minirst: don't choke on empty text

mercurial/minirst.py

@@ -1,561 +1,562 b''
 # minirst.py - minimal reStructuredText parser
 #
 # Copyright 2009, 2010 Matt Mackall <[e-mail]> and others
 #
 # This software may be used and distributed according to the terms of the
 # GNU General Public License version 2 or any later version.
 
 """simplified reStructuredText parser.
 
 This parser knows just enough about reStructuredText to parse the
 Mercurial docstrings.
 
 It cheats in a major way: nested blocks are not really nested. They
 are just indented blocks that look like they are nested. This relies
 on the user to keep the right indentation for the blocks.
 
 Remember to update http://mercurial.selenic.com/wiki/HelpStyleGuide
 when adding support for new constructs.
 """
 
 import re
 import util, encoding
 from i18n import _
 
 def replace(text, substs):
     for f, t in substs:
         text = text.replace(f, t)
     return text
 
 _blockre = re.compile(r"\n(?:\s*\n)+")
 
 def findblocks(text):
     """Find continuous blocks of lines in text.
 
     Returns a list of dictionaries representing the blocks. Each block
     has an 'indent' field and a 'lines' field.
     """
     blocks = []
     for b in _blockre.split(text.lstrip('\n').rstrip()):
         lines = b.splitlines()
+        if lines:
         indent = min((len(l) - len(l.lstrip())) for l in lines)
         lines = [l[indent:] for l in lines]
         blocks.append(dict(indent=indent, lines=lines))
     return blocks
 
 def findliteralblocks(blocks):
     """Finds literal blocks and adds a 'type' field to the blocks.
 
     Literal blocks are given the type 'literal', all other blocks are
     given type the 'paragraph'.
     """
     i = 0
     while i < len(blocks):
         # Searching for a block that looks like this:
         #
         # +------------------------------+
         # | paragraph                    |
         # | (ends with "::")             |
         # +------------------------------+
         #    +---------------------------+
         #    | indented literal block    |
         #    +---------------------------+
         blocks[i]['type'] = 'paragraph'
         if blocks[i]['lines'][-1].endswith('::') and i + 1 < len(blocks):
             indent = blocks[i]['indent']
             adjustment = blocks[i + 1]['indent'] - indent
 
             if blocks[i]['lines'] == ['::']:
                 # Expanded form: remove block
                 del blocks[i]
                 i -= 1
             elif blocks[i]['lines'][-1].endswith(' ::'):
                 # Partially minimized form: remove space and both
                 # colons.
                 blocks[i]['lines'][-1] = blocks[i]['lines'][-1][:-3]
             else:
                 # Fully minimized form: remove just one colon.
                 blocks[i]['lines'][-1] = blocks[i]['lines'][-1][:-1]
 
             # List items are formatted with a hanging indent. We must
             # correct for this here while we still have the original
             # information on the indentation of the subsequent literal
             # blocks available.
             m = _bulletre.match(blocks[i]['lines'][0])
             if m:
                 indent += m.end()
                 adjustment -= m.end()
 
             # Mark the following indented blocks.
             while i + 1 < len(blocks) and blocks[i + 1]['indent'] > indent:
                 blocks[i + 1]['type'] = 'literal'
                 blocks[i + 1]['indent'] -= adjustment
                 i += 1
         i += 1
     return blocks
 
 _bulletre = re.compile(r'(-|[0-9A-Za-z]+\.|\(?[0-9A-Za-z]+\)|\|) ')
 _optionre = re.compile(r'^(-([a-zA-Z0-9]), )?(--[a-z0-9-]+)'
                        r'((.*)  +)(.*)$')
 _fieldre = re.compile(r':(?![: ])([^:]*)(?<! ):[ ]+(.*)')
 _definitionre = re.compile(r'[^ ]')
 _tablere = re.compile(r'(=+\s+)*=+')
 
 def splitparagraphs(blocks):
     """Split paragraphs into lists."""
     # Tuples with (list type, item regexp, single line items?). Order
     # matters: definition lists has the least specific regexp and must
     # come last.
     listtypes = [('bullet', _bulletre, True),
                  ('option', _optionre, True),
                  ('field', _fieldre, True),
                  ('definition', _definitionre, False)]
 
     def match(lines, i, itemre, singleline):
         """Does itemre match an item at line i?
 
