Source code for docutils.parsers.rst

# $Id: 9258 2022-11-21 14:51:43Z milde $
# Author: David Goodger <>
# Copyright: This module has been placed in the public domain.

This is ``docutils.parsers.rst`` package. It exports a single class, `Parser`,
the reStructuredText parser.


1. Create a parser::

       parser = docutils.parsers.rst.Parser()

   Several optional arguments may be passed to modify the parser's behavior.
   Please see `Customizing the Parser`_ below for details.

2. Gather input (a multi-line string), by reading a file or the standard

       input =

3. Create a new empty `docutils.nodes.document` tree::

       document = docutils.utils.new_document(source, settings)

   See `docutils.utils.new_document()` for parameter details.

4. Run the parser, populating the document tree::

       parser.parse(input, document)

Parser Overview

The reStructuredText parser is implemented as a state machine, examining its
input one line at a time. To understand how the parser works, please first
become familiar with the `docutils.statemachine` module, then see the
`states` module.

Customizing the Parser

Anything that isn't already customizable is that way simply because that type
of customizability hasn't been implemented yet.  Patches welcome!

When instantiating an object of the `Parser` class, two parameters may be
passed: ``rfc2822`` and ``inliner``.  Pass ``rfc2822=True`` to enable an
initial RFC-2822 style header block, parsed as a "field_list" element (with
"class" attribute set to "rfc2822").  Currently this is the only body-level
element which is customizable without subclassing.  (Tip: subclass `Parser`
and change its "state_classes" and "initial_state" attributes to refer to new
classes. Contact the author if you need more details.)

The ``inliner`` parameter takes an instance of `states.Inliner` or a subclass.
It handles inline markup recognition.  A common extension is the addition of
further implicit hyperlinks, like "RFC 2822".  This can be done by subclassing
`states.Inliner`, adding a new method for the implicit markup, and adding a
``(pattern, method)`` pair to the "implicit_dispatch" attribute of the
subclass.  See `states.Inliner.implicit_inline()` for details.  Explicit
inline markup can be customized in a `states.Inliner` subclass via the
``patterns.initial`` and ``dispatch`` attributes (and new methods as

__docformat__ = 'reStructuredText'

import docutils.parsers
import docutils.statemachine
from docutils.parsers.rst import roles, states
from docutils import frontend, nodes
from docutils.transforms import universal

class Parser(docutils.parsers.Parser):

    """The reStructuredText parser."""

    supported = ('rst', 'restructuredtext', 'rest', 'restx', 'rtxt', 'rstx')
    """Aliases this parser supports."""

    settings_spec = docutils.parsers.Parser.settings_spec + (
        'reStructuredText Parser Options',
        (('Recognize and link to standalone PEP references (like "PEP 258").',
          {'action': 'store_true', 'validator': frontend.validate_boolean}),
         ('Base URL for PEP references '
          '(default "").',
          {'metavar': '<URL>', 'default': '',
           'validator': frontend.validate_url_trailing_slash}),
         ('Template for PEP file part of URL. (default "pep-%04d")',
          {'metavar': '<URL>', 'default': 'pep-%04d'}),
         ('Recognize and link to standalone RFC references (like "RFC 822").',
          {'action': 'store_true', 'validator': frontend.validate_boolean}),
         ('Base URL for RFC references '
          '(default "").',
          {'metavar': '<URL>', 'default': '',
           'validator': frontend.validate_url_trailing_slash}),
         ('Set number of spaces for tab expansion (default 8).',
          {'metavar': '<width>', 'type': 'int', 'default': 8,
           'validator': frontend.validate_nonnegative_int}),
         ('Remove spaces before footnote references.',
          {'action': 'store_true', 'validator': frontend.validate_boolean}),
         ('Leave spaces before footnote references.',
          {'action': 'store_false', 'dest': 'trim_footnote_reference_space'}),
         ('Token name set for parsing code with Pygments: one of '
          '"long", "short", or "none" (no parsing). Default is "long".',
          {'choices': ['long', 'short', 'none'],
           'default': 'long', 'metavar': '<format>'}),
         ('Change straight quotation marks to typographic form: '
          'one of "yes", "no", "alt[ernative]" (default "no").',
          {'default': False, 'metavar': '<yes/no/alt>',
           'validator': frontend.validate_ternary}),
         ('Characters to use as "smart quotes" for <language>. ',
          {'metavar': '<language:quotes[,language:quotes,...]>',
           'action': 'append',
           'validator': frontend.validate_smartquotes_locales}),
         ('Inline markup recognized at word boundaries only '
          '(adjacent to punctuation or whitespace). '
          'Force character-level inline markup recognition with '
          '"\\ " (backslash + space). Default.',
          {'action': 'store_false', 'dest': 'character_level_inline_markup'}),
         ('Inline markup recognized anywhere, regardless of surrounding '
          'characters. Backslash-escapes must be used to avoid unwanted '
          'markup recognition. Useful for East Asian languages. '
          {'action': 'store_true', 'default': False,
           'dest': 'character_level_inline_markup'}),

