All files / lib readline.js

97.81% Statements 1293/1322
97.74% Branches 346/354
98.21% Functions 55/56
97.81% Lines 1293/1322

Press n or j to go to the next uncovered block, b, p or k for the previous block.

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 13232x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 78x 78x 78x 2x 2x 388x 388x 1x 1x 387x 387x 387x 387x 387x 387x 387x 387x 387x 387x 387x 387x 387x 387x 387x 387x 387x 388x 385x 385x 385x 385x 385x 385x 385x 385x 4x 4x 4x 382x 385x 165x 165x 385x 5x 1x 5x 4x 4x 4x 4x 4x 5x 378x 385x 4x 4x 377x 377x 377x 377x 379x 388x 7x 7x 372x 384x 365x 388x 7x 7x 365x 384x 288x 288x 365x 384x 388x 388x 7x 7x 358x 358x 358x 388x 24x 24x 358x 358x 358x 358x 358x 358x 358x 358x 358x 358x 388x 388x 388x 388x 205x 205x 8x 17x 205x 205x 358x 358x 358x 358x 358x 358x 358x 388x 8x 8x 358x 358x 2x 2x 358x 358x 824x 824x 358x 358x 62x 62x 13x 13x 62x 62x 358x 358x 4x 2x 2x 4x 4x 358x 358x 8193x 8193x 7855x 7855x 7855x 7855x 7855x 7855x 7855x 8193x 358x 358x     358x 358x 358x 358x 358x 384x 201x 158x 158x 158x 158x 201x 201x 201x 201x 201x 388x 157x 135x 135x 135x 135x 134x 134x 135x 157x 157x 157x 157x 157x 157x 157x 157x 157x 157x 157x 157x 157x 157x 157x 157x 157x 157x 157x 157x 358x 388x 3x 3x 1x 3x 2x 2x 2x 3x 358x 358x 358x 358x 358x 388x 2x 2x 2x 2x 2x 2x 2x 2x 9448x 9448x 9382x 9448x 2x 2x 2x 2x 2x 2x 2x 2x 1550x 2x 2x 2x 2x 2x 2x 2x 509x 2x 2x 2x 2x 639x 639x 639x 6x 6x 639x 639x 2x 2x 2x 2x 2x 2x 2x 2x 1146x 1146x 258x 258x 1143x 888x 888x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 18x 18x 18x 18x 6x 2x 2x 4x 4x 4x 4x 4x 16x 16x 16x 2x 16x 14x 14x 14x 14x 14x 16x 2x 2x 2x 6x 6x 6x 2x 2x 4x 4x 4x 4x 4x 2x 2x 2x 2x 4x 2x 2x 4x 4x 4x 4x 4x 4x 4x 2x 2x 2x 1099x 6x 6x 6x 6x 1099x 1093x 1093x 2x 2x 2x 8783x 8783x 8783x 8727x 8727x 2x 2x 2x 305x 276x 276x 305x 275x 275x 305x 271x 305x 266x 5x 5x 5x 5x 266x 266x 266x 266x 266x 266x 271x 271x 271x 271x 271x 271x 271x 271x 271x 271x 271x 271x 2x 2x 2x 2x 434x 434x 434x 434x 434x 434x 434x 434x 434x 434x 434x 434x 2x 2x 434x 434x 434x 434x 434x 434x 434x 434x 434x 434x 434x 32x 32x 434x 434x 434x 434x 434x 434x 1x 1x 434x 434x 2x 2x 2x 2x 2x 2x 2x 325x 293x 325x 135x 135x 293x 293x 2x 2x 2x 2x 2x 2x 2x 419x 413x 413x 413x 413x 2x 2x 2x 2x 2x 2x 2x 158x 121x 121x 121x 121x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 144x 144x 83x 138x 61x 61x 2x 2x 2x 885x     885x 885x 885x 6x 6x 6x 885x 885x 885x 885x 885x 328x 328x 328x 885x 544x 544x 544x 544x 544x 544x 544x 544x 544x 885x 333x 333x 333x 2x 2x 2x 7008x 9x 9x 9x 9x 9x 7008x 6999x 6999x 6999x 6999x 11x 6999x 6988x 6988x 6999x 2x 2x 2x 22x 22x 22x 22x 22x 22x 1x 1x 1x 21x 21x 21x 21x 22x 3x 3x 18x 18x 18x 18x 18x 1x 1x 1x 17x 19x 10x 10x 7x 7x 7x 7x 7x 22x 22x 1x 1x 7x 7x 7x 15x 33x 33x 11x 11x 11x 33x 22x 22x 33x 27x 27x 27x 33x 6x 6x 33x 7x 7x 7x 7x 7x 22x 2x 2x 2x 25x 24x 24x 24x 24x 24x 24x 24x 24x 2x 2x 2x 2x 12x 11x 11x 11x 11x 2x 2x 2x 24x 23x 23x 23x 23x 23x 23x 23x 23x 2x 2x 2x 2x 5x 3x 3x 3x 