summaryrefslogtreecommitdiff
path: root/macros/latex/contrib/ted/ted.dtx
blob: 4916436ade38dd64bbc1042b67a4b6c2ba7ef519 (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
%
% \iffalse  /!\  this file contains non-ascii --  encoding is utf-8 /!\
% 
%     ted package by Manuel P\'egouri\'e-Gonnard <mpg@elzevir.fr>
%     -----------------------------------------------------------
%
% This work may be distributed and/or modified under the conditions of
% the LaTeX Project Public License, either version 1.3c of this license
% or (at your option) any later version.  The latest version of this
% license is in:
%
%   http://www.latex-project.org/lppl.txt
%
% and version 1.3c or later is part of all distributions of LaTeX
% version 2006/05/20 or later.
%
% This work has the LPPL maintenance status `maintained'.
%
% The current maintainer of this work is Manuel P\'egouri\'e-Gonnard.
%
% This work consists of the file ted.dtx and the derived files ted.sty,
% ted.pdf and ted-fr.pdf.
%
%
%<*gobble>
\ProvidesFile{ted.dtx}
%</gobble>
%<package>\NeedsTeXFormat{LaTeX2e}
%<package>\ProvidesPackage{ted}
%<*package>
% \fi
% \ProvidesFile{ted.dtx}
  [2008/03/07 v1.06 \space a token list editor \space (mpg)]
% \iffalse
%</package>
% \fi
% \CheckSum{816}
% \CharacterTable
%  {Upper-case    \A\B\C\D\E\F\G\H\I\J\K\L\M\N\O\P\Q\R\S\T\U\V\W\X\Y\Z
%   Lower-case    \a\b\c\d\e\f\g\h\i\j\k\l\m\n\o\p\q\r\s\t\u\v\w\x\y\z
%   Digits        \0\1\2\3\4\5\6\7\8\9
%   Exclamation   \!     Double quote  \"     Hash (number) \#
%   Dollar        \$     Percent       \%     Ampersand     \&
%   Acute accent  \'     Left paren    \(     Right paren   \)
%   Asterisk      \*     Plus          \+     Comma         \,
%   Minus         \-     Point         \.     Solidus       \/
%   Colon         \:     Semicolon     \;     Less than     \<
%   Equals        \=     Greater than  \>     Question mark \?
%   Commercial at \@     Left bracket  \[     Backslash     \\
%   Right bracket \]     Circumflex    \^     Underscore    \_
%   Grave accent  \`     Left brace    \{     Vertical bar  \|
%   Right brace   \}     Tilde         \~}
% \iffalse
%<*gobble>
\begingroup
%</gobble>
%<*batchfile>
\input docstrip
\keepsilent
\preamble

ted package by Manuel P\string\'egouri\string\'e-Gonnard %
<mpg@elzevir.fr>
This is a generated file. See ted.dtx for license information.

\endpreamble
\askforoverwritefalse
%\generate{\file{ted.ins}{\from{ted.dtx}{batchfile}}}
%\generate{\file{ted.drv}{\from{ted.dtx}{driver}}}
\generate{\file{ted.sty}{\from{ted.dtx}{package}}}
\generate{\file{ted-fr.drv}{\from{ted.dtx}{pilote}}}
%</batchfile>
%<*gobble>
\endgroup
%</gobble>
%<*driver|pilote>
\documentclass[oneside, a4paper]{ltxdoc}
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\usepackage{lmodern}
\usepackage[babel=true, expansion=false]{microtype}
\usepackage{fixltx2e}
\expandafter\newif\csname iffrenchdoc\endcsname % cachez ce if...
%<pilote>\frenchdoctrue
%</driver|pilote>
%<*gobble>
\iffrenchdoc
%</gobble>
%<*pilote>
\usepackage[lmargin=4.5cm, rmargin=3cm]{geometry}
\OnlyDescription
\usepackage[english, french]{babel}
\FrenchFootnotes \AddThinSpaceBeforeFootnotes
\newcommand*\eng[1]{\emph{\foreignlanguage{english}{#1}}}
\usepackage[bookmarks=false]{hyperref}
\hypersetup{%
  pdftitle=L'extension ted
  pdfsubject=Un éditeur de liste de lexèmes pour LaTeX2e}
%</pilote>
%<*gobble>
\else
%</gobble>
%<*driver>
\AlsoImplementation
\usepackage[english]{babel}
\usepackage[bookmarks=true, bookmarksnumbered=true, bookmarksopen=true,
  bookmarksopenlevel=2]{hyperref}
\hypersetup{%
  pdftitle=The ted package,
  pdfsubject=A token list editor for LaTex2e}
\settowidth\MacroIndent{\rmfamily\scriptsize 000\ }
\setlength\MacroTopsep{0pt}
\setcounter{tocdepth}{1}
\usepackage[nohints, english]{minitoc}
\mtcsetpagenumbers{secttoc}{off}
\mtcsetrules{secttoc}{off}
\mtcsetdepth{secttoc}{3}
\setlength{\stcindent}{0pt}
\mtcsetfont{secttoc}{subsection}{\normalfont}
\newcommand\tocwithmini{%
  \dosecttoc[n]
  \setcounter{tocdepth}{1}\tableofcontents
  \setcounter{tocdepth}{3}\faketableofcontents
  }
%</driver>
%<*gobble>
\fi
%</gobble>
%<*driver|pilote>
\hypersetup{%
  colorlinks=true, linkcolor=black, urlcolor=black,
  pdfauthor=Manuel Pégourié-Gonnard}
\newcommand\pf{\textsf}
\newcommand\optstar{\meta{$*$}}
\newcommand\topcs[1]{\texorpdfstring{\cs{#1}}{#1}}
\begin{document}
  \DocInput{ted.dtx}
\end{document}
%</driver|pilote>
%<*package>
% \fi
%
% \GetFileInfo{ted.dtx}
%
% \title{\iffrenchdoc L'extension \pf{ted}\else The \pf{ted} package\fi}
% \author{Manuel Pégourié-Gonnard\\ 
%   \href{mailto:mpg@elzevir.fr}{mpg@elzevir.fr}}
% \date{\fileversion\ (\filedate)}
%
% \maketitle
% \iffrenchdoc\else \tocwithmini \fi
%
% \section{Introduction}
%
% \iffrenchdoc
%
% Le nom de l'extension \pf{ted} signifie \eng{token list editor}, soit
% en français \og éditeur de listes de lexèmes \fg{}. Comparé à
% \texttt{sed} dont son nom s'inspire, il n'est pas très puissant : il
% ne sait faire actuellement que deux choses avec les listes de lexèmes,
% à savoir les afficher en détail, et y opérer des substitutions.
% Toutefois, sa caractéristique principale est de travailler vraiment au
% niveau des lexèmes, et non des simples caractères.
%
% L'extension \pf{ted} est capable de faire des substitutions même à
% l'intérieur d'une paire d'accolades, et n'a pas de problèmes avec des
% lexèmes particuliers. En fait, elle est conçue pour fonctionner même
% avec des listes comportant des lexèmes très exotiques.
%
% \else
%
% Just like \texttt{sed} is a stream editor, \pf{ted} is a token list
% editor.  Actually, it is not as powerful as \texttt{sed}, but its
% main feature is that it really works with tokens, not only characters.
% At the moment, it can do only two things with token lists: display it
% with full information on each token, and perform substitutions (that
% is, replacing every occurrence of a sublist with another token list).
%
% The \pf{ted} package can perform substitutions inside groups, and
% don't forbid any token in the lists. Actually, \pf{ted} is designed to
% work well even if strange tokens (that is, unusual (charcode,
% \cs{catcode}) pairs or tokens with a confusing \cs{meaning}) occur in
% the list.