    config_section = 'restructuredtext parser'
    config_section_dependencies = ('parsers',)

    def __init__(self, rfc2822=False, inliner=None):
        if rfc2822:
            self.initial_state = 'RFC2822Body'
            self.initial_state = 'Body'
        self.state_classes = states.state_classes
        self.inliner = inliner

    def get_transforms(self):
        return super().get_transforms() + [universal.SmartQuotes]

    def parse(self, inputstring, document):
        """Parse `inputstring` and populate `document`, a document tree."""
        self.setup_parse(inputstring, document)
        # provide fallbacks in case the document has only generic settings
        self.document.settings.setdefault('tab_width', 8)
        self.document.settings.setdefault('syntax_highlight', 'long')
        self.statemachine = states.RSTStateMachine(
        inputlines = docutils.statemachine.string2lines(
              inputstring, tab_width=document.settings.tab_width,
        for i, line in enumerate(inputlines):
            if len(line) > self.document.settings.line_length_limit:
                error = self.document.reporter.error(
                            'Line %d exceeds the line-length-limit.'%(i+1))
  , document, inliner=self.inliner)
        # restore the "default" default role after parsing a document
        if '' in roles._roles:
            del roles._roles['']

class DirectiveError(Exception):

    Store a message and a system message level.

    To be thrown from inside directive code.

    Do not instantiate directly -- use `Directive.directive_error()`

    def __init__(self, level, message):
        """Set error `message` and `level`"""
        self.level = level
        self.msg = message

