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# minirst.py - minimal reStructuredText parser
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#
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# Copyright 2009 Matt Mackall <mpm@selenic.com> and others
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#
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# This software may be used and distributed according to the terms of the
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# GNU General Public License version 2 or any later version.
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"""simplified reStructuredText parser.
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This parser knows just enough about reStructuredText to parse the
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Mercurial docstrings.
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It cheats in a major way: nested blocks are not really nested. They
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are just indented blocks that look like they are nested. This relies
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on the user to keep the right indentation for the blocks.
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It only supports a small subset of reStructuredText:
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- sections
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- paragraphs
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- literal blocks
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- definition lists
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- bullet lists (items must start with '-')
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- enumerated lists (no autonumbering)
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- field lists (colons cannot be escaped)
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- option lists (supports only long options without arguments)
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- inline literals (no other inline markup is not recognized)
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"""
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import re, sys, textwrap
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def findblocks(text):
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"""Find continuous blocks of lines in text.
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Returns a list of dictionaries representing the blocks. Each block
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has an 'indent' field and a 'lines' field.
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"""
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blocks = [[]]
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lines = text.splitlines()
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for line in lines:
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if line.strip():
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blocks[-1].append(line)
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elif blocks[-1]:
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blocks.append([])
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if not blocks[-1]:
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del blocks[-1]
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for i, block in enumerate(blocks):
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indent = min((len(l) - len(l.lstrip())) for l in block)
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blocks[i] = dict(indent=indent, lines=[l[indent:] for l in block])
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return blocks
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def findliteralblocks(blocks):
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"""Finds literal blocks and adds a 'type' field to the blocks.
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Literal blocks are given the type 'literal', all other blocks are
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given type the 'paragraph'.
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"""
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i = 0
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while i < len(blocks):
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# Searching for a block that looks like this:
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#
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# +------------------------------+
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# | paragraph |
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# | (ends with "::") |
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# +------------------------------+
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# +---------------------------+
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# | indented literal block |
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# +---------------------------+
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blocks[i]['type'] = 'paragraph'
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if blocks[i]['lines'][-1].endswith('::') and i + 1 < len(blocks):
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indent = blocks[i]['indent']
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adjustment = blocks[i + 1]['indent'] - indent
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if blocks[i]['lines'] == ['::']:
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# Expanded form: remove block
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del blocks[i]
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i -= 1
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elif blocks[i]['lines'][-1].endswith(' ::'):
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# Partially minimized form: remove space and both
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# colons.
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blocks[i]['lines'][-1] = blocks[i]['lines'][-1][:-3]
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else:
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# Fully minimized form: remove just one colon.
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blocks[i]['lines'][-1] = blocks[i]['lines'][-1][:-1]
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# List items are formatted with a hanging indent. We must
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# correct for this here while we still have the original
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# information on the indentation of the subsequent literal
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# blocks available.
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m = _bulletre.match(blocks[i]['lines'][0])
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if m:
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indent += m.end()
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adjustment -= m.end()
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# Mark the following indented blocks.
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while i + 1 < len(blocks) and blocks[i + 1]['indent'] > indent:
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blocks[i + 1]['type'] = 'literal'
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blocks[i + 1]['indent'] -= adjustment
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i += 1
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i += 1
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return blocks
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_bulletre = re.compile(r'(-|[0-9A-Za-z]+\.|\(?[0-9A-Za-z]+\)) ')
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_optionre = re.compile(r'^(--[a-z-]+)((?:[ =][a-zA-Z][\w-]*)? +)(.*)$')
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_fieldre = re.compile(r':(?![: ])([^:]*)(?<! ):[ ]+(.*)')
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_definitionre = re.compile(r'[^ ]')
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def splitparagraphs(blocks):
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"""Split paragraphs into lists."""
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# Tuples with (list type, item regexp, single line items?). Order
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# matters: definition lists has the least specific regexp and must
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# come last.
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listtypes = [('bullet', _bulletre, True),
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('option', _optionre, True),
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('field', _fieldre, True),
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('definition', _definitionre, False)]
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def match(lines, i, itemre, singleline):
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"""Does itemre match an item at line i?
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A list item can be followed by an idented line or another list
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item (but only if singleline is True).
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"""
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line1 = lines[i]
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line2 = i + 1 < len(lines) and lines[i + 1] or ''
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if not itemre.match(line1):
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return False
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if singleline:
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return line2 == '' or line2[0] == ' ' or itemre.match(line2)
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else:
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return line2.startswith(' ')
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i = 0
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while i < len(blocks):
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if blocks[i]['type'] == 'paragraph':
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lines = blocks[i]['lines']
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for type, itemre, singleline in listtypes:
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if match(lines, 0, itemre, singleline):
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items = []
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for j, line in enumerate(lines):
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if match(lines, j, itemre, singleline):
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items.append(dict(type=type, lines=[],
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indent=blocks[i]['indent']))
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items[-1]['lines'].append(line)
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blocks[i:i + 1] = items
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break
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i += 1
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return blocks
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_fieldwidth = 12
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def updatefieldlists(blocks):
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"""Find key and maximum key width for field lists."""
