Source

ocaml / stdlib / format.ml

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
(***********************************************************************)
(*                                                                     *)
(*                                OCaml                                *)
(*                                                                     *)
(*            Pierre Weis, projet Cristal, INRIA Rocquencourt          *)
(*                                                                     *)
(*  Copyright 1996 Institut National de Recherche en Informatique et   *)
(*  en Automatique.  All rights reserved.  This file is distributed    *)
(*  under the terms of the GNU Library General Public License, with    *)
(*  the special exception on linking described in file ../LICENSE.     *)
(*                                                                     *)
(***********************************************************************)

(* $Id$ *)

(* A pretty-printing facility and definition of formatters for ``parallel''
   (i.e. unrelated or independent) pretty-printing on multiple out channels. *)

(**************************************************************

  Data structures definitions.

 **************************************************************)

type size;;

external size_of_int : int -> size = "%identity"
;;
external int_of_size : size -> int = "%identity"
;;

(* Tokens are one of the following : *)

type pp_token =
| Pp_text of string            (* normal text *)
| Pp_break of int * int        (* complete break *)
| Pp_tbreak of int * int       (* go to next tabulation *)
| Pp_stab                      (* set a tabulation *)
| Pp_begin of int * block_type (* beginning of a block *)
| Pp_end                       (* end of a block *)
| Pp_tbegin of tblock          (* beginning of a tabulation block *)
| Pp_tend                      (* end of a tabulation block *)
| Pp_newline                   (* to force a newline inside a block *)
| Pp_if_newline                (* to do something only if this very
                                  line has been broken *)
| Pp_open_tag of tag           (* opening a tag name *)
| Pp_close_tag                 (* closing the most recently opened tag *)

and tag = string

and block_type =
| Pp_hbox   (* Horizontal block no line breaking *)
| Pp_vbox   (* Vertical block each break leads to a new line *)
| Pp_hvbox  (* Horizontal-vertical block: same as vbox, except if this block
               is small enough to fit on a single line *)
| Pp_hovbox (* Horizontal or Vertical block: breaks lead to new line
               only when necessary to print the content of the block *)
| Pp_box    (* Horizontal or Indent block: breaks lead to new line
               only when necessary to print the content of the block, or
               when it leads to a new indentation of the current line *)
| Pp_fits   (* Internal usage: when a block fits on a single line *)

and tblock =
  | Pp_tbox of int list ref  (* Tabulation box *)
;;

(* The Queue:
   contains all formatting elements.
   elements are tuples (size, token, length), where
   size is set when the size of the block is known
   len is the declared length of the token. *)
type pp_queue_elem = {
  mutable elem_size : size;
  token : pp_token;
  length : int;
}
;;

(* Scan stack:
   each element is (left_total, queue element) where left_total
   is the value of pp_left_total when the element has been enqueued. *)
type pp_scan_elem = Scan_elem of int * pp_queue_elem;;

(* Formatting stack:
   used to break the lines while printing tokens.
   The formatting stack contains the description of
   the currently active blocks. *)
type pp_format_elem = Format_elem of block_type * int;;

(* General purpose queues, used in the formatter. *)
type 'a queue_elem =
   | Nil
   | Cons of 'a queue_cell

and 'a queue_cell = {
  mutable head : 'a;
  mutable tail : 'a queue_elem;
}
;;

type 'a queue = {
  mutable insert : 'a queue_elem;
  mutable body : 'a queue_elem;
}
;;

(* The formatter specific tag handling functions. *)
type formatter_tag_functions = {
  mark_open_tag : tag -> string;
  mark_close_tag : tag -> string;
  print_open_tag : tag -> unit;
  print_close_tag : tag -> unit;
}
;;

(* A formatter with all its machinery. *)
type formatter = {
  mutable pp_scan_stack : pp_scan_elem list;
  mutable pp_format_stack : pp_format_elem list;
  mutable pp_tbox_stack : tblock list;
  mutable pp_tag_stack : tag list;
  mutable pp_mark_stack : tag list;
  (* Global variables: default initialization is
     set_margin 78
     set_min_space_left 0. *)
  (* Value of right margin. *)
  mutable pp_margin : int;
  (* Minimal space left before margin, when opening a block. *)
  mutable pp_min_space_left : int;
  (* Maximum value of indentation:
     no blocks can be opened further. *)
  mutable pp_max_indent : int;
  (* Space remaining on the current line. *)
  mutable pp_space_left : int;
  (* Current value of indentation. *)
  mutable pp_current_indent : int;
  (* True when the line has been broken by the pretty-printer. *)
  mutable pp_is_new_line : bool;
  (* Total width of tokens already printed. *)
  mutable pp_left_total : int;
  (* Total width of tokens ever put in queue. *)
  mutable pp_right_total : int;
  (* Current number of opened blocks. *)
  mutable pp_curr_depth : int;
  (* Maximum number of blocks which can be simultaneously opened. *)
  mutable pp_max_boxes : int;
  (* Ellipsis string. *)
  mutable pp_ellipsis : string;
  (* Output function. *)
  mutable pp_out_string : string -> int -> int -> unit;
  (* Flushing function. *)
  mutable pp_out_flush : unit -> unit;
  (* Output of new lines. *)
  mutable pp_out_newline : unit -> unit;
  (* Output of indentation spaces. *)
  mutable pp_out_spaces : int -> unit;
  (* Are tags printed ? *)
  mutable pp_print_tags : bool;
  (* Are tags marked ? *)
  mutable pp_mark_tags : bool;
  (* Find opening and closing markers of tags. *)
  mutable pp_mark_open_tag : tag -> string;
  mutable pp_mark_close_tag : tag -> string;
  mutable pp_print_open_tag : tag -> unit;
  mutable pp_print_close_tag : tag -> unit;
  (* The pretty-printer queue. *)
  mutable pp_queue : pp_queue_elem queue;
}
;;

(**************************************************************

  Auxilliaries and basic functions.

