Source

scikits_index / code / docutils / transforms / references.py

  1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
# $Id: references.py 6167 2009-10-11 14:51:42Z grubert $
# Author: David Goodger <goodger@python.org>
# Copyright: This module has been placed in the public domain.

"""
Transforms for resolving references.
"""

__docformat__ = 'reStructuredText'

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


class PropagateTargets(Transform):

    """
    Propagate empty internal targets to the next element.

    Given the following nodes::

        <target ids="internal1" names="internal1">
        <target anonymous="1" ids="id1">
        <target ids="internal2" names="internal2">
        <paragraph>
            This is a test.

    PropagateTargets propagates the ids and names of the internal
    targets preceding the paragraph to the paragraph itself::

        <target refid="internal1">
        <target anonymous="1" refid="id1">
        <target refid="internal2">
        <paragraph ids="internal2 id1 internal1" names="internal2 internal1">
            This is a test.
    """

    default_priority = 260

    def apply(self):
        for target in self.document.traverse(nodes.target):
            # Only block-level targets without reference (like ".. target:"):
            if (isinstance(target.parent, nodes.TextElement) or
                (target.hasattr('refid') or target.hasattr('refuri') or
                 target.hasattr('refname'))):
                continue
            assert len(target) == 0, 'error: block-level target has children'
            next_node = target.next_node(ascend=1)
            # Do not move names and ids into Invisibles (we'd lose the
            # attributes) or different Targetables (e.g. footnotes).
            if (next_node is not None and
                ((not isinstance(next_node, nodes.Invisible) and
                  not isinstance(next_node, nodes.Targetable)) or
                 isinstance(next_node, nodes.target))):
                next_node['ids'].extend(target['ids'])
                next_node['names'].extend(target['names'])
                # Set defaults for next_node.expect_referenced_by_name/id.
                if not hasattr(next_node, 'expect_referenced_by_name'):
                    next_node.expect_referenced_by_name = {}
                if not hasattr(next_node, 'expect_referenced_by_id'):
                    next_node.expect_referenced_by_id = {}
                for id in target['ids']:
                    # Update IDs to node mapping.
                    self.document.ids[id] = next_node
                    # If next_node is referenced by id ``id``, this
                    # target shall be marked as referenced.
                    next_node.expect_referenced_by_id[id] = target
                for name in target['names']:
                    next_node.expect_referenced_by_name[name] = target
                # If there are any expect_referenced_by_... attributes
                # in target set, copy them to next_node.
                next_node.expect_referenced_by_name.update(
                    getattr(target, 'expect_referenced_by_name', {}))
                next_node.expect_referenced_by_id.update(
                    getattr(target, 'expect_referenced_by_id', {}))
                # Set refid to point to the first former ID of target
                # which is now an ID of next_node.
                target['refid'] = target['ids'][0]
                # Clear ids and names; they have been moved to
                # next_node.
                target['ids'] = []
                target['names'] = []
                self.document.note_refid(target)


class AnonymousHyperlinks(Transform):

    """
    Link anonymous references to targets.  Given::

        <paragraph>
            <reference anonymous="1">
                internal
            <reference anonymous="1">
                external
        <target anonymous="1" ids="id1">
        <target anonymous="1" ids="id2" refuri="http://external">

    Corresponding references are linked via "refid" or resolved via "refuri"::

        <paragraph>
            <reference anonymous="1" refid="id1">
                text
            <reference anonymous="1" refuri="http://external">
                external
        <target anonymous="1" ids="id1">
        <target anonymous="1" ids="id2" refuri="http://external">
    """

