summaryrefslogtreecommitdiff
path: root/systems/texlive/tlnet/tlpkg/tlperl/lib/Pod/Simple.pm
blob: f2544d0ef10c60fd03412d52cb228dce08cf5ab7 (plain)
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
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643

require 5;
package Pod::Simple;
use strict;
use Carp ();
BEGIN           { *DEBUG = sub () {0} unless defined &DEBUG }
use integer;
use Pod::Escapes 1.04 ();
use Pod::Simple::LinkSection ();
use Pod::Simple::BlackBox ();
#use utf8;

use vars qw(
  $VERSION @ISA
  @Known_formatting_codes  @Known_directives
  %Known_formatting_codes  %Known_directives
  $NL
);

@ISA = ('Pod::Simple::BlackBox');
$VERSION = '3.42';

@Known_formatting_codes = qw(I B C L E F S X Z); 
%Known_formatting_codes = map(($_=>1), @Known_formatting_codes);
@Known_directives       = qw(head1 head2 head3 head4 head5 head6 item over back); 
%Known_directives       = map(($_=>'Plain'), @Known_directives);
$NL = $/ unless defined $NL;

#-----------------------------------------------------------------------------
# Set up some constants:

BEGIN {
  if(defined &ASCII)    { }
  elsif(chr(65) eq 'A') { *ASCII = sub () {1}  }
  else                  { *ASCII = sub () {''} }

  unless(defined &MANY_LINES) { *MANY_LINES = sub () {20} }
  DEBUG > 4 and print STDERR "MANY_LINES is ", MANY_LINES(), "\n";
  unless(MANY_LINES() >= 1) {
    die "MANY_LINES is too small (", MANY_LINES(), ")!\nAborting";
  }
  if(defined &UNICODE) { }
  elsif($] >= 5.008)   { *UNICODE = sub() {1}  }
  else                 { *UNICODE = sub() {''} }
}
if(DEBUG > 2) {
  print STDERR "# We are ", ASCII ? '' : 'not ', "in ASCII-land\n";
  print STDERR "# We are under a Unicode-safe Perl.\n";
}

# The NO BREAK SPACE and SOFT HYHPEN are used in several submodules.
if ($] ge 5.007_003) {  # On sufficiently modern Perls we can handle any
                        # character set
  $Pod::Simple::nbsp = chr utf8::unicode_to_native(0xA0);
  $Pod::Simple::shy  = chr utf8::unicode_to_native(0xAD);
}
elsif (Pod::Simple::ASCII) {  # Hard code ASCII early Perl
  $Pod::Simple::nbsp = "\xA0";
  $Pod::Simple::shy  = "\xAD";
}
else { # EBCDIC on early Perl.  We know what the values are for the code
        # pages supported then.
  $Pod::Simple::nbsp = "\x41";
  $Pod::Simple::shy  = "\xCA";
}

# Design note:
# This is a parser for Pod.  It is not a parser for the set of Pod-like
#  languages which happens to contain Pod -- it is just for Pod, plus possibly
#  some extensions.

# @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @
#@ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @
#@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@

__PACKAGE__->_accessorize(
  '_output_is_for_JustPod', # For use only by Pod::Simple::JustPod,
                       # If non-zero, don't expand Z<> E<> S<> L<>,
                       # and count how many brackets in format codes
  'nbsp_for_S',        # Whether to map S<...>'s to \xA0 characters
  'source_filename',   # Filename of the source, for use in warnings
  'source_dead',       # Whether to consider this parser's source dead

  'output_fh',         # The filehandle we're writing to, if applicable.
                       # Used only in some derived classes.

  'hide_line_numbers', # For some dumping subclasses: whether to pointedly
                       # suppress the start_line attribute

  'line_count',        # the current line number
  'pod_para_count',    # count of pod paragraphs seen so far

  'no_whining',        # whether to suppress whining
  'no_errata_section', # whether to suppress the errata section
  'complain_stderr',   # whether to complain to stderr

  'doc_has_started',   # whether we've fired the open-Document event yet

  'bare_output',       # For some subclasses: whether to prepend
                       #  header-code and postpend footer-code

  'keep_encoding_directive',  # whether to emit =encoding
  'nix_X_codes',       # whether to ignore X<...> codes
  'merge_text',        # whether to avoid breaking a single piece of
                       #  text up into several events

  'preserve_whitespace', # whether to try to keep whitespace as-is
  'strip_verbatim_indent', # What indent to strip from verbatim
  'expand_verbatim_tabs',  # 0: preserve tabs in verbatim blocks
                           # n: expand tabs to stops every n columns

  'parse_characters',  # Whether parser should expect chars rather than octets

 'content_seen',      # whether we've seen any real Pod content
 'errors_seen',       # TODO: document.  whether we've seen any errors (fatal or not)

 'codes_in_verbatim', # for PseudoPod extensions

 'code_handler',      # coderef to call when a code (non-pod) line is seen
 'cut_handler',       # ... when a =cut line is seen
 'pod_handler',       # ... when a =pod line is seen
 'whiteline_handler', # ... when a line with only whitespace is seen
 #Called like:
 # $code_handler->($line, $self->{'line_count'}, $self) if $code_handler;
 #  $cut_handler->($line, $self->{'line_count'}, $self) if $cut_handler;
 #  $pod_handler->($line, $self->{'line_count'}, $self) if $pod_handler;
 #   $wl_handler->($line, $self->{'line_count'}, $self) if $wl_handler;
 'parse_empty_lists', # whether to acknowledge empty =over/=back blocks
 'raw_mode',          # to report entire raw lines instead of Pod elements
);

#@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@

sub any_errata_seen {  # good for using as an exit() value...
  return shift->{'errors_seen'} || 0;
}

sub errata_seen {
  return shift->{'all_errata'} || {};
}

# Returns the encoding only if it was recognized as being handled and set
sub detected_encoding {
  return shift->{'detected_encoding'};
}

sub encoding {
  my $this = shift;
  return $this->{'encoding'} unless @_;  # GET.

  $this->_handle_encoding_line("=encoding $_[0]");
  if ($this->{'_processed_encoding'}) {
    delete $this->{'_processed_encoding'};
    if(! $this->{'encoding_command_statuses'} ) {
      DEBUG > 2 and print STDERR " CRAZY ERROR: encoding wasn't really handled?!\n";
    } elsif( $this->{'encoding_command_statuses'}[-1] ) {
      $this->scream( "=encoding $_[0]",
         sprintf "Couldn't do %s: %s",
         $this->{'encoding_command_reqs'  }[-1],
         $this->{'encoding_command_statuses'}[-1],
      );
    } else {
      DEBUG > 2 and print STDERR " (encoding successfully handled.)\n";
    }
    return $this->{'encoding'};
  } else {
    return undef;
  }
}

#@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
# Pull in some functions that, for some reason, I expect to see here too:
BEGIN {
  *pretty        = \&Pod::Simple::BlackBox::pretty;
  *stringify_lol = \&Pod::Simple::BlackBox::stringify_lol;
  *my_qr         = \&Pod::Simple::BlackBox::my_qr;
}

#@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@

sub version_report {
  my $class = ref($_[0]) || $_[0];
  if($class eq __PACKAGE__) {
    return "$class $VERSION";
  } else {
    my $v = $class->VERSION;
    return "$class $v (" . __PACKAGE__ . " $VERSION)";
  }
}

