Source

emacs / lisp / pcomplete.el

Full commit
   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
;;; pcomplete.el --- programmable completion -*- lexical-binding: t -*-

;; Copyright (C) 1999-2011 Free Software Foundation, Inc.

;; Author: John Wiegley <johnw@gnu.org>
;; Keywords: processes abbrev

;; This file is part of GNU Emacs.

;; GNU Emacs is free software: you can redistribute it and/or modify
;; it under the terms of the GNU General Public License as published by
;; the Free Software Foundation, either version 3 of the License, or
;; (at your option) any later version.

;; GNU Emacs is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
;; GNU General Public License for more details.

;; You should have received a copy of the GNU General Public License
;; along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.

;;; Commentary:

;; This module provides a programmable completion facility using
;; "completion functions".  Each completion function is responsible
;; for producing a list of possible completions relevant to the current
;; argument position.
;;
;; To use pcomplete with shell-mode, for example, you will need the
;; following in your .emacs file:
;;
;;   (add-hook 'shell-mode-hook 'pcomplete-shell-setup)
;;
;; Most of the code below simply provides support mechanisms for
;; writing completion functions.  Completion functions themselves are
;; very easy to write.  They have few requirements beyond those of
;; regular Lisp functions.
;;
;; Consider the following example, which will complete against
;; filenames for the first two arguments, and directories for all
;; remaining arguments:
;;
;;   (defun pcomplete/my-command ()
;;     (pcomplete-here (pcomplete-entries))
;;     (pcomplete-here (pcomplete-entries))
;;     (while (pcomplete-here (pcomplete-dirs))))
;;
;; Here are the requirements for completion functions:
;;
;; @ They must be called "pcomplete/MAJOR-MODE/NAME", or
;;   "pcomplete/NAME".  This is how they are looked up, using the NAME
;;   specified in the command argument (the argument in first
;;   position).
;;
;; @ They must be callable with no arguments.
;;
;; @ Their return value is ignored.  If they actually return normally,
;;   it means no completions were available.
;;
;; @ In order to provide completions, they must throw the tag
;;   `pcomplete-completions'.  The value must be a completion table
;;   (i.e. a table that can be passed to try-completion and friends)
;;   for the final argument.
;;
;; @ To simplify completion function logic, the tag `pcompleted' may
;;   be thrown with a value of nil in order to abort the function.  It
;;   means that there were no completions available.
;;
;; When a completion function is called, the variable `pcomplete-args'
;; is in scope, and contains all of the arguments specified on the
;; command line.  The variable `pcomplete-last' is the index of the
;; last argument in that list.
;;
;; The variable `pcomplete-index' is used by the completion code to
;; know which argument the completion function is currently examining.
;; It always begins at 1, meaning the first argument after the command
;; name.
;;
;; To facilitate writing completion logic, a special macro,
;; `pcomplete-here', has been provided which does several things:
;;
;;  1. It will throw `pcompleted' (with a value of nil) whenever
;;     `pcomplete-index' exceeds `pcomplete-last'.
;;
;;  2. It will increment `pcomplete-index' if the final argument has
;;     not been reached yet.
;;
;;  3. It will evaluate the form passed to it, and throw the result
;;     using the `pcomplete-completions' tag, if it is called when
;;     `pcomplete-index' is pointing to the final argument.
;;
;; Sometimes a completion function will want to vary the possible
;; completions for an argument based on the previous one.  To
;; facilitate tests like this, the function `pcomplete-test' and
;; `pcomplete-match' are provided.  Called with one argument, they
;; test the value of the previous command argument.  Otherwise, a
;; relative index may be given as an optional second argument, where 0
;; refers to the current argument, 1 the previous, 2 the one before
;; that, etc.  The symbols `first' and `last' specify absolute
;; offsets.
;;
;; Here is an example which will only complete against directories for
;; the second argument if the first argument is also a directory:
;;
;;   (defun pcomplete/example ()
;;      (pcomplete-here (pcomplete-entries))
;;      (if (pcomplete-test 'file-directory-p)
;;          (pcomplete-here (pcomplete-dirs))
;;        (pcomplete-here (pcomplete-entries))))
;;
;; For generating completion lists based on directory contents, see
;; the functions `pcomplete-entries', `pcomplete-dirs',
;; `pcomplete-executables' and `pcomplete-all-entries'.
;;
;; Consult the documentation for `pcomplete-here' for information
;; about its other arguments.

;;; Code:

(eval-when-compile (require 'cl))

(defgroup pcomplete nil
  "Programmable completion."
  :version "21.1"
  :group 'processes)

;;; User Variables:

(defcustom pcomplete-file-ignore nil
  "A regexp of filenames to be disregarded during file completion."
  :type '(choice regexp (const :tag "None" nil))
  :group 'pcomplete)

(defcustom pcomplete-dir-ignore nil
  "A regexp of names to be disregarded during directory completion."
  :type '(choice regexp (const :tag "None" nil))
  :group 'pcomplete)

(defcustom pcomplete-ignore-case (memq system-type '(ms-dos windows-nt cygwin))
  ;; FIXME: the doc mentions file-name completion, but the code
  ;; seems to apply it to all completions.
  "If non-nil, ignore case when doing filename completion."
  :type 'boolean
  :group 'pcomplete)

(defcustom pcomplete-autolist nil
  "If non-nil, automatically list possibilities on partial completion.
This mirrors the optional behavior of tcsh."
  :type 'boolean
  :group 'pcomplete)

(defcustom pcomplete-suffix-list (list ?/ ?:)
  "A list of characters which constitute a proper suffix."
  :type '(repeat character)
  :group 'pcomplete)
(make-obsolete-variable 'pcomplete-suffix-list nil "24.1")

(defcustom pcomplete-recexact nil
  "If non-nil, use shortest completion if characters cannot be added.
This mirrors the optional behavior of tcsh.

