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# Source code for docutils.parsers.rst

    # $Id: __init__.py 7961 2016-07-28 22:02:47Z milde $
    # Author: David Goodger <goodger@python.org>
    # 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.

    Usage
    =====

    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::

           input = sys.stdin.read()

    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
    appropriate).
    """

    __docformat__ = 'reStructuredText'

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

    class Parser(docutils.parsers.Parser):

        """The reStructuredText parser."""

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

        settings_spec = (
            'reStructuredText Parser Options',
            None,
            (('Recognize and link to standalone PEP references (like "PEP 258").',
              ['--pep-references'],
              {'action': 'store_true', 'validator': frontend.validate_boolean}),
             ('Base URL for PEP references '
              '(default "http://www.python.org/dev/peps/").',
              ['--pep-base-url'],
              {'metavar': '<URL>', 'default': 'http://www.python.org/dev/peps/',
               'validator': frontend.validate_url_trailing_slash}),
             ('Template for PEP file part of URL. (default "pep-%04d")',
              ['--pep-file-url-template'],
              {'metavar': '<URL>', 'default': 'pep-%04d'}),
             ('Recognize and link to standalone RFC references (like "RFC 822").',
              ['--rfc-references'],
              {'action': 'store_true', 'validator': frontend.validate_boolean}),
             ('Base URL for RFC references (default "http://tools.ietf.org/html/").',
              ['--rfc-base-url'],
              {'metavar': '<URL>', 'default': 'http://tools.ietf.org/html/',
               'validator': frontend.validate_url_trailing_slash}),
             ('Set number of spaces for tab expansion (default 8).',
              ['--tab-width'],
              {'metavar': '<width>', 'type': 'int', 'default': 8,
               'validator': frontend.validate_nonnegative_int}),
             ('Remove spaces before footnote references.',
              ['--trim-footnote-reference-space'],
              {'action': 'store_true', 'validator': frontend.validate_boolean}),
             ('Leave spaces before footnote references.',
              ['--leave-footnote-reference-space'],
              {'action': 'store_false', 'dest': 'trim_footnote_reference_space'}),
             ('Disable directives that insert the contents of external file '
              '("include" & "raw"); replaced with a "warning" system message.',
              ['--no-file-insertion'],
              {'action': 'store_false', 'default': 1,
               'dest': 'file_insertion_enabled',
               'validator': frontend.validate_boolean}),
             ('Enable directives that insert the contents of external file '
              '("include" & "raw").  Enabled by default.',
              ['--file-insertion-enabled'],
              {'action': 'store_true'}),
             ('Disable the "raw" directives; replaced with a "warning" '
              'system message.',
              ['--no-raw'],
              {'action': 'store_false', 'default': 1, 'dest': 'raw_enabled',
               'validator': frontend.validate_boolean}),
             ('Enable the "raw" directive.  Enabled by default.',
              ['--raw-enabled'],
              {'action': 'store_true'}),
             ('Token name set for parsing code with Pygments: one of '
              '"long", "short", or "none (no parsing)". Default is "long".',
              ['--syntax-highlight'],
              {'choices': ['long', 'short', 'none'],
               'default': 'long', 'metavar': '<format>'}),
             ('Change straight quotation marks to typographic form: '
              'one of "yes", "no", "alt[ernative]" (default "no").',
              ['--smart-quotes'],
              {'default': False, 'validator': frontend.validate_ternary}),
             ('Inline markup recognized at word boundaries only '
              '(adjacent to punctuation or whitespace). '
              'Force character-level inline markup recognition with '
              '"\ " (backslash + space). Default.',
              ['--word-level-inline-markup'],
              {'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. '
              'Experimental.',
              ['--character-level-inline-markup'],
              {'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'
            else:
                self.initial_state = 'Body'
            self.state_classes = states.state_classes
            self.inliner = inliner

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

        def parse(self, inputstring, document):
            """Parse `inputstring` and populate `document`, a document tree."""
            self.setup_parse(inputstring, document)
            self.statemachine = states.RSTStateMachine(
                  state_classes=self.state_classes,
                  initial_state=self.initial_state,
                  debug=document.reporter.debug_flag)
            inputlines = docutils.statemachine.string2lines(
                  inputstring, tab_width=document.settings.tab_width,
                  convert_whitespace=True)
            self.statemachine.run(inputlines, document, inliner=self.inliner)
            self.finish_parse()

    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()`
        instead!
        """

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

    class Directive(object):

        """
        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/__init__.py 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.

        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 = state_machine.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
        # <http://docutils.sf.net/docs/howto/rst-directives.html>.  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):
            self.name = 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

        def run(self):
            raise NotImplementedError('Must override run() is 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.' % self.name)

        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.name, 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