#@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@

#sub curr_open { # read-only list accessor
#  return @{ $_[0]{'curr_open'} || return() };
#}
#sub _curr_open_listref { $_[0]{'curr_open'} ||= [] }


sub output_string {
  # Works by faking out output_fh.  Simplifies our code.
  #
  my $this = shift;
  return $this->{'output_string'} unless @_;  # GET.
  
  require Pod::Simple::TiedOutFH;
  my $x = (defined($_[0]) and ref($_[0])) ? $_[0] : \( $_[0] );
  $$x = '' unless defined $$x;
  DEBUG > 4 and print STDERR "# Output string set to $x ($$x)\n";
  $this->{'output_fh'} = Pod::Simple::TiedOutFH->handle_on($_[0]);
  return
    $this->{'output_string'} = $_[0];
    #${ ${ $this->{'output_fh'} } };
}

sub abandon_output_string { $_[0]->abandon_output_fh; delete $_[0]{'output_string'} }
sub abandon_output_fh     { $_[0]->output_fh(undef) }
# These don't delete the string or close the FH -- they just delete our
#  references to it/them.
# TODO: document these

#@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@

sub new {
  # takes no parameters
  my $class = ref($_[0]) || $_[0];
  #Carp::croak(__PACKAGE__ . " is a virtual base class -- see perldoc "
  #  . __PACKAGE__ );
  my $obj = bless {
    'accept_codes'      => { map( ($_=>$_), @Known_formatting_codes ) },
    'accept_directives' => { %Known_directives },
    'accept_targets'    => {},
  }, $class;

  $obj->expand_verbatim_tabs(8);
  return $obj;
}



# TODO: an option for whether to interpolate E<...>'s, or just resolve to codes.

#@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@

sub _handle_element_start {     # OVERRIDE IN DERIVED CLASS
  my($self, $element_name, $attr_hash_r) = @_;
  return;
}

sub _handle_element_end {       # OVERRIDE IN DERIVED CLASS
  my($self, $element_name) = @_;
  return;
}

sub _handle_text          {     # OVERRIDE IN DERIVED CLASS
  my($self, $text) = @_;
  return;
}

#@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
#
# And now directives (not targets)

sub accept_directive_as_verbatim  { shift->_accept_directives('Verbatim', @_) }
sub accept_directive_as_data      { shift->_accept_directives('Data',     @_) }
sub accept_directive_as_processed { shift->_accept_directives('Plain',    @_) }

sub _accept_directives {
  my($this, $type) = splice @_,0,2;
  foreach my $d (@_) {
    next unless defined $d and length $d;
    Carp::croak "\"$d\" isn't a valid directive name"
     unless $d =~ m/^[a-zA-Z][a-zA-Z0-9]*$/s;
    Carp::croak "\"$d\" is already a reserved Pod directive name"
     if exists $Known_directives{$d};
    $this->{'accept_directives'}{$d} = $type;
    DEBUG > 2 and print STDERR "Learning to accept \"=$d\" as directive of type $type\n";
  }
  DEBUG > 6 and print STDERR "$this\'s accept_directives : ",
   pretty($this->{'accept_directives'}), "\n";
  
  return sort keys %{ $this->{'accept_directives'} } if wantarray;
  return;
}

#--------------------------------------------------------------------------
# TODO: document these:

sub unaccept_directive { shift->unaccept_directives(@_) };

sub unaccept_directives {
  my $this = shift;
  foreach my $d (@_) {
    next unless defined $d and length $d;
    Carp::croak "\"$d\" isn't a valid directive name"
     unless $d =~ m/^[a-zA-Z][a-zA-Z0-9]*$/s;
    Carp::croak "But you must accept \"$d\" directives -- it's a builtin!"
     if exists $Known_directives{$d};
    delete $this->{'accept_directives'}{$d};
    DEBUG > 2 and print STDERR "OK, won't accept \"=$d\" as directive.\n";
  }
  return sort keys %{ $this->{'accept_directives'} } if wantarray;
  return
}

#@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
#
# And now targets (not directives)

sub accept_target         { shift->accept_targets(@_)         } # alias
sub accept_target_as_text { shift->accept_targets_as_text(@_) } # alias


sub accept_targets         { shift->_accept_targets('1', @_) }

sub accept_targets_as_text { shift->_accept_targets('force_resolve', @_) }
 # forces them to be processed, even when there's no ":".

sub _accept_targets {
  my($this, $type) = splice @_,0,2;
  foreach my $t (@_) {
    next unless defined $t and length $t;
    # TODO: enforce some limitations on what a target name can be?
    $this->{'accept_targets'}{$t} = $type;
    DEBUG > 2 and print STDERR "Learning to accept \"$t\" as target of type $type\n";
  }    
  return sort keys %{ $this->{'accept_targets'} } if wantarray;
  return;
}

#--------------------------------------------------------------------------
sub unaccept_target         { shift->unaccept_targets(@_) }

sub unaccept_targets {
  my $this = shift;
  foreach my $t (@_) {
    next unless defined $t and length $t;
    # TODO: enforce some limitations on what a target name can be?
    delete $this->{'accept_targets'}{$t};
    DEBUG > 2 and print STDERR "OK, won't accept \"$t\" as target.\n";
  }    
  return sort keys %{ $this->{'accept_targets'} } if wantarray;
  return;
}

#@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
#
# And now codes (not targets or directives)

# XXX Probably it is an error that the digit '9' is excluded from these re's.
# Broken for early Perls on EBCDIC
my $xml_name_re = my_qr('[^-.0-8:A-Z_a-z[:^ascii:]]', '9');
$xml_name_re = qr/[\x00-\x2C\x2F\x39\x3B-\x40\x5B-\x5E\x60\x7B-\x7F]/
                                                            unless $xml_name_re;

sub accept_code { shift->accept_codes(@_) } # alias

sub accept_codes {  # Add some codes
  my $this = shift;
  
  foreach my $new_code (@_) {
    next unless defined $new_code and length $new_code;
    # A good-enough check that it's good as an XML Name symbol:
    Carp::croak "\"$new_code\" isn't a valid element name"
      if $new_code =~ $xml_name_re
          # Characters under 0x80 that aren't legal in an XML Name.
      or $new_code =~ m/^[-\.0-9]/s
      or $new_code =~ m/:[-\.0-9]/s;
          # The legal under-0x80 Name characters that
          #  an XML Name still can't start with.

    $this->{'accept_codes'}{$new_code} = $new_code;

    # Yes, map to itself -- just so that when we
    #  see "=extend W [whatever] thatelementname", we say that W maps
    #  to whatever $this->{accept_codes}{thatelementname} is,
    #  i.e., "thatelementname".  Then when we go re-mapping,
    #  a "W" in the treelet turns into "thatelementname".  We only
    #  remap once.
    # If we say we accept "W", then a "W" in the treelet simply turns
    #  into "W".
  }
  
  return;
}

#--------------------------------------------------------------------------
sub unaccept_code { shift->unaccept_codes(@_) }

sub unaccept_codes { # remove some codes
  my $this = shift;
  
  foreach my $new_code (@_) {
    next unless defined $new_code and length $new_code;
    # A good-enough check that it's good as an XML Name symbol:
    Carp::croak "\"$new_code\" isn't a valid element name"
      if $new_code =~ $xml_name_re
          # Characters under 0x80 that aren't legal in an XML Name.
      or $new_code =~ m/^[-\.0-9]/s
      or $new_code =~ m/:[-\.0-9]/s;
          # The legal under-0x80 Name characters that
          #  an XML Name still can't start with.