3x 3x 3x 2x 2x 2x 2x 9x 4x 4x 4x 4x 4x 4x 4x 4x 4x 4x 4x 4x 4x 2x 2x 2x 2x 13x 9x 9x 9x 9x 9x 9x 2x 2x 2x 2x 15x 15x 15x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 355x 355x 355x 355x 355x 2x 2x 2x 2x 305x 305x 305x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 26x 24x 24x 24x 15x 24x 1x 1x 24x 10x 23x 14x 14x 24x 24x 24x 24x 2x 2x 2x 71x 54x 54x 54x 54x 54x 7x 7x 54x 7x 54x 47x 47x 54x 54x 54x 54x 2x 2x 2x 2x 9442x 9442x 9442x 9442x 9442x 2951457x 9x 9x 9x 9x 9x 2951448x 2951457x 32x 32x 32x 2951416x 2951457x 2918627x 2951457x 32789x     32789x 32789x 2951457x 9442x 9442x 9442x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 8456x 8456x 8456x 2x 2x 2x 2x 2x 2x 460x 5x 5x 455x 455x 455x 455x 460x 20x 460x 380x 380x 455x 455x 455x 455x 455x 454x 454x 460x 1x 1x 2x 2x 81x 81x 81x 81x 80x 81x 81x 80x 81x 5x 1x   1x 1x 1x 1x 1x 1x 5x 1x 1x 1x 5x 78x 78x 81x 1x 1x 1x 81x 81x 8x 8x 8x 8x 8x 8x 8x 81x 81x 69x 65x 65x 65x 65x 81x 81x 2x 2x 2x 8168x 8168x 8168x 8168x 8168x 8168x 8168x 88x 39x 39x 8168x 39x 39x 39x 2x 2x 39x 8168x 8168x 8168x 8168x 8157x 8168x 7x 7x 7x 7x 7x 1x 1x 7x 7x 1x 1x 7x 7x 8168x 140x 140x 140x 140x 8x 7x 8x 1x 1x 1x 8x 140x 140x 2x 2x 140x 140x 42x 39x 39x 42x 2x 2x 42x 140x 140x 14x 14x 140x 140x 1x 1x 140x 140x 14x 14x 140x 140x 5x 5x 140x 140x 2x 2x 140x 140x 2x 2x 140x 140x 1x 1x 1x 1x 140x 140x 2x 2x 140x 140x 1x 1x 140x 140x                                             140x 140x 140x 140x 140x 140x 5x 5x 140x 140x 3x 3x 140x 140x 18x 18x 140x 140x 5x 5x 140x 140x 8150x 41x 41x 41x 41x 7x 7x 41x 41x 7x 7x 41x 41x 41x 10x 10x 41x 41x 4x 4x 41x 41x 8010x 7969x 7969x 7969x 7969x 7969x 7969x 7969x 7969x 24x 24x 24x 7969x 7969x 268x 268x 268x 259x 259x 268x 268x 7969x 7969x 22x 22x 7969x 7969x 3x 3x 7969x 7969x 18x 18x 18x 7969x 7969x 15x 15x 7969x 7969x 6x 6x 7969x 7969x 8x 8x 7969x 7969x 70x 70x 7969x 7969x 24x 24x 7969x 7969x 29x 29x 22x 22x 22x 22x 7969x 7969x 7489x 6981x 6981x 6994x 13x 13x 6994x 6994x 6981x 7969x 7969x 2x 2x 2x 2x 2x 2x 2x 2x 30x 22x 4x 4x 22x 22x 22x 35x 22x 22x 22x 22x 22x 22x 22x 22x 22x 52x 3x 3x 3x 22x 22x 16x 22x 22x 1x 22x 22x 22x 22x 22x 22x 30x 30x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x  
// Copyright Joyent, Inc. and other Node contributors.
//
// Permission is hereby granted, free of charge, to any person obtaining a
// copy of this software and associated documentation files (the
// "Software"), to deal in the Software without restriction, including
// without limitation the rights to use, copy, modify, merge, publish,
// distribute, sublicense, and/or sell copies of the Software, and to permit
// persons to whom the Software is furnished to do so, subject to the
// following conditions:
//
// The above copyright notice and this permission notice shall be included
// in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN
// NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
// DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
// USE OR OTHER DEALINGS IN THE SOFTWARE.
 