A non-nil value is useful if `pcomplete-autolist' is non-nil too."
  :type 'boolean
  :group 'pcomplete)

(defcustom pcomplete-arg-quote-list nil
  "List of characters to quote when completing an argument."
  :type '(choice (repeat character)
		 (const :tag "Don't quote" nil))
  :group 'pcomplete)

(defcustom pcomplete-quote-arg-hook nil
  "A hook which is run to quote a character within a filename.
Each function is passed both the filename to be quoted, and the index
to be considered.  If the function wishes to provide an alternate
quoted form, it need only return the replacement string.  If no
function provides a replacement, quoting shall proceed as normal,
using a backslash to quote any character which is a member of
`pcomplete-arg-quote-list'."
  :type 'hook
  :group 'pcomplete)

(defcustom pcomplete-man-function 'man
  "A function to that will be called to display a manual page.
It will be passed the name of the command to document."
  :type 'function
  :group 'pcomplete)

(defcustom pcomplete-compare-entry-function 'string-lessp
  "This function is used to order file entries for completion.
The behavior of most all shells is to sort alphabetically."
  :type '(radio (function-item string-lessp)
		(function-item file-newer-than-file-p)
		(function :tag "Other"))
  :group 'pcomplete)

(defcustom pcomplete-help nil
  "A string or function (or nil) used for context-sensitive help.
If a string, it should name an Info node that will be jumped to.
If non-nil, it must a sexp that will be evaluated, and whose
result will be shown in the minibuffer.
If nil, the function `pcomplete-man-function' will be called with the
current command argument."
  :type '(choice string sexp (const :tag "Use man page" nil))
  :group 'pcomplete)

(defcustom pcomplete-expand-before-complete nil
  "If non-nil, expand the current argument before completing it.
This means that typing something such as '$HOME/bi' followed by
\\[pcomplete-argument] will cause the variable reference to be
resolved first, and the resultant value that will be completed against
to be inserted in the buffer.  Note that exactly what gets expanded
and how is entirely up to the behavior of the
`pcomplete-parse-arguments-function'."
  :type 'boolean
  :group 'pcomplete)

(defcustom pcomplete-parse-arguments-function
  'pcomplete-parse-buffer-arguments
  "A function to call to parse the current line's arguments.
It should be called with no parameters, and with point at the position
of the argument that is to be completed.

It must either return nil, or a cons cell of the form:

  ((ARG...) (BEG-POS...))

The two lists must be identical in length.  The first gives the final
value of each command line argument (which need not match the textual
representation of that argument), and BEG-POS gives the beginning
position of each argument, as it is seen by the user.  The establishes
a relationship between the fully resolved value of the argument, and
the textual representation of the argument."
  :type 'function
  :group 'pcomplete)

(defcustom pcomplete-cycle-completions t
  "If non-nil, hitting the TAB key cycles through the completion list.
Typical Emacs behavior is to complete as much as possible, then pause
waiting for further input.  Then if TAB is hit again, show a list of
possible completions.  When `pcomplete-cycle-completions' is non-nil,
it acts more like zsh or 4nt, showing the first maximal match first,
followed by any further matches on each subsequent pressing of the TAB
key.  \\[pcomplete-list] is the key to press if the user wants to see
the list of possible completions."
  :type 'boolean
  :group 'pcomplete)

(defcustom pcomplete-cycle-cutoff-length 5
  "If the number of completions is greater than this, don't cycle.
This variable is a compromise between the traditional Emacs style of
completion, and the \"cycling\" style.  Basically, if there are more
than this number of completions possible, don't automatically pick the
first one and then expect the user to press TAB to cycle through them.
Typically, when there are a large number of completion possibilities,
the user wants to see them in a list buffer so that they can know what
options are available.  But if the list is small, it means the user
has already entered enough input to disambiguate most of the
possibilities, and therefore they are probably most interested in
cycling through the candidates.  Set this value to nil if you want
cycling to always be enabled."
  :type '(choice integer (const :tag "Always cycle" nil))
  :group 'pcomplete)

(defcustom pcomplete-restore-window-delay 1
  "The number of seconds to wait before restoring completion windows.
Once the completion window has been displayed, if the user then goes
on to type something else, that completion window will be removed from
the display (actually, the original window configuration before it was
displayed will be restored), after this many seconds of idle time.  If
set to nil, completion windows will be left on second until the user
removes them manually.  If set to 0, they will disappear immediately
after the user enters a key other than TAB."
  :type '(choice integer (const :tag "Never restore" nil))
  :group 'pcomplete)

(defcustom pcomplete-try-first-hook nil
  "A list of functions which are called before completing an argument.
This can be used, for example, for completing things which might apply
to all arguments, such as variable names after a $."
  :type 'hook
  :group 'pcomplete)

(defsubst pcomplete-executables (&optional regexp)
  "Complete amongst a list of directories and executables."
  (pcomplete-entries regexp 'file-executable-p))

(defcustom pcomplete-command-completion-function
  (function
   (lambda ()
     (pcomplete-here (pcomplete-executables))))
  "Function called for completing the initial command argument."
  :type 'function
  :group 'pcomplete)

(defcustom pcomplete-command-name-function 'pcomplete-command-name
  "Function called for determining the current command name."
  :type 'function
  :group 'pcomplete)

(defcustom pcomplete-default-completion-function
  (function
   (lambda ()
     (while (pcomplete-here (pcomplete-entries)))))
  "Function called when no completion rule can be found.
This function is used to generate completions for every argument."
  :type 'function
  :group 'pcomplete)

(defcustom pcomplete-use-paring t
  "If t, pare alternatives that have already been used.
If nil, you will always see the completion set of possible options, no
matter which of those options have already been used in previous
command arguments."
  :type 'boolean
  :group 'pcomplete)

(defcustom pcomplete-termination-string " "
  "A string that is inserted after any completion or expansion.
This is usually a space character, useful when completing lists of
words separated by spaces.  However, if your list uses a different
separator character, or if the completion occurs in a word that is
already terminated by a character, this variable should be locally
modified to be an empty string, or the desired separation string."
  :type 'string
  :group 'pcomplete)

;;; Internal Variables:

;; for cycling completion support
(defvar pcomplete-current-completions nil)
(defvar pcomplete-last-completion-length)
(defvar pcomplete-last-completion-stub)
(defvar pcomplete-last-completion-raw)
(defvar pcomplete-last-window-config nil)
(defvar pcomplete-window-restore-timer nil)

(make-variable-buffer-local 'pcomplete-current-completions)
(make-variable-buffer-local 'pcomplete-last-completion-length)
(make-variable-buffer-local 'pcomplete-last-completion-stub)
(make-variable-buffer-local 'pcomplete-last-completion-raw)
(make-variable-buffer-local 'pcomplete-last-window-config)
(make-variable-buffer-local 'pcomplete-window-restore-timer)

;; used for altering pcomplete's behavior.  These global variables
;; should always be nil.
(defvar pcomplete-show-help nil)
(defvar pcomplete-show-list nil)
(defvar pcomplete-expand-only-p nil)

;; for the sake of the bye-compiler, when compiling other files that
;; contain completion functions
(defvar pcomplete-args nil)
(defvar pcomplete-begins nil)
(defvar pcomplete-last nil)
(defvar pcomplete-index nil)
(defvar pcomplete-stub nil)
(defvar pcomplete-seen nil)
(defvar pcomplete-norm-func nil)

;;; User Functions:

;;; Alternative front-end using the standard completion facilities.