    Carp::croak "But you must accept \"$new_code\" codes -- it's a builtin!"
     if grep $new_code eq $_, @Known_formatting_codes;

    delete $this->{'accept_codes'}{$new_code};

    DEBUG > 2 and print STDERR "OK, won't accept the code $new_code<...>.\n";
  }
  
  return;
}


#@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
#@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@

sub parse_string_document {
  my $self = shift;
  my @lines;
  foreach my $line_group (@_) {
    next unless defined $line_group and length $line_group;
    pos($line_group) = 0;
    while($line_group =~
      m/([^\n\r]*)(\r?\n?)/g # supports \r, \n ,\r\n
      #m/([^\n\r]*)((?:\r?\n)?)/g
    ) {
      #print(">> $1\n"),
      $self->parse_lines($1)
       if length($1) or length($2)
        or pos($line_group) != length($line_group);
       # I.e., unless it's a zero-length "empty line" at the very
       #  end of "foo\nbar\n" (i.e., between the \n and the EOS).
    }
  }
  $self->parse_lines(undef); # to signal EOF
  return $self;
}

sub _init_fh_source {
  my($self, $source) = @_;

  #DEBUG > 1 and print STDERR "Declaring $source as :raw for starters\n";
  #$self->_apply_binmode($source, ':raw');
  #binmode($source, ":raw");

  return;
}

#:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.
#

sub parse_file {
  my($self, $source) = (@_);

  if(!defined $source) {
    Carp::croak("Can't use empty-string as a source for parse_file");
  } elsif(ref(\$source) eq 'GLOB') {
    $self->{'source_filename'} = '' . ($source);
  } elsif(ref $source) {
    $self->{'source_filename'} = '' . ($source);
  } elsif(!length $source) {
    Carp::croak("Can't use empty-string as a source for parse_file");
  } else {
    {
      local *PODSOURCE;
      open(PODSOURCE, "<$source") || Carp::croak("Can't open $source: $!");
      $self->{'source_filename'} = $source;
      $source = *PODSOURCE{IO};
    }
    $self->_init_fh_source($source);
  }
  # By here, $source is a FH.

  $self->{'source_fh'} = $source;

  my($i, @lines);
  until( $self->{'source_dead'} ) {
    splice @lines;

    for($i = MANY_LINES; $i--;) {  # read those many lines at a time
      local $/ = $NL;
      push @lines, scalar(<$source>);  # readline
      last unless defined $lines[-1];
       # but pass thru the undef, which will set source_dead to true
    }

    my $at_eof = ! $lines[-1]; # keep track of the undef
    pop @lines if $at_eof; # silence warnings

    # be eol agnostic
    s/\r\n?/\n/g for @lines;
 
    # make sure there are only one line elements for parse_lines
    @lines = split(/(?<=\n)/, join('', @lines));

    # push the undef back after popping it to set source_dead to true
    push @lines, undef if $at_eof;

    $self->parse_lines(@lines);
  }
  delete($self->{'source_fh'}); # so it can be GC'd
  return $self;
}

#:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.

sub parse_from_file {
  # An emulation of Pod::Parser's interface, for the sake of Perldoc.
  # Basically just a wrapper around parse_file.

  my($self, $source, $to) = @_;
  $self = $self->new unless ref($self); # so we tolerate being a class method
  
  if(!defined $source)             { $source = *STDIN{IO}
  } elsif(ref(\$source) eq 'GLOB') { # stet
  } elsif(ref($source)           ) { # stet
  } elsif(!length $source
     or $source eq '-' or $source =~ m/^<&(?:STDIN|0)$/i
  ) { 
    $source = *STDIN{IO};
  }

  if(!defined $to) {             $self->output_fh( *STDOUT{IO}   );
  } elsif(ref(\$to) eq 'GLOB') { $self->output_fh( $to );
  } elsif(ref($to)) {            $self->output_fh( $to );
  } elsif(!length $to
     or $to eq '-' or $to =~ m/^>&?(?:STDOUT|1)$/i
  ) {
    $self->output_fh( *STDOUT{IO} );
  } elsif($to =~ m/^>&(?:STDERR|2)$/i) {
    $self->output_fh( *STDERR{IO} );
  } else {
    require Symbol;
    my $out_fh = Symbol::gensym();
    DEBUG and print STDERR "Write-opening to $to\n";
    open($out_fh, ">$to")  or  Carp::croak "Can't write-open $to: $!";
    binmode($out_fh)
     if $self->can('write_with_binmode') and $self->write_with_binmode;
    $self->output_fh($out_fh);
  }

  return $self->parse_file($source);
}

#-----------------------------------------------------------------------------

sub whine {
  #my($self,$line,$complaint) = @_;
  my $self = shift(@_);
  ++$self->{'errors_seen'};
  if($self->{'no_whining'}) {
    DEBUG > 9 and print STDERR "Discarding complaint (at line $_[0]) $_[1]\n because no_whining is on.\n";
    return;
  }
  push @{$self->{'all_errata'}{$_[0]}}, $_[1];
  return $self->_complain_warn(@_) if $self->{'complain_stderr'};
  return $self->_complain_errata(@_);
}

sub scream {    # like whine, but not suppressible
  #my($self,$line,$complaint) = @_;
  my $self = shift(@_);
  ++$self->{'errors_seen'};
  push @{$self->{'all_errata'}{$_[0]}}, $_[1];
  return $self->_complain_warn(@_) if $self->{'complain_stderr'};
  return $self->_complain_errata(@_);
}

sub _complain_warn {
  my($self,$line,$complaint) = @_;
  return printf STDERR "%s around line %s: %s\n",
    $self->{'source_filename'} || 'Pod input', $line, $complaint;
}

sub _complain_errata {
  my($self,$line,$complaint) = @_;
  if( $self->{'no_errata_section'} ) {
    DEBUG > 9 and print STDERR "Discarding erratum (at line $line) $complaint\n because no_errata_section is on.\n";
  } else {
    DEBUG > 9 and print STDERR "Queuing erratum (at line $line) $complaint\n";
    push @{$self->{'errata'}{$line}}, $complaint
      # for a report to be generated later!
  }
  return 1;
}

#@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@

sub _get_initial_item_type {
  # A hack-wrapper here for when you have like "=over\n\n=item 456\n\n"
  my($self, $para) = @_;
  return $para->[1]{'~type'}  if $para->[1]{'~type'};

  return $para->[1]{'~type'} = 'text'
   if join("\n", @{$para}[2 .. $#$para]) =~ m/^\s*(\d+)\.?\s*$/s and $1 ne '1';
  # Else fall thru to the general case:
  return $self->_get_item_type($para);
}



sub _get_item_type {       # mutates the item!!
  my($self, $para) = @_;
  return $para->[1]{'~type'} if $para->[1]{'~type'};


  # Otherwise we haven't yet been to this node.  Maybe alter it...
  
  my $content = join "\n", @{$para}[2 .. $#$para];

  if($content =~ m/^\s*\*\s*$/s or $content =~ m/^\s*$/s) {
    # Like: "=item *", "=item   *   ", "=item"
    splice @$para, 2; # so it ends up just being ['=item', { attrhash } ]
    $para->[1]{'~orig_content'} = $content;
    return $para->[1]{'~type'} = 'bullet';