    default_priority = 440

    def apply(self):
        anonymous_refs = []
        anonymous_targets = []
        for node in self.document.traverse(nodes.reference):
            if node.get('anonymous'):
                anonymous_refs.append(node)
        for node in self.document.traverse(nodes.target):
            if node.get('anonymous'):
                anonymous_targets.append(node)
        if len(anonymous_refs) \
              != len(anonymous_targets):
            msg = self.document.reporter.error(
                  'Anonymous hyperlink mismatch: %s references but %s '
                  'targets.\nSee "backrefs" attribute for IDs.'
                  % (len(anonymous_refs), len(anonymous_targets)))
            msgid = self.document.set_id(msg)
            for ref in anonymous_refs:
                prb = nodes.problematic(
                      ref.rawsource, ref.rawsource, refid=msgid)
                prbid = self.document.set_id(prb)
                msg.add_backref(prbid)
                ref.replace_self(prb)
            return
        for ref, target in zip(anonymous_refs, anonymous_targets):
            target.referenced = 1
            while 1:
                if target.hasattr('refuri'):
                    ref['refuri'] = target['refuri']
                    ref.resolved = 1
                    break
                else:
                    if not target['ids']:
                        # Propagated target.
                        target = self.document.ids[target['refid']]
                        continue
                    ref['refid'] = target['ids'][0]
                    self.document.note_refid(ref)
                    break


class IndirectHyperlinks(Transform):

    """
    a) Indirect external references::

           <paragraph>
               <reference refname="indirect external">
                   indirect external
           <target id="id1" name="direct external"
               refuri="http://indirect">
           <target id="id2" name="indirect external"
               refname="direct external">

       The "refuri" attribute is migrated back to all indirect targets
       from the final direct target (i.e. a target not referring to
       another indirect target)::

           <paragraph>
               <reference refname="indirect external">
                   indirect external
           <target id="id1" name="direct external"
               refuri="http://indirect">
           <target id="id2" name="indirect external"
               refuri="http://indirect">

       Once the attribute is migrated, the preexisting "refname" attribute
       is dropped.

    b) Indirect internal references::

           <target id="id1" name="final target">
           <paragraph>
               <reference refname="indirect internal">
                   indirect internal
           <target id="id2" name="indirect internal 2"
               refname="final target">
           <target id="id3" name="indirect internal"
               refname="indirect internal 2">

       Targets which indirectly refer to an internal target become one-hop
       indirect (their "refid" attributes are directly set to the internal
       target's "id"). References which indirectly refer to an internal
       target become direct internal references::

           <target id="id1" name="final target">
           <paragraph>
               <reference refid="id1">
                   indirect internal
           <target id="id2" name="indirect internal 2" refid="id1">
           <target id="id3" name="indirect internal" refid="id1">
    """

    default_priority = 460

    def apply(self):
        for target in self.document.indirect_targets:
            if not target.resolved:
                self.resolve_indirect_target(target)
            self.resolve_indirect_references(target)

    def resolve_indirect_target(self, target):
        refname = target.get('refname')
        if refname is None:
            reftarget_id = target['refid']
        else:
            reftarget_id = self.document.nameids.get(refname)
            if not reftarget_id:
                # Check the unknown_reference_resolvers
                for resolver_function in \
                        self.document.transformer.unknown_reference_resolvers:
                    if resolver_function(target):
                        break
                else:
                    self.nonexistent_indirect_target(target)
                return
        reftarget = self.document.ids[reftarget_id]
        reftarget.note_referenced_by(id=reftarget_id)
        if isinstance(reftarget, nodes.target) \
               and not reftarget.resolved and reftarget.hasattr('refname'):
            if hasattr(target, 'multiply_indirect'):
                #and target.multiply_indirect):
                #del target.multiply_indirect
                self.circular_indirect_reference(target)
                return
            target.multiply_indirect = 1
            self.resolve_indirect_target(reftarget) # multiply indirect
            del target.multiply_indirect
        if reftarget.hasattr('refuri'):
            target['refuri'] = reftarget['refuri']
            if 'refid' in target:
                del target['refid']
        elif reftarget.hasattr('refid'):
            target['refid'] = reftarget['refid']
            self.document.note_refid(target)
        else:
            if reftarget['ids']:
                target['refid'] = reftarget_id
                self.document.note_refid(target)
            else:
                self.nonexistent_indirect_target(target)
                return
        if refname is not None:
            del target['refname']
        target.resolved = 1