[docs] class Directive: """ Base class for reStructuredText directives. The following attributes may be set by subclasses. They are interpreted by the directive parser (which runs the directive class): - `required_arguments`: The number of required arguments (default: 0). - `optional_arguments`: The number of optional arguments (default: 0). - `final_argument_whitespace`: A boolean, indicating if the final argument may contain whitespace (default: False). - `option_spec`: A dictionary, mapping known option names to conversion functions such as `int` or `float` (default: {}, no options). Several conversion functions are defined in the directives/ module. Option conversion functions take a single parameter, the option argument (a string or ``None``), validate it and/or convert it to the appropriate form. Conversion functions may raise `ValueError` and `TypeError` exceptions. - `has_content`: A boolean; True if content is allowed. Client code must handle the case where content is required but not supplied (an empty content list will be supplied). Arguments are normally single whitespace-separated words. The final argument may contain whitespace and/or newlines if `final_argument_whitespace` is True. If the form of the arguments is more complex, specify only one argument (either required or optional) and set `final_argument_whitespace` to True; the client code must do any context-sensitive parsing. When a directive implementation is being run, the directive class is instantiated, and the `run()` method is executed. During instantiation, the following instance variables are set: - ``name`` is the directive type or name (string). - ``arguments`` is the list of positional arguments (strings). - ``options`` is a dictionary mapping option names (strings) to values (type depends on option conversion functions; see `option_spec` above). - ``content`` is a list of strings, the directive content line by line. - ``lineno`` is the absolute line number of the first line of the directive. - ``content_offset`` is the line offset of the first line of the content from the beginning of the current input. Used when initiating a nested parse. - ``block_text`` is a string containing the entire directive. - ``state`` is the state which called the directive function. - ``state_machine`` is the state machine which controls the state which called the directive function. - ``reporter`` is the state machine's `reporter` instance. Directive functions return a list of nodes which will be inserted into the document tree at the point where the directive was encountered. This can be an empty list if there is nothing to insert. For ordinary directives, the list must contain body elements or structural elements. Some directives are intended specifically for substitution definitions, and must return a list of `Text` nodes and/or inline elements (suitable for inline insertion, in place of the substitution reference). Such directives must verify substitution definition context, typically using code like this:: if not isinstance(state, states.SubstitutionDef): error = self.reporter.error( 'Invalid context: the "%s" directive can only be used ' 'within a substitution definition.' % (name), nodes.literal_block(block_text, block_text), line=lineno) return [error] """ # There is a "Creating reStructuredText Directives" how-to at # <>. If you # update this docstring, please update the how-to as well. required_arguments = 0 """Number of required directive arguments.""" optional_arguments = 0 """Number of optional arguments after the required arguments.""" final_argument_whitespace = False """May the final argument contain whitespace?""" option_spec = None """Mapping of option names to validator functions.""" has_content = False """May the directive have content?""" def __init__(self, name, arguments, options, content, lineno, content_offset, block_text, state, state_machine): = name self.arguments = arguments self.options = options self.content = content self.lineno = lineno self.content_offset = content_offset self.block_text = block_text self.state = state self.state_machine = state_machine self.reporter = state_machine.reporter
[docs] def run(self): raise NotImplementedError('Must override run() in subclass.')
# Directive errors: def directive_error(self, level, message): """ Return a DirectiveError suitable for being thrown as an exception. Call "raise self.directive_error(level, message)" from within a directive implementation to return one single system message at level `level`, which automatically gets the directive block and the line number added. Preferably use the `debug`, `info`, `warning`, `error`, or `severe` wrapper methods, e.g. ``self.error(message)`` to generate an ERROR-level directive error. """ return DirectiveError(level, message) def debug(self, message): return self.directive_error(0, message) def info(self, message): return self.directive_error(1, message) def warning(self, message): return self.directive_error(2, message) def error(self, message): return self.directive_error(3, message) def severe(self, message): return self.directive_error(4, message) # Convenience methods: def assert_has_content(self): """ Throw an ERROR-level DirectiveError if the directive doesn't have contents. """ if not self.content: raise self.error('Content block expected for the "%s" directive; ' 'none found.' % def add_name(self, node): """Append self.options['name'] to node['names'] if it exists. Also normalize the name string and register it as explicit target. """ if 'name' in self.options: name = nodes.fully_normalize_name(self.options.pop('name')) if 'name' in node: del node['name'] node['names'].append(name) self.state.document.note_explicit_target(node, node)
def convert_directive_function(directive_fn): """ Define & return a directive class generated from `directive_fn`. `directive_fn` uses the old-style, functional interface. """ class FunctionalDirective(Directive): option_spec = getattr(directive_fn, 'options', None) has_content = getattr(directive_fn, 'content', False) _argument_spec = getattr(directive_fn, 'arguments', (0, 0, False)) required_arguments, optional_arguments, final_argument_whitespace \ = _argument_spec def run(self): return directive_fn(, self.arguments, self.options, self.content, self.lineno, self.content_offset, self.block_text, self.state, self.state_machine) # Return new-style directive. return FunctionalDirective