  } elsif($content =~ m/^\s*\*\s+(.+)/s) {  # tolerance
  
    # Like: "=item * Foo bar baz";
    $para->[1]{'~orig_content'}      = $content;
    $para->[1]{'~_freaky_para_hack'} = $1;
    DEBUG > 2 and print STDERR " Tolerating $$para[2] as =item *\\n\\n$1\n";
    splice @$para, 2; # so it ends up just being ['=item', { attrhash } ]
    return $para->[1]{'~type'} = 'bullet';

  } elsif($content =~ m/^\s*(\d+)\.?\s*$/s) {
    # Like: "=item 1.", "=item    123412"
    
    $para->[1]{'~orig_content'} = $content;
    $para->[1]{'number'} = $1;  # Yes, stores the number there!

    splice @$para, 2; # so it ends up just being ['=item', { attrhash } ]
    return $para->[1]{'~type'} = 'number';
    
  } else {
    # It's anything else.
    return $para->[1]{'~type'} = 'text';

  }
}

#-----------------------------------------------------------------------------

sub _make_treelet {
  my $self = shift;  # and ($para, $start_line)
  my $treelet;
  if(!@_) {
    return [''];
  } if(ref $_[0] and ref $_[0][0] and $_[0][0][0] eq '~Top') {
    # Hack so we can pass in fake-o pre-cooked paragraphs:
    #  just have the first line be a reference to a ['~Top', {}, ...]
    # We use this feechure in gen_errata and stuff.

    DEBUG and print STDERR "Applying precooked treelet hack to $_[0][0]\n";
    $treelet = $_[0][0];
    splice @$treelet, 0, 2;  # lop the top off
    return $treelet;
  } else {
    $treelet = $self->_treelet_from_formatting_codes(@_);
  }
  
  if( ! $self->{'_output_is_for_JustPod'}   # Retain these as-is for pod output
     && $self->_remap_sequences($treelet) )
  {
    $self->_treat_Zs($treelet);  # Might as well nix these first
    $self->_treat_Ls($treelet);  # L has to precede E and S
    $self->_treat_Es($treelet);
    $self->_treat_Ss($treelet);  # S has to come after E
    $self->_wrap_up($treelet); # Nix X's and merge texties
    
  } else {
    DEBUG and print STDERR "Formatless treelet gets fast-tracked.\n";
     # Very common case!
  }
  
  splice @$treelet, 0, 2;  # lop the top off

  return $treelet;
}

#:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.

sub _wrap_up {
  my($self, @stack) = @_;
  my $nixx  = $self->{'nix_X_codes'};
  my $merge = $self->{'merge_text' };
  return unless $nixx or $merge;

  DEBUG > 2 and print STDERR "\nStarting _wrap_up traversal.\n",
   $merge ? (" Merge mode on\n") : (),
   $nixx  ? (" Nix-X mode on\n") : (),
  ;    
  

  my($i, $treelet);
  while($treelet = shift @stack) {
    DEBUG > 3 and print STDERR " Considering children of this $treelet->[0] node...\n";
    for($i = 2; $i < @$treelet; ++$i) { # iterate over children
      DEBUG > 3 and print STDERR " Considering child at $i ", pretty($treelet->[$i]), "\n";
      if($nixx and ref $treelet->[$i] and $treelet->[$i][0] eq 'X') {
        DEBUG > 3 and print STDERR "   Nixing X node at $i\n";
        splice(@$treelet, $i, 1); # just nix this node (and its descendants)
        # no need to back-update the counter just yet
        redo;

      } elsif($merge and $i != 2 and  # non-initial
         !ref $treelet->[$i] and !ref $treelet->[$i - 1]
      ) {
        DEBUG > 3 and print STDERR "   Merging ", $i-1,
         ":[$treelet->[$i-1]] and $i\:[$treelet->[$i]]\n";
        $treelet->[$i-1] .= ( splice(@$treelet, $i, 1) )[0];
        DEBUG > 4 and print STDERR "    Now: ", $i-1, ":[$treelet->[$i-1]]\n";
        --$i;
        next; 
        # since we just pulled the possibly last node out from under
        #  ourselves, we can't just redo()

      } elsif( ref $treelet->[$i] ) {
        DEBUG > 4 and print STDERR "  Enqueuing ", pretty($treelet->[$i]), " for traversal.\n";
        push @stack, $treelet->[$i];

        if($treelet->[$i][0] eq 'L') {
          my $thing;
          foreach my $attrname ('section', 'to') {        
            if(defined($thing = $treelet->[$i][1]{$attrname}) and ref $thing) {
              unshift @stack, $thing;
              DEBUG > 4 and print STDERR "  +Enqueuing ",
               pretty( $treelet->[$i][1]{$attrname} ),
               " as an attribute value to tweak.\n";
            }
          }
        }
      }
    }
  }
  DEBUG > 2 and print STDERR "End of _wrap_up traversal.\n\n";

  return;
}

#:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.

sub _remap_sequences {
  my($self,@stack) = @_;
  
  if(@stack == 1 and @{ $stack[0] } == 3 and !ref $stack[0][2]) {
    # VERY common case: abort it.
    DEBUG and print STDERR "Skipping _remap_sequences: formatless treelet.\n";
    return 0;
  }
  
  my $map = ($self->{'accept_codes'} || die "NO accept_codes in $self?!?");

  my $start_line = $stack[0][1]{'start_line'};
  DEBUG > 2 and printf
   "\nAbout to start _remap_sequences on treelet from line %s.\n",
   $start_line || '[?]'
  ;
  DEBUG > 3 and print STDERR " Map: ",
    join('; ', map "$_=" . (
        ref($map->{$_}) ? join(",", @{$map->{$_}}) : $map->{$_}
      ),
      sort keys %$map ),
    ("B~C~E~F~I~L~S~X~Z" eq join '~', sort keys %$map)
     ? "  (all normal)\n" : "\n"
  ;

  # A recursive algorithm implemented iteratively!  Whee!
  
  my($is, $was, $i, $treelet); # scratch
  while($treelet = shift @stack) {
    DEBUG > 3 and print STDERR " Considering children of this $treelet->[0] node...\n";
    for($i = 2; $i < @$treelet; ++$i) { # iterate over children
      next unless ref $treelet->[$i];  # text nodes are uninteresting
      
      DEBUG > 4 and print STDERR "  Noting child $i : $treelet->[$i][0]<...>\n";
      
      $is = $treelet->[$i][0] = $map->{ $was = $treelet->[$i][0] };
      if( DEBUG > 3 ) {
        if(!defined $is) {
          print STDERR "   Code $was<> is UNKNOWN!\n";
        } elsif($is eq $was) {
          DEBUG > 4 and print STDERR "   Code $was<> stays the same.\n";
        } else  {
          print STDERR "   Code $was<> maps to ",
           ref($is)
            ? ( "tags ", map("$_<", @$is), '...', map('>', @$is), "\n" )
            : "tag $is<...>.\n";
        }
      }
      
      if(!defined $is) {
        $self->whine($start_line, "Deleting unknown formatting code $was<>");
        $is = $treelet->[$i][0] = '1';  # But saving the children!
        # I could also insert a leading "$was<" and tailing ">" as
        # children of this node, but something about that seems icky.
      }
      if(ref $is) {
        my @dynasty = @$is;
        DEBUG > 4 and print STDERR "    Renaming $was node to $dynasty[-1]\n";
        $treelet->[$i][0] = pop @dynasty;
        my $nugget;
        while(@dynasty) {
          DEBUG > 4 and printf
           "    Grafting a new %s node between %s and %s\n",
           $dynasty[-1], $treelet->[0], $treelet->[$i][0], 
          ;
          
