# $Id: __init__.py 4802 2006-11-12 18:02:17Z goodger $

# 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=1`` 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

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://www.faqs.org/rfcs/").',

          ['--rfc-base-url'],

          {'metavar': '<URL>', 'default': 'http://www.faqs.org/rfcs/',

           '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'}),))

    config_section = 'restructuredtext parser'

    config_section_dependencies = ('parsers',)

    def __init__(self, rfc2822=None, inliner=None):

        if rfc2822:

            self.initial_state = 'RFC2822Body'

        else:

            self.initial_state = 'Body'

        self.state_classes = states.state_classes

        self.inliner = inliner

    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=1)

        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):

        """

        Initialize with message `message`.  `level` is a system message level.

        """

        Exception.__init__(self)

        self.level = level

        self.message = message

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/__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 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.

        You'd often use self.error(message) instead, which will

        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 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