;; The way pcomplete-parse-arguments, pcomplete-stub, and
;; pcomplete-quote-argument work only works because of some deep
;; hypothesis about the way the completion work.  Basically, it makes
;; it pretty much impossible to have completion other than
;; prefix-completion.
;;
;; pcomplete--common-quoted-suffix and pcomplete--table-subvert try to
;; work around this difficulty with heuristics, but it's
;; really a hack.

(defvar pcomplete-unquote-argument-function nil)

(defun pcomplete-unquote-argument (s)
  (cond
   (pcomplete-unquote-argument-function
    (funcall pcomplete-unquote-argument-function s))
   ((null pcomplete-arg-quote-list) s)
   (t
    (replace-regexp-in-string "\\\\\\(.\\)" "\\1" s t))))

(defun pcomplete--common-suffix (s1 s2)
  (assert (not (or (string-match "\n" s1) (string-match "\n" s2))))
  ;; Since S2 is expected to be the "unquoted/expanded" version of S1,
  ;; there shouldn't be any case difference, even if the completion is
  ;; case-insensitive.
  (let ((case-fold-search nil)) ;; pcomplete-ignore-case
    (string-match ".*?\\(.*\\)\n.*\\1\\'" (concat s1 "\n" s2))
    (- (match-end 1) (match-beginning 1))))

(defun pcomplete--common-quoted-suffix (s1 s2)
  "Find the common suffix between S1 and S2 where S1 is the expanded S2.
S1 is expected to be the unquoted and expanded version of S1.
Returns (PS1 . PS2), i.e. the shortest prefixes of S1 and S2, such that
S1 = (concat PS1 SS1) and S2 = (concat PS2 SS2) and
SS1 = (unquote SS2)."
  (let* ((cs (pcomplete--common-suffix s1 s2))
         (ss1 (substring s1 (- (length s1) cs)))
         (qss1 (pcomplete-quote-argument ss1))
         qc)
    (if (and (not (equal ss1 qss1))
             (setq qc (pcomplete-quote-argument (substring ss1 0 1)))
             (eq t (compare-strings s2 (- (length s2) cs (length qc) -1)
                                    (- (length s2) cs -1)
                                    qc nil nil)))
        ;; The difference found is just that one char is quoted in S2
        ;; but not in S1, keep looking before this difference.
        (pcomplete--common-quoted-suffix
         (substring s1 0 (- (length s1) cs))
         (substring s2 0 (- (length s2) cs (length qc) -1)))
      (cons (substring s1 0 (- (length s1) cs))
            (substring s2 0 (- (length s2) cs))))))

(defun pcomplete--table-subvert (table s1 s2 string pred action)
  "Completion table that replaces the prefix S1 with S2 in STRING.
When TABLE, S1 and S2 are provided by `apply-partially', the result
is a completion table which completes strings of the form (concat S1 S)
in the same way as TABLE completes strings of the form (concat S2 S)."
  (let* ((str (if (eq t (compare-strings string 0 (length s1) s1 nil nil
                                         completion-ignore-case))
                  (concat s2 (pcomplete-unquote-argument
                              (substring string (length s1))))))
         (res (if str (complete-with-action action table str pred))))
    (when res
      (cond
       ((and (eq (car-safe action) 'boundaries))
        (let ((beg (or (and (eq (car-safe res) 'boundaries) (cadr res)) 0)))
          (list* 'boundaries
                 (max (length s1)
                      ;; FIXME: Adjust because of quoting/unquoting.
                      (+ beg (- (length s1) (length s2))))
                 (and (eq (car-safe res) 'boundaries) (cddr res)))))
       ((stringp res)
        (if (eq t (compare-strings res 0 (length s2) s2 nil nil
                                   completion-ignore-case))
            (concat s1 (pcomplete-quote-argument
                        (substring res (length s2))))))
       ((eq action t)
        (let ((bounds (completion-boundaries str table pred "")))
          (if (>= (car bounds) (length s2))
              res
            (let ((re (concat "\\`"
                              (regexp-quote (substring s2 (car bounds))))))
              (delq nil
                    (mapcar (lambda (c)
                              (if (string-match re c)
                                  (substring c (match-end 0))))
                            res))))))))))

;; I don't think such commands are usable before first setting up buffer-local
;; variables to parse args, so there's no point autoloading it.
;; ;;;###autoload
(defun pcomplete-completions-at-point ()
  "Provide standard completion using pcomplete's completion tables.
Same as `pcomplete' but using the standard completion UI."
  ;; FIXME: it only completes the text before point, whereas the
  ;; standard UI may also consider text after point.
  ;; FIXME: the `pcomplete' UI may be used internally during
  ;; pcomplete-completions and then throw to `pcompleted', thus
  ;; imposing the pcomplete UI over the standard UI.
  (catch 'pcompleted
    (let* ((pcomplete-stub)
           pcomplete-seen pcomplete-norm-func
           pcomplete-args pcomplete-last pcomplete-index
           (pcomplete-autolist pcomplete-autolist)
           (pcomplete-suffix-list pcomplete-suffix-list)
           ;; Apparently the vars above are global vars modified by
           ;; side-effects, whereas pcomplete-completions is the core
           ;; function that finds the chunk of text to complete
           ;; (returned indirectly in pcomplete-stub) and the set of
           ;; possible completions.
           (completions (pcomplete-completions))
           ;; Usually there's some close connection between pcomplete-stub
           ;; and the text before point.  But depending on what
           ;; pcomplete-parse-arguments-function does, that connection
           ;; might not be that close.  E.g. in eshell,
           ;; pcomplete-parse-arguments-function expands envvars.
           ;;
           ;; Since we use minibuffer-complete, which doesn't know
           ;; pcomplete-stub and works from the buffer's text instead,
           ;; we need to trick minibuffer-complete, into using
           ;; pcomplete-stub without its knowledge.  To that end, we
           ;; use pcomplete--table-subvert to construct a completion
           ;; table which expects strings using a prefix from the
           ;; buffer's text but internally uses the corresponding
           ;; prefix from pcomplete-stub.
           (beg (max (- (point) (length pcomplete-stub))
                     (pcomplete-begin)))
           (buftext (buffer-substring beg (point))))
      (when completions
        (let ((table
               (cond
                ((not (equal pcomplete-stub buftext))
                 ;; This isn't always strictly right (e.g. if
                 ;; FOO="toto/$FOO", then completion of /$FOO/bar may
                 ;; result in something incorrect), but given the lack of
                 ;; any other info, it's about as good as it gets, and in
                 ;; practice it should work just fine (fingers crossed).
                 (let ((prefixes (pcomplete--common-quoted-suffix
                                  pcomplete-stub buftext)))
                   (apply-partially #'pcomplete--table-subvert
                                    completions
                                    (cdr prefixes) (car prefixes))))
                (t
                 (lambda (string pred action)
                   (let ((res (complete-with-action
                               action completions string pred)))
                     (if (stringp res)
                         (pcomplete-quote-argument res)
                       res))))))
              (pred
               ;; Pare it down, if applicable.
               (when (and pcomplete-use-paring pcomplete-seen)
                 ;; Capture the dynbound values for later use.
                 (let ((norm-func pcomplete-norm-func)
                       (seen
			(mapcar (lambda (f)
				  (funcall pcomplete-norm-func
					   (directory-file-name f)))
				pcomplete-seen)))
                   (lambda (f)
                     (not (member
                           (funcall norm-func (directory-file-name f))
                           seen)))))))
          (when pcomplete-ignore-case
            (setq table
                  (apply-partially #'completion-table-case-fold table)))
          (list beg (point) table
                :predicate pred
                :exit-function
                (unless (zerop (length pcomplete-termination-string))
                  (lambda (_s finished)
                    (when (memq finished '(sole finished))
                      (if (looking-at
                           (regexp-quote pcomplete-termination-string))
                          (goto-char (match-end 0))
                        (insert pcomplete-termination-string)))))))))))