%
% \fi
%
% \section{Usage}
%
% \iffrenchdoc
%
% L'extension \pf{ted} définit essentiellement deux macros publiques :
% \cs{Substitute} et \cs{ShowTokens}. La première est la raison d'être
% de \pf{ted}, mais au cours du développement de l'extension, la partie
% la plus difficile et intéressante a été d'être capable d'écrire la
% deuxième. J'ai donc décidé de la proposer à l'utilisateur, car je
% pense qu'elle peut être utile, soit pour déboguer du code, soit pour
% apprendre \TeX.
%
% \subsection{\topcs{Substitute}}
%
% \DescribeMacro{\Substitute}
% La syntaxe de \cs{Substitute} est la suivante.
% \begin{quote}
% \cs{Substitute}\optstar\oarg{sortie}\marg{entrée}\marg{de}\marg{vers}
% \end{quote}
% Commençons par l'usage le plus simple : sans étoile ni argument
% optionel. Sous cette forme, \cs{Substitute} remplace chaque occurrence
% de la sous-liste \meta{de} par \meta{vers} dans l'\meta{entrée}, et
% place le résultat dans le registre à lexèmes \cs{ted@toks}. Comme
% \cs{Substitute} est sans doute destiné à être utilisé par des auteurs
% de classe ou d'extensions, le |@| dans le nom de ce registre ne
% devrait pas poser de problèmes la plupart du temps.
%
% Quoi qu'il en soit, vous pouvez changer facilement le nom du registre
% utilisé pour la sortie avec l'argument optionnel en spécifiant le nom
% d'un registre à lexèmes dans \meta{sortie}. En fait, vous voulez
% peut-être que la sortie soit placée dans une macro et non un registre
% : dans ce cas, vous pouvez spécifier par exemple \cs{def}\cs{macro}
% (ou \cs{long}\cs{def}\cs{macro} etc.) comme argument optionnel. Dans
% tous les cas, \meta{sortie}|{trucs}| doit être une syntaxe légale
% d'affectation de |truc| dans la sortie. Bien sûr, si vous demandez à
% ce que la sortie soit placée dans une macro, vous devez veiller à ce
% qu'elle ne contienne pas de dièses (caractère de paramètre) mal
% placés. Exemples :
%
% \begin{quote}
% |\Substitute{a#b#c}{a}{A}|\\
% |\newtoks\vostoks \Substitute[\vostoks]{a#b#c}{a}{A}|\\
% |\Substitute[\def\votremacro]{a#b#c}{#}{##}|
% \end{quote}
%
% La version étoilée de \cs{Substitute} a pour but de vous simplifier la
% vie quand vous ne voulez pas spécifier explicitement une liste de
% lexèmes en entrée, mais plutôt utiliser le contenu d'une macro ou d'un
% registre, en développant une fois son premier argument obligatoire
% avant de commencer à travailler dessus. Ceci vous évite d'avoir à
% placer vous-même des \cs{expandafter}, surtout dans le cas ou vous
% souhaitez utiliser l'argument optionnel. Cette fois, l'usage est
% inversé par rapport à l'argument optionnel : c'est la cas d'une macro
% qui est le plus naturel. Pour un registre de lexèmes, vous devez
% écrire le \cs{the} vous même : ainsi, votre \meta{entrée} pourra être
% de la forme \cs{macro}, ou \cs{the}\cs{toksreg}, ou toute autre chose
% dont le 1-développement donne ce que vous voulez. Par exemple :
%
% \begin{quote}
% |\def\abc{abccdef} \newtoks\abctoks \abctoks{abc}|\\
% |\Substitute{\abc}{cc}{C} %| donne |\abc|\\
% |\Substitute*{\abc}{cc}{C} %| donne |abCdef|\\
% |\Substitute*{\the\abctoks}{cc}{C} %| aussi
% \end{quote}
%
% La version avec deux étoiles a aussi pour but de vous épargner la
% peine de contrôler vous-même le développement des arguments. Elle
% fonctionne comme la version étoilée simple, mais développe cette fois
% ses trois arguments obligatoires une fois avant de commencer à
% travailler. La même remarque que pour la version étoilée simple
% s'applique concernant les macros et les registres à lexèmes. J'espère
% que ces trois cas (de zéro à deux étoiles) couvriront la plupart des
% usage courants. Pour une gestion plus souple du développement des
% arguments, attendez \LaTeX$3$ !
%
% Le comportement de \cs{Substitute} devrait être évident la plupart du
% temps. Seul un cas particulier mérite sans doute une petite remarque :
% dans le cas ou la liste \meta{de} est vide, la liste \meta{vers} est
% insérée entre chaque paire de lexèmes de l'\meta{entrée} : en
% particulier elle n'est pas insérée au début ni à la fin. Par exemple,
% |\Substitute{abc}{}{1}| placera |a1b1c| dans \cs{ted@toks}.
% 
% Enfin, il peut être utile de savoir qu'une fois que \cs{Substitute} a
% fini son travail, le nombre de substitutions effectuées est accessible
% dans le registre \cs{ted@count}. On peut ainsi s'en servir pour
% compter, par exemple, le nombre d'espaces (donc approximativement de
% mots) dans un texte, en faisant semblant d'opérer une substitution
% dessus.
%
% \subsection{\topcs{ShowTokens}}
%
% \DescribeMacro{\ShowTokens}
% La syntaxe de \cs{ShowTokens} est la suivante.
% \begin{quote}
% \cs{ShowTokens}\optstar\marg{liste}
% \end{quote}
% Dans sa forme simple, \cs{ShowTokens} se contente d'afficher la liste
% de lexèmes, un par ligne. Pour les lexèmes de type caractère,
% l'affichage comporte le caractère lui-même, suivi de l'indication de
% son code de catégorie sous la forme utilisée par \cs{show}.  Je
% rappelle ci-dessous (table~\ref{cc}) pour la commodité du lecteur les
% différents \cs{catcode}s possibles dans une liste de lexème, ainsi
% qu'un exemple et la façon dont ils sont affichés par \cs{ShowTokens}.
%
% \begin{table}
% \begin{tabular}{rcl}
% 1  & |{| & |(begin-group character {)|\\
% 2  & |}| & |(end-group character })|\\
% 3  & |$| & |(math shift character $)|\\
% 4  & |&| & |(alignment tab character &)|\\
% 6  & |#| & |(macro parameter character #)|\\
% 7  & |^| & |(superscript character ^)|\\
% 8  & |_| & |(subscript character _)|\\
% 10 & | | & |(blank space  )|\\
% 11 & |a| & |(the letter a)|\\
% 12 & |0| & |(the character 0)|\\
% 13 & |~| & |(active character=macro:->\nobreakspace {})|\\
% \end{tabular}
% \caption{Les \cs{catcode} : code, exemple, et description.}\label{cc}
% \end{table}
% 
% Pour les séquence de contrôles et les caractères actifs, le (début du)
% \cs{meaning} est également affiché, sans dépasser les~$80$ colonnes de
% large afin de ne pas perturber l'affichage par ligne. Il s'agit bien
% sûr du sens courant au moment de l'appel à \cs{ShowTokens}.
% 
% \DescribeMacro{\ShowTokensLogonly} \DescribeMacro{\ShowTokensOnline}
% Le comportement par défaut est d'afficher ces listes à la fois sur le
% terminal et dans le fichier log. Si vous préférez que l'affichage
% n'ait lieu que dans le fichier log, vous n'avez qu'à dire
% \cs{ShowTokensLogonly}. Si vous souhaitez ensuite revenir au
% comportement par défaut, dites seulement \cs{ShowTokensOnline}.