 **************************************************************)


(* Queues auxilliaries. *)
let make_queue () = { insert = Nil; body = Nil; };;

let clear_queue q = q.insert <- Nil; q.body <- Nil;;

let add_queue x q =
  let c = Cons { head = x; tail = Nil; } in
  match q with
  | { insert = Cons cell; body = _; } ->
    q.insert <- c; cell.tail <- c
  (* Invariant: when insert is Nil body should be Nil. *)
  | { insert = Nil; body = _; } ->
    q.insert <- c; q.body <- c
;;

exception Empty_queue;;

let peek_queue = function
  | { body = Cons { head = x; tail = _; }; _ } -> x
  | { body = Nil; insert = _; } -> raise Empty_queue
;;

let take_queue = function
  | { body = Cons { head = x; tail = tl; }; _ } as q ->
    q.body <- tl;
    if tl = Nil then q.insert <- Nil; (* Maintain the invariant. *)
    x
  | { body = Nil; insert = _; } -> raise Empty_queue
;;

(* Enter a token in the pretty-printer queue. *)
let pp_enqueue state ({ length = len; _} as token) =
  state.pp_right_total <- state.pp_right_total + len;
  add_queue token state.pp_queue
;;

let pp_clear_queue state =
  state.pp_left_total <- 1; state.pp_right_total <- 1;
  clear_queue state.pp_queue
;;

(* Pp_infinity: large value for default tokens size.

   Pp_infinity is documented as being greater than 1e10; to avoid
   confusion about the word ``greater'', we choose pp_infinity greater
   than 1e10 + 1; for correct handling of tests in the algorithm,
   pp_infinity must be even one more than 1e10 + 1; let's stand on the
   safe side by choosing 1.e10+10.

   Pp_infinity could probably be 1073741823 that is 2^30 - 1, that is
   the minimal upper bound for integers; now that max_int is defined,
   this limit could also be defined as max_int - 1.

   However, before setting pp_infinity to something around max_int, we
   must carefully double-check all the integer arithmetic operations
   that involve pp_infinity, since any overflow would wreck havoc the
   pretty-printing algorithm's invariants. Given that this arithmetic
   correctness check is difficult and error prone and given that 1e10
   + 1 is in practice large enough, there is no need to attempt to set
   pp_infinity to the theoretically maximum limit. It is not worth the
   burden ! *)

let pp_infinity = 1000000010;;

(* Output functions for the formatter. *)
let pp_output_string state s = state.pp_out_string s 0 (String.length s)
and pp_output_newline state = state.pp_out_newline ()
and pp_output_spaces state n = state.pp_out_spaces n
;;

(* To format a break, indenting a new line. *)
let break_new_line state offset width =
  pp_output_newline state;
  state.pp_is_new_line <- true;
  let indent = state.pp_margin - width + offset in
  (* Don't indent more than pp_max_indent. *)
  let real_indent = min state.pp_max_indent indent in
  state.pp_current_indent <- real_indent;
  state.pp_space_left <- state.pp_margin - state.pp_current_indent;
  pp_output_spaces state state.pp_current_indent
;;

(* To force a line break inside a block: no offset is added. *)
let break_line state width = break_new_line state 0 width;;

(* To format a break that fits on the current line. *)
let break_same_line state width =
  state.pp_space_left <- state.pp_space_left - width;
  pp_output_spaces state width
;;

(* To indent no more than pp_max_indent, if one tries to open a block
   beyond pp_max_indent, then the block is rejected on the left
   by simulating a break. *)
let pp_force_break_line state =
  match state.pp_format_stack with
  | Format_elem (bl_ty, width) :: _ ->
    if width > state.pp_space_left then
      (match bl_ty with
       | Pp_fits -> () | Pp_hbox -> ()
       | Pp_vbox | Pp_hvbox | Pp_hovbox | Pp_box ->
         break_line state width)
  | [] -> pp_output_newline state
;;

(* To skip a token, if the previous line has been broken. *)
let pp_skip_token state =
  (* When calling pp_skip_token the queue cannot be empty. *)
  match take_queue state.pp_queue with
  | { elem_size = size; length = len; token = _; } ->
    state.pp_left_total <- state.pp_left_total - len;
    state.pp_space_left <- state.pp_space_left + int_of_size size
;;

(**************************************************************

  The main pretty printing functions.

 **************************************************************)

(* To format a token. *)
let format_pp_token state size = function

  | Pp_text s ->
    state.pp_space_left <- state.pp_space_left - size;
    pp_output_string state s;
    state.pp_is_new_line <- false

  | Pp_begin (off, ty) ->
    let insertion_point = state.pp_margin - state.pp_space_left in
    if insertion_point > state.pp_max_indent then
      (* can't open a block right there. *)
      begin pp_force_break_line state end;
    let offset = state.pp_space_left - off in
    let bl_type =
      begin match ty with
      | Pp_vbox -> Pp_vbox
      | Pp_hbox | Pp_hvbox | Pp_hovbox | Pp_box | Pp_fits ->
        if size > state.pp_space_left then ty else Pp_fits
      end in
    state.pp_format_stack <-
      Format_elem (bl_type, offset) :: state.pp_format_stack

  | Pp_end ->
    begin match state.pp_format_stack with
    | _ :: ls -> state.pp_format_stack <- ls
    | [] -> () (* No more block to close. *)
    end

  | Pp_tbegin (Pp_tbox _ as tbox) ->
    state.pp_tbox_stack <- tbox :: state.pp_tbox_stack

  | Pp_tend ->
    begin match state.pp_tbox_stack with
    | _ :: ls -> state.pp_tbox_stack <- ls
    | [] -> () (* No more tabulation block to close. *)
    end