 ;; I don't think such commands are usable before first setting up buffer-local
 ;; variables to parse args, so there's no point autoloading it.
 ;; ;;;###autoload
(defun pcomplete-std-complete ()
  (let ((data (pcomplete-completions-at-point)))
    (completion-in-region (nth 0 data) (nth 1 data) (nth 2 data)
                          (plist-get :predicate (nthcdr 3 data)))))

;;; Pcomplete's native UI.

;;;###autoload
(defun pcomplete (&optional interactively)
  "Support extensible programmable completion.
To use this function, just bind the TAB key to it, or add it to your
completion functions list (it should occur fairly early in the list)."
  (interactive "p")
  (if (and interactively
	   pcomplete-cycle-completions
	   pcomplete-current-completions
	   (memq last-command '(pcomplete
				pcomplete-expand-and-complete
				pcomplete-reverse)))
      (progn
	(delete-char (- pcomplete-last-completion-length))
	(if (eq this-command 'pcomplete-reverse)
	    (progn
              (push (car (last pcomplete-current-completions))
                    pcomplete-current-completions)
	      (setcdr (last pcomplete-current-completions 2) nil))
	  (nconc pcomplete-current-completions
		 (list (car pcomplete-current-completions)))
	  (setq pcomplete-current-completions
		(cdr pcomplete-current-completions)))
	(pcomplete-insert-entry pcomplete-last-completion-stub
                                (car pcomplete-current-completions)
				nil pcomplete-last-completion-raw))
    (setq pcomplete-current-completions nil
	  pcomplete-last-completion-raw nil)
    (catch 'pcompleted
      (let* ((pcomplete-stub)
	     pcomplete-seen pcomplete-norm-func
	     pcomplete-args pcomplete-last pcomplete-index
	     (pcomplete-autolist pcomplete-autolist)
	     (pcomplete-suffix-list pcomplete-suffix-list)
	     (completions (pcomplete-completions))
	     (result (pcomplete-do-complete pcomplete-stub completions)))
	(and result
	     (not (eq (car result) 'listed))
	     (cdr result)
	     (pcomplete-insert-entry pcomplete-stub (cdr result)
				     (memq (car result)
					   '(sole shortest))
				     pcomplete-last-completion-raw))))))

;;;###autoload
(defun pcomplete-reverse ()
  "If cycling completion is in use, cycle backwards."
  (interactive)
  (call-interactively 'pcomplete))

;;;###autoload
(defun pcomplete-expand-and-complete ()
  "Expand the textual value of the current argument.
This will modify the current buffer."
  (interactive)
  (let ((pcomplete-expand-before-complete t))
    (pcomplete)))

;;;###autoload
(defun pcomplete-continue ()
  "Complete without reference to any cycling completions."
  (interactive)
  (setq pcomplete-current-completions nil
	pcomplete-last-completion-raw nil)
  (call-interactively 'pcomplete))

;;;###autoload
(defun pcomplete-expand ()
  "Expand the textual value of the current argument.
This will modify the current buffer."
  (interactive)
  (let ((pcomplete-expand-before-complete t)
	(pcomplete-expand-only-p t))
    (pcomplete)
    (when (and pcomplete-current-completions
	       (> (length pcomplete-current-completions) 0)) ;??
      (delete-char (- pcomplete-last-completion-length))
      (while pcomplete-current-completions
	(unless (pcomplete-insert-entry
		 "" (car pcomplete-current-completions) t
                 pcomplete-last-completion-raw)
	  (insert-and-inherit pcomplete-termination-string))
	(setq pcomplete-current-completions
	      (cdr pcomplete-current-completions))))))

;;;###autoload
(defun pcomplete-help ()
  "Display any help information relative to the current argument."
  (interactive)
  (let ((pcomplete-show-help t))
    (pcomplete)))

;;;###autoload
(defun pcomplete-list ()
  "Show the list of possible completions for the current argument."
  (interactive)
  (when (and pcomplete-cycle-completions
	     pcomplete-current-completions
	     (eq last-command 'pcomplete-argument))
    (delete-char (- pcomplete-last-completion-length))
    (setq pcomplete-current-completions nil
	  pcomplete-last-completion-raw nil))
  (let ((pcomplete-show-list t))
    (pcomplete)))

;;; Internal Functions:

;; argument handling
(defun pcomplete-arg (&optional index offset)
  "Return the textual content of the INDEXth argument.
INDEX is based from the current processing position.  If INDEX is
positive, values returned are closer to the command argument; if
negative, they are closer to the last argument.  If the INDEX is
outside of the argument list, nil is returned.  The default value for
INDEX is 0, meaning the current argument being examined.

The special indices `first' and `last' may be used to access those
parts of the list.

The OFFSET argument is added to/taken away from the index that will be
used.  This is really only useful with `first' and `last', for
accessing absolute argument positions."
  (setq index
	(if (eq index 'first)
	    0
	  (if (eq index 'last)
	      pcomplete-last
	    (- pcomplete-index (or index 0)))))
  (if offset
      (setq index (+ index offset)))
  (nth index pcomplete-args))

(defun pcomplete-begin (&optional index offset)
  "Return the beginning position of the INDEXth argument.
See the documentation for `pcomplete-arg'."
  (setq index
	(if (eq index 'first)
	    0
	  (if (eq index 'last)
	      pcomplete-last
	    (- pcomplete-index (or index 0)))))
  (if offset
      (setq index (+ index offset)))
  (nth index pcomplete-begins))

(defsubst pcomplete-actual-arg (&optional index offset)
  "Return the actual text representation of the last argument.
This is different from `pcomplete-arg', which returns the textual value
that the last argument evaluated to.  This function returns what the
user actually typed in."
  (buffer-substring (pcomplete-begin index offset) (point)))