    def nonexistent_indirect_target(self, target):
        if target['refname'] in self.document.nameids:
            self.indirect_target_error(target, 'which is a duplicate, and '
                                       'cannot be used as a unique reference')
        else:
            self.indirect_target_error(target, 'which does not exist')

    def circular_indirect_reference(self, target):
        self.indirect_target_error(target, 'forming a circular reference')

    def indirect_target_error(self, target, explanation):
        naming = ''
        reflist = []
        if target['names']:
            naming = '"%s" ' % target['names'][0]
        for name in target['names']:
            reflist.extend(self.document.refnames.get(name, []))
        for id in target['ids']:
            reflist.extend(self.document.refids.get(id, []))
        naming += '(id="%s")' % target['ids'][0]
        msg = self.document.reporter.error(
              'Indirect hyperlink target %s refers to target "%s", %s.'
              % (naming, target['refname'], explanation), base_node=target)
        msgid = self.document.set_id(msg)
        for ref in utils.uniq(reflist):
            prb = nodes.problematic(
                  ref.rawsource, ref.rawsource, refid=msgid)
            prbid = self.document.set_id(prb)
            msg.add_backref(prbid)
            ref.replace_self(prb)
        target.resolved = 1

    def resolve_indirect_references(self, target):
        if target.hasattr('refid'):
            attname = 'refid'
            call_method = self.document.note_refid
        elif target.hasattr('refuri'):
            attname = 'refuri'
            call_method = None
        else:
            return
        attval = target[attname]
        for name in target['names']:
            reflist = self.document.refnames.get(name, [])
            if reflist:
                target.note_referenced_by(name=name)
            for ref in reflist:
                if ref.resolved:
                    continue
                del ref['refname']
                ref[attname] = attval
                if call_method:
                    call_method(ref)
                ref.resolved = 1
                if isinstance(ref, nodes.target):
                    self.resolve_indirect_references(ref)
        for id in target['ids']:
            reflist = self.document.refids.get(id, [])
            if reflist:
                target.note_referenced_by(id=id)
            for ref in reflist:
                if ref.resolved:
                    continue
                del ref['refid']
                ref[attname] = attval
                if call_method:
                    call_method(ref)
                ref.resolved = 1
                if isinstance(ref, nodes.target):
                    self.resolve_indirect_references(ref)


class ExternalTargets(Transform):

    """
    Given::

        <paragraph>
            <reference refname="direct external">
                direct external
        <target id="id1" name="direct external" refuri="http://direct">

    The "refname" attribute is replaced by the direct "refuri" attribute::

        <paragraph>
            <reference refuri="http://direct">
                direct external
        <target id="id1" name="direct external" refuri="http://direct">
    """

    default_priority = 640

    def apply(self):
        for target in self.document.traverse(nodes.target):
            if target.hasattr('refuri'):
                refuri = target['refuri']
                for name in target['names']:
                    reflist = self.document.refnames.get(name, [])
                    if reflist:
                        target.note_referenced_by(name=name)
                    for ref in reflist:
                        if ref.resolved:
                            continue
                        del ref['refname']
                        ref['refuri'] = refuri
                        ref.resolved = 1


class InternalTargets(Transform):

    default_priority = 660

    def apply(self):
        for target in self.document.traverse(nodes.target):
            if not target.hasattr('refuri') and not target.hasattr('refid'):
                self.resolve_reference_ids(target)

    def resolve_reference_ids(self, target):
        """
        Given::

            <paragraph>
                <reference refname="direct internal">
                    direct internal
            <target id="id1" name="direct internal">

        The "refname" attribute is replaced by "refid" linking to the target's
        "id"::

            <paragraph>
                <reference refid="id1">
                    direct internal
            <target id="id1" name="direct internal">
        """
        for name in target['names']:
            refid = self.document.nameids[name]
            reflist = self.document.refnames.get(name, [])
            if reflist:
                target.note_referenced_by(name=name)
            for ref in reflist:
                if ref.resolved:
                    continue
                del ref['refname']
                ref['refid'] = refid
                ref.resolved = 1


class Footnotes(Transform):

    """
    Assign numbers to autonumbered footnotes, and resolve links to footnotes,
    citations, and their references.