          #$nugget = ;
          splice @$treelet, $i, 1, [pop(@dynasty), {}, $treelet->[$i]];
            # relace node with a new parent
        }
      } elsif($is eq '0') {
        splice(@$treelet, $i, 1); # just nix this node (and its descendants)
        --$i;  # back-update the counter
      } elsif($is eq '1') {
        splice(@$treelet, $i, 1 # replace this node with its children!
          => splice @{ $treelet->[$i] },2
              # (not catching its first two (non-child) items)
        );
        --$i;  # back up for new stuff
      } else {
        # otherwise it's unremarkable
        unshift @stack, $treelet->[$i];  # just recurse
      }
    }
  }
  
  DEBUG > 2 and print STDERR "End of _remap_sequences traversal.\n\n";

  if(@_ == 2 and @{ $_[1] } == 3 and !ref $_[1][2]) {
    DEBUG and print STDERR "Noting that the treelet is now formatless.\n";
    return 0;
  }
  return 1;
}

# . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

sub _ponder_extend {

  # "Go to an extreme, move back to a more comfortable place"
  #  -- /Oblique Strategies/,  Brian Eno and Peter Schmidt
  
  my($self, $para) = @_;
  my $content = join ' ', splice @$para, 2;
  $content =~ s/^\s+//s;
  $content =~ s/\s+$//s;

  DEBUG > 2 and print STDERR "Ogling extensor: =extend $content\n";

  if($content =~
    m/^
      (\S+)         # 1 : new item
      \s+
      (\S+)         # 2 : fallback(s)
      (?:\s+(\S+))? # 3 : element name(s)
      \s*
      $
    /xs
  ) {
    my $new_letter = $1;
    my $fallbacks_one = $2;
    my $elements_one;
    $elements_one = defined($3) ? $3 : $1;

    DEBUG > 2 and print STDERR "Extensor has good syntax.\n";

    unless($new_letter =~ m/^[A-Z]$/s or $new_letter) {
      DEBUG > 2 and print STDERR " $new_letter isn't a valid thing to entend.\n";
      $self->whine(
        $para->[1]{'start_line'},
        "You can extend only formatting codes A-Z, not like \"$new_letter\""
      );
      return;
    }
    
    if(grep $new_letter eq $_, @Known_formatting_codes) {
      DEBUG > 2 and print STDERR " $new_letter isn't a good thing to extend, because known.\n";
      $self->whine(
        $para->[1]{'start_line'},
        "You can't extend an established code like \"$new_letter\""
      );
      
      #TODO: or allow if last bit is same?
      
      return;
    }

    unless($fallbacks_one =~ m/^[A-Z](,[A-Z])*$/s  # like "B", "M,I", etc.
      or $fallbacks_one eq '0' or $fallbacks_one eq '1'
    ) {
      $self->whine(
        $para->[1]{'start_line'},
        "Format for second =extend parameter must be like"
        . " M or 1 or 0 or M,N or M,N,O but you have it like "
        . $fallbacks_one
      );
      return;
    }
    
    unless($elements_one =~ m/^[^ ,]+(,[^ ,]+)*$/s) { # like "B", "M,I", etc.
      $self->whine(
        $para->[1]{'start_line'},
        "Format for third =extend parameter: like foo or bar,Baz,qu:ux but not like "
        . $elements_one
      );
      return;
    }

    my @fallbacks  = split ',', $fallbacks_one,  -1;
    my @elements   = split ',', $elements_one, -1;

    foreach my $f (@fallbacks) {
      next if exists $Known_formatting_codes{$f} or $f eq '0' or $f eq '1';
      DEBUG > 2 and print STDERR "  Can't fall back on unknown code $f\n";
      $self->whine(
        $para->[1]{'start_line'},
        "Can't use unknown formatting code '$f' as a fallback for '$new_letter'"
      );
      return;
    }

    DEBUG > 3 and printf STDERR "Extensor: Fallbacks <%s> Elements <%s>.\n",
     @fallbacks, @elements;

    my $canonical_form;
    foreach my $e (@elements) {
      if(exists $self->{'accept_codes'}{$e}) {
        DEBUG > 1 and print STDERR " Mapping '$new_letter' to known extension '$e'\n";
        $canonical_form = $e;
        last; # first acceptable elementname wins!
      } else {
        DEBUG > 1 and print STDERR " Can't map '$new_letter' to unknown extension '$e'\n";
      }
    }


    if( defined $canonical_form ) {
      # We found a good N => elementname mapping
      $self->{'accept_codes'}{$new_letter} = $canonical_form;
      DEBUG > 2 and print
       "Extensor maps $new_letter => known element $canonical_form.\n";
    } else {
      # We have to use the fallback(s), which might be '0', or '1'.
      $self->{'accept_codes'}{$new_letter}
        = (@fallbacks == 1) ? $fallbacks[0] : \@fallbacks;
      DEBUG > 2 and print
       "Extensor maps $new_letter => fallbacks @fallbacks.\n";
    }

  } else {
    DEBUG > 2 and print STDERR "Extensor has bad syntax.\n";
    $self->whine(
      $para->[1]{'start_line'},
      "Unknown =extend syntax: $content"
    )
  }
  return;
}


#:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.

sub _treat_Zs {  # Nix Z<...>'s
  my($self,@stack) = @_;

  my($i, $treelet);
  my $start_line = $stack[0][1]{'start_line'};

  # A recursive algorithm implemented iteratively!  Whee!

  while($treelet = shift @stack) {
    for($i = 2; $i < @$treelet; ++$i) { # iterate over children
      next unless ref $treelet->[$i];  # text nodes are uninteresting
      unless($treelet->[$i][0] eq 'Z') {
        unshift @stack, $treelet->[$i]; # recurse
        next;
      }
        
      DEBUG > 1 and print STDERR "Nixing Z node @{$treelet->[$i]}\n";
        
      # bitch UNLESS it's empty
      unless(  @{$treelet->[$i]} == 2
           or (@{$treelet->[$i]} == 3 and $treelet->[$i][2] eq '')
      ) {
        $self->whine( $start_line, "A non-empty Z<>" );
      }      # but kill it anyway
        
      splice(@$treelet, $i, 1); # thereby just nix this node.
      --$i;
        
    }
  }
  
  return;
}

# . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

# Quoting perlpodspec:

# In parsing an L<...> code, Pod parsers must distinguish at least four
# attributes:

############# Not used.  Expressed via the element children plus
#############  the value of the "content-implicit" flag.
# First:
# The link-text. If there is none, this must be undef. (E.g., in "L<Perl
# Functions|perlfunc>", the link-text is "Perl Functions". In
# "L<Time::HiRes>" and even "L<|Time::HiRes>", there is no link text. Note
# that link text may contain formatting.)
# 

############# The element children
# Second:
# The possibly inferred link-text -- i.e., if there was no real link text,
# then this is the text that we'll infer in its place. (E.g., for
# "L<Getopt::Std>", the inferred link text is "Getopt::Std".)
#

############# The "to" attribute (which might be text, or a treelet)
# Third:
# The name or URL, or undef if none. (E.g., in "L<Perl
# Functions|perlfunc>", the name -- also sometimes called the page -- is
# "perlfunc". In "L</CAVEATS>", the name is undef.)
# 

############# The "section" attribute (which might be next, or a treelet)
# Fourth:
# The section (AKA "item" in older perlpods), or undef if none. E.g., in
# Getopt::Std/DESCRIPTION, "DESCRIPTION" is the section. (Note that this
# is not the same as a manpage section like the "5" in "man 5 crontab".
# "Section Foo" in the Pod sense means the part of the text that's
# introduced by the heading or item whose text is "Foo".)
# 
# Pod parsers may also note additional attributes including:
#

############# The "type" attribute.
# Fifth:
# A flag for whether item 3 (if present) is a URL (like
# "http://lists.perl.org" is), in which case there should be no section
# attribute; a Pod name (like "perldoc" and "Getopt::Std" are); or
# possibly a man page name (like "crontab(5)" is).
#

############# The "raw" attribute that is already there.
# Sixth:
# The raw original L<...> content, before text is split on "|", "/", etc,
# and before E<...> codes are expanded.