%
% La version étoilée de \cs{ShowTokens} fonctionne de la même façon que
% dans le cas de \cs{Substitute} en développant son argument une fois
% avant d'en commencer l'analyse. La même remarque que précédemment
% s'applique concernant les macros et les registres. Imaginons par
% exemple que vous vouliez vérifier, après la définition d'une macro,
% que vous avez bien les bons \cs{catcode}s :
%
% \begin{quote}
% |\begingroup \uccode`\~=32 \uppercase{\endgroup|\\
% |  \def\macro{1~2}}|\\
% |\ShowTokens*{\macro} %| donne à l'écran : [...]\\
% |1 (the character 1)|\\
% |  (active character=macro:-> )|\\
% |2 (the character 2)|
% \end{quote}
% 
% \medskip
% J'aimerais conclure par la remarque suivante : au cours de la
% conception de \pf{ted}, j'ai vraiment essayé de ne faire aucune
% hypothèse sur les lexèmes présents dans la liste. Ainsi, vous pouvez
% utiliser librement des accolades, des dièses, des espaces, des
% \cs{par}, des \cs{if}s, des \cs{bgroup} ou \cs{egroup} dans toutes les
% listes de lexèmes. À ma connaissance à ce jour, la seule limitation
% est que les séquences de contrôle qui apparaissent ne doivent pas être
% (ou être \cs{let}-égales à) des macros intimes de \pf{ted},
% c'est-à-dire celles commençant par \cs{ted@@}.
%
% \begin{quote}
% Vous savez maintenant tout ce qu'il y a à savoir sur l'utilisation de
% \pf{ted}. Si vous souhaitez vous pencher sur son implémentation, il
% vous faudra lire les commentaires en anglais car je n'ai pas eu le
% courage de documenter mon code en deux langues. 
% \end{quote}
%
% \begin{center}\large
% C'est tout pour cette fois ! \\
% Amusez-vous bien avec \LaTeX{} !
% \end{center}
%
% \else
%
% The \pf{ted} package provides two user macros: \cs{Substitute} and
% \cs{ShowTokens}. The first one is the primary goal of the package, but
% to be able to do the second was the more interesting part while
% writing the package. I made it into a user macro since I believe it
% can be useful for debugging things, or for learning \TeX.
%
% \subsection{\topcs{Substitute}}
%
% \DescribeMacro{\Substitute}
% The syntax of \cs{Substitute} is as follows.
% \begin{quote}
% \cs{Substitute}\optstar\oarg{output}\marg{input}\marg{from}\marg{to}
% \end{quote}
% Let's begin with the basics. Without star or optional argument, the
% \cs{Substitute} macro will replace each occurrence of the \meta{from}
% token list with \marg{to} in the \meta{input}, and put the result in
% the \cs{toks} register \cs{ted@toks}. This macro has a |@| in its
% name, but since I think the \cs{Substitute} macro will be essentially
% be used by class or package writers, this should be ok.
%
% Anyway, if you don't like this name, you can specify another one as
% \meta{output} using the optional argument. Your \meta{output} should
% be the name of a \cs{toks} register. If you want the output to be put
% in a macro, use \cs{def}\cs{macro} (or \cs{long}\cs{def}\cs{macro}
% or\ldots) as the optional argument. Anyway, \meta{output}\marg{stuff}
% must be a legal syntax for an assignment: using \cs{macro} as optional
% argument will not work (and may actually result in chaos). Of course,
% if you want your output to be placed in a macro, it should not contain
% improperly placed hash signs (that is, macro parameter tokens). 
%
% \begin{quote}
% |\Substitute{a#b#c}{a}{A}|\\
% |\newtoks\yourtoks \Substitute[\yourtoks]{a#b#c}{a}{A}|\\
% |\Substitute[\def\yourmacro]{a#b#c}{#}{##}|
% \end{quote}
%
% The one-starred form of \cs{Substitute} is meant to help you when your
% \meta{input} is not an explicit token list, but the contents of either
% a macro or a \cs{toks} register, by expanding once its first mandatory
% argument before proceeding. It spares you the pain of using
% \cs{expandafter}s, especially in case you want to use the optional
% argument too. This time, things are reversed compared to the optional
% argument : using a macro instead of a toks register is easier.
% Actually, with the starred form, the first argument can be \cs{macro}
% or \cs{the}\cs{toksreg}, or anything whose one-time expansion is the
% token list you want \cs{Substitute} to act upon.
%
% \begin{quote}
% |\def\abc{abccdef} \newtoks\abctoks \abctoks{abc}|\\
% |\Substitute{\abc}{cc}{C} %| gives |\abc|\\
% |\Substitute*{\abc}{cc}{C} %| gives |abCdef|\\
% |\Substitute*{\the\abctoks}{cc}{C} %| too
% \end{quote}
%
% The two-starred form is also meant to avoid you trouble with
% development. It expands its three mandatory arguments once before
% executing. The remark about macros and \cs{toks} register still
% holds. I hope this three cases (from zero to two stars) will suffice
% for most purpose. For a better handling of arguments expansion, wait
% for \LaTeX$3$!
%
% The action of \cs{Substitute} is pretty obvious most of the time.
% Maybe a particular case needs some precision: when \meta{from} is
% empty, then the \meta{to} list gets inserted between each two tokens
% of the \cs{input}, but not before the first one. For example,
% \cs{Substitute}|{abc}{}{1}| puts |a1b1c| in \cs{ted@toks}.
%
% Finally, it may be useful to know that, after \cs{Subsitute} finished
% its job, it leaves the number of replaced occurrences in the count
% register \cs{ted@count}. This can be used, for example, to count
% spaces (hence words) in a text, by making a fake substitution on it.
%
% \subsection{\topcs{ShowTokens}}
%
% \DescribeMacro{\ShowTokens}
% The syntax of \cs{ShowTokens} is as follows.
% \begin{quote}
% \cs{ShowTokens}\optstar\marg{list}
% \end{quote}
% In its simple form, \cs{ShowTokens} just shows the list, one token per
% line.  For characters tokens, its prints the character, and its
% category code in human-friendly form. For the sake of readability,
% here is (table~\ref{cc}) a reminder of the possible \cs{catcode}s,
% with an exemple and the way \cs{ShowTokens} displays them.
%
% \begin{table}
% \begin{tabular}{rcl}
% 1  & |{| & |(begin-group character {)|\\
% 2  & |}| & |(end-group character })|\\
% 3  & |$| & |(math shift character $)|\\
% 4  & |&| & |(alignment tab character &)|\\
% 6  & |#| & |(macro parameter character #)|\\
% 7  & |^| & |(superscript character ^)|\\
% 8  & |_| & |(subscript character _)|\\
% 10 & | | & |(blank space  )|\\
% 11 & |a| & |(the letter a)|\\
% 12 & |0| & |(the character 0)|\\
% 13 & |~| & |(active character=macro:->\nobreakspace {})|\\
% \end{tabular}
% \caption{Possible \cs{catcode}s: code, example, and description.}\label{cc}
% \end{table}
% 
% For control sequences and active characters, it
% also prints their current \cs{meaning} as a bonus, or only the
% beginning of it (ending with \cs{ETC.}) if it is more than one line
% ($80$ columns) long.
%
% \DescribeMacro{\ShowTokensLogonly}
% \DescribeMacro{\ShowTokensOnline}
% The default is to show this list both in the terminal and in the log
% file.  If you don't want it to be printed on the terminal, just say
% \cs{ShowTokensLogonly}. If you change your mind latter, you can
% restore the default behaviour with \cs{ShowTokensOnline}.