    Given the following ``document`` as input::

        <document>
            <paragraph>
                A labeled autonumbered footnote referece:
                <footnote_reference auto="1" id="id1" refname="footnote">
            <paragraph>
                An unlabeled autonumbered footnote referece:
                <footnote_reference auto="1" id="id2">
            <footnote auto="1" id="id3">
                <paragraph>
                    Unlabeled autonumbered footnote.
            <footnote auto="1" id="footnote" name="footnote">
                <paragraph>
                    Labeled autonumbered footnote.

    Auto-numbered footnotes have attribute ``auto="1"`` and no label.
    Auto-numbered footnote_references have no reference text (they're
    empty elements). When resolving the numbering, a ``label`` element
    is added to the beginning of the ``footnote``, and reference text
    to the ``footnote_reference``.

    The transformed result will be::

        <document>
            <paragraph>
                A labeled autonumbered footnote referece:
                <footnote_reference auto="1" id="id1" refid="footnote">
                    2
            <paragraph>
                An unlabeled autonumbered footnote referece:
                <footnote_reference auto="1" id="id2" refid="id3">
                    1
            <footnote auto="1" id="id3" backrefs="id2">
                <label>
                    1
                <paragraph>
                    Unlabeled autonumbered footnote.
            <footnote auto="1" id="footnote" name="footnote" backrefs="id1">
                <label>
                    2
                <paragraph>
                    Labeled autonumbered footnote.

    Note that the footnotes are not in the same order as the references.

    The labels and reference text are added to the auto-numbered ``footnote``
    and ``footnote_reference`` elements.  Footnote elements are backlinked to
    their references via "refids" attributes.  References are assigned "id"
    and "refid" attributes.

    After adding labels and reference text, the "auto" attributes can be
    ignored.
    """

    default_priority = 620

    autofootnote_labels = None
    """Keep track of unlabeled autonumbered footnotes."""

    symbols = [
          # Entries 1-4 and 6 below are from section 12.51 of
          # The Chicago Manual of Style, 14th edition.
          '*',                          # asterisk/star
          u'\u2020',                    # dagger &dagger;
          u'\u2021',                    # double dagger &Dagger;
          u'\u00A7',                    # section mark &sect;
          u'\u00B6',                    # paragraph mark (pilcrow) &para;
                                        # (parallels ['||'] in CMoS)
          '#',                          # number sign
          # The entries below were chosen arbitrarily.
          u'\u2660',                    # spade suit &spades;
          u'\u2665',                    # heart suit &hearts;
          u'\u2666',                    # diamond suit &diams;
          u'\u2663',                    # club suit &clubs;
          ]

    def apply(self):
        self.autofootnote_labels = []
        startnum = self.document.autofootnote_start
        self.document.autofootnote_start = self.number_footnotes(startnum)
        self.number_footnote_references(startnum)
        self.symbolize_footnotes()
        self.resolve_footnotes_and_citations()

    def number_footnotes(self, startnum):
        """
        Assign numbers to autonumbered footnotes.

        For labeled autonumbered footnotes, copy the number over to
        corresponding footnote references.
        """
        for footnote in self.document.autofootnotes:
            while 1:
                label = str(startnum)
                startnum += 1
                if label not in self.document.nameids:
                    break
            footnote.insert(0, nodes.label('', label))
            for name in footnote['names']:
                for ref in self.document.footnote_refs.get(name, []):
                    ref += nodes.Text(label)
                    ref.delattr('refname')
                    assert len(footnote['ids']) == len(ref['ids']) == 1
                    ref['refid'] = footnote['ids'][0]
                    footnote.add_backref(ref['ids'][0])
                    self.document.note_refid(ref)
                    ref.resolved = 1
            if not footnote['names'] and not footnote['dupnames']:
                footnote['names'].append(label)
                self.document.note_explicit_target(footnote, footnote)
                self.autofootnote_labels.append(label)
        return startnum