         A list item can be followed by an idented line or another list
         item (but only if singleline is True).
         """
         line1 = lines[i]
         line2 = i + 1 < len(lines) and lines[i + 1] or ''
         if not itemre.match(line1):
             return False
         if singleline:
             return line2 == '' or line2[0] == ' ' or itemre.match(line2)
         else:
             return line2.startswith(' ')
 
     i = 0
     while i < len(blocks):
         if blocks[i]['type'] == 'paragraph':
             lines = blocks[i]['lines']
             for type, itemre, singleline in listtypes:
                 if match(lines, 0, itemre, singleline):
                     items = []
                     for j, line in enumerate(lines):
                         if match(lines, j, itemre, singleline):
                             items.append(dict(type=type, lines=[],
                                               indent=blocks[i]['indent']))
                         items[-1]['lines'].append(line)
                     blocks[i:i + 1] = items
                     break
         i += 1
     return blocks
 
 _fieldwidth = 12
 
 def updatefieldlists(blocks):
     """Find key and maximum key width for field lists."""
     i = 0
     while i < len(blocks):
         if blocks[i]['type'] != 'field':
             i += 1
             continue
 
         keywidth = 0
         j = i
         while j < len(blocks) and blocks[j]['type'] == 'field':
             m = _fieldre.match(blocks[j]['lines'][0])
             key, rest = m.groups()
             blocks[j]['lines'][0] = rest
             blocks[j]['key'] = key
             keywidth = max(keywidth, len(key))
             j += 1
 
         for block in blocks[i:j]:
             block['keywidth'] = keywidth
         i = j + 1
 
     return blocks
 
 def updateoptionlists(blocks):
     i = 0
     while i < len(blocks):
         if blocks[i]['type'] != 'option':
             i += 1
             continue
 
         optstrwidth = 0
         j = i
         while j < len(blocks) and blocks[j]['type'] == 'option':
             m = _optionre.match(blocks[j]['lines'][0])
 
             shortoption = m.group(2)
             group3 = m.group(3)
             longoption = group3[2:].strip()
             desc = m.group(6).strip()
             longoptionarg = m.group(5).strip()
             blocks[j]['lines'][0] = desc
 
             noshortop = ''
             if not shortoption:
                 noshortop = '   '
 
             opt = "%s%s" %   (shortoption and "-%s " % shortoption or '',
                             ("%s--%s %s") % (noshortop, longoption,
                                              longoptionarg))
             opt = opt.rstrip()
             blocks[j]['optstr'] = opt
             optstrwidth = max(optstrwidth, encoding.colwidth(opt))
             j += 1
 
         for block in blocks[i:j]:
             block['optstrwidth'] = optstrwidth
         i = j + 1
     return blocks
 
 def prunecontainers(blocks, keep):
     """Prune unwanted containers.
 
     The blocks must have a 'type' field, i.e., they should have been
     run through findliteralblocks first.
     """
     pruned = []
     i = 0
     while i + 1 < len(blocks):
         # Searching for a block that looks like this:
         #
         # +-------+---------------------------+
         # | ".. container ::" type            |
         # +---+                               |
         #     | blocks                        |
         #     +-------------------------------+
         if (blocks[i]['type'] == 'paragraph' and
             blocks[i]['lines'][0].startswith('.. container::')):
             indent = blocks[i]['indent']
             adjustment = blocks[i + 1]['indent'] - indent
             containertype = blocks[i]['lines'][0][15:]
             prune = containertype not in keep
             if prune:
                 pruned.append(containertype)
 
             # Always delete "..container:: type" block
             del blocks[i]
             j = i
             i -= 1
             while j < len(blocks) and blocks[j]['indent'] > indent:
                 if prune:
                     del blocks[j]
                 else:
                     blocks[j]['indent'] -= adjustment
                     j += 1
         i += 1
     return blocks, pruned
 
 _sectionre = re.compile(r"""^([-=`:.'"~^_*+#])\1+$""")
 
 def findtables(blocks):
     '''Find simple tables
 
        Only simple one-line table elements are supported
     '''
 
     for block in blocks:
         # Searching for a block that looks like this:
         #
         # === ==== ===
         #  A    B   C
         # === ==== ===  <- optional
         #  1    2   3
         #  x    y   z
         # === ==== ===
         if (block['type'] == 'paragraph' and
             len(block['lines']) > 4 and
             _tablere.match(block['lines'][0]) and
             block['lines'][0] == block['lines'][-1]):
             block['type'] = 'table'
             block['header'] = False
             div = block['lines'][0]
             columns = [x for x in xrange(len(div))
                        if div[x] == '=' and (x == 0 or div[x - 1] == ' ')]
             rows = []
             for l in block['lines'][1:-1]:
                 if l == div:
                     block['header'] = True
                     continue
                 row = []
                 for n, start in enumerate(columns):
                     if n + 1 < len(columns):
                         row.append(l[start:columns[n + 1]].strip())
                     else:
                         row.append(l[start:].strip())
                 rows.append(row)
             block['table'] = rows
 
     return blocks
 
 def findsections(blocks):
     """Finds sections.
 