  | Pp_stab ->
    begin match state.pp_tbox_stack with
    | Pp_tbox tabs :: _ ->
      let rec add_tab n = function
        | [] -> [n]
        | x :: l as ls -> if n < x then n :: ls else x :: add_tab n l in
      tabs := add_tab (state.pp_margin - state.pp_space_left) !tabs
    | [] -> () (* No opened tabulation block. *)
    end

  | Pp_tbreak (n, off) ->
    let insertion_point = state.pp_margin - state.pp_space_left in
    begin match state.pp_tbox_stack with
    | Pp_tbox tabs :: _ ->
      let rec find n = function
        | x :: l -> if x >= n then x else find n l
        | [] -> raise Not_found in
      let tab =
        match !tabs with
        | x :: _ ->
          begin
            try find insertion_point !tabs with
            | Not_found -> x
          end
        | _ -> insertion_point in
      let offset = tab - insertion_point in
      if offset >= 0
      then break_same_line state (offset + n)
      else break_new_line state (tab + off) state.pp_margin
    | [] -> () (* No opened tabulation block. *)
    end

  | Pp_newline ->
    begin match state.pp_format_stack with
    | Format_elem (_, width) :: _ -> break_line state width
    | [] -> pp_output_newline state (* No opened block. *)
    end

  | Pp_if_newline ->
    if state.pp_current_indent != state.pp_margin - state.pp_space_left
    then pp_skip_token state

  | Pp_break (n, off) ->
    begin match state.pp_format_stack with
    | Format_elem (ty, width) :: _ ->
      begin match ty with
      | Pp_hovbox ->
        if size > state.pp_space_left
        then break_new_line state off width
        else break_same_line state n
      | Pp_box ->
        (* Have the line just been broken here ? *)
        if state.pp_is_new_line then break_same_line state n else
        if size > state.pp_space_left
         then break_new_line state off width else
        (* break the line here leads to new indentation ? *)
        if state.pp_current_indent > state.pp_margin - width + off
        then break_new_line state off width
        else break_same_line state n
      | Pp_hvbox -> break_new_line state off width
      | Pp_fits -> break_same_line state n
      | Pp_vbox -> break_new_line state off width
      | Pp_hbox -> break_same_line state n
      end
    | [] -> () (* No opened block. *)
    end

   | Pp_open_tag tag_name ->
     let marker = state.pp_mark_open_tag tag_name in
     pp_output_string state marker;
     state.pp_mark_stack <- tag_name :: state.pp_mark_stack

   | Pp_close_tag ->
     begin match state.pp_mark_stack with
     | tag_name :: tags ->
       let marker = state.pp_mark_close_tag tag_name in
       pp_output_string state marker;
       state.pp_mark_stack <- tags
     | [] -> () (* No more tag to close. *)
     end
;;

(* Print if token size is known or printing is delayed.
   Size is known when not negative.
   Printing is delayed when the text waiting in the queue requires
   more room to format than exists on the current line.

   Note: [advance_loop] must be tail recursive to prevent stack overflows. *)
let rec advance_loop state =
  match peek_queue state.pp_queue with
  | {elem_size = size; token = tok; length = len} ->
    let size = int_of_size size in
    if not
         (size < 0 &&
          (state.pp_right_total - state.pp_left_total < state.pp_space_left))
    then begin
      ignore (take_queue state.pp_queue);
      format_pp_token state (if size < 0 then pp_infinity else size) tok;
      state.pp_left_total <- len + state.pp_left_total;
      advance_loop state
    end
;;

let advance_left state =
  try advance_loop state with
  | Empty_queue -> ()
;;

let enqueue_advance state tok = pp_enqueue state tok; advance_left state;;

(* To enqueue a string : try to advance. *)
let make_queue_elem size tok len =
  { elem_size = size; token = tok; length = len; };;

let enqueue_string_as state size s =
  let len = int_of_size size in
  enqueue_advance state (make_queue_elem size (Pp_text s) len)
;;

let enqueue_string state s =
  let len = String.length s in
  enqueue_string_as state (size_of_int len) s
;;

(* Routines for scan stack
   determine sizes of blocks. *)

(* The scan_stack is never empty. *)
let scan_stack_bottom =
  let q_elem = make_queue_elem (size_of_int (-1)) (Pp_text "") 0 in
  [Scan_elem (-1, q_elem)]
;;

(* Set size of blocks on scan stack:
   if ty = true then size of break is set else size of block is set;
   in each case pp_scan_stack is popped. *)
let clear_scan_stack state = state.pp_scan_stack <- scan_stack_bottom;;

(* Pattern matching on scan stack is exhaustive,
   since scan_stack is never empty.
   Pattern matching on token in scan stack is also exhaustive,
   since scan_push is used on breaks and opening of boxes. *)
let set_size state ty =
  match state.pp_scan_stack with
  | Scan_elem
      (left_tot,
       ({ elem_size = size; token = tok; length = _; } as queue_elem)) :: t ->
    let size = int_of_size size in
    (* test if scan stack contains any data that is not obsolete. *)
    if left_tot < state.pp_left_total then clear_scan_stack state else
      begin match tok with
      | Pp_break (_, _) | Pp_tbreak (_, _) ->
        if ty then
        begin
          queue_elem.elem_size <- size_of_int (state.pp_right_total + size);
          state.pp_scan_stack <- t
        end
      | Pp_begin (_, _) ->
        if not ty then
        begin
          queue_elem.elem_size <- size_of_int (state.pp_right_total + size);
          state.pp_scan_stack <- t
        end
      | Pp_text _ | Pp_stab | Pp_tbegin _ | Pp_tend | Pp_end
      | Pp_newline | Pp_if_newline
      | Pp_open_tag _ | Pp_close_tag ->
        () (* scan_push is only used for breaks and boxes. *)
      end
  | [] -> () (* scan_stack is never empty. *)
;;