    def number_footnote_references(self, startnum):
        """Assign numbers to autonumbered footnote references."""
        i = 0
        for ref in self.document.autofootnote_refs:
            if ref.resolved or ref.hasattr('refid'):
                continue
            try:
                label = self.autofootnote_labels[i]
            except IndexError:
                msg = self.document.reporter.error(
                      'Too many autonumbered footnote references: only %s '
                      'corresponding footnotes available.'
                      % len(self.autofootnote_labels), base_node=ref)
                msgid = self.document.set_id(msg)
                for ref in self.document.autofootnote_refs[i:]:
                    if ref.resolved or ref.hasattr('refname'):
                        continue
                    prb = nodes.problematic(
                          ref.rawsource, ref.rawsource, refid=msgid)
                    prbid = self.document.set_id(prb)
                    msg.add_backref(prbid)
                    ref.replace_self(prb)
                break
            ref += nodes.Text(label)
            id = self.document.nameids[label]
            footnote = self.document.ids[id]
            ref['refid'] = id
            self.document.note_refid(ref)
            assert len(ref['ids']) == 1
            footnote.add_backref(ref['ids'][0])
            ref.resolved = 1
            i += 1

    def symbolize_footnotes(self):
        """Add symbols indexes to "[*]"-style footnotes and references."""
        labels = []
        for footnote in self.document.symbol_footnotes:
            reps, index = divmod(self.document.symbol_footnote_start,
                                 len(self.symbols))
            labeltext = self.symbols[index] * (reps + 1)
            labels.append(labeltext)
            footnote.insert(0, nodes.label('', labeltext))
            self.document.symbol_footnote_start += 1
            self.document.set_id(footnote)
        i = 0
        for ref in self.document.symbol_footnote_refs:
            try:
                ref += nodes.Text(labels[i])
            except IndexError:
                msg = self.document.reporter.error(
                      'Too many symbol footnote references: only %s '
                      'corresponding footnotes available.' % len(labels),
                      base_node=ref)
                msgid = self.document.set_id(msg)
                for ref in self.document.symbol_footnote_refs[i:]:
                    if ref.resolved or ref.hasattr('refid'):
                        continue
                    prb = nodes.problematic(
                          ref.rawsource, ref.rawsource, refid=msgid)
                    prbid = self.document.set_id(prb)
                    msg.add_backref(prbid)
                    ref.replace_self(prb)
                break
            footnote = self.document.symbol_footnotes[i]
            assert len(footnote['ids']) == 1
            ref['refid'] = footnote['ids'][0]
            self.document.note_refid(ref)
            footnote.add_backref(ref['ids'][0])
            i += 1

    def resolve_footnotes_and_citations(self):
        """
        Link manually-labeled footnotes and citations to/from their
        references.
        """
        for footnote in self.document.footnotes:
            for label in footnote['names']:
                if label in self.document.footnote_refs:
                    reflist = self.document.footnote_refs[label]
                    self.resolve_references(footnote, reflist)
        for citation in self.document.citations:
            for label in citation['names']:
                if label in self.document.citation_refs:
                    reflist = self.document.citation_refs[label]
                    self.resolve_references(citation, reflist)

    def resolve_references(self, note, reflist):
        assert len(note['ids']) == 1
        id = note['ids'][0]
        for ref in reflist:
            if ref.resolved:
                continue
            ref.delattr('refname')
            ref['refid'] = id
            assert len(ref['ids']) == 1
            note.add_backref(ref['ids'][0])
            ref.resolved = 1
        note.resolved = 1


class CircularSubstitutionDefinitionError(Exception): pass


class Substitutions(Transform):

    """
    Given the following ``document`` as input::

        <document>
            <paragraph>
                The
                <substitution_reference refname="biohazard">
                    biohazard
                 symbol is deservedly scary-looking.
            <substitution_definition name="biohazard">
                <image alt="biohazard" uri="biohazard.png">

    The ``substitution_reference`` will simply be replaced by the
    contents of the corresponding ``substitution_definition``.