# For L<...> codes without a "name|" part, only E<...> and Z<> codes may
# occur -- no other formatting codes. That is, authors should not use
# "L<B<Foo::Bar>>".
#
# Note, however, that formatting codes and Z<>'s can occur in any and all
# parts of an L<...> (i.e., in name, section, text, and url).

sub _treat_Ls {  # Process our dear dear friends, the L<...> sequences

  # L<name>
  # L<name/"sec"> or L<name/sec>
  # L</"sec"> or L</sec> or L<"sec">
  # L<text|name>
  # L<text|name/"sec"> or L<text|name/sec>
  # L<text|/"sec"> or L<text|/sec> or L<text|"sec">
  # L<scheme:...>
  # L<text|scheme:...>

  my($self,@stack) = @_;

  my($i, $treelet);
  my $start_line = $stack[0][1]{'start_line'};

  # A recursive algorithm implemented iteratively!  Whee!

  while($treelet = shift @stack) {
    for(my $i = 2; $i < @$treelet; ++$i) {
      # iterate over children of current tree node
      next unless ref $treelet->[$i];  # text nodes are uninteresting
      unless($treelet->[$i][0] eq 'L') {
        unshift @stack, $treelet->[$i]; # recurse
        next;
      }
      
      
      # By here, $treelet->[$i] is definitely an L node
      my $ell = $treelet->[$i];
      DEBUG > 1 and print STDERR "Ogling L node " . pretty($ell) . "\n";
        
      # bitch if it's empty or is just '/'
      if (@{$ell} == 3 and $ell->[2] =~ m!\A\s*/\s*\z!) {
        $self->whine( $start_line, "L<> contains only '/'" );
        $treelet->[$i] = 'L</>';  # just make it a text node
        next;  # and move on
      }
      if(  @{$ell} == 2
       or (@{$ell} == 3 and $ell->[2] eq '')
      ) {
        $self->whine( $start_line, "An empty L<>" );
        $treelet->[$i] = 'L<>';  # just make it a text node
        next;  # and move on
      }

      if( (! ref $ell->[2]  && $ell->[2] =~ /\A\s/)
        ||(! ref $ell->[-1] && $ell->[-1] =~ /\s\z/)
      ) {
        $self->whine( $start_line, "L<> starts or ends with whitespace" );
      }
     
      # Catch URLs:

      # there are a number of possible cases:
      # 1) text node containing url: http://foo.com
      #   -> [ 'http://foo.com' ]
      # 2) text node containing url and text: foo|http://foo.com
      #   -> [ 'foo|http://foo.com' ]
      # 3) text node containing url start: mailto:xE<at>foo.com
      #   -> [ 'mailto:x', [ E ... ], 'foo.com' ]
      # 4) text node containing url start and text: foo|mailto:xE<at>foo.com
      #   -> [ 'foo|mailto:x', [ E ... ], 'foo.com' ]
      # 5) other nodes containing text and url start: OE<39>Malley|http://foo.com
      #   -> [ 'O', [ E ... ], 'Malley', '|http://foo.com' ]
      # ... etc.

      # anything before the url is part of the text.
      # anything after it is part of the url.
      # the url text node itself may contain parts of both.

      if (my ($url_index, $text_part, $url_part) =
        # grep is no good here; we want to bail out immediately so that we can
        # use $1, $2, etc. without having to do the match twice.
        sub {
          for (2..$#$ell) {
            next if ref $ell->[$_];
            next unless $ell->[$_] =~ m/^(?:([^|]*)\|)?(\w+:[^:\s]\S*)$/s;
            return ($_, $1, $2);
          }
          return;
        }->()
      ) {
        $ell->[1]{'type'} = 'url';

        my @text = @{$ell}[2..$url_index-1];
        push @text, $text_part if defined $text_part;

        my @url  = @{$ell}[$url_index+1..$#$ell];
        unshift @url, $url_part;

        unless (@text) {
          $ell->[1]{'content-implicit'} = 'yes';
          @text = @url;
        }

        $ell->[1]{to} = Pod::Simple::LinkSection->new(
          @url == 1
          ? $url[0]
          : [ '', {}, @url ],
        );

        splice @$ell, 2, $#$ell, @text;

        next;
      }
      
      # Catch some very simple and/or common cases
      if(@{$ell} == 3 and ! ref $ell->[2]) {
        my $it = $ell->[2];
        if($it =~ m{^[^/|]+[(][-a-zA-Z0-9]+[)]$}s) { # man sections
          # Hopefully neither too broad nor too restrictive a RE
          DEBUG > 1 and print STDERR "Catching \"$it\" as manpage link.\n";
          $ell->[1]{'type'} = 'man';
          # This's the only place where man links can get made.
          $ell->[1]{'content-implicit'} = 'yes';
          $ell->[1]{'to'  } =
            Pod::Simple::LinkSection->new( $it ); # treelet!

          next;
        }
        if($it =~ m/^[^\/\|,\$\%\@\ \"\<\>\:\#\&\*\{\}\[\]\(\)]+(\:\:[^\/\|,\$\%\@\ \"\<\>\:\#\&\*\{\}\[\]\(\)]+)*$/s) {
          # Extremely forgiving idea of what constitutes a bare
          #  modulename link like L<Foo::Bar> or even L<Thing::1.0::Docs::Tralala>
          DEBUG > 1 and print STDERR "Catching \"$it\" as ho-hum L<Modulename> link.\n";
          $ell->[1]{'type'} = 'pod';
          $ell->[1]{'content-implicit'} = 'yes';
          $ell->[1]{'to'  } =
            Pod::Simple::LinkSection->new( $it ); # treelet!
          next;
        }
        # else fall thru...
      }
      
      

      # ...Uhoh, here's the real L<...> parsing stuff...
      # "With the ill behavior, with the ill behavior, with the ill behavior..."