(defsubst pcomplete-next-arg ()
  "Move the various pointers to the next argument."
  (setq pcomplete-index (1+ pcomplete-index)
	pcomplete-stub (pcomplete-arg))
  (if (> pcomplete-index pcomplete-last)
      (progn
	(message "No completions")
	(throw 'pcompleted nil))))

(defun pcomplete-command-name ()
  "Return the command name of the first argument."
  (file-name-nondirectory (pcomplete-arg 'first)))

(defun pcomplete-match (regexp &optional index offset start)
  "Like `string-match', but on the current completion argument."
  (let ((arg (pcomplete-arg (or index 1) offset)))
    (if arg
	(string-match regexp arg start)
      (throw 'pcompleted nil))))

(defun pcomplete-match-string (which &optional index offset)
  "Like `match-string', but on the current completion argument."
  (let ((arg (pcomplete-arg (or index 1) offset)))
    (if arg
	(match-string which arg)
      (throw 'pcompleted nil))))

(defalias 'pcomplete-match-beginning 'match-beginning)
(defalias 'pcomplete-match-end 'match-end)

(defsubst pcomplete--test (pred arg)
  "Perform a programmable completion predicate match."
  (and pred
       (cond ((eq pred t) t)
	     ((functionp pred)
	      (funcall pred arg))
	     ((stringp pred)
	      (string-match (concat "^" pred "$") arg)))
       pred))

(defun pcomplete-test (predicates &optional index offset)
  "Predicates to test the current programmable argument with."
  (let ((arg (pcomplete-arg (or index 1) offset)))
    (unless (null predicates)
      (if (not (listp predicates))
	  (pcomplete--test predicates arg)
	(let ((pred predicates)
	      found)
	  (while (and pred (not found))
	    (setq found (pcomplete--test (car pred) arg)
		  pred (cdr pred)))
	  found)))))

(defun pcomplete-parse-buffer-arguments ()
  "Parse whitespace separated arguments in the current region."
  (let ((begin (point-min))
	(end (point-max))
	begins args)
    (save-excursion
      (goto-char begin)
      (while (< (point) end)
	(skip-chars-forward " \t\n")
	(push (point) begins)
	(skip-chars-forward "^ \t\n")
	(push (buffer-substring-no-properties
               (car begins) (point))
              args))
      (cons (nreverse args) (nreverse begins)))))

;;;###autoload
(defun pcomplete-comint-setup (completef-sym)
  "Setup a comint buffer to use pcomplete.
COMPLETEF-SYM should be the symbol where the
dynamic-complete-functions are kept.  For comint mode itself,
this is `comint-dynamic-complete-functions'."
  (set (make-local-variable 'pcomplete-parse-arguments-function)
       'pcomplete-parse-comint-arguments)
  (add-hook 'completion-at-point-functions
            'pcomplete-completions-at-point nil 'local)
  (set (make-local-variable completef-sym)
       (copy-sequence (symbol-value completef-sym)))
  (let* ((funs (symbol-value completef-sym))
	 (elem (or (memq 'comint-filename-completion funs)
                   (memq 'shell-filename-completion funs)
                   (memq 'shell-dynamic-complete-filename funs)
		   (memq 'comint-dynamic-complete-filename funs))))
    (if elem
	(setcar elem 'pcomplete)
      (add-to-list completef-sym 'pcomplete))))

;;;###autoload
(defun pcomplete-shell-setup ()
  "Setup `shell-mode' to use pcomplete."
  ;; FIXME: insufficient
  (pcomplete-comint-setup 'comint-dynamic-complete-functions))

(declare-function comint-bol "comint" (&optional arg))

(defun pcomplete-parse-comint-arguments ()
  "Parse whitespace separated arguments in the current region."
  (let ((begin (save-excursion (comint-bol nil) (point)))
	(end (point))
	begins args)
    (save-excursion
      (goto-char begin)
      (while (< (point) end)
	(skip-chars-forward " \t\n")
	(push (point) begins)
        (while
            (progn
              (skip-chars-forward "^ \t\n\\")
              (when (eq (char-after) ?\\)
                (forward-char 1)
                (unless (eolp)
                  (forward-char 1)
                  t))))
	(push (buffer-substring-no-properties (car begins) (point))
              args))
      (cons (nreverse args) (nreverse begins)))))
(make-obsolete 'pcomplete-parse-comint-arguments
               'comint-parse-pcomplete-arguments "24.1")

(defun pcomplete-parse-arguments (&optional expand-p)
  "Parse the command line arguments.  Most completions need this info."
  (let ((results (funcall pcomplete-parse-arguments-function)))
    (when results
      (setq pcomplete-args (or (car results) (list ""))
	    pcomplete-begins (or (cdr results) (list (point)))
	    pcomplete-last (1- (length pcomplete-args))
	    pcomplete-index 0
	    pcomplete-stub (pcomplete-arg 'last))
      (let ((begin (pcomplete-begin 'last)))
	(if (and pcomplete-cycle-completions
		 (listp pcomplete-stub) ;??
		 (not pcomplete-expand-only-p))
	    (let* ((completions pcomplete-stub) ;??
		   (common-stub (car completions))
		   (c completions)
		   (len (length common-stub)))
	      (while (and c (> len 0))
		(while (and (> len 0)
			    (not (string=
				  (substring common-stub 0 len)
				  (substring (car c) 0
					     (min (length (car c))
						  len)))))
		  (setq len (1- len)))
		(setq c (cdr c)))
	      (setq pcomplete-stub (substring common-stub 0 len)
		    pcomplete-autolist t)
	      (when (and begin (not pcomplete-show-list))
		(delete-region begin (point))
		(pcomplete-insert-entry "" pcomplete-stub))
	      (throw 'pcomplete-completions completions))
	  (when expand-p
	    (if (stringp pcomplete-stub)
		(when begin
		  (delete-region begin (point))
		  (insert-and-inherit pcomplete-stub))
	      (if (and (listp pcomplete-stub)
		       pcomplete-expand-only-p)
		  ;; this is for the benefit of `pcomplete-expand'
		  (setq pcomplete-last-completion-length (- (point) begin)
			pcomplete-current-completions pcomplete-stub)
		(error "Cannot expand argument"))))
	  (if pcomplete-expand-only-p
	      (throw 'pcompleted t)
	    pcomplete-args))))))

(defun pcomplete-quote-argument (filename)
  "Return FILENAME with magic characters quoted.
Magic characters are those in `pcomplete-arg-quote-list'."
  (if (null pcomplete-arg-quote-list)
      filename
    (let ((index 0))
      (mapconcat (lambda (c)
                   (prog1
                       (or (run-hook-with-args-until-success
                            'pcomplete-quote-arg-hook filename index)
                           (when (memq c pcomplete-arg-quote-list)
                             (string ?\\ c))
                           (char-to-string c))
                     (setq index (1+ index))))
                 filename
                 ""))))