%
% The starred form of \cs{ShowTokens} works the same as for
% \cs{Substitute}: it expands its argument once before analysing and
% displaying it. The same remarks hold: use \cs{macro} or
% \cs{the}\cs{toksreg} in the argument.
%
% \begin{quote}
% |\begingroup \uccode`\~=32 \uppercase{\endgroup|\\
% |  \def\macro{1~2}}|\\
% |\ShowTokens*{\macro} %| prints on screen: [...]\\
% |1 (the character 1)|\\
% |  (active character=macro:-> )|\\
% |2 (the character 2)|
% \end{quote}
%
% \medskip
% I would like to conclude with the following remark: I have really
% tried to make sure \pf{ted}'s macros will work fine even with the
% wierdest token list.  In particular, you can freely use begin-group
% and end-group characters, hash signs, spaces, \cs{bgroup} and
% \cs{egroup}, \cs{par}, \cs{if}s, as well as exotic
% charcode-\cs{catcode} pairs in every argument of the macros. As far as
% I am aware, the only restriction is you should not use the very
% private macros of \pf{ted} (those beginning with \cs{ted@@}) in your
% token lists.
%
% \fi
%
% \StopEventually{}
%
% \section{Implementation}
%
% A important problem, when trying to substitute things in token lists,
% is to handle begin-group and end-group tokens, since they prevent us
% from to reading the tokens one by one, and tend to be difficult to
% handle individually.  Two more kinds of tokens are special: the space
% tokens, since they\footnote{Actually, only tokens with charcode $32$
% and \cs{catcode}~$10$ (i.e. $32_{10}$ tokens) are concerned.} cannot
% be grabbed as the non-delimited argument of a macro, and the parameter
% tokens (hash signs), since they cannot be part of the delimiters in
% the parameter text of a macro. From now on, ``special tokens'' thus
% denotes tokens with \cs{catcode} $1$, $2$, $6$ or $10$.
%
% To get rid of these problems, the \cs{Substitute} command proceeds in
% three steps. First, encode the input, replacing all special tokens
% with nice control sequences representing them, then do the actual
% substitution, and finally decode the output, replacing the special
% control sequences with the initial special tokens.
%
% Encoding is the hard part. The idea is to try reading the tokens one
% by one; for this we have two means: using a macro with one
% non-delimited argument, or something like \cs{let}. The former doesn't
% work well with \cs{catcode}~$1$, $2$ or $10$ tokens, and the later do
% not see the name of the token (its character code, or its name for a
% CS). So we need to use both \cs{futurelet}, a ``grabbing'' macro with
% argument, and \cs{string} in order to scan the tokens. Actually, the
% encoding proceeds in two passes: in the first, we try and detect the
% special tokens, storing their character codes for later use, then do
% the actual encoding in the last pass.
%
% Decoding also processes the tokens one by one, and is simpler, since
% special cases are already detected. There is, however, a trick with
% groups since, when we encounter a begin-group character, we have to
% wait for the corresponding end-group before adding the whole thing to
% the output. There is also a simpler version of decoding, for
% \cs{ShowTokens}, for screen/log output, with no need to use this
% trick, since it only outputs \cs{catcode}-$12$ characters. Finally,
% the substitution part uses a macro with delimited argument, defined on
% the fly.
%
% The code is divided as follows. 
% \par\vspace{-0.5\baselineskip}
% \secttoc
% \par\vspace{-0.5\baselineskip}
%
% \begin{macro}{\ted@toks}
% \begin{macro}{\ted@list}
% \begin{macro}{\ted@code}
% Before we begin, just allocate (or give a nice name to) a few
% registers.
%    \begin{macrocode}
\@ifdefinable\ted@toks{\newtoks\ted@toks}
\@ifdefinable\ted@list{\let\ted@list\toks@}
\@ifdefinable\ted@code{\let\ted@code\count@}
\@ifdefinable\ted@count{\newcount\ted@count}
%    \end{macrocode}
% \end{macro}
% \end{macro}
% \end{macro}
%
% \subsection{Encoding}
%
% \begin{macro}{\ted@encloop}
% \begin{macro}{\ted@encloop@}
% The two passes use the same loop for reading the input almost token
% by token. This loop grabs the next token through a
% \cs{futurelet}\ldots
%    \begin{macrocode}
\newcommand\ted@encloop{%
  \futurelet\@let@token
  \ted@encloop@}
%    \end{macrocode}
% \ldots then looks at it with some \cs{ifx} and \cs{ifcat} (non nested,
% since the token could be an \cs{if} itself), in order to distinguish
% between three cases: normal token, end reached, or special token. In
% the later case, remember which kind of special token it is, using a
% numeric code.
%    \begin{macrocode}
\newcommand\ted@encloop@{%
  \let\next\ted@do@normal
  \ifx\@let@token\ted@@end
    \let\next\ted@gobble@end
  \fi
  \ifcat\noexpand\@let@token##%
    \ted@code0
    \let\next\ted@do@special
  \fi
  \ifcat\noexpand\@let@token\@sptoken
    \ted@code1
    \let\next\ted@do@special
  \fi
  \ifcat\noexpand\@let@token\bgroup
    \ted@code2
    \let\next\ted@do@special
  \fi
  \ifcat\noexpand\@let@token\egroup
    \ted@code3
    \let\next\ted@do@special
  \fi
  \next}
%    \end{macrocode}
% \end{macro}
% \end{macro}
% \begin{macro}{\ted@@end}
% \begin{macro}{\ted@gobble@end}
% Here we used the following to detect the end, then gobble it when
% reached.
%    \begin{macrocode}
\newcommand\ted@@end{\ted@@end@}
%    \end{macrocode}
%    \begin{macrocode}
\@ifdefinable\ted@gobble@end{%
  \def\ted@gobble@end\ted@@end{}}
%    \end{macrocode}
% \end{macro}
% \end{macro}
%
% \begin{macro}{\ted@sanitize}
% \begin{macro}{\ted@@active}
% Now, this detection method, with \cs{futurelet} and \cs{ifcat}, is
% unable to distinguish the following three cases for potential special
% tokens: (i) a ``true'' (explicit) special token, (ii) a CS
% \cs{let}-equal to a special token, (iii) an active character
% \cs{let}-equal to a special token.  While this is pre-scanning's job
% to detect the (ii) case, the (iii) can be easily got rid of by
% redefining locally all active characters.
%    \begin{macrocode}
\count@\catcode\z@ \catcode\z@\active
\newcommand\ted@sanitize{%
  \count@\z@ \@whilenum\count@<\@cclvi \do{%
    \uccode\z@\count@
    \uppercase{\let^^00\ted@@active}%
    \advance\count@\@ne}}
\catcode\z@\count@
%    \end{macrocode}
%    \begin{macrocode}
\newcommand\ted@@active{\ted@@active@}
%    \end{macrocode}
% This sanitizing macro also mark active characters by \cs{let}-ing them
% equal to \cs{ted@@active} in order to detect them easily later, for
% example while displaying on-screen token analysis.  All operations
% (scanning, replacing, display and decoding) are going to happen inside
% a group where \cs{ted@sanitize} has been executed, so that active
% characters are no longer an issue.  \end{macro} \end{macro}
%
% \begin{macro}{\ted@encode} \begin{macro}{\ted@do@normal}
% \begin{macro}{\ted@do@special} The \cs{ted@encode} macro is the master
% macro for encoding. It only initialise a few things and launches the
% two loops. We select one of the tree steps by \cs{let}-ing
% \cs{ted@do@normal} and \cs{ted@do@special} to the appropriate action.