     The blocks must have a 'type' field, i.e., they should have been
     run through findliteralblocks first.
     """
     for block in blocks:
         # Searching for a block that looks like this:
         #
         # +------------------------------+
         # | Section title                |
         # | -------------                |
         # +------------------------------+
         if (block['type'] == 'paragraph' and
             len(block['lines']) == 2 and
             encoding.colwidth(block['lines'][0]) == len(block['lines'][1]) and
             _sectionre.match(block['lines'][1])):
             block['underline'] = block['lines'][1][0]
             block['type'] = 'section'
             del block['lines'][1]
     return blocks
 
 def inlineliterals(blocks):
     substs = [('``', '"')]
     for b in blocks:
         if b['type'] in ('paragraph', 'section'):
             b['lines'] = [replace(l, substs) for l in b['lines']]
     return blocks
 
 def hgrole(blocks):
     substs = [(':hg:`', '"hg '), ('`', '"')]
     for b in blocks:
         if b['type'] in ('paragraph', 'section'):
             # Turn :hg:`command` into "hg command". This also works
             # when there is a line break in the command and relies on
             # the fact that we have no stray back-quotes in the input
             # (run the blocks through inlineliterals first).
             b['lines'] = [replace(l, substs) for l in b['lines']]
     return blocks
 
 def addmargins(blocks):
     """Adds empty blocks for vertical spacing.
 
     This groups bullets, options, and definitions together with no vertical
     space between them, and adds an empty block between all other blocks.
     """
     i = 1
     while i < len(blocks):
         if (blocks[i]['type'] == blocks[i - 1]['type'] and
             blocks[i]['type'] in ('bullet', 'option', 'field')):
             i += 1
         else:
             blocks.insert(i, dict(lines=[''], indent=0, type='margin'))
             i += 2
     return blocks
 
 def prunecomments(blocks):
     """Remove comments."""
     i = 0
     while i < len(blocks):
         b = blocks[i]
         if b['type'] == 'paragraph' and (b['lines'][0].startswith('.. ') or
                                          b['lines'] == ['..']):
             del blocks[i]
             if i < len(blocks) and blocks[i]['type'] == 'margin':
                 del blocks[i]
         else:
             i += 1
     return blocks
 
 _admonitionre = re.compile(r"\.\. (admonition|attention|caution|danger|"
                            r"error|hint|important|note|tip|warning)::",
                            flags=re.IGNORECASE)
 
 def findadmonitions(blocks):
     """
     Makes the type of the block an admonition block if
     the first line is an admonition directive
     """
     i = 0
     while i < len(blocks):
         m = _admonitionre.match(blocks[i]['lines'][0])
         if m:
             blocks[i]['type'] = 'admonition'
             admonitiontitle = blocks[i]['lines'][0][3:m.end() - 2].lower()
 
             firstline = blocks[i]['lines'][0][m.end() + 1:]
             if firstline:
                 blocks[i]['lines'].insert(1, '   ' + firstline)
 
             blocks[i]['admonitiontitle'] = admonitiontitle
             del blocks[i]['lines'][0]
         i = i + 1
     return blocks
 
 _admonitiontitles = {'attention': _('Attention:'),
                      'caution': _('Caution:'),
                      'danger': _('!Danger!')  ,
                      'error': _('Error:'),
                      'hint': _('Hint:'),
                      'important': _('Important:'),
                      'note': _('Note:'),
                      'tip': _('Tip:'),
                      'warning': _('Warning!')}
 
 def formatoption(block, width):
     desc = ' '.join(map(str.strip, block['lines']))
     colwidth = encoding.colwidth(block['optstr'])
     usablewidth = width - 1
     hanging = block['optstrwidth']
     initindent = '%s%s  ' % (block['optstr'], ' ' * ((hanging - colwidth)))
     hangindent = ' ' * (encoding.colwidth(initindent) + 1)
     return ' %s' % (util.wrap(desc, usablewidth,
                                            initindent=initindent,
                                            hangindent=hangindent))
 
 def formatblock(block, width):
     """Format a block according to width."""
     if width <= 0:
         width = 78
     indent = ' ' * block['indent']
     if block['type'] == 'admonition':
         admonition = _admonitiontitles[block['admonitiontitle']]
         hang = len(block['lines'][-1]) - len(block['lines'][-1].lstrip())
 
         defindent = indent + hang * ' '
         text = ' '.join(map(str.strip, block['lines']))
         return '%s\n%s' % (indent + admonition, util.wrap(text, width=width,
                                            initindent=defindent,
                                            hangindent=defindent))
     if block['type'] == 'margin':
         return ''
     if block['type'] == 'literal':
         indent += '  '
         return indent + ('\n' + indent).join(block['lines'])
     if block['type'] == 'section':
         underline = encoding.colwidth(block['lines'][0]) * block['underline']
         return "%s%s\n%s%s" % (indent, block['lines'][0],indent, underline)
     if block['type'] == 'table':
         table = block['table']
         # compute column widths
         widths = [max([encoding.colwidth(e) for e in c]) for c in zip(*table)]
         text = ''
         span = sum(widths) + len(widths) - 1
         indent = ' ' * block['indent']
         hang = ' ' * (len(indent) + span - widths[-1])
         f = ' '.join('%%-%ds' % n for n in widths)
 