;; file-system completion lists

(defsubst pcomplete-dirs-or-entries (&optional regexp predicate)
  "Return either directories, or qualified entries."
  (pcomplete-entries
   nil
   (lambda (f)
     (or (file-directory-p f)
         (and (or (null regexp) (string-match regexp f))
              (or (null predicate) (funcall predicate f)))))))

(defun pcomplete--entries (&optional regexp predicate)
  "Like `pcomplete-entries' but without env-var handling."
  (let* ((ign-pred
          (when (or pcomplete-file-ignore pcomplete-dir-ignore)
            ;; Capture the dynbound value for later use.
            (let ((file-ignore pcomplete-file-ignore)
                  (dir-ignore pcomplete-dir-ignore))
              (lambda (file)
                (not
                 (if (eq (aref file (1- (length file))) ?/)
                     (and dir-ignore (string-match dir-ignore file))
                   (and file-ignore (string-match file-ignore file))))))))
         (reg-pred (if regexp (lambda (file) (string-match regexp file))))
         (pred (cond
                ((null (or ign-pred reg-pred))  predicate)
                ((null (or ign-pred predicate)) reg-pred)
                ((null (or reg-pred predicate)) ign-pred)
                (t (lambda (f)
                     (and (or (null reg-pred)  (funcall reg-pred f))
                          (or (null ign-pred)  (funcall ign-pred f))
                          (or (null predicate) (funcall predicate f))))))))
    (lambda (s p a)
      (if (and (eq a 'metadata) pcomplete-compare-entry-function)
          `(metadata (cycle-sort-function
                      . ,(lambda (comps)
                           (sort comps pcomplete-compare-entry-function)))
                     ,@(cdr (completion-file-name-table s p a)))
        (let ((completion-ignored-extensions nil))
          (completion-table-with-predicate
           'completion-file-name-table pred 'strict s p a))))))

(defconst pcomplete--env-regexp
  "\\(?:\\`\\|[^\\]\\)\\(?:\\\\\\\\\\)*\\(\\$\\(?:{\\([^}]+\\)}\\|\\(?2:[[:alnum:]_]+\\)\\)\\)")

(defun pcomplete-entries (&optional regexp predicate)
  "Complete against a list of directory candidates.
If REGEXP is non-nil, it is a regular expression used to refine the
match (files not matching the REGEXP will be excluded).
If PREDICATE is non-nil, it will also be used to refine the match
\(files for which the PREDICATE returns nil will be excluded).
If no directory information can be extracted from the completed
component, `default-directory' is used as the basis for completion."
  ;; FIXME: The old code did env-var expansion here, so we reproduce this
  ;; behavior for now, but really env-var handling should be performed globally
  ;; rather than here since it also applies to non-file arguments.
  (let ((table (pcomplete--entries regexp predicate)))
    (lambda (string pred action)
      (let ((strings nil)
            (orig-length (length string)))
        ;; Perform env-var expansion.
        (while (string-match pcomplete--env-regexp string)
          (push (substring string 0 (match-beginning 1)) strings)
          (push (getenv (match-string 2 string)) strings)
          (setq string (substring string (match-end 1))))
        (if (not (and strings
                      (or (eq action t)
                          (eq (car-safe action) 'boundaries))))
            (let ((newstring
                   (mapconcat 'identity (nreverse (cons string strings)) "")))
              ;; FIXME: We could also try to return unexpanded envvars.
              (complete-with-action action table newstring pred))
          (let* ((envpos (apply #'+ (mapcar #' length strings)))
                 (newstring
                  (mapconcat 'identity (nreverse (cons string strings)) ""))
                 (bounds (completion-boundaries newstring table pred
                                                (or (cdr-safe action) ""))))
            (if (>= (car bounds) envpos)
                ;; The env-var is "out of bounds".
                (if (eq action t)
                    (complete-with-action action table newstring pred)
                  (list* 'boundaries
                         (+ (car bounds) (- orig-length (length newstring)))
                         (cdr bounds)))
              ;; The env-var is in the file bounds.
              (if (eq action t)
                  (let ((comps (complete-with-action
                                action table newstring pred))
                        (len (- envpos (car bounds))))
                    ;; Strip the part of each completion that's actually
                    ;; coming from the env-var.
                    (mapcar (lambda (s) (substring s len)) comps))
                (list* 'boundaries
                       (+ envpos (- orig-length (length newstring)))
                       (cdr bounds))))))))))

(defsubst pcomplete-all-entries (&optional regexp predicate)
  "Like `pcomplete-entries', but doesn't ignore any entries."
  (let (pcomplete-file-ignore
	pcomplete-dir-ignore)
    (pcomplete-entries regexp predicate)))

(defsubst pcomplete-dirs (&optional regexp)
  "Complete amongst a list of directories."
  (pcomplete-entries regexp 'file-directory-p))

;; generation of completion lists

(defun pcomplete-find-completion-function (command)
  "Find the completion function to call for the given COMMAND."
  (let ((sym (intern-soft
	      (concat "pcomplete/" (symbol-name major-mode) "/" command))))
    (unless sym
      (setq sym (intern-soft (concat "pcomplete/" command))))
    (and sym (fboundp sym) sym)))

(defun pcomplete-completions ()
  "Return a list of completions for the current argument position."
  (catch 'pcomplete-completions
    (when (pcomplete-parse-arguments pcomplete-expand-before-complete)
      (if (= pcomplete-index pcomplete-last)
	  (funcall pcomplete-command-completion-function)
	(let ((sym (or (pcomplete-find-completion-function
			(funcall pcomplete-command-name-function))
		       pcomplete-default-completion-function)))
	  (ignore
	   (pcomplete-next-arg)
	   (funcall sym)))))))