%    \begin{macrocode}
\newcommand\ted@encode[1]{%
  \ted@list{}%
  \let\ted@do@normal\ted@gobble@encloop
  \let\ted@do@special\ted@scan@special
  \ted@encloop#1\ted@@end 
  \ted@toks{}%
  \let\ted@do@normal\ted@addtoks@encloop
  \let\ted@do@special\ted@special@out
  \ted@encloop#1\ted@@end
  \ted@assert@listempty}
%    \end{macrocode}
% \end{macro}
% \end{macro}
% \end{macro}
% \begin{macro}{\ted@assert@listempty}
% After the last loop, \cs{ted@list} should be empty. If it's not, it
% means something very weird happened during the encoding procedure. I
% hope the code below will never be executed :)
%    \begin{macrocode}
\newcommand\ted@assert@listempty{%
  \edef\next{\the\ted@list}%
  \ifx\next\@empty \else
    \PackageError{ted}{%
      Assertion `\string\ted@list\space is empty' failed}{%
      This should not happen. Please report this bug to the author.
      \MessageBreak By the way, you're in trouble there... I'm sorry.}%
  \fi}
%    \end{macrocode}
% \end{macro}
%
% \subsubsection{Pre-scanning}
%
% \begin{macro}{\ted@gobble@encloop}
% For normal tokens, things are pretty easy: just gobble them!
%    \begin{macrocode}
\newcommand\ted@gobble@encloop{%
  \afterassignment\ted@encloop
  \let\@let@token= }
%    \end{macrocode}
% \end{macro}
% \begin{macro}{\ted@scan@special}
% For special tokens, it's harder. We must distinguish explicit
% character tokens from control sequences \cs{let}-equal to special
% tokens.  For this, we use \cs{string}, then grab the next character to
% see whether its code is \cs{escapechar} or not.  Actually, things are
% not this easy, for two reasons. First, we have to make sure the next
% character's code is not already \cs{escapechar} before the
% \cs{string}, by accident. For this purpose, we set \cs{escapechar}
% to~$0$ except if next character's code is also~$0$, in which case we
% prefer~$1$.
%    \begin{macrocode}
\count@\catcode\z@ \catcode\z@ 12
\newcommand\ted@scan@special{%
  \begingroup
  \escapechar\if\@let@token^^00 \@ne \else \z@ \fi
  \expandafter\ted@check@space\string}
\catcode\z@\count@
%    \end{macrocode}
% \end{macro}
% \begin{macro}{\ted@check@space}
% \begin{macro}{\ted@check@space@}
% Second, we have to handle carefully the case of the next token being
% the $32_{10}$ token, since we cannot grab this one with a macro. We
% are in this case if and only if the token we just \cs{string}ed was a
% character token with code $32$, and it is enough to check if next
% token's \cs{catcode} is $10$ in order to detect it, since it will be
% $12$ otherwise. In order to check this, we use \cs{futurelet} again
% for pre-scanning.
%    \begin{macrocode}
\newcommand\ted@check@space{%
  \futurelet\@let@token
  \ted@check@space@}
%    \end{macrocode}
%    \begin{macrocode}
\newcommand\ted@check@space@{%
  \ifcat\@let@token\@sptoken
    \endgroup
    \ted@addlist{32}%
    \expandafter\ted@gobble@encloop
  \else
    \expandafter\ted@list@special
  \fi}
%    \end{macrocode}
% \end{macro}
% \end{macro}
% \begin{macro}{\ted@list@special}
% Now that we got rid of this nasty space problem, we know for sure that
% the next token has \cs{catcode} $12$, so we can easily grab it as an
% argument, find its charcode, and decide whether the original token was
% a control sequence or not. Note the \cs{expandafter} over
% \cs{endgroup} trick, since we need to add the charcode to the list
% outside the group (opened for the modified \cs{escapechar}) though it
% was set inside. 
%    \begin{macrocode}
\newcommand*\ted@list@special[1]{%
  \ted@code`#1\relax
  \expandafter\expandafter\expandafter
  \endgroup
  \ifnum\ted@code=\escapechar
    \ted@addlist{\m@ne}%
  \else
    \expandafter\ted@addlist\expandafter{\the\ted@code}%
  \fi
  \ted@encloop}
%    \end{macrocode}
% \end{macro}
% \begin{macro}{\ted@addlist}
% Here we used the following macro to add an element to the list, which
% is space-separated.
%    \begin{macrocode}
\newcommand*\ted@addlist[1]{%
  \ted@list\expandafter{\the\ted@list#1 }}
%    \end{macrocode}
% \end{macro}
%
% \subsubsection{Actually encoding}
%
% Remember that, before this last encoding pass, \cs{ted@encode} did the
% following:
% \begin{quote}
% \cs{let}\cs{ted@do@normal}\cs{ted@addtoks@encloop}\\
% \cs{let}\cs{ted@do@special}\cs{ted@special@out}
% \end{quote}
% \begin{macro}{\ted@addtoks@encloop}
% The first one is very easy : normal tokens are just grabbed as
% arguments and appended to the output, then the loop continues.
%    \begin{macrocode}
\newcommand\ted@addtoks@encloop[1]{%
  \ted@toks\expandafter{\the\ted@toks#1}%
  \ted@encloop}
%    \end{macrocode}
% \end{macro}
% \begin{macro}{\ted@special@out}
% Special tokens need to be encoded, but before, just check if they are
% really special: they aren't if the corresponding code is $-1$.
%    \begin{macrocode}
\newcommand\ted@special@out{%
  \ifnum\ted@list@read=\m@ne
    \ted@list@advance
    \expandafter\ted@cs@clean
  \else
    \expandafter\ted@special@encode
  \fi}
%    \end{macrocode}
% \end{macro}
% \begin{macro}{\ted@cs@clean}
% Even if the potentially special token was not a real one, we have work
% to do.  Indeed, in the first pass we did break it using a \cs{string},
% and thus we introduced some foreign tokens in the stream. Most of them
% are not important since they have \cs{catcode}~$12$. Anyway, some of
% them may be space tokens : in this case we have extra $32$'s in our
% list. So, we need to check this before going any further.
%    \begin{macrocode}
\newcommand\ted@cs@clean[1]{%
  \expandafter\ted@add@toks{#1}%
  \expandafter\ted@cscl@loop\string#1 \@nil}
%    \end{macrocode}
% \end{macro}
% \begin{macro}{\ted@cscl@loop}
% We first add the CS to the output, then break it with a \cs{string} in
% order to look at its name with the following loop. It first grabs
% everything to the first space\ldots
%    \begin{macrocode}
\@ifdefinable\ted@cscl@loop{%
  \def\ted@cscl@loop#1 {%
    \futurelet\@let@token
    \ted@cscl@loop@}}
%    \end{macrocode}
% \end{macro}
% \begin{macro}{\ted@cscl@loop@}
% \ldots and carefully look at the next token in order to know if we are
% finished or not. 
%    \begin{macrocode}
\newcommand\ted@cscl@loop@{%
  \ifx\@let@token\@nil 
    \expandafter\ted@gobble@encloop
  \else
    \ted@list@advance
    \expandafter\ted@cscl@loop
  \fi}
%    \end{macrocode}
% \end{macro}
%
% \begin{macro}{\ted@special@encode}
% Now, let's come back to the special tokens. As we don't need the token
% to encode it (we already know its \cs{catcode} from \cs{ted@code},
% and its charcode is stored in the list), we first gobble it in order
% to prepare for next iteration.