      DEBUG > 1 and print STDERR "Running a real parse on this non-trivial L\n";
      
      
      my $link_text; # set to an arrayref if found
      my @ell_content = @$ell;
      splice @ell_content,0,2; # Knock off the 'L' and {} bits

      DEBUG > 3 and print STDERR " Ell content to start: ",
       pretty(@ell_content), "\n";


      # Look for the "|" -- only in CHILDREN (not all underlings!)
      # Like L<I like the strictness|strict>
      DEBUG > 3 and
         print STDERR "  Peering at L content for a '|' ...\n";
      for(my $j = 0; $j < @ell_content; ++$j) {
        next if ref $ell_content[$j];
        DEBUG > 3 and
         print STDERR "    Peering at L-content text bit \"$ell_content[$j]\" for a '|'.\n";

        if($ell_content[$j] =~ m/^([^\|]*)\|(.*)$/s) {
          my @link_text = ($1);   # might be 0-length
          $ell_content[$j] = $2;  # might be 0-length

          DEBUG > 3 and
           print STDERR "     FOUND a '|' in it.  Splitting into [$1] + [$2]\n";

          if ($link_text[0] =~ m{[|/]}) {
            $self->whine(
              $start_line,
              "alternative text '$link_text[0]' contains non-escaped | or /"
            );
          }

          unshift @link_text, splice @ell_content, 0, $j;
            # leaving only things at J and after
          @ell_content =  grep ref($_)||length($_), @ell_content ;
          $link_text   = [grep ref($_)||length($_), @link_text  ];
          DEBUG > 3 and printf
           "  So link text is %s\n  and remaining ell content is %s\n",
            pretty($link_text), pretty(@ell_content);
          last;
        }
      }
      
      
      # Now look for the "/" -- only in CHILDREN (not all underlings!)
      # And afterward, anything left in @ell_content will be the raw name
      # Like L<Foo::Bar/Object Methods>
      my $section_name;  # set to arrayref if found
      DEBUG > 3 and print STDERR "  Peering at L-content for a '/' ...\n";
      for(my $j = 0; $j < @ell_content; ++$j) {
        next if ref $ell_content[$j];
        DEBUG > 3 and
         print STDERR "    Peering at L-content text bit \"$ell_content[$j]\" for a '/'.\n";

        if($ell_content[$j] =~ m/^([^\/]*)\/(.*)$/s) {
          my @section_name = ($2); # might be 0-length
          $ell_content[$j] =  $1;  # might be 0-length

          DEBUG > 3 and
           print STDERR "     FOUND a '/' in it.",
             "  Splitting to page [...$1] + section [$2...]\n";

          push @section_name, splice @ell_content, 1+$j;
            # leaving only things before and including J
          
          @ell_content  = grep ref($_)||length($_), @ell_content  ;
          @section_name = grep ref($_)||length($_), @section_name ;

          # Turn L<.../"foo"> into L<.../foo>
          if(@section_name
            and !ref($section_name[0]) and !ref($section_name[-1])
            and $section_name[ 0] =~ m/^\"/s
            and $section_name[-1] =~ m/\"$/s
            and !( # catch weird degenerate case of L<"> !
              @section_name == 1 and $section_name[0] eq '"'
            )
          ) {
            $section_name[ 0] =~ s/^\"//s;
            $section_name[-1] =~ s/\"$//s;
            DEBUG > 3 and
             print STDERR "     Quotes removed: ", pretty(@section_name), "\n";
          } else {
            DEBUG > 3 and
             print STDERR "     No need to remove quotes in ", pretty(@section_name), "\n";
          }

          $section_name = \@section_name;
          last;
        }
      }

      # Turn L<"Foo Bar"> into L</Foo Bar>
      if(!$section_name and @ell_content
         and !ref($ell_content[0]) and !ref($ell_content[-1])
         and $ell_content[ 0] =~ m/^\"/s
         and $ell_content[-1] =~ m/\"$/s
         and !( # catch weird degenerate case of L<"> !
           @ell_content == 1 and $ell_content[0] eq '"'
         )
      ) {
        $section_name = [splice @ell_content];
        $section_name->[ 0] =~ s/^\"//s;
        $section_name->[-1] =~ s/\"$//s;
        $ell->[1]{'~tolerated'} = 1;
      }

      # Turn L<Foo Bar> into L</Foo Bar>.
      if(!$section_name and !$link_text and @ell_content
         and grep !ref($_) && m/ /s, @ell_content
      ) {
        $section_name = [splice @ell_content];
        $ell->[1]{'~deprecated'} = 1;
        # That's support for the now-deprecated syntax.
        # Note that it deliberately won't work on L<...|Foo Bar>
      }


      # Now make up the link_text
      # L<Foo>     -> L<Foo|Foo>
      # L</Bar>    -> L<"Bar"|Bar>
      # L<Foo/Bar> -> L<"Bar" in Foo/Foo>
      unless($link_text) {
        $ell->[1]{'content-implicit'} = 'yes';
        $link_text = [];
        push @$link_text, '"', @$section_name, '"' if $section_name;

        if(@ell_content) {
          $link_text->[-1] .= ' in ' if $section_name;
          push @$link_text, @ell_content;
        }
      }


      # And the E resolver will have to deal with all our treeletty things:

      if(@ell_content == 1 and !ref($ell_content[0])
         and $ell_content[0] =~ m{^[^/]+[(][-a-zA-Z0-9]+[)]$}s
      ) {
        $ell->[1]{'type'}    = 'man';
        DEBUG > 3 and print STDERR "Considering this ($ell_content[0]) a man link.\n";
      } else {
        $ell->[1]{'type'}    = 'pod';
        DEBUG > 3 and print STDERR "Considering this a pod link (not man or url).\n";
      }

      if( defined $section_name ) {
        $ell->[1]{'section'} = Pod::Simple::LinkSection->new(
          ['', {}, @$section_name]
        );
        DEBUG > 3 and print STDERR "L-section content: ", pretty($ell->[1]{'section'}), "\n";
      }

      if( @ell_content ) {
        $ell->[1]{'to'} = Pod::Simple::LinkSection->new(
          ['', {}, @ell_content]
        );
        DEBUG > 3 and print STDERR "L-to content: ", pretty($ell->[1]{'to'}), "\n";
      }
      
      # And update children to be the link-text:
      @$ell = (@$ell[0,1], defined($link_text) ? splice(@$link_text) : '');
      
      DEBUG > 2 and print STDERR "End of L-parsing for this node " . pretty($treelet->[$i]) . "\n";

      unshift @stack, $treelet->[$i]; # might as well recurse
    }
  }

  return;
}

# . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

sub _treat_Es {
  my($self,@stack) = @_;

  my($i, $treelet, $content, $replacer, $charnum);
  my $start_line = $stack[0][1]{'start_line'};

  # A recursive algorithm implemented iteratively!  Whee!


  # Has frightening side effects on L nodes' attributes.

  #my @ells_to_tweak;

  while($treelet = shift @stack) {
    for(my $i = 2; $i < @$treelet; ++$i) { # iterate over children
      next unless ref $treelet->[$i];  # text nodes are uninteresting
      if($treelet->[$i][0] eq 'L') {
        # SPECIAL STUFF for semi-processed L<>'s
        
        my $thing;
        foreach my $attrname ('section', 'to') {        
          if(defined($thing = $treelet->[$i][1]{$attrname}) and ref $thing) {
            unshift @stack, $thing;
            DEBUG > 2 and print STDERR "  Enqueuing ",
             pretty( $treelet->[$i][1]{$attrname} ),
             " as an attribute value to tweak.\n";
          }
        }
        
        unshift @stack, $treelet->[$i]; # recurse
        next;
      } elsif($treelet->[$i][0] ne 'E') {
        unshift @stack, $treelet->[$i]; # recurse
        next;
      }
      
      DEBUG > 1 and print STDERR "Ogling E node ", pretty($treelet->[$i]), "\n";

      # bitch if it's empty
      if(  @{$treelet->[$i]} == 2
       or (@{$treelet->[$i]} == 3 and $treelet->[$i][2] eq '')
      ) {
        $self->whine( $start_line, "An empty E<>" );
        $treelet->[$i] = 'E<>'; # splice in a literal
        next;
      }
        
      # bitch if content is weird
      unless(@{$treelet->[$i]} == 3 and !ref($content = $treelet->[$i][2])) {
        $self->whine( $start_line, "An E<...> surrounding strange content" );
        $replacer = $treelet->[$i]; # scratch
        splice(@$treelet, $i, 1,   # fake out a literal
          'E<',
          splice(@$replacer,2), # promote its content
          '>'
        );
        # Don't need to do --$i, as the 'E<' we just added isn't interesting.
        next;
      }

      DEBUG > 1 and print STDERR "Ogling E<$content>\n";

      # XXX E<>'s contents *should* be a valid char in the scope of the current
      # =encoding directive. Defaults to iso-8859-1, I believe. Fix this in the
      # future sometime.