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i = 0
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while i < len(blocks):
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if blocks[i]['type'] != 'field':
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i += 1
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continue
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keywidth = 0
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j = i
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while j < len(blocks) and blocks[j]['type'] == 'field':
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m = _fieldre.match(blocks[j]['lines'][0])
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key, rest = m.groups()
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blocks[j]['lines'][0] = rest
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blocks[j]['key'] = key
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keywidth = max(keywidth, len(key))
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j += 1
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for block in blocks[i:j]:
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block['keywidth'] = keywidth
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i = j + 1
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return blocks
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def findsections(blocks):
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"""Finds sections.
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The blocks must have a 'type' field, i.e., they should have been
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run through findliteralblocks first.
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"""
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for block in blocks:
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# Searching for a block that looks like this:
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#
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# +------------------------------+
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# | Section title |
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# | ------------- |
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# +------------------------------+
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if (block['type'] == 'paragraph' and
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len(block['lines']) == 2 and
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block['lines'][1] == '-' * len(block['lines'][0])):
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block['type'] = 'section'
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return blocks
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def inlineliterals(blocks):
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for b in blocks:
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if b['type'] == 'paragraph':
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b['lines'] = [l.replace('``', '"') for l in b['lines']]
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return blocks
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def addmargins(blocks):
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"""Adds empty blocks for vertical spacing.
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This groups bullets, options, and definitions together with no vertical
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space between them, and adds an empty block between all other blocks.
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"""
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i = 1
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while i < len(blocks):
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if (blocks[i]['type'] == blocks[i - 1]['type'] and
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blocks[i]['type'] in ('bullet', 'option', 'field', 'definition')):
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i += 1
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else:
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blocks.insert(i, dict(lines=[''], indent=0, type='margin'))
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i += 2
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return blocks
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def formatblock(block, width):
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"""Format a block according to width."""
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if width <= 0:
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width = 78
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indent = ' ' * block['indent']
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if block['type'] == 'margin':
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return ''
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if block['type'] == 'literal':
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indent += ' '
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return indent + ('\n' + indent).join(block['lines'])
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if block['type'] == 'section':
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return indent + ('\n' + indent).join(block['lines'])
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if block['type'] == 'definition':
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term = indent + block['lines'][0]
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hang = len(block['lines'][-1]) - len(block['lines'][-1].lstrip())
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defindent = indent + hang * ' '
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text = ' '.join(map(str.strip, block['lines'][1:]))
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return "%s\n%s" % (term, textwrap.fill(text, width=width,
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initial_indent=defindent,
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subsequent_indent=defindent))
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initindent = subindent = indent
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if block['type'] == 'bullet':
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m = _bulletre.match(block['lines'][0])
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subindent = indent + m.end() * ' '
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elif block['type'] == 'field':
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keywidth = block['keywidth']
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key = block['key']
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subindent = indent + _fieldwidth * ' '
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if len(key) + 2 > _fieldwidth:
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# key too large, use full line width
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key = key.ljust(width)
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elif keywidth + 2 < _fieldwidth:
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# all keys are small, add only two spaces
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key = key.ljust(keywidth + 2)
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subindent = indent + (keywidth + 2) * ' '
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else:
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# mixed sizes, use fieldwidth for this one
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key = key.ljust(_fieldwidth)
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block['lines'][0] = key + block['lines'][0]
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elif block['type'] == 'option':
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m = _optionre.match(block['lines'][0])
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option, arg, rest = m.groups()
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subindent = indent + (len(option) + len(arg)) * ' '
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text = ' '.join(map(str.strip, block['lines']))
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return textwrap.fill(text, width=width,
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initial_indent=initindent,
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subsequent_indent=subindent)
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def format(text, width, indent=0):
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"""Parse and format the text according to width."""
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blocks = findblocks(text)
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for b in blocks:
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b['indent'] += indent
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blocks = findliteralblocks(blocks)
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blocks = inlineliterals(blocks)
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blocks = splitparagraphs(blocks)
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blocks = updatefieldlists(blocks)
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blocks = findsections(blocks)
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blocks = addmargins(blocks)
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return '\n'.join(formatblock(b, width) for b in blocks)
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if __name__ == "__main__":
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from pprint import pprint
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def debug(func, blocks):
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blocks = func(blocks)
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print "*** after %s:" % func.__name__
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pprint(blocks)
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print
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return blocks
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text = open(sys.argv[1]).read()
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blocks = debug(findblocks, text)
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blocks = debug(findliteralblocks, blocks)
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blocks = debug(inlineliterals, blocks)
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blocks = debug(splitparagraphs, blocks)
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blocks = debug(updatefieldlists, blocks)
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blocks = debug(findsections, blocks)
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blocks = debug(addmargins, blocks)
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print '\n'.join(formatblock(b, 30) for b in blocks)
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