%    \begin{macrocode}
\newcommand\ted@special@encode{%
    \afterassignment\ted@special@encode@
  \let\@let@token= }
%    \end{macrocode}
% \end{macro}
% \begin{macro}{\ted@special@encode@}
% Then we encode it in two steps : first, create a control sequence with
% name \cs{ted@@}\meta{code}\meta{charcode}, where code is a digit
% denoting\footnote{I don't store the \cs{catcode} for two reasons:
% first, having a single digit is easier; second, having the true
% catcode would be useless (though it could maybe make the code more
% readable).} the \cs{catcode} of the special token, \ldots
%    \begin{macrocode}
\newcommand\ted@special@encode@{%
  \expandafter\ted@special@encode@@\expandafter{%
    \csname ted@@\the\ted@code\ted@list@read\endcsname}}
%    \end{macrocode}
% \end{macro}
% \begin{macro}{\ted@special@encode@@}
% \begin{macro}{\ted@@special}
% \ldots then, mark this CS as a special token encoding, in order to
% make it easier to detect later, add it to the output and loop again.
%    \begin{macrocode}
\newcommand*\ted@special@encode@@[1]{%
  \ted@list@advance
  \let#1\ted@@special
  \ted@addtoks@encloop{#1}}
%    \end{macrocode}
%    \begin{macrocode}
\newcommand\ted@@special{\ted@@special@}
%    \end{macrocode}
% \end{macro}
% \end{macro}
% 
% \begin{macro}{\ted@list@read}
% \begin{macro}{\ted@list@read@}
% Here we used the following macros in order to manage our charcode list.
% The reading one is fully expandable.
%    \begin{macrocode}
\newcommand\ted@list@read{%
  \expandafter\ted@list@read@\the\ted@list\@nil}
%    \end{macrocode}
%    \begin{macrocode}
\@ifdefinable\ted@list@read@{%
  \def\ted@list@read@#1 #2\@nil{%
    #1}}
%    \end{macrocode}
% \end{macro}
% \end{macro}
% \begin{macro}{\ted@list@advance}
% \begin{macro}{\ted@list@advance@}
% Since it's expandable, it cannot change the list, so we need a
% separate macro to remove the first element from the list, once read.
%    \begin{macrocode}
\newcommand\ted@list@advance{%
  \expandafter\ted@list@advance@\the\ted@list\@nil}
%    \end{macrocode}
%    \begin{macrocode}
\@ifdefinable\ted@list@advance@{
  \def\ted@list@advance@#1 #2\@nil{%
    \ted@list{#2}}}
%    \end{macrocode}
% \end{macro}
% \end{macro}
%
% \subsection{Decoding}
%
% \begin{macro}{\ted@add@toks}
% Main decoding macro is \cs{ted@decode}. It is again a loop, processing
% the token list one by one. For normal tokens, things are easy as
% always: just add them to the output, via
%    \begin{macrocode}
\newcommand\ted@add@toks[1]{%
  \ted@toks\expandafter{\the\ted@toks#1}}
%    \end{macrocode}
% \end{macro}
% \begin{macro}{\ted@decode}
% Encoded special tokens are easily recognized, since they were \cs{let}
% equal to \cs{ted@@special}. In order to decode it, we use the name of
% the CS. The following macro uses \LaTeX-style \cs{if} in order to
% avoid potential nesting problems when \cs{ifs} are present in the
% token list being processed.
%    \begin{macrocode}
\newcommand\ted@decode[1]{%
  \ifx#1\ted@@end \expandafter\@gobble\else\expandafter\@firstofone\fi{%
    \ifx#1\ted@@special
      \expandafter\@firstoftwo
    \else
      \expandafter\@secondoftwo
    \fi{%
      \begingroup \escapechar\m@ne \expandafter\endgroup
      \expandafter\ted@decode@special\string#1\@nil
      }{%
      \ted@add@toks{#1}}%
    \ted@decode}}
%    \end{macrocode}
% \end{macro}
% \begin{macro}{\ted@decode@special}
% The next macro should then gobble the |ted@@| part of the CS name, and
% use the last part as two numeric codes (here we use the fact that the
% first one is only a digit). 
%    \begin{macrocode}
\@ifdefinable\ted@decode@special{%
  \begingroup\escapechar\m@ne \expandafter\endgroup\expandafter
  \def\expandafter\ted@decode@special\string\ted@@#1#2\@nil{%
%    \end{macrocode}
% It then proceeds according to the first code, building back the
% original token and adding it to the output. The first two kinds of
% tokens (macro parameter characters and blank spaces) are easily dealt
% with.
%    \begin{macrocode}
    \ifcase#1
      \begingroup \uccode`##=#2 \uppercase{\endgroup
        \ted@add@toks{##}}%
    \or
      \begingroup \uccode32=#2 \uppercase{\endgroup
        \ted@add@toks{ }}%
    \or
%    \end{macrocode}
% For begin-group and end-group characters, we have a problem, since
% they are impossible to handle individually: we can only add a
% \meta{balanced text} to the output. So, when we find a begin-group
% character, we just open a group (a real one), and start decoding again
% inside the group, until we find the corresponding end-group character.
% Then, we enclose the local decoded list of tokens into the correct
% begin-group/end-group pair, and then add it to the output one group
% level below, using the \cs{expandafter}-over-\cs{endgroup} trick
% (essential here).
%    \begin{macrocode}
      \begingroup \ted@toks{}%
      \uccode`{=#2
    \or
      \uccode`}=#2
      \uppercase{\ted@toks\expandafter{\expandafter{\the\ted@toks}}}%
      \expandafter\endgroup
      \expandafter\ted@add@toks\expandafter{\the\ted@toks}%
    \fi}}
%    \end{macrocode}
% \end{macro}
%
% \subsection{Substitution}
%
% For this part, the idea\footnote{for which I am grateful to Jean-Côme
% Charpentier, who first taught me the clever use delimited arguments
% (and lots of other wonderful things) in \nolinkurl{fr.comp.text.tex}}
% is to use a macro whose first argument is delimited with the
% \meta{from} string, which outputs the first argument followed by the
% \meta{to} string, and loops. Obviously this macro has to be defined on
% the fly. All tokens lists need to be encoded first, and the output
% decoded at end. Since all this needs to happens inside a group (for
% \cs{ted@sanitize} and the marking up of special-characters control
% sequences), remember to ``export'' \cs{ted@toks} when done.
%
% \begin{macro}{\ted@Substitude}
% The main substitution macro is as follows. Arguments are \meta{input},
% \meta{from}, \meta{to}.  \cs{ted@output} will be discussed later.
%    \begin{macrocode}
\newcommand\ted@Substitute[3]{%
  \begingroup \ted@sanitize
  \ted@encode{#3}%
  \expandafter\ted@def@subsmac\expandafter{\the\ted@toks}{#2}%
  \ted@encode{#1}%
  \ted@subsmac
  \ted@toks\expandafter{\expandafter}%
  \expandafter\ted@decode\the\ted@toks\ted@@end
  \expandafter\endgroup
  \expandafter\ted@output\expandafter{\the\ted@toks}}
%    \end{macrocode}
% \end{macro}
% \begin{macro}{\ted@def@subsmac}
% The actual iterative substitution macro is defined by the following
% macro, whose arguments are the \meta{to} string, encoded, and the
% plain \meta{from} string.