(defun pcomplete-opt (options &optional prefix _no-ganging _args-follow)
  "Complete a set of OPTIONS, each beginning with PREFIX (?- by default).
PREFIX may be t, in which case no PREFIX character is necessary.
If NO-GANGING is non-nil, each option is separate (-xy is not allowed).
If ARGS-FOLLOW is non-nil, then options which take arguments may have
the argument appear after a ganged set of options.  This is how tar
behaves, for example.
Arguments NO-GANGING and ARGS-FOLLOW are currently ignored."
  (if (and (= pcomplete-index pcomplete-last)
	   (string= (pcomplete-arg) "-"))
      (let ((len (length options))
	    (index 0)
	    char choices)
	(while (< index len)
	  (setq char (aref options index))
	  (if (eq char ?\()
	      (let ((result (read-from-string options index)))
		(setq index (cdr result)))
	    (unless (memq char '(?/ ?* ?? ?.))
	      (push (char-to-string char) choices))
	    (setq index (1+ index))))
	(throw 'pcomplete-completions
	       (mapcar
		(function
		 (lambda (opt)
		   (concat "-" opt)))
		(pcomplete-uniqify-list choices))))
    (let ((arg (pcomplete-arg)))
      (when (and (> (length arg) 1)
		 (stringp arg)
		 (eq (aref arg 0) (or prefix ?-)))
	(pcomplete-next-arg)
	(let ((char (aref arg 1))
	      (len (length options))
	      (index 0)
	      opt-char arg-char result)
	  (while (< (1+ index) len)
	    (setq opt-char (aref options index)
		  arg-char (aref options (1+ index)))
	    (if (eq arg-char ?\()
		(setq result
		      (read-from-string options (1+ index))
		      index (cdr result)
		      result (car result))
	      (setq result nil))
	    (when (and (eq char opt-char)
		       (memq arg-char '(?\( ?/ ?* ?? ?.)))
	      (if (< pcomplete-index pcomplete-last)
		  (pcomplete-next-arg)
		(throw 'pcomplete-completions
		       (cond ((eq arg-char ?/) (pcomplete-dirs))
			     ((eq arg-char ?*) (pcomplete-executables))
			     ((eq arg-char ??) nil)
			     ((eq arg-char ?.) (pcomplete-entries))
			     ((eq arg-char ?\() (eval result))))))
	    (setq index (1+ index))))))))

(defun pcomplete--here (&optional form stub paring form-only)
  "Complete against the current argument, if at the end.
See the documentation for `pcomplete-here'."
  (if (< pcomplete-index pcomplete-last)
      (progn
	(if (eq paring 0)
	    (setq pcomplete-seen nil)
	  (unless (eq paring t)
	    (let ((arg (pcomplete-arg)))
	      (when (stringp arg)
                (push (if paring
                          (funcall paring arg)
                        (file-truename arg))
                      pcomplete-seen)))))
	(pcomplete-next-arg)
	t)
    (when pcomplete-show-help
      (pcomplete--help)
      (throw 'pcompleted t))
    (if stub
	(setq pcomplete-stub stub))
    (if (or (eq paring t) (eq paring 0))
	(setq pcomplete-seen nil)
      (setq pcomplete-norm-func (or paring 'file-truename)))
    (unless form-only
      (run-hooks 'pcomplete-try-first-hook))
    (throw 'pcomplete-completions
           (if (functionp form)
               (funcall form)
             ;; Old calling convention, might still be used by files
             ;; byte-compiled with the older code.
             (eval form)))))

(defmacro pcomplete-here (&optional form stub paring form-only)
  "Complete against the current argument, if at the end.
If completion is to be done here, evaluate FORM to generate the completion
table which will be used for completion purposes.  If STUB is a
string, use it as the completion stub instead of the default (which is
the entire text of the current argument).

For an example of when you might want to use STUB: if the current
argument text is 'long-path-name/', you don't want the completions
list display to be cluttered by 'long-path-name/' appearing at the
beginning of every alternative.  Not only does this make things less
intelligible, but it is also inefficient.  Yet, if the completion list
does not begin with this string for every entry, the current argument
won't complete correctly.

The solution is to specify a relative stub.  It allows you to
substitute a different argument from the current argument, almost
always for the sake of efficiency.

If PARING is nil, this argument will be pared against previous
arguments using the function `file-truename' to normalize them.
PARING may be a function, in which case that function is used for
normalization.  If PARING is t, the argument dealt with by this
call will not participate in argument paring.  If it is the
integer 0, all previous arguments that have been seen will be
cleared.

If FORM-ONLY is non-nil, only the result of FORM will be used to
generate the completions list.  This means that the hook
`pcomplete-try-first-hook' will not be run."
  (declare (debug t))
  `(pcomplete--here (lambda () ,form) ,stub ,paring ,form-only))


(defmacro pcomplete-here* (&optional form stub form-only)
  "An alternate form which does not participate in argument paring."
  (declare (debug t))
  `(pcomplete-here ,form ,stub t ,form-only))

;; display support

(defun pcomplete-restore-windows ()
  "If the only window change was due to Completions, restore things."
  (if pcomplete-last-window-config
      (let* ((cbuf (get-buffer "*Completions*"))
	     (cwin (and cbuf (get-buffer-window cbuf))))
	(when (window-live-p cwin)
	  (bury-buffer cbuf)
	  (set-window-configuration pcomplete-last-window-config))))
  (setq pcomplete-last-window-config nil
	pcomplete-window-restore-timer nil))

;; Abstractions so that the code below will work for both Emacs 20 and
;; XEmacs 21

(defalias 'pcomplete-event-matches-key-specifier-p
  (if (featurep 'xemacs)
      'event-matches-key-specifier-p
  'eq))

(defun pcomplete-read-event (&optional prompt)
  (if (fboundp 'read-event)
      (read-event prompt)
    (aref (read-key-sequence prompt) 0)))

(defun pcomplete-show-completions (completions)
  "List in help buffer sorted COMPLETIONS.
Typing SPC flushes the help buffer."
  (when pcomplete-window-restore-timer
    (cancel-timer pcomplete-window-restore-timer)
    (setq pcomplete-window-restore-timer nil))
  (unless pcomplete-last-window-config
    (setq pcomplete-last-window-config (current-window-configuration)))
  (with-output-to-temp-buffer "*Completions*"
    (display-completion-list completions))
  (message "Hit space to flush")
  (let (event)
    (prog1
        (catch 'done
          (while (with-current-buffer (get-buffer "*Completions*")
                   (setq event (pcomplete-read-event)))
            (cond
             ((pcomplete-event-matches-key-specifier-p event ?\s)
              (set-window-configuration pcomplete-last-window-config)
              (setq pcomplete-last-window-config nil)
              (throw 'done nil))
             ((or (pcomplete-event-matches-key-specifier-p event 'tab)
                  ;; Needed on a terminal
                  (pcomplete-event-matches-key-specifier-p event 9))
              (let ((win (or (get-buffer-window "*Completions*" 0)
                             (display-buffer "*Completions*"
                                             'not-this-window))))
                (with-selected-window win
                  (if (pos-visible-in-window-p (point-max))
                      (goto-char (point-min))
                    (scroll-up))))
              (message ""))
             (t
              (setq unread-command-events (list event))
              (throw 'done nil)))))
      (if (and pcomplete-last-window-config
               pcomplete-restore-window-delay)
          (setq pcomplete-window-restore-timer
                (run-with-timer pcomplete-restore-window-delay nil
                                'pcomplete-restore-windows))))))