(* Push a token on scan stack. If b is true set_size is called. *)
let scan_push state b tok =
  pp_enqueue state tok;
  if b then set_size state true;
  state.pp_scan_stack <-
    Scan_elem (state.pp_right_total, tok) :: state.pp_scan_stack
;;

(* To open a new block :
   the user may set the depth bound pp_max_boxes
   any text nested deeper is printed as the ellipsis string. *)
let pp_open_box_gen state indent br_ty =
  state.pp_curr_depth <- state.pp_curr_depth + 1;
  if state.pp_curr_depth < state.pp_max_boxes then
    let elem =
      make_queue_elem
        (size_of_int (- state.pp_right_total))
        (Pp_begin (indent, br_ty))
        0 in
    scan_push state false elem else
  if state.pp_curr_depth = state.pp_max_boxes
  then enqueue_string state state.pp_ellipsis
;;

(* The box which is always opened. *)
let pp_open_sys_box state = pp_open_box_gen state 0 Pp_hovbox;;

(* Close a block, setting sizes of its sub blocks. *)
let pp_close_box state () =
  if state.pp_curr_depth > 1 then
  begin
    if state.pp_curr_depth < state.pp_max_boxes then
    begin
      pp_enqueue state
        { elem_size = size_of_int 0; token = Pp_end; length = 0; };
      set_size state true; set_size state false
    end;
    state.pp_curr_depth <- state.pp_curr_depth - 1;
  end
;;

(* Open a tag, pushing it on the tag stack. *)
let pp_open_tag state tag_name =
  if state.pp_print_tags then
  begin
    state.pp_tag_stack <- tag_name :: state.pp_tag_stack;
    state.pp_print_open_tag tag_name
  end;
  if state.pp_mark_tags then
    pp_enqueue state {
      elem_size = size_of_int 0;
      token = Pp_open_tag tag_name;
      length = 0;
    }
;;

(* Close a tag, popping it from the tag stack. *)
let pp_close_tag state () =
  if state.pp_mark_tags then
    pp_enqueue state {
      elem_size = size_of_int 0;
      token = Pp_close_tag;
      length = 0;
    };
  if state.pp_print_tags then
  begin
    match state.pp_tag_stack with
    | tag_name :: tags ->
      state.pp_print_close_tag tag_name;
      state.pp_tag_stack <- tags
    | _ -> () (* No more tag to close. *)
  end
;;

let pp_set_print_tags state b = state.pp_print_tags <- b;;
let pp_set_mark_tags state b = state.pp_mark_tags <- b;;
let pp_get_print_tags state () = state.pp_print_tags;;
let pp_get_mark_tags state () = state.pp_mark_tags;;
let pp_set_tags state b = pp_set_print_tags state b; pp_set_mark_tags state b;;

let pp_get_formatter_tag_functions state () = {
  mark_open_tag = state.pp_mark_open_tag;
  mark_close_tag = state.pp_mark_close_tag;
  print_open_tag = state.pp_print_open_tag;
  print_close_tag = state.pp_print_close_tag;
}
;;

let pp_set_formatter_tag_functions state {
     mark_open_tag = mot;
     mark_close_tag = mct;
     print_open_tag = pot;
     print_close_tag = pct;
  } =
   state.pp_mark_open_tag <- mot;
   state.pp_mark_close_tag <- mct;
   state.pp_print_open_tag <- pot;
   state.pp_print_close_tag <- pct
;;

(* Initialize pretty-printer. *)
let pp_rinit state =
  pp_clear_queue state;
  clear_scan_stack state;
  state.pp_format_stack <- [];
  state.pp_tbox_stack <- [];
  state.pp_tag_stack <- [];
  state.pp_mark_stack <- [];
  state.pp_current_indent <- 0;
  state.pp_curr_depth <- 0;
  state.pp_space_left <- state.pp_margin;
  pp_open_sys_box state;;

(* Flushing pretty-printer queue. *)
let pp_flush_queue state b =
  while state.pp_curr_depth > 1 do
    pp_close_box state ()
  done;
  state.pp_right_total <- pp_infinity;
  advance_left state;
  if b then pp_output_newline state;
  pp_rinit state
;;

(**************************************************************

  Procedures to format objects, and use boxes

 **************************************************************)

(* To format a string. *)
let pp_print_as_size state size s =
  if state.pp_curr_depth < state.pp_max_boxes
  then enqueue_string_as state size s
;;

let pp_print_as state isize s =
  pp_print_as_size state (size_of_int isize) s
;;

let pp_print_string state s =
  pp_print_as state (String.length s) s
;;

(* To format an integer. *)
let pp_print_int state i = pp_print_string state (string_of_int i);;

(* To format a float. *)
let pp_print_float state f = pp_print_string state (string_of_float f);;

(* To format a boolean. *)
let pp_print_bool state b = pp_print_string state (string_of_bool b);;

(* To format a char. *)
let pp_print_char state c =
  let s = String.create 1 in
  s.[0] <- c;
  pp_print_as state 1 s
;;

(* Opening boxes. *)
let pp_open_hbox state () = pp_open_box_gen state 0 Pp_hbox
and pp_open_vbox state indent = pp_open_box_gen state indent Pp_vbox

and pp_open_hvbox state indent = pp_open_box_gen state indent Pp_hvbox
and pp_open_hovbox state indent = pp_open_box_gen state indent Pp_hovbox
and pp_open_box state indent = pp_open_box_gen state indent Pp_box;;

(* Print a new line after printing all queued text
   (same for print_flush but without a newline). *)
let pp_print_newline state () =
  pp_flush_queue state true; state.pp_out_flush ()
and pp_print_flush state () =
  pp_flush_queue state false; state.pp_out_flush ();;