%    \begin{macrocode}
\newcommand\ted@def@subsmac[2]{%
  \ted@encode{#2}%
  \long\expandafter\def\expandafter\ted@subsmac@loop
  \expandafter##\expandafter1\the\ted@toks##2{%
    \ted@add@toks{##1}%
    \ifx##2\ted@@end 
      \expandafter\@firstoftwo
    \else
      \expandafter\@secondoftwo
    \fi{%
      \expandafter\ted@remove@nil\the\ted@toks
      }{%
      \global\advance\ted@count\@ne
      \ted@add@toks{#1}\ted@subsmac@loop##2}}%
  \expandafter\ted@def@subsmac@\expandafter{\the\ted@toks}}
%    \end{macrocode}
% \end{macro}
% \begin{macro}{\ted@def@subsmac@}
% While we have the encoded \meta{from} string at hand, define the
% start-loop macro.
%    \begin{macrocode}
\newcommand\ted@def@subsmac@[1]{%
  \def\ted@subsmac{%
    \global\ted@count\z@
    \ted@toks\expandafter{\expandafter}%
    \expandafter\ted@subsmac@loop\the\ted@toks\ted@@nil#1\ted@@end}}
%    \end{macrocode}
% \end{macro}
% \begin{macro}{\ted@remove@nil}
% You probably noticed the \cs{ted@@nil} after \cs{ted@toks} in the
% above definition. This is to avoid problems while trying to
% substitute something like ``AA'' in a list ending with ``A'' (new in
% v1.05). We need to remove it when finished.
%    \begin{macrocode}
\@ifdefinable\ted@remove@nil{%
  \long\def\ted@remove@nil#1\ted@@nil{%
    \ted@toks{#1}}}
%    \end{macrocode}
% \end{macro}
%
% \subsection{Display}
% 
% \begin{macro}{\ted@ShowTokens}
% In order to display the tokens one by one, we first encode the string.
%    \begin{macrocode}
\newcommand\ted@ShowTokens[1]{%
  \begingroup \ted@sanitize
  \ted@toks{#1}%
  \ted@typeout{--- Begin token decomposition of:}%
  \ted@typeout{\@spaces \the\ted@toks}%
  \ted@encode{#1}%
  \expandafter\ted@show@toks\the\ted@toks\ted@@end
  \endgroup
  \ted@typeout{--- End token decomposition.}}
%    \end{macrocode}
% \end{macro}
% \begin{macro}{\ted@show@toks}
% Then we proceed, almost like decoding, iteratively, processing the
% encoded tokens one by one. We detect control sequences the same way as
% in pre-scanning. For our tests (and also for use in
% \cs{ted@show@toks@}) we embed |#1| into \cs{ted@toks} in order to
% nest the \cs{if}s without fear. There are four cases that need to be
% typeset in different ways : active character, CS that represent a
% special token, normal CS, normal character token. However, we need to
% do one more test to detect the character tokens whose charcode is
% $32$, before we apply \cs{string} to it in order to check if it was a
% control sequence.
%    \begin{macrocode}
\count@\catcode\z@ \catcode\z@ 12
\newcommand\ted@show@toks[1]{%
  \ted@toks{#1}\expandafter
  \ifx\the\ted@toks\ted@@end \else\expandafter
    \ifx\the\ted@toks\ted@@active
%    \end{macrocode}
% It's time to think about the following: we are inside a group where
% all active characters were redefined, but we nonetheless want to
% display their meaning. In order to do this, the display need to
% actually happen after the current group is finished. For this we use
% \cs{aftergroup} (with specialized macro for displaying each kind of
% token).
%    \begin{macrocode}
      \aftergroup\ted@type@active
      \expandafter\aftergroup\the\ted@toks
    \else
      \if\expandafter\noexpand\the\ted@toks\@sptoken
        \aftergroup\ted@type@normal
        \expandafter\aftergroup\the\ted@toks
      \else
        \begingroup
        \escapechar\if\noexpand#1^^00 \@ne \else \z@ \fi
        \expandafter\expandafter\expandafter\ted@show@toks@
        \expandafter\string\the\ted@toks\@nil
      \fi
    \fi
    \expandafter\ted@show@toks
  \fi}
\catcode\z@\count@
%    \end{macrocode}
% \end{macro}
% \begin{macro}{\ted@show@toks@}
% Now test the remaining cases : special CS, normal CS, or normal
% character. 
%    \begin{macrocode}
\@ifdefinable\ted@show@toks@{%
  \long\def\ted@show@toks@#1#2\@nil{%
    \expandafter\endgroup
    \ifnum`#1=\escapechar
      \expandafter\ifx\the\ted@toks\ted@@special
        \ted@show@special#2\@nil
      \else
        \aftergroup\ted@type@cs
        \expandafter\aftergroup\the\ted@toks
      \fi
    \else
      \aftergroup\ted@type@normal
      \expandafter\aftergroup\the\ted@toks
    \fi}}
%    \end{macrocode}
% \end{macro}
% \begin{macro}{\ted@show@special}
% Let's begin our tour of specialized display macro with the most
% important one: \cs{ted@show@special}. Displaying the special token
% goes mostly the same way as decoding them, but is far easier, since we
% don't need to care about groups: display is done with
% \cs{catcode}~$12$ characters.
%    \begin{macrocode}
\@ifdefinable\ted@show@special{%
  \begingroup\escapechar\m@ne \expandafter\endgroup
  \expandafter\def\expandafter\ted@show@special\string\ted@@#1#2\@nil{%
    \ifcase#1
      \aftergroup\ted@type@hash
    \or
      \aftergroup\ted@type@blank
    \or
      \aftergroup\ted@type@bgroup
    \or
      \aftergroup\ted@type@egroup
    \fi
    \begingroup \uccode`1#2
    \uppercase{\endgroup\aftergroup1}}}
%    \end{macrocode}
% \end{macro}
% \begin{macro}{\ted@type@hash}
% \begin{macro}{\ted@type@blank}
% \begin{macro}{\ted@type@bgroup}
% \begin{macro}{\ted@type@egroup}
% \begin{macro}{\ted@type@normal}
% The four macros for special tokens are obvious. So is the macro for
% normal tokens. By the way, \cs{ted@typeout} will be discussed in the
% next section.
%    \begin{macrocode}
\newcommand\ted@type@hash[1]{%
  \ted@typeout{#1 (macro parameter character #1)}}
%    \end{macrocode}
%    \begin{macrocode}
\newcommand\ted@type@blank[1]{%
  \ted@typeout{#1 (blank space #1)}}
%    \end{macrocode}
%    \begin{macrocode}
\newcommand\ted@type@bgroup[1]{%
  \ted@typeout{#1 (begin-group character #1)}}
%    \end{macrocode}
%    \begin{macrocode}
\newcommand\ted@type@egroup[1]{%
  \ted@typeout{#1 (end-group character #1)}}
%    \end{macrocode}
%    \begin{macrocode}
\newcommand\ted@type@normal[1]{%
  \ted@typeout{#1 (\meaning#1)}}
%    \end{macrocode}
% \end{macro}
% \end{macro}
% \end{macro}
% \end{macro}
% \end{macro}
% \begin{macro}{\ted@type@cs}
% \begin{macro}{\ted@type@active}
% For control sequences and active characters, we use more sophisticated
% macros. Indeed, their \cs{meaning} can be quite long, and since it is
% not so important (\pf{ted}'s work is lexical analysis, displaying the
% \cs{meaning} is just an add-on), we cut it so that lines are shorter
% than~$80$ colons, in order to save our one-token-a-line presentation.
%    \begin{macrocode}
\newcommand\ted@type@cs[1]{%
  \ted@type@long{\string#1 (control sequence=\meaning#1}}%
%    \end{macrocode}
%    \begin{macrocode}
\newcommand\ted@type@active[1]{%
  \ted@type@long{\string#1 (active character=\meaning#1}}%
%    \end{macrocode}
% \end{macro}
% \end{macro}
% \begin{macro}{\ted@type@long}
% Lines are cut and displayed by \cs{ted@type@long}. This macro uses a
% loop, counting down how many columns remain on the current line. The
% input need to be fully expanded first, and the output is stored in
% \cs{ted@toks}.