      $charnum  = Pod::Escapes::e2charnum($content);
      DEBUG > 1 and print STDERR " Considering E<$content> with char ",
        defined($charnum) ? $charnum : "undef", ".\n";

      if(!defined( $charnum )) {
        DEBUG > 1 and print STDERR "I don't know how to deal with E<$content>.\n";
        $self->whine( $start_line, "Unknown E content in E<$content>" );
        $replacer = "E<$content>"; # better than nothing
      } elsif($charnum >= 255 and !UNICODE) {
        $replacer = ASCII ? "\xA4" : "?";
        DEBUG > 1 and print STDERR "This Perl version can't handle ",
          "E<$content> (chr $charnum), so replacing with $replacer\n";
      } else {
        $replacer = Pod::Escapes::e2char($content);
        DEBUG > 1 and print STDERR " Replacing E<$content> with $replacer\n";
      }

      splice(@$treelet, $i, 1, $replacer); # no need to back up $i, tho
    }
  }

  return;
}


# . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

sub _treat_Ss {
  my($self,$treelet) = @_;
  
  _change_S_to_nbsp($treelet,0) if $self->{'nbsp_for_S'};

  # TODO: or a change_nbsp_to_S
  #  Normalizing nbsp's to S is harder: for each text node, make S content
  #  out of anything matching m/([^ \xA0]*(?:\xA0+[^ \xA0]*)+)/


  return;
}

sub _change_S_to_nbsp { #  a recursive function
  # Sanely assumes that the top node in the excursion won't be an S node.
  my($treelet, $in_s) = @_;
  
  my $is_s = ('S' eq $treelet->[0]);
  $in_s ||= $is_s; # So in_s is on either by this being an S element,
                   #  or by an ancestor being an S element.

  for(my $i = 2; $i < @$treelet; ++$i) {
    if(ref $treelet->[$i]) {
      if( _change_S_to_nbsp( $treelet->[$i], $in_s ) ) {
        my $to_pull_up = $treelet->[$i];
        splice @$to_pull_up,0,2;   # ...leaving just its content
        splice @$treelet, $i, 1, @$to_pull_up;  # Pull up content
        $i +=  @$to_pull_up - 1;   # Make $i skip the pulled-up stuff
      }
    } else {
      $treelet->[$i] =~ s/\s/$Pod::Simple::nbsp/g if $in_s;
       
       # Note that if you apply nbsp_for_S to text, and so turn
       # "foo S<bar baz> quux" into "foo bar&#160;faz quux", you
       # end up with something that fails to say "and don't hyphenate
       # any part of 'bar baz'".  However, hyphenation is such a vexing
       # problem anyway, that most Pod renderers just don't render it
       # at all.  But if you do want to implement hyphenation, I guess
       # that you'd better have nbsp_for_S off.
    }
  }

  return $is_s;
}

#-----------------------------------------------------------------------------

sub _accessorize {  # A simple-minded method-maker
  no strict 'refs';
  foreach my $attrname (@_) {
    next if $attrname =~ m/::/; # a hack
    *{caller() . '::' . $attrname} = sub {
      use strict;
      $Carp::CarpLevel = 1,  Carp::croak(
       "Accessor usage: \$obj->$attrname() or \$obj->$attrname(\$new_value)"
      ) unless (@_ == 1 or @_ == 2) and ref $_[0];

      (@_ == 1) ?  $_[0]->{$attrname}
                : ($_[0]->{$attrname} = $_[1]);
    };
  }
  # Ya know, they say accessories make the ensemble!
  return;
}

# . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
# . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
#=============================================================================

sub filter {
  my($class, $source) = @_;
  my $new = $class->new;
  $new->output_fh(*STDOUT{IO});
  
  if(ref($source || '') eq 'SCALAR') {
    $new->parse_string_document( $$source );
  } elsif(ref($source)) {  # it's a file handle
    $new->parse_file($source);
  } else {  # it's a filename
    $new->parse_file($source);
  }
  
  return $new;
}


#-----------------------------------------------------------------------------

sub _out {
  # For use in testing: Class->_out($source)
  #  returns the transformation of $source
  
  my $class = shift(@_);

  my $mutor = shift(@_) if @_ and ref($_[0] || '') eq 'CODE';

  DEBUG and print STDERR "\n\n", '#' x 76,
   "\nAbout to parse source: {{\n$_[0]\n}}\n\n";
  
  
  my $parser = ref $class && $class->isa(__PACKAGE__) ? $class : $class->new;
  $parser->hide_line_numbers(1);

  my $out = '';
  $parser->output_string( \$out );
  DEBUG and print STDERR " _out to ", \$out, "\n";
  
  $mutor->($parser) if $mutor;

  $parser->parse_string_document( $_[0] );
  # use Data::Dumper; print STDERR Dumper($parser), "\n";
  return $out;
}


sub _duo {
  # For use in testing: Class->_duo($source1, $source2)
  #  returns the parse trees of $source1 and $source2.
  # Good in things like: &ok( Class->duo(... , ...) );
  
  my $class = shift(@_);
  
  Carp::croak "But $class->_duo is useful only in list context!"
   unless wantarray;

  my $mutor = shift(@_) if @_ and ref($_[0] || '') eq 'CODE';

  Carp::croak "But $class->_duo takes two parameters, not: @_"
   unless @_ == 2;

  my(@out);
  
  while( @_ ) {
    my $parser = $class->new;

    push @out, '';
    $parser->output_string( \( $out[-1] ) );

    DEBUG and print STDERR " _duo out to ", $parser->output_string(),
      " = $parser->{'output_string'}\n";

    $parser->hide_line_numbers(1);
    $mutor->($parser) if $mutor;
    $parser->parse_string_document( shift( @_ ) );
    # use Data::Dumper; print STDERR Dumper($parser), "\n";
  }

  return @out;
}



#-----------------------------------------------------------------------------
1;
__END__

TODO:
A start_formatting_code and end_formatting_code methods, which in the
base class call start_L, end_L, start_C, end_C, etc., if they are
defined.

have the POD FORMATTING ERRORS section note the localtime, and the
version of Pod::Simple.

option to delete all E<shy>s?
option to scream if under-0x20 literals are found in the input, or
under-E<32> E codes are found in the tree. And ditto \x7f-\x9f

Option to turn highbit characters into their compromised form? (applies
to E parsing too)

TODO: BOM/encoding things.

TODO: ascii-compat things in the XML classes?