(* To get a newline when one does not want to close the current block. *)
let pp_force_newline state () =
  if state.pp_curr_depth < state.pp_max_boxes then
    enqueue_advance state (make_queue_elem (size_of_int 0) Pp_newline 0)
;;

(* To format something if the line has just been broken. *)
let pp_print_if_newline state () =
  if state.pp_curr_depth < state.pp_max_boxes then
    enqueue_advance state (make_queue_elem (size_of_int 0) Pp_if_newline 0)
;;

(* Breaks: indicate where a block may be broken.
   If line is broken then offset is added to the indentation of the current
   block else (the value of) width blanks are printed.
   To do (?) : add a maximum width and offset value. *)
let pp_print_break state width offset =
  if state.pp_curr_depth < state.pp_max_boxes then
    let elem =
      make_queue_elem
        (size_of_int (- state.pp_right_total))
        (Pp_break (width, offset))
        width in
    scan_push state true elem
;;

let pp_print_space state () = pp_print_break state 1 0
and pp_print_cut state () = pp_print_break state 0 0
;;

(* Tabulation boxes. *)
let pp_open_tbox state () =
  state.pp_curr_depth <- state.pp_curr_depth + 1;
  if state.pp_curr_depth < state.pp_max_boxes then
    let elem =
      make_queue_elem (size_of_int 0) (Pp_tbegin (Pp_tbox (ref []))) 0 in
    enqueue_advance state elem
;;

(* Close a tabulation block. *)
let pp_close_tbox state () =
  if state.pp_curr_depth > 1 then
  begin
   if state.pp_curr_depth < state.pp_max_boxes then
     let elem = make_queue_elem (size_of_int 0) Pp_tend 0 in
     enqueue_advance state elem;
     state.pp_curr_depth <- state.pp_curr_depth - 1
  end
;;

(* Print a tabulation break. *)
let pp_print_tbreak state width offset =
  if state.pp_curr_depth < state.pp_max_boxes then
    let elem =
      make_queue_elem
        (size_of_int (- state.pp_right_total))
        (Pp_tbreak (width, offset))
        width in
    scan_push state true elem
;;

let pp_print_tab state () = pp_print_tbreak state 0 0;;

let pp_set_tab state () =
  if state.pp_curr_depth < state.pp_max_boxes then
    let elem =
      make_queue_elem (size_of_int 0) Pp_stab 0 in
    enqueue_advance state elem
;;

(**************************************************************

  Procedures to control the pretty-printers

 **************************************************************)

(* Fit max_boxes. *)
let pp_set_max_boxes state n = if n > 1 then state.pp_max_boxes <- n;;

(* To know the current maximum number of boxes allowed. *)
let pp_get_max_boxes state () = state.pp_max_boxes;;

let pp_over_max_boxes state () = state.pp_curr_depth = state.pp_max_boxes;;

(* Ellipsis. *)
let pp_set_ellipsis_text state s = state.pp_ellipsis <- s
and pp_get_ellipsis_text state () = state.pp_ellipsis
;;

(* To set the margin of pretty-printer. *)
let pp_limit n =
  if n < pp_infinity then n else pred pp_infinity
;;

let pp_set_min_space_left state n =
  if n >= 1 then
    let n = pp_limit n in
    state.pp_min_space_left <- n;
    state.pp_max_indent <- state.pp_margin - state.pp_min_space_left;
    pp_rinit state
;;

(* Initially, we have :
  pp_max_indent = pp_margin - pp_min_space_left, and
  pp_space_left = pp_margin. *)
let pp_set_max_indent state n =
  pp_set_min_space_left state (state.pp_margin - n)
;;
let pp_get_max_indent state () = state.pp_max_indent;;

let pp_set_margin state n =
  if n >= 1 then
    let n = pp_limit n in
    state.pp_margin <- n;
    let new_max_indent =
      (* Try to maintain max_indent to its actual value. *)
      if state.pp_max_indent <= state.pp_margin
      then state.pp_max_indent else
      (* If possible maintain pp_min_space_left to its actual value,
         if this leads to a too small max_indent, take half of the
         new margin, if it is greater than 1. *)
       max (max (state.pp_margin - state.pp_min_space_left)
                (state.pp_margin / 2)) 1 in
    (* Rebuild invariants. *)
    pp_set_max_indent state new_max_indent
;;

let pp_get_margin state () = state.pp_margin;;

type formatter_out_functions = {
  out_string : string -> int -> int -> unit;
  out_flush : unit -> unit;
  out_newline : unit -> unit;
  out_spaces : int -> unit;
}
;;

let pp_set_formatter_out_functions state {
      out_string = f;
      out_flush = g;
      out_newline = h;
      out_spaces = i;
    } =
  state.pp_out_string <- f;
  state.pp_out_flush <- g;
  state.pp_out_newline <- h;
  state.pp_out_spaces <- i;
;;

let pp_get_formatter_out_functions state () = {
  out_string = state.pp_out_string;
  out_flush = state.pp_out_flush;
  out_newline = state.pp_out_newline;
  out_spaces = state.pp_out_spaces;
}
;;

let pp_set_formatter_output_functions state f g =
  state.pp_out_string <- f; state.pp_out_flush <- g;;
let pp_get_formatter_output_functions state () =
  (state.pp_out_string, state.pp_out_flush)
;;

let pp_set_all_formatter_output_functions state
    ~out:f ~flush:g ~newline:h ~spaces:i =
  pp_set_formatter_output_functions state f g;
  state.pp_out_newline <- h;
  state.pp_out_spaces <- i;
;;
let pp_get_all_formatter_output_functions state () =
  (state.pp_out_string, state.pp_out_flush,
   state.pp_out_newline, state.pp_out_spaces)
;;

(* Default function to output new lines. *)
let display_newline state () = state.pp_out_string "\n" 0  1;;

