1 files changed, 54 insertions, 0 deletions
diff --git a/docutils/transforms/components.py b/docutils/transforms/components.py
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+++ b/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.replace_self(pending.details['nodes'])
+        else:
+            pending.parent.remove(pending)