    The transformed result will be::

        <document>
            <paragraph>
                The
                <image alt="biohazard" uri="biohazard.png">
                 symbol is deservedly scary-looking.
            <substitution_definition name="biohazard">
                <image alt="biohazard" uri="biohazard.png">
    """

    default_priority = 220
    """The Substitutions transform has to be applied very early, before
    `docutils.tranforms.frontmatter.DocTitle` and others."""

    def apply(self):
        defs = self.document.substitution_defs
        normed = self.document.substitution_names
        subreflist = self.document.traverse(nodes.substitution_reference)
        nested = {}
        for ref in subreflist:
            refname = ref['refname']
            key = None
            if refname in defs:
                key = refname
            else:
                normed_name = refname.lower()
                if normed_name in normed:
                    key = normed[normed_name]
            if key is None:
                msg = self.document.reporter.error(
                      'Undefined substitution referenced: "%s".'
                      % refname, base_node=ref)
                msgid = self.document.set_id(msg)
                prb = nodes.problematic(
                      ref.rawsource, ref.rawsource, refid=msgid)
                prbid = self.document.set_id(prb)
                msg.add_backref(prbid)
                ref.replace_self(prb)
            else:
                subdef = defs[key]
                parent = ref.parent
                index = parent.index(ref)
                if  ('ltrim' in subdef.attributes
                     or 'trim' in subdef.attributes):
                    if index > 0 and isinstance(parent[index - 1],
                                                nodes.Text):
                        parent.replace(parent[index - 1],
                                       parent[index - 1].rstrip())
                if  ('rtrim' in subdef.attributes
                     or 'trim' in subdef.attributes):
                    if  (len(parent) > index + 1
                         and isinstance(parent[index + 1], nodes.Text)):
                        parent.replace(parent[index + 1],
                                       parent[index + 1].lstrip())
                subdef_copy = subdef.deepcopy()
                try:
                    # Take care of nested substitution references:
                    for nested_ref in subdef_copy.traverse(
                          nodes.substitution_reference):
                        nested_name = normed[nested_ref['refname'].lower()]
                        if nested_name in nested.setdefault(nested_name, []):
                            raise CircularSubstitutionDefinitionError
                        else:
                            nested[nested_name].append(key)
                            subreflist.append(nested_ref)
                except CircularSubstitutionDefinitionError:
                    parent = ref.parent
                    if isinstance(parent, nodes.substitution_definition):
                        msg = self.document.reporter.error(
                            'Circular substitution definition detected:',
                            nodes.literal_block(parent.rawsource,
                                                parent.rawsource),
                            line=parent.line, base_node=parent)
                        parent.replace_self(msg)
                    else:
                        msg = self.document.reporter.error(
                            'Circular substitution definition referenced: "%s".'
                            % refname, base_node=ref)
                        msgid = self.document.set_id(msg)
                        prb = nodes.problematic(
                            ref.rawsource, ref.rawsource, refid=msgid)
                        prbid = self.document.set_id(prb)
                        msg.add_backref(prbid)
                        ref.replace_self(prb)
                else:
                    ref.replace_self(subdef_copy.children)
                    # register refname of the replacment node(s)
                    # (needed for resolution of references)
                    for node in subdef_copy.children:
                        if isinstance(node, nodes.Referential):
                            # HACK: verify refname attribute exists.
                            # Test with docs/dev/todo.txt, see. |donate|
                            if 'refname' in node:
                                self.document.note_refname(node)


class TargetNotes(Transform):

    """
    Creates a footnote for each external target in the text, and corresponding
    footnote references after each reference.
    """

    default_priority = 540
    """The TargetNotes transform has to be applied after `IndirectHyperlinks`
    but before `Footnotes`."""