(* Default function to output spaces. *)
let blank_line = String.make 80 ' ';;
let rec display_blanks state n =
  if n > 0 then
  if n <= 80 then state.pp_out_string blank_line 0 n else
  begin
    state.pp_out_string blank_line 0 80;
    display_blanks state (n - 80)
  end
;;

let pp_set_formatter_out_channel state os =
  state.pp_out_string <- output os;
  state.pp_out_flush <- (fun () -> flush os);
  state.pp_out_newline <- display_newline state;
  state.pp_out_spaces <- display_blanks state;
;;

(**************************************************************

  Creation of specific formatters

 **************************************************************)

let default_pp_mark_open_tag s = "<" ^ s ^ ">";;
let default_pp_mark_close_tag s = "</" ^ s ^ ">";;

let default_pp_print_open_tag = ignore;;
let default_pp_print_close_tag = ignore;;

let pp_make_formatter f g h i =
  (* The initial state of the formatter contains a dummy box. *)
  let pp_q = make_queue () in
  let sys_tok =
    make_queue_elem (size_of_int (-1)) (Pp_begin (0, Pp_hovbox)) 0 in
  add_queue sys_tok pp_q;
  let sys_scan_stack =
      (Scan_elem (1, sys_tok)) :: scan_stack_bottom in
  {
   pp_scan_stack = sys_scan_stack;
   pp_format_stack = [];
   pp_tbox_stack = [];
   pp_tag_stack = [];
   pp_mark_stack = [];
   pp_margin = 78;
   pp_min_space_left = 10;
   pp_max_indent = 78 - 10;
   pp_space_left = 78;
   pp_current_indent = 0;
   pp_is_new_line = true;
   pp_left_total = 1;
   pp_right_total = 1;
   pp_curr_depth = 1;
   pp_max_boxes = max_int;
   pp_ellipsis = ".";
   pp_out_string = f;
   pp_out_flush = g;
   pp_out_newline = h;
   pp_out_spaces = i;
   pp_print_tags = false;
   pp_mark_tags = false;
   pp_mark_open_tag = default_pp_mark_open_tag;
   pp_mark_close_tag = default_pp_mark_close_tag;
   pp_print_open_tag = default_pp_print_open_tag;
   pp_print_close_tag = default_pp_print_close_tag;
   pp_queue = pp_q;
  }
;;

(* Make a formatter with default functions to output spaces and new lines. *)
let make_formatter output flush =
  let ppf = pp_make_formatter output flush ignore ignore in
  ppf.pp_out_newline <- display_newline ppf;
  ppf.pp_out_spaces <- display_blanks ppf;
  ppf
;;

let formatter_of_out_channel oc =
  make_formatter (output oc) (fun () -> flush oc)
;;

let formatter_of_buffer b =
  make_formatter (Buffer.add_substring b) ignore
;;

let stdbuf = Buffer.create 512;;

(* Predefined formatters. *)
let std_formatter = formatter_of_out_channel Pervasives.stdout
and err_formatter = formatter_of_out_channel Pervasives.stderr
and str_formatter = formatter_of_buffer stdbuf
;;

let flush_str_formatter () =
  pp_flush_queue str_formatter false;
  let s = Buffer.contents stdbuf in
  Buffer.reset stdbuf;
  s
;;

(**************************************************************

  Basic functions on the standard formatter

 **************************************************************)

let open_hbox = pp_open_hbox std_formatter
and open_vbox = pp_open_vbox std_formatter
and open_hvbox = pp_open_hvbox std_formatter
and open_hovbox = pp_open_hovbox std_formatter
and open_box = pp_open_box std_formatter
and close_box = pp_close_box std_formatter
and open_tag = pp_open_tag std_formatter
and close_tag = pp_close_tag std_formatter
and print_as = pp_print_as std_formatter
and print_string = pp_print_string std_formatter
and print_int = pp_print_int std_formatter
and print_float = pp_print_float std_formatter
and print_char = pp_print_char std_formatter
and print_bool = pp_print_bool std_formatter
and print_break = pp_print_break std_formatter
and print_cut = pp_print_cut std_formatter
and print_space = pp_print_space std_formatter
and force_newline = pp_force_newline std_formatter
and print_flush = pp_print_flush std_formatter
and print_newline = pp_print_newline std_formatter
and print_if_newline = pp_print_if_newline std_formatter

and open_tbox = pp_open_tbox std_formatter
and close_tbox = pp_close_tbox std_formatter
and print_tbreak = pp_print_tbreak std_formatter

and set_tab = pp_set_tab std_formatter
and print_tab = pp_print_tab std_formatter

and set_margin = pp_set_margin std_formatter
and get_margin = pp_get_margin std_formatter

and set_max_indent = pp_set_max_indent std_formatter
and get_max_indent = pp_get_max_indent std_formatter

and set_max_boxes = pp_set_max_boxes std_formatter
and get_max_boxes = pp_get_max_boxes std_formatter
and over_max_boxes = pp_over_max_boxes std_formatter

and set_ellipsis_text = pp_set_ellipsis_text std_formatter
and get_ellipsis_text = pp_get_ellipsis_text std_formatter

and set_formatter_out_channel =
  pp_set_formatter_out_channel std_formatter

and set_formatter_out_functions =
  pp_set_formatter_out_functions std_formatter
and get_formatter_out_functions =
  pp_get_formatter_out_functions std_formatter

and set_formatter_output_functions =
  pp_set_formatter_output_functions std_formatter
and get_formatter_output_functions =
  pp_get_formatter_output_functions std_formatter

and set_all_formatter_output_functions =
  pp_set_all_formatter_output_functions std_formatter
and get_all_formatter_output_functions =
  pp_get_all_formatter_output_functions std_formatter

and set_formatter_tag_functions =
  pp_set_formatter_tag_functions std_formatter
and get_formatter_tag_functions =
  pp_get_formatter_tag_functions std_formatter
and set_print_tags =
  pp_set_print_tags std_formatter
and get_print_tags =
  pp_get_print_tags std_formatter
and set_mark_tags =
  pp_set_mark_tags std_formatter
and get_mark_tags =
  pp_get_mark_tags std_formatter
and set_tags =
  pp_set_tags std_formatter
;;


(**************************************************************

  Printf implementation.