%    \begin{macrocode}
\newcommand\ted@type@long[1]{%
  \ted@toks{}%
  \ted@code72 
  \edef\next{#1}%
  \expandafter\ted@tl@loop\next\@nil}
%    \end{macrocode}
% \end{macro}
% \begin{macro}{\ted@tl@loop}
% The only difficult thing in this loop is to take care of space tokens.
% For this we use again our \cs{futurelet} trick:
%    \begin{macrocode}
\newcommand\ted@tl@loop{%
  \futurelet\@let@token
  \ted@tl@loop@}
%    \end{macrocode}
% \end{macro}
% \begin{macro}{\ted@tl@loop@}
% \ldots then check what to do.
%    \begin{macrocode}
\newcommand\ted@tl@loop@{%
  \ifx\@let@token\@nil
    \let\next\ted@tl@finish
  \else
    \advance\ted@code\m@ne
    \ifnum\ted@code<\z@
      \let\next\ted@tl@finish
    \else
      \ifx\@let@token\@sptoken
        \let\next\ted@tl@space
      \else
        \let\next\ted@tl@add
      \fi
    \fi
  \fi
  \next}
%    \end{macrocode}
% \end{macro}
% \begin{macro}{\ted@tl@add}
% \begin{macro}{\ted@tl@space}
% Normal characters are just grabbed and added without care, and spaces
% are gobbled with a special macro which also add a space to the output.
%    \begin{macrocode}
\newcommand*\ted@tl@add[1]{%
  \ted@toks\expandafter{\the\ted@toks #1}%
  \ted@tl@loop}
%    \end{macrocode}
%    \begin{macrocode}
\@ifdefinable\ted@tl@space{%
  \expandafter\def\expandafter\ted@tl@space\space{%
    \ted@tl@add{ }}}
%    \end{macrocode}
% \end{macro}
% \end{macro}
% \begin{macro}{\ted@tl@finish}
% When the end has been reached (either because a \cs{@nil} was
% encountered or because the line is almost full), it's time to
% actually display the result.  We add \cs{ETC.} at the end when the
% full \cs{meaning} isn't displayed.
%    \begin{macrocode}
\@ifdefinable\ted@tl@finish{%
  \def\ted@tl@finish#1\@nil{%
    \ifnum\ted@code<\z@
      \ted@typeout{\the\ted@toks\string\ETC.)}
    \else
      \ted@typeout{\the\ted@toks)}
    \fi}}
%    \end{macrocode}
% \end{macro}
%
% \subsection{User macros}
%
% \begin{macro}{\ted@typeout}
% Since we just discussed display, let's see the related user commands.
% Output is done with
%    \begin{macrocode}
\newcommand\ted@typeout{%
  \immediate\write\ted@outfile}
%    \end{macrocode}
% \end{macro}
% \begin{macro}{\ShowTokensOnline}
% \begin{macro}{\ShowTokensLogonly}
% allowing the user to choose between online display, or log output.
% Default is online.
%    \begin{macrocode}
\newcommand\ShowTokensOnline{%
  \let\ted@outfile\@unused}
%    \end{macrocode}
%    \begin{macrocode}
\newcommand\ShowTokensLogonly{%
  \let\ted@outfile\m@ne}
%    \end{macrocode}
%    \begin{macrocode}
\ShowTokensOnline
%    \end{macrocode}
% \end{macro}
% \end{macro}
% \begin{macro}{\ShowTokens}
% \begin{macro}{\ted@ShowTokens@exp}
% The user macro for showing tokens is a simple call to the internal
% macro, just expanding its argument once in its stared form.
%    \begin{macrocode}
\newcommand\ShowTokens{%
  \@ifstar{\ted@ShowTokens@exp}{\ted@ShowTokens}}
%    \end{macrocode}
%    \begin{macrocode}
\newcommand\ted@ShowTokens@exp[1]{%
  \expandafter\ted@ShowTokens\expandafter{#1}}
%    \end{macrocode}
% \end{macro}
% \end{macro}
%
% \begin{macro}{\Substitute}
% \begin{macro}{\ted@Subs@star}
% Now, the user macro for substitution. First, check how many stars
% there are, if any, and set \cs{ted@subs@cmd} accordingly.
%    \begin{macrocode}
\newcommand\Substitute{%
  \@ifstar
  {\ted@Subs@star}
  {\let\ted@Subs@cmd\ted@Substitute \ted@Subs}}
%    \end{macrocode}
%    \begin{macrocode}
\newcommand\ted@Subs@star{%
  \@ifstar
  {\let\ted@Subs@cmd\ted@Subs@exp@iii \ted@Subs}
  {\let\ted@Subs@cmd\ted@Subs@exp@i \ted@Subs}}
%    \end{macrocode}
% \end{macro}
% \end{macro}
% \begin{macro}{\ted@Subs@exp@i}
% \begin{macro}{\ted@Subs@exp@iii}
% Here are the intermediate macros that expand either the first or all
% three arguments before calling \cs{ted@Substitute}.
%    \begin{macrocode}
\newcommand\ted@Subs@exp@i{%
  \expandafter\ted@Substitute\expandafter}
%    \end{macrocode}
%    \begin{macrocode}
\newcommand\ted@Subs@exp@iii[3]{%
  \begingroup
  \toks0{\ted@Substitute}%
  \toks2\expandafter{#1}%
  \toks4\expandafter{#2}%
  \toks6\expandafter{#3}%
  \xdef\ted@Subs@cmd{\the\toks0{\the\toks2}{\the\toks4}{\the\toks6}}%
  \endgroup
  \ted@Subs@cmd}
%    \end{macrocode}
% \end{macro}
% \end{macro}
% \begin{macro}{\ted@Subs}
% Now, the last macro checks and process the optional argument. Here we
% set \cs{ted@output}, which will be used at the end of
% \cs{ted@Substitute}.
%    \begin{macrocode}
\newcommand\ted@Subs[1][\ted@toks]{%
  \def\ted@output{#1}%
  \ted@Subs@cmd}
%    \end{macrocode}
% \end{macro}
% \begin{macro}{\ted@output}
% Finally set a default \cs{ted@output} for advanced users who may want
% to use \cs{ted@Substitute} directly.
%    \begin{macrocode}
\let\ted@output\ted@toks
%    \end{macrocode}
% \end{macro}
%
% \bigskip
% \begin{center}\Large
% That's all folks!\\
% Happy \TeX ing!
% \end{center}
%
% \Finale
% 
% \iffalse
%</package>
%<*batchfile>
% \fi
% \begingroup\obeyspaces
% \typeout{*****************************************************}
% \typeout{*                                                   *}
% \typeout{* To finish the installation you have to move the   *}
% \typeout{* following file into a directory searched by TeX:  *}
% \typeout{*                                                   *}
% \typeout{*      ted.sty                                      *}
% \typeout{*                                                   *}
% \typeout{* Documentation is in ted.dvi or ted.pdf            *}
% \typeout{*                                                   *}
% \typeout{* To produce the french documentation, run          *}
% \typeout{*      (pdf)latex ted-fr.drv                        *}
% \typeout{*                                                   *}
% \typeout{* Happy TeXing!                                     *}
% \typeout{*                                                   *}
% \typeout{*****************************************************}
% \endgroup
% \iffalse
%</batchfile>
% \fi
\endinput