think of a clean soltution,
 58            # so we hack away
 59            block_suffix = ""
 60            if not newdata[-1]:
 61                block_suffix = "\n"
 62                newdata = newdata[:-1]
 63            builder = lambda item, prefix=comment_header: prefix+item
 64            newdata = '\n'.join(map(builder, newdata)) + block_suffix
 65        else:
 66            # Just a normal text format
 67            newdata = reformat_paragraph(data, maxformatwidth)
 68        text.tag_remove("sel", "1.0", "end")
 69        if newdata != data:
 70            text.mark_set("insert", first)
 71            text.undo_block_start()
 72            text.delete(first, last)
 73            text.insert(first, newdata)
 74            text.undo_block_stop()
 75        else:
 76            text.mark_set("insert", last)
 77        text.see("insert")
 78        return "break"
 79
 80def find_paragraph(text, mark):
 81    lineno, col = map(int, mark.split("."))
 82    line = text.get("%d.0" % lineno, "%d.0 lineend" % lineno)
 83    while text.compare("%d.0" % lineno, "<", "end") and is_all_white(line):
 84        lineno = lineno + 1
 85        line = text.get("%d.0" % lineno, "%d.0 lineend" % lineno)
 86    first_lineno = lineno
 87    comment_header = get_comment_header(line)
 88    comment_header_len = len(comment_header)
 89    while get_comment_header(line)==comment_header and \
 90              not is_all_white(line[comment_header_len:]):
 91        lineno = lineno + 1
 92        line = text.get("%d.0" % lineno, "%d.0 lineend" % lineno)
 93    last = "%d.0" % lineno
 94    # Search back to beginning of paragraph
 95    lineno = first_lineno - 1
 96    line = text.get("%d.0" % lineno, "%d.0 lineend" % lineno)
 97    while lineno > 0 and \
 98              get_comment_header(line)==comment_header and \
 99              not is_all_white(line[comment_header_len:]):
100        lineno = lineno - 1
101        line = text.get("%d.0" % lineno, "%d.0 lineend" % lineno)
102    first = "%d.0" % (lineno+1)
103    return first, last, comment_header, text.get(first, last)
104
105def reformat_paragraph(data, limit):
106    lines = data.split("\n")
107    i = 0
108    n = len(lines)
109    while i < n and is_all_white(lines[i]):
110        i = i+1
111    if i >= n:
112        return data
113    indent1 = get_indent(lines[i])
114    if i+1 < n and not is_all_white(lines[i+1]):
115        indent2 = get_indent(lines[i+1])
116    else:
117        indent2 = indent1
118    new = lines[:i]
119    partial = indent1
120    while i < n and not is_all_white(lines[i]):
121        # XXX Should take double space after period (etc.) into account
122        words = re.split("(\s+)", lines[i])
123        for j in range(0, len(words), 2):
124            word = words[j]
125            if not word:
126                continue # Can happen when line ends in whitespace
127            if len((partial + word).expandtabs()) > limit and \
128               partial != indent1:
129                new.append(partial.rstrip())
130                partial = indent2
131            partial = partial + word + " "
132            if j+1 < len(words) and words[j+1] != " ":
133                partial = partial + " "
134        i = i+1
135    new.append(partial.rstrip())
136    # XXX Should reformat remaining paragraphs as well
137    new.extend(lines[i:])
138    return "\n".join(new)
139
140def is_all_white(line):
141    return re.match(r"^\s*$", line) is not None
142
143def get_indent(line):
144    return re.match(r"^(\s*)", line).group()
145
146def get_comment_header(line):
147    m = re.match(r"^(\s*#*)", line)
148    if m is None: return ""
149    return m.group(1)