python-peps/docutils/transforms/components.py

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# Author: David Goodger
# Contact: goodger@users.sourceforge.net
# Revision: $Revision$
# Date: $Date$
# Copyright: This module has been placed in the public domain.
"""
Docutils component-related transforms.
"""
__docformat__ = 'reStructuredText'
import sys
import os
import re
import time
from docutils import nodes, utils
from docutils import ApplicationError, DataError
from docutils.transforms import Transform, TransformError
class Filter(Transform):
"""
Include or exclude elements which depend on a specific Docutils component.
For use with `nodes.pending` elements. A "pending" element's dictionary
attribute ``details`` must contain the keys "component" and "format". The
value of ``details['component']`` must match the type name of the
component the elements depend on (e.g. "writer"). The value of
``details['format']`` is the name of a specific format or context of that
component (e.g. "html"). If the matching Docutils component supports that
format or context, the "pending" element is replaced by the contents of
``details['nodes']`` (a list of nodes); otherwise, the "pending" element
is removed.
For example, the reStructuredText "meta" directive creates a "pending"
element containing a "meta" element (in ``pending.details['nodes']``).
Only writers (``pending.details['component'] == 'writer'``) supporting the
"html" format (``pending.details['format'] == 'html'``) will include the
"meta" element; it will be deleted from the output of all other writers.
"""
default_priority = 780
def apply(self):
pending = self.startnode
component_type = pending.details['component'] # 'reader' or 'writer'
format = pending.details['format']
component = self.document.transformer.components[component_type]
if component.supports(format):
pending.parent.replace(pending, pending.details['nodes'])
else:
pending.parent.remove(pending)