minirst: combine list parsing in one function

Bullet, option, field, and definition lists were parsed very similar
code. They are now parsed by a single function (splitparagraphs).

Some logic from the old parsing functions has been moved down to
formatblock. This simplifies the parsing while putting the logic where
it's really needed.

mercurial/minirst.py

@@ -1,354 +1,272 b''
 # minirst.py - minimal reStructuredText parser
 #
 # Copyright 2009 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, incorporated herein by reference.
 
 """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.
 
 It only supports a small subset of reStructuredText:
 
 - paragraphs
 
 - definition lists (must use '  ' to indent definitions)
 
 - lists (items must start with '-')
 
 - field lists (colons cannot be escaped)
 
 - literal blocks
 
 - option lists (supports only long options without arguments)
 
 - inline markup is not recognized at all.
 """
 
 import re, sys, textwrap
 
 
 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 = [[]]
     lines = text.splitlines()
     for line in lines:
         if line.strip():
             blocks[-1].append(line)
         elif blocks[-1]:
             blocks.append([])
     if not blocks[-1]:
         del blocks[-1]
 
     for i, block in enumerate(blocks):
         indent = min((len(l) - len(l.lstrip())) for l in block)
         blocks[i] = dict(indent=indent, lines=[l[indent:] for l in block])
     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.
             if blocks[i]['lines'][0].startswith('- '):
                 indent += 2
                 adjustment -= 2
 
             # 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'- ')
+_optionre = re.compile(r'^(--[a-z-]+)((?:[ =][a-zA-Z][\w-]*)?  +)(.*)$')
+_fieldre = re.compile(r':(?![: ])([^:]*)(?<! ):( +)(.*)')
+_definitionre = re.compile(r'[^ ]')
+
+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
+
 
 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
             block['lines'][1] == '-' * len(block['lines'][0])):
             block['type'] = 'section'
     return blocks
 
 
-def findbulletlists(blocks):
-    """Finds bullet lists.
-
-    The blocks must have a 'type' field, i.e., they should have been
-    run through findliteralblocks first.
-    """
-    i = 0
-    while i < len(blocks):
-        # Searching for a paragraph that looks like this:
-        #
-        # +------+-----------------------+
-        # | "- " | list item             |
-        # +------| (body elements)+      |
-        #        +-----------------------+
-        if (blocks[i]['type'] == 'paragraph' and
-            blocks[i]['lines'][0].startswith('- ')):
-            items = []
-            for line in blocks[i]['lines']:
-                if line.startswith('- '):
-                    items.append(dict(type='bullet', lines=[],
-                                      indent=blocks[i]['indent']))
-                    line = line[2:]
-                items[-1]['lines'].append(line)
-            blocks[i:i+1] = items
-            i += len(items) - 1
-        i += 1
-    return blocks
-
-
-_optionre = re.compile(r'^(--[a-z-]+)((?:[ =][a-zA-Z][\w-]*)?  +)(.*)$')
-def findoptionlists(blocks):
-    """Finds option lists.
-
-    The blocks must have a 'type' field, i.e., they should have been
-    run through findliteralblocks first.
-    """
-    i = 0
-    while i < len(blocks):
-        # Searching for a paragraph that looks like this:
-        #
-        # +----------------------------+-------------+
-        # | "--" option "  "           | description |
-        # +-------+--------------------+             |
-        #         | (body elements)+                 |
-        #         +----------------------------------+
-        if (blocks[i]['type'] == 'paragraph' and
-            _optionre.match(blocks[i]['lines'][0])):
-            options = []
-            for line in blocks[i]['lines']:
-                m = _optionre.match(line)
-                if m:
-                    option, arg, rest = m.groups()
-                    width = len(option) + len(arg)
-                    options.append(dict(type='option', lines=[],
-                                        indent=blocks[i]['indent'],
-                                        width=width))
-                options[-1]['lines'].append(line)
-            blocks[i:i+1] = options
-            i += len(options) - 1
-        i += 1
-    return blocks
-
-
-_fieldre = re.compile(r':(?![: ])([^:]*)(?<! ):( +)(.*)')
-def findfieldlists(blocks):
-    """Finds fields lists.
-
-    The blocks must have a 'type' field, i.e., they should have been
-    run through findliteralblocks first.
-    """
-    i = 0
-    while i < len(blocks):
-        # Searching for a paragraph that looks like this:
-        #
-        #
-        # +--------------------+----------------------+
-        # | ":" field name ":" | field body           |
-        # +-------+------------+                      |
-        #         | (body elements)+                  |
-        #         +-----------------------------------+
-        if (blocks[i]['type'] == 'paragraph' and
-            _fieldre.match(blocks[i]['lines'][0])):
-            indent = blocks[i]['indent']
-            fields = []
-            for line in blocks[i]['lines']:
-                m = _fieldre.match(line)
-                if m:
-                    key, spaces, rest = m.groups()
-                    width = 2 + len(key) + len(spaces)
-                    fields.append(dict(type='field', lines=[],
-                                       indent=indent, width=width))
-                    # Turn ":foo: bar" into "foo   bar".
-                    line = '%s  %s%s' % (key, spaces, rest)
-                fields[-1]['lines'].append(line)
-            blocks[i:i+1] = fields
-            i += len(fields) - 1
-        i += 1
-    return blocks
-
-
-def finddefinitionlists(blocks):
-    """Finds definition lists.
-
-    The blocks must have a 'type' field, i.e., they should have been
-    run through findliteralblocks first.
-    """
-    i = 0
-    while i < len(blocks):
-        # Searching for a paragraph that looks like this:
-        #
-        # +----------------------------+
-        # | term                       |
-        # +--+-------------------------+--+
-        #    | definition                 |
-        #    | (body elements)+           |
-        #    +----------------------------+
-        if (blocks[i]['type'] == 'paragraph' and
-            len(blocks[i]['lines']) > 1 and
-            not blocks[i]['lines'][0].startswith('  ') and
-            blocks[i]['lines'][1].startswith('  ')):
-            definitions = []
-            for line in blocks[i]['lines']:
-                if not line.startswith('  '):
-                    definitions.append(dict(type='definition', lines=[],
-                                            indent=blocks[i]['indent']))
-                definitions[-1]['lines'].append(line)
-                definitions[-1]['hang'] = len(line) - len(line.lstrip())
-            blocks[i:i+1] = definitions
-            i += len(definitions) - 1
-        i += 1
-    return blocks
-
-
 def inlineliterals(blocks):
     for b in blocks:
         if b['type'] == 'paragraph':
             b['lines'] = [l.replace('``', '"') 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', 'definition')):
             i += 1
         else:
             blocks.insert(i, dict(lines=[''], indent=0, type='margin'))
             i += 2
     return blocks
 
