python-peps/docutils/transforms/universal.py

# Authors: David Goodger, Ueli Schlaepfer
# Contact: goodger@users.sourceforge.net
# Revision: $Revision$
# Date: $Date$
# Copyright: This module has been placed in the public domain.

"""
Transforms needed by most or all documents:

- `Decorations`: Generate a document's header & footer.
- `Messages`: Placement of system messages stored in
  `nodes.document.transform_messages`.
- `TestMessages`: Like `Messages`, used on test runs.
- `FinalReferences`: Resolve remaining references.
"""

__docformat__ = 'reStructuredText'

import re
import sys
import time
from docutils import nodes, utils
from docutils.transforms import TransformError, Transform


class Decorations(Transform):

    """
    Populate a document's decoration element (header, footer).
    """

    default_priority = 820

    def apply(self):
        header = self.generate_header()
        footer = self.generate_footer()
        if header or footer:
            decoration = nodes.decoration()
            decoration += header
            decoration += footer
            document = self.document
            index = document.first_child_not_matching_class(
                nodes.PreDecorative)
            if index is None:
                document += decoration
            else:
                document[index:index] = [decoration]

    def generate_header(self):
        return None

    def generate_footer(self):
        # @@@ Text is hard-coded for now.
        # Should be made dynamic (language-dependent).
        settings = self.document.settings
        if settings.generator or settings.datestamp or settings.source_link \
               or settings.source_url:
            text = []
            if settings.source_link and settings._source \
                   or settings.source_url:
                if settings.source_url:
                    source = settings.source_url
                else:
                    source = utils.relative_path(settings._destination,
                                                 settings._source)
                text.extend([
                    nodes.reference('', 'View document source',
                                    refuri=source),
                    nodes.Text('.\n')])
            if settings.datestamp:
                datestamp = time.strftime(settings.datestamp, time.gmtime())
                text.append(nodes.Text('Generated on: ' + datestamp + '.\n'))
            if settings.generator:
                text.extend([
                    nodes.Text('Generated by '),
                    nodes.reference('', 'Docutils', refuri=
                                    'http://docutils.sourceforge.net/'),
                    nodes.Text(' from '),
                    nodes.reference('', 'reStructuredText', refuri='http://'
                                    'docutils.sourceforge.net/rst.html'),
                    nodes.Text(' source.\n')])
            footer = nodes.footer()
            footer += nodes.paragraph('', '', *text)
            return footer
        else:
            return None


class Messages(Transform):

    """
    Place any system messages generated after parsing into a dedicated section
    of the document.
    """

    default_priority = 860

    def apply(self):
        unfiltered = self.document.transform_messages
        threshold = self.document.reporter['writer'].report_level
        messages = []
        for msg in unfiltered:
            if msg['level'] >= threshold and not msg.parent:
                messages.append(msg)
        if len(messages) > 0:
            section = nodes.section(CLASS='system-messages')
            # @@@ get this from the language module?
            section += nodes.title('', 'Docutils System Messages')
            section += messages
            self.document.transform_messages[:] = []
            self.document += section


class TestMessages(Transform):

    """
    Append all post-parse system messages to the end of the document.
    """

    default_priority = 890

    def apply(self):
        for msg in self.document.transform_messages:
            if not msg.parent:
                self.document += msg


class FinalChecks(Transform):

    """
    Perform last-minute checks.

    - Check for dangling references (incl. footnote & citation).
    """

    default_priority = 840

    def apply(self):
        visitor = FinalCheckVisitor(self.document)
        self.document.walk(visitor)
        if self.document.settings.expose_internals:
            visitor = InternalAttributeExposer(self.document)
            self.document.walk(visitor)


class FinalCheckVisitor(nodes.SparseNodeVisitor):

    def unknown_visit(self, node):
        pass

    def visit_reference(self, node):
        if node.resolved or not node.hasattr('refname'):
            return
        refname = node['refname']
        id = self.document.nameids.get(refname)
        if id is None:
            msg = self.document.reporter.error(
                  'Unknown target name: "%s".' % (node['refname']),
                  base_node=node)
            msgid = self.document.set_id(msg)
            prb = nodes.problematic(
                  node.rawsource, node.rawsource, refid=msgid)
            prbid = self.document.set_id(prb)
            msg.add_backref(prbid)
            node.parent.replace(node, prb)
        else:
            del node['refname']
            node['refid'] = id
            self.document.ids[id].referenced = 1
            node.resolved = 1

    visit_footnote_reference = visit_citation_reference = visit_reference


class InternalAttributeExposer(nodes.GenericNodeVisitor):

    def __init__(self, document):
        nodes.GenericNodeVisitor.__init__(self, document)
        self.internal_attributes = document.settings.expose_internals

    def default_visit(self, node):
        for att in self.internal_attributes:
            value = getattr(node, att, None)
            if value is not None:
                node['internal:' + att] = value