;; insert completion at point

(defun pcomplete-insert-entry (stub entry &optional addsuffix raw-p)
  "Insert a completion entry at point.
Returns non-nil if a space was appended at the end."
  (let ((here (point)))
    (if (not pcomplete-ignore-case)
	(insert-and-inherit (if raw-p
				(substring entry (length stub))
			      (pcomplete-quote-argument
			       (substring entry (length stub)))))
      ;; the stub is not quoted at this time, so to determine the
      ;; length of what should be in the buffer, we must quote it
      ;; FIXME: Here we presume that quoting `stub' gives us the exact
      ;; text in the buffer before point, which is not guaranteed;
      ;; e.g. it is not the case in eshell when completing ${FOO}tm[TAB].
      (delete-char (- (length (pcomplete-quote-argument stub))))
      ;; if there is already a backslash present to handle the first
      ;; character, don't bother quoting it
      (when (eq (char-before) ?\\)
	(insert-and-inherit (substring entry 0 1))
	(setq entry (substring entry 1)))
      (insert-and-inherit (if raw-p
			      entry
			    (pcomplete-quote-argument entry))))
    (let (space-added)
      (when (and (not (memq (char-before) pcomplete-suffix-list))
		 addsuffix)
	(insert-and-inherit pcomplete-termination-string)
	(setq space-added t))
      (setq pcomplete-last-completion-length (- (point) here)
	    pcomplete-last-completion-stub stub)
      space-added)))

;; selection of completions

(defun pcomplete-do-complete (stub completions)
  "Dynamically complete at point using STUB and COMPLETIONS.
This is basically just a wrapper for `pcomplete-stub' which does some
extra checking, and munging of the COMPLETIONS list."
  (unless (stringp stub)
    (message "Cannot complete argument")
    (throw 'pcompleted nil))
  (if (null completions)
      (ignore
       (if (and stub (> (length stub) 0))
	   (message "No completions of %s" stub)
	 (message "No completions")))
    ;; pare it down, if applicable
    (when (and pcomplete-use-paring pcomplete-seen)
      (setq pcomplete-seen
            (mapcar 'directory-file-name pcomplete-seen))
      (dolist (p pcomplete-seen)
        (add-to-list 'pcomplete-seen
                     (funcall pcomplete-norm-func p)))
      (setq completions
            (apply-partially 'completion-table-with-predicate
                             completions
                             (when pcomplete-seen
                               (lambda (f)
                                 (not (member
                                       (funcall pcomplete-norm-func
                                                (directory-file-name f))
                                       pcomplete-seen))))
                             'strict)))
    ;; OK, we've got a list of completions.
    (if pcomplete-show-list
        ;; FIXME: pay attention to boundaries.
	(pcomplete-show-completions (all-completions stub completions))
      (pcomplete-stub stub completions))))

(defun pcomplete-stub (stub candidates &optional cycle-p)
  "Dynamically complete STUB from CANDIDATES list.
This function inserts completion characters at point by completing
STUB from the strings in CANDIDATES.  A completions listing may be
shown in a help buffer if completion is ambiguous.

Returns nil if no completion was inserted.
Returns `sole' if completed with the only completion match.
Returns `shortest' if completed with the shortest of the matches.
Returns `partial' if completed as far as possible with the matches.
Returns `listed' if a completion listing was shown.

See also `pcomplete-filename'."
  (let* ((completion-ignore-case pcomplete-ignore-case)
	 (completions (all-completions stub candidates))
         (entry (try-completion stub candidates))
         result)
    (cond
     ((null entry)
      (if (and stub (> (length stub) 0))
          (message "No completions of %s" stub)
        (message "No completions")))
     ((eq entry t)
      (setq entry stub)
      (message "Sole completion")
      (setq result 'sole))
     ((= 1 (length completions))
      (setq result 'sole))
     ((and pcomplete-cycle-completions
           (or cycle-p
               (not pcomplete-cycle-cutoff-length)
               (<= (length completions)
                   pcomplete-cycle-cutoff-length)))
      (let ((bound (car (completion-boundaries stub candidates nil ""))))
        (unless (zerop bound)
          (setq completions (mapcar (lambda (c) (concat (substring stub 0 bound) c))
                                    completions)))
        (setq entry (car completions)
              pcomplete-current-completions completions)))
     ((and pcomplete-recexact
           (string-equal stub entry)
           (member entry completions))
      ;; It's not unique, but user wants shortest match.
      (message "Completed shortest")
      (setq result 'shortest))
     ((or pcomplete-autolist
          (string-equal stub entry))
      ;; It's not unique, list possible completions.
      ;; FIXME: pay attention to boundaries.
      (pcomplete-show-completions completions)
      (setq result 'listed))
     (t
      (message "Partially completed")
      (setq result 'partial)))
    (cons result entry)))

;; context sensitive help

(defun pcomplete--help ()
  "Produce context-sensitive help for the current argument.
If specific documentation can't be given, be generic."
  (if (and pcomplete-help
	   (or (and (stringp pcomplete-help)
		    (fboundp 'Info-goto-node))
	       (listp pcomplete-help)))
      (if (listp pcomplete-help)
	  (message "%s" (eval pcomplete-help))
	(save-window-excursion (info))
	(switch-to-buffer-other-window "*info*")
	(funcall (symbol-function 'Info-goto-node) pcomplete-help))
    (if pcomplete-man-function
	(let ((cmd (funcall pcomplete-command-name-function)))
	  (if (and cmd (> (length cmd) 0))
	      (funcall pcomplete-man-function cmd)))
      (message "No context-sensitive help available"))))

;; general utilities

(defun pcomplete-uniqify-list (l)
  "Sort and remove multiples in L."
  (setq l (sort l 'string-lessp))
  (let ((m l))
    (while m
      (while (and (cdr m)
		  (string= (car m)
			   (cadr m)))
	(setcdr m (cddr m)))
      (setq m (cdr m))))
  l)

(defun pcomplete-process-result (cmd &rest args)
  "Call CMD using `call-process' and return the simplest result."
  (with-temp-buffer
    (apply 'call-process cmd nil t nil args)
    (skip-chars-backward "\n")
    (buffer-substring (point-min) (point))))

;; create a set of aliases which allow completion functions to be not
;; quite so verbose

;;; jww (1999-10-20): are these a good idea?
;; (defalias 'pc-here 'pcomplete-here)
;; (defalias 'pc-test 'pcomplete-test)
;; (defalias 'pc-opt 'pcomplete-opt)
;; (defalias 'pc-match 'pcomplete-match)
;; (defalias 'pc-match-string 'pcomplete-match-string)
;; (defalias 'pc-match-beginning 'pcomplete-match-beginning)
;; (defalias 'pc-match-end 'pcomplete-match-end)

(provide 'pcomplete)

;;; pcomplete.el ends here