 **************************************************************)

module Sformat = Printf.CamlinternalPr.Sformat;;
module Tformat = Printf.CamlinternalPr.Tformat;;

(* Error messages when processing formats. *)

(* Trailer: giving up at character number ... *)
let giving_up mess fmt i =
  Printf.sprintf
    "Format.fprintf: %s ``%s'', giving up at character number %d%s"
    mess (Sformat.to_string fmt) i
    (if i < Sformat.length fmt
     then Printf.sprintf " (%c)." (Sformat.get fmt i)
     else Printf.sprintf "%c" '.')
;;

(* When an invalid format deserves a special error explanation. *)
let format_invalid_arg mess fmt i = invalid_arg (giving_up mess fmt i);;

(* Standard invalid format. *)
let invalid_format fmt i = format_invalid_arg "bad format" fmt i;;

(* Cannot find a valid integer into that format. *)
let invalid_integer fmt i =
  invalid_arg (giving_up "bad integer specification" fmt i);;

(* Finding an integer size out of a sub-string of the format. *)
let format_int_of_string fmt i s =
  let sz =
    try int_of_string s with
    | Failure _ -> invalid_integer fmt i in
  size_of_int sz
;;

(* Getting strings out of buffers. *)
let get_buffer_out b =
  let s = Buffer.contents b in
  Buffer.reset b;
  s
;;

(* [ppf] is supposed to be a pretty-printer that outputs to buffer [b]:
   to extract the contents of [ppf] as a string we flush [ppf] and get the
   string out of [b]. *)
let string_out b ppf =
  pp_flush_queue ppf false;
  get_buffer_out b
;;

(* Applies [printer] to a formatter that outputs on a fresh buffer,
   then returns the resulting material. *)
let exstring printer arg =
  let b = Buffer.create 512 in
  let ppf = formatter_of_buffer b in
  printer ppf arg;
  string_out b ppf
;;

(* To turn out a character accumulator into the proper string result. *)
let implode_rev s0 = function
  | [] -> s0
  | l -> String.concat "" (List.rev (s0 :: l))
;;

(* [mkprintf] is the printf-like function generator: given the
   - [to_s] flag that tells if we are printing into a string,
   - the [get_out] function that has to be called to get a [ppf] function to
     output onto,
   it generates a [kprintf] function that takes as arguments a [k]
   continuation function to be called at the end of formatting,
   and a printing format string to print the rest of the arguments
   according to the format string.
   Regular [fprintf]-like functions of this module are obtained via partial
   applications of [mkprintf]. *)
let mkprintf to_s get_out =

  let rec kprintf k fmt =

    let len = Sformat.length fmt in

    let kpr fmt v =
      let ppf = get_out fmt in
      let print_as = ref None in
      let pp_print_as_char c =
        match !print_as with
        | None -> pp_print_char ppf c
        | Some size ->
          pp_print_as_size ppf size (String.make 1 c);
          print_as := None
      and pp_print_as_string s =
        match !print_as with
        | None -> pp_print_string ppf s
        | Some size ->
          pp_print_as_size ppf size s;
          print_as := None in

      let rec doprn n i =
        if i >= len then Obj.magic (k ppf) else
        match Sformat.get fmt i with
        | '%' ->
          Tformat.scan_format fmt v n i cont_s cont_a cont_t cont_f cont_m
        | '@' ->
          let i = succ i in
          if i >= len then invalid_format fmt i else
          begin match Sformat.get fmt i with
          | '[' ->
            do_pp_open_box ppf n (succ i)
          | ']' ->
            pp_close_box ppf ();
            doprn n (succ i)
          | '{' ->
            do_pp_open_tag ppf n (succ i)
          | '}' ->
            pp_close_tag ppf ();
            doprn n (succ i)
          | ' ' ->
            pp_print_space ppf ();
            doprn n (succ i)
          | ',' ->
            pp_print_cut ppf ();
            doprn n (succ i)
          | '?' ->
            pp_print_flush ppf ();
            doprn n (succ i)
          | '.' ->
            pp_print_newline ppf ();
            doprn n (succ i)
          | '\n' ->
            pp_force_newline ppf ();
            doprn n (succ i)
          | ';' ->
            do_pp_break ppf n (succ i)
          | '<' ->
            let got_size size n i =
              print_as := Some size;
              doprn n (skip_gt i) in
            get_int n (succ i) got_size
          | '@' | '%' as c ->
            pp_print_as_char c;
            doprn n (succ i)
          | _ -> invalid_format fmt i
          end
        | c ->
          pp_print_as_char c;
          doprn n (succ i)

      and cont_s n s i =
        pp_print_as_string s; doprn n i
      and cont_a n printer arg i =
        if to_s then
          pp_print_as_string ((Obj.magic printer : unit -> _ -> string) () arg)
        else
          printer ppf arg;
        doprn n i
      and cont_t n printer i =
        if to_s then
          pp_print_as_string ((Obj.magic printer : unit -> string) ())
        else
          printer ppf;
        doprn n i
      and cont_f n i =
        pp_print_flush ppf (); doprn n i
      and cont_m n sfmt i =
        kprintf (Obj.magic (fun _ -> doprn n i)) sfmt