    def __init__(self, document, startnode):
        Transform.__init__(self, document, startnode=startnode)

        self.classes = startnode.details.get('class', [])

    def apply(self):
        notes = {}
        nodelist = []
        for target in self.document.traverse(nodes.target):
            # Only external targets.
            if not target.hasattr('refuri'):
                continue
            names = target['names']
            refs = []
            for name in names:
                refs.extend(self.document.refnames.get(name, []))
            if not refs:
                continue
            footnote = self.make_target_footnote(target['refuri'], refs,
                                                 notes)
            if target['refuri'] not in notes:
                notes[target['refuri']] = footnote
                nodelist.append(footnote)
        # Take care of anonymous references.
        for ref in self.document.traverse(nodes.reference):
            if not ref.get('anonymous'):
                continue
            if ref.hasattr('refuri'):
                footnote = self.make_target_footnote(ref['refuri'], [ref],
                                                     notes)
                if ref['refuri'] not in notes:
                    notes[ref['refuri']] = footnote
                    nodelist.append(footnote)
        self.startnode.replace_self(nodelist)

    def make_target_footnote(self, refuri, refs, notes):
        if refuri in notes:  # duplicate?
            footnote = notes[refuri]
            assert len(footnote['names']) == 1
            footnote_name = footnote['names'][0]
        else:                           # original
            footnote = nodes.footnote()
            footnote_id = self.document.set_id(footnote)
            # Use uppercase letters and a colon; they can't be
            # produced inside names by the parser.
            footnote_name = 'TARGET_NOTE: ' + footnote_id
            footnote['auto'] = 1
            footnote['names'] = [footnote_name]
            footnote_paragraph = nodes.paragraph()
            footnote_paragraph += nodes.reference('', refuri, refuri=refuri)
            footnote += footnote_paragraph
            self.document.note_autofootnote(footnote)
            self.document.note_explicit_target(footnote, footnote)
        for ref in refs:
            if isinstance(ref, nodes.target):
                continue
            refnode = nodes.footnote_reference(
                refname=footnote_name, auto=1)
            refnode['classes'] += self.classes
            self.document.note_autofootnote_ref(refnode)
            self.document.note_footnote_ref(refnode)
            index = ref.parent.index(ref) + 1
            reflist = [refnode]
            if not utils.get_trim_footnote_ref_space(self.document.settings):
                if self.classes:
                    reflist.insert(0, nodes.inline(text=' ', Classes=self.classes))
                else:
                    reflist.insert(0, nodes.Text(' '))
            ref.parent.insert(index, reflist)
        return footnote


class DanglingReferences(Transform):

    """
    Check for dangling references (incl. footnote & citation) and for
    unreferenced targets.
    """

    default_priority = 850

    def apply(self):
        visitor = DanglingReferencesVisitor(
            self.document,
            self.document.transformer.unknown_reference_resolvers)
        self.document.walk(visitor)
        # *After* resolving all references, check for unreferenced
        # targets:
        for target in self.document.traverse(nodes.target):
            if not target.referenced:
                if target.get('anonymous'):
                    # If we have unreferenced anonymous targets, there
                    # is already an error message about anonymous
                    # hyperlink mismatch; no need to generate another
                    # message.
                    continue
                if target['names']:
                    naming = target['names'][0]
                elif target['ids']:
                    naming = target['ids'][0]
                else:
                    # Hack: Propagated targets always have their refid
                    # attribute set.
                    naming = target['refid']
                self.document.reporter.info(
                    'Hyperlink target "%s" is not referenced.'
                    % naming, base_node=target)


class DanglingReferencesVisitor(nodes.SparseNodeVisitor):
    
    def __init__(self, document, unknown_reference_resolvers):
        nodes.SparseNodeVisitor.__init__(self, document)
        self.document = document
        self.unknown_reference_resolvers = unknown_reference_resolvers

    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:
            for resolver_function in self.unknown_reference_resolvers:
                if resolver_function(node):
                    break
            else:
                if refname in self.document.nameids:
                    msg = self.document.reporter.error(
                        'Duplicate target name, cannot be used as a unique '
                        'reference: "%s".' % (node['refname']), base_node=node)
                else:
                    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.replace_self(prb)
        else:
            del node['refname']
            node['refid'] = id
            self.document.ids[id].note_referenced_by(id=id)
            node.resolved = 1

    visit_footnote_reference = visit_citation_reference = visit_reference