 
 def formatblock(block, width):
     """Format a block according to width."""
     if width <= 0:
         width = 78
     indent = ' ' * block['indent']
     if block['type'] == 'margin':
         return ''
     if block['type'] == 'literal':
         indent += '  '
         return indent + ('\n' + indent).join(block['lines'])
     if block['type'] == 'section':
         return indent + ('\n' + indent).join(block['lines'])
     if block['type'] == 'definition':
         term = indent + block['lines'][0]
-        defindent = indent + block['hang'] * ' '
+        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, textwrap.fill(text, width=width,
                                                initial_indent=defindent,
                                                subsequent_indent=defindent))
     initindent = subindent = indent
-    text = ' '.join(map(str.strip, block['lines']))
     if block['type'] == 'bullet':
-        initindent = indent + '- '
         subindent = indent + '  '
-    elif block['type'] in ('option', 'field'):
-        subindent = indent + block['width'] * ' '
+    elif block['type'] == 'field':
+        m = _fieldre.match(block['lines'][0])
+        if m:
+            key, spaces, rest = m.groups()
+            # Turn ":foo: bar" into "foo   bar".
+            block['lines'][0] = '%s  %s%s' % (key, spaces, rest)
+            subindent = indent + (2 + len(key) + len(spaces)) * ' '
+    elif block['type'] == 'option':
+        m = _optionre.match(block['lines'][0])
+        if m:
+            option, arg, rest = m.groups()
+            subindent = indent + (len(option) + len(arg)) * ' '
 
+    text = ' '.join(map(str.strip, block['lines']))
     return textwrap.fill(text, width=width,
                          initial_indent=initindent,
                          subsequent_indent=subindent)
 
 
 def format(text, width, indent=0):
     """Parse and format the text according to width."""
     blocks = findblocks(text)
     for b in blocks:
         b['indent'] += indent
     blocks = findliteralblocks(blocks)
     blocks = inlineliterals(blocks)
+    blocks = splitparagraphs(blocks)
     blocks = findsections(blocks)
-    blocks = findbulletlists(blocks)
-    blocks = findoptionlists(blocks)
-    blocks = findfieldlists(blocks)
-    blocks = finddefinitionlists(blocks)
     blocks = addmargins(blocks)
     return '\n'.join(formatblock(b, width) for b in blocks)
 
 
 if __name__ == "__main__":
     from pprint import pprint
 
     def debug(func, blocks):
         blocks = func(blocks)
         print "*** after %s:" % func.__name__
         pprint(blocks)
         print
         return blocks
 
     text = open(sys.argv[1]).read()
     blocks = debug(findblocks, text)
     blocks = debug(findliteralblocks, blocks)
+    blocks = debug(splitparagraphs, blocks)
     blocks = debug(findsections, blocks)
-    blocks = debug(findbulletlists, blocks)
-    blocks = debug(findoptionlists, blocks)
-    blocks = debug(findfieldlists, blocks)
-    blocks = debug(finddefinitionlists, blocks)
     blocks = debug(addmargins, blocks)
     print '\n'.join(formatblock(b, 30) for b in blocks)