      and get_int n i c =
        if i >= len then invalid_integer fmt i else
        match Sformat.get fmt i with
        | ' ' -> get_int n (succ i) c
        | '%' ->
          let cont_s n s i = c (format_int_of_string fmt i s) n i
          and cont_a _n _printer _arg i = invalid_integer fmt i
          and cont_t _n _printer i = invalid_integer fmt i
          and cont_f _n i = invalid_integer fmt i
          and cont_m _n _sfmt i = invalid_integer fmt i in
          Tformat.scan_format fmt v n i cont_s cont_a cont_t cont_f cont_m
        | _ ->
          let rec get j =
            if j >= len then invalid_integer fmt j else
            match Sformat.get fmt j with
            | '0' .. '9' | '-' -> get (succ j)
            | _ ->
              let size =
                if j = i then size_of_int 0 else
                let s = Sformat.sub fmt (Sformat.index_of_int i) (j - i) in
                format_int_of_string fmt j s in
              c size n j in
          get i

      and skip_gt i =
        if i >= len then invalid_format fmt i else
        match Sformat.get fmt i with
        | ' ' -> skip_gt (succ i)
        | '>' -> succ i
        | _ -> invalid_format fmt i

      and get_box_kind i =
        if i >= len then Pp_box, i else
        match Sformat.get fmt i with
        | 'h' ->
           let i = succ i in
           if i >= len then Pp_hbox, i else
           begin match Sformat.get fmt i with
           | 'o' ->
             let i = succ i in
             if i >= len then format_invalid_arg "bad box format" fmt i else
             begin match Sformat.get fmt i with
             | 'v' -> Pp_hovbox, succ i
             | c ->
               format_invalid_arg
                 ("bad box name ho" ^ String.make 1 c) fmt i
             end
           | 'v' -> Pp_hvbox, succ i
           | _ -> Pp_hbox, i
           end
        | 'b' -> Pp_box, succ i
        | 'v' -> Pp_vbox, succ i
        | _ -> Pp_box, i

      and get_tag_name n i c =
        let rec get accu n i j =
          if j >= len then
            c (implode_rev
                 (Sformat.sub fmt (Sformat.index_of_int i) (j - i))
                 accu)
              n j else
          match Sformat.get fmt j with
          | '>' ->
            c (implode_rev
                 (Sformat.sub fmt (Sformat.index_of_int i) (j - i))
                 accu)
              n j
          | '%' ->
            let s0 = Sformat.sub fmt (Sformat.index_of_int i) (j - i) in
            let cont_s n s i = get (s :: s0 :: accu) n i i
            and cont_a n printer arg i =
              let s =
                if to_s
                then (Obj.magic printer : unit -> _ -> string) () arg
                else exstring printer arg in
              get (s :: s0 :: accu) n i i
            and cont_t n printer i =
              let s =
                if to_s
                then (Obj.magic printer : unit -> string) ()
                else exstring (fun ppf () -> printer ppf) () in
              get (s :: s0 :: accu) n i i
            and cont_f _n i =
              format_invalid_arg "bad tag name specification" fmt i
            and cont_m _n _sfmt i =
              format_invalid_arg "bad tag name specification" fmt i in
            Tformat.scan_format fmt v n j cont_s cont_a cont_t cont_f cont_m
          | _ -> get accu n i (succ j) in
        get [] n i i

      and do_pp_break ppf n i =
        if i >= len then begin pp_print_space ppf (); doprn n i end else
        match Sformat.get fmt i with
        | '<' ->
          let rec got_nspaces nspaces n i =
            get_int n i (got_offset nspaces)
          and got_offset nspaces offset n i =
            pp_print_break ppf (int_of_size nspaces) (int_of_size offset);
            doprn n (skip_gt i) in
          get_int n (succ i) got_nspaces
        | _c -> pp_print_space ppf (); doprn n i

      and do_pp_open_box ppf n i =
        if i >= len then begin pp_open_box_gen ppf 0 Pp_box; doprn n i end else
        match Sformat.get fmt i with
        | '<' ->
          let kind, i = get_box_kind (succ i) in
          let got_size size n i =
            pp_open_box_gen ppf (int_of_size size) kind;
            doprn n (skip_gt i) in
          get_int n i got_size
        | _c -> pp_open_box_gen ppf 0 Pp_box; doprn n i

      and do_pp_open_tag ppf n i =
        if i >= len then begin pp_open_tag ppf ""; doprn n i end else
        match Sformat.get fmt i with
        | '<' ->
          let got_name tag_name n i =
            pp_open_tag ppf tag_name;
            doprn n (skip_gt i) in
          get_tag_name n (succ i) got_name
        | _c -> pp_open_tag ppf ""; doprn n i in

      doprn (Sformat.index_of_int 0) 0 in

    Tformat.kapr kpr fmt in

  kprintf
;;

(**************************************************************

  Defining [fprintf] and various flavors of [fprintf].

 **************************************************************)

let kfprintf k ppf = mkprintf false (fun _ -> ppf) k;;
let ikfprintf k ppf = Tformat.kapr (fun _ _ -> Obj.magic (k ppf));;

let fprintf ppf = kfprintf ignore ppf;;
let ifprintf ppf = ikfprintf ignore ppf;;
let printf fmt = fprintf std_formatter fmt;;
let eprintf fmt = fprintf err_formatter fmt;;

let ksprintf k =
  let b = Buffer.create 512 in
  let k ppf = k (string_out b ppf) in
  mkprintf true (fun _ -> formatter_of_buffer b) k
;;

let sprintf fmt = ksprintf (fun s -> s) fmt;;

(**************************************************************

  Deprecated stuff.

 **************************************************************)

let kbprintf k b =
  mkprintf false (fun _ -> formatter_of_buffer b) k
;;

(* Deprecated error prone function bprintf. *)
let bprintf b =
  let k ppf = pp_flush_queue ppf false in
  kbprintf k b
;;

(* Deprecated alias for ksprintf. *)
let kprintf = ksprintf;;

(* Output everything left in the pretty printer queue at end of execution. *)
at_exit print_flush
;;