         for row in table:
             l = f % tuple(row)
             l = util.wrap(l, width=width, initindent=indent, hangindent=hang)
             if not text and block['header']:
                 text = l + '\n' + indent + '-' * (min(width, span)) + '\n'
             else:
                 text += l + "\n"
         return text
     if block['type'] == 'definition':
         term = indent + block['lines'][0]
         hang = len(block['lines'][-1]) - len(block['lines'][-1].lstrip())
         defindent = indent + hang * ' '
         text = ' '.join(map(str.strip, block['lines'][1:]))
         return '%s\n%s' % (term, util.wrap(text, width=width,
                                            initindent=defindent,
                                            hangindent=defindent))
     subindent = indent
     if block['type'] == 'bullet':
         if block['lines'][0].startswith('| '):
             # Remove bullet for line blocks and add no extra
             # indention.
             block['lines'][0] = block['lines'][0][2:]
         else:
             m = _bulletre.match(block['lines'][0])
             subindent = indent + m.end() * ' '
     elif block['type'] == 'field':
         keywidth = block['keywidth']
         key = block['key']
 
         subindent = indent + _fieldwidth * ' '
         if len(key) + 2 > _fieldwidth:
             # key too large, use full line width
             key = key.ljust(width)
         elif keywidth + 2 < _fieldwidth:
             # all keys are small, add only two spaces
             key = key.ljust(keywidth + 2)
             subindent = indent + (keywidth + 2) * ' '
         else:
             # mixed sizes, use fieldwidth for this one
             key = key.ljust(_fieldwidth)
         block['lines'][0] = key + block['lines'][0]
     elif block['type'] == 'option':
         return formatoption(block, width)
 
     text = ' '.join(map(str.strip, block['lines']))
     return util.wrap(text, width=width,
                      initindent=indent,
                      hangindent=subindent)
 
 def parse(text, indent=0, keep=None):
     """Parse text into a list of blocks"""
     pruned = []
     blocks = findblocks(text)
     for b in blocks:
         b['indent'] += indent
     blocks = findliteralblocks(blocks)
     blocks = findtables(blocks)
     blocks, pruned = prunecontainers(blocks, keep or [])
     blocks = findsections(blocks)
     blocks = inlineliterals(blocks)
     blocks = hgrole(blocks)
     blocks = splitparagraphs(blocks)
     blocks = updatefieldlists(blocks)
     blocks = updateoptionlists(blocks)
     blocks = addmargins(blocks)
     blocks = prunecomments(blocks)
     blocks = findadmonitions(blocks)
     return blocks, pruned
 
 def formatblocks(blocks, width):
     text = '\n'.join(formatblock(b, width) for b in blocks)
     return text
 
 def format(text, width, indent=0, keep=None):
     """Parse and format the text according to width."""
     blocks, pruned = parse(text, indent, keep or [])
     text = '\n'.join(formatblock(b, width) for b in blocks)
     if keep is None:
         return text
     else:
         return text, pruned
 
 def getsections(blocks):
     '''return a list of (section name, nesting level, blocks) tuples'''
     nest = ""
     level = 0
     secs = []
     for b in blocks:
         if b['type'] == 'section':
             i = b['underline']
             if i not in nest:
                 nest += i
             level = nest.index(i) + 1
             nest = nest[:level]
             secs.append((b['lines'][0], level, [b]))
         else:
             if not secs:
                 # add an initial empty section
                 secs = [('', 0, [])]
             secs[-1][2].append(b)
     return secs
 
 def decorateblocks(blocks, width):
     '''generate a list of (section name, line text) pairs for search'''
     lines = []
     for s in getsections(blocks):
         section = s[0]
         text = formatblocks(s[2], width)
         lines.append([(section, l) for l in text.splitlines(True)])
     return lines
 
 def maketable(data, indent=0, header=False):
     '''Generate an RST table for the given table data'''
 
     widths = [max(encoding.colwidth(e) for e in c) for c in zip(*data)]
     indent = ' ' * indent
     f = indent + ' '.join('%%-%ds' % w for w in widths) + '\n'
     div = indent + ' '.join('=' * w for w in widths) + '\n'
 
     out = [div]
     for row in data:
         out.append(f % tuple(row))
     if header and len(data) > 1:
         out.insert(2, div)
     out.append(div)
     return ''.join(out)