// Inspiration for this code comes from Salvatore Sanfilippo's linenoise.
// https://github.com/antirez/linenoise
// Reference:
// * https://invisible-island.net/xterm/ctlseqs/ctlseqs.html
// * http://www.3waylabs.com/nw/WWW/products/wizcon/vt220.html
 
'use strict';
 
const {
  ArrayFrom,
  ArrayPrototypeFilter,
  ArrayPrototypeIndexOf,
  ArrayPrototypeJoin,
  ArrayPrototypeMap,
  ArrayPrototypePop,
  ArrayPrototypeReverse,
  ArrayPrototypeSplice,
  ArrayPrototypeUnshift,
  DateNow,
  FunctionPrototypeBind,
  FunctionPrototypeCall,
  MathCeil,
  MathFloor,
  MathMax,
  MathMaxApply,
  NumberIsFinite,
  NumberIsNaN,
  ObjectDefineProperty,
  ObjectSetPrototypeOf,
  RegExpPrototypeTest,
  StringPrototypeCodePointAt,
  StringPrototypeEndsWith,
  StringPrototypeMatch,
  StringPrototypeRepeat,
  StringPrototypeReplace,
  StringPrototypeSlice,
  StringPrototypeSplit,
  StringPrototypeStartsWith,
  StringPrototypeTrim,
  Promise,
  PromiseReject,
  Symbol,
  SymbolAsyncIterator,
  SafeStringIterator,
} = primordials;
 
const {
  clearLine,
  clearScreenDown,
  cursorTo,
  moveCursor,
} = require('internal/readline/callbacks');
const emitKeypressEvents = require('internal/readline/emitKeypressEvents');
 
const {
  AbortError,
  codes
} = require('internal/errors');
 
const {
  ERR_INVALID_ARG_VALUE,
} = codes;
const {
  validateAbortSignal,
  validateArray,
  validateString,
  validateUint32,
} = require('internal/validators');
const {
  inspect,
  getStringWidth,
  stripVTControlCharacters,
} = require('internal/util/inspect');
const EventEmitter = require('events');
const {
  charLengthAt,
  charLengthLeft,
  commonPrefix,
  kSubstringSearch,
} = require('internal/readline/utils');
 
const { promisify } = require('internal/util');
 
const { StringDecoder } = require('string_decoder');
 
// Lazy load Readable for startup performance.
let Readable;
 
/**
 * @typedef {import('./stream.js').Readable} Readable
 * @typedef {import('./stream.js').Writable} Writable
 */
 
const kHistorySize = 30;
const kMincrlfDelay = 100;
// \r\n, \n, or \r followed by something other than \n
const lineEnding = /\r?\n|\r(?!\n)/;
 
const kLineObjectStream = Symbol('line object stream');
const kQuestionCancel = Symbol('kQuestionCancel');
 
// GNU readline library - keyseq-timeout is 500ms (default)
const ESCAPE_CODE_TIMEOUT = 500;
 
/**
 * Creates a new `readline.Interface` instance.
 * @param {Readable | {
 *   input: Readable;
 *   output: Writable;
 *   completer?: Function;
 *   terminal?: boolean;
 *   history?: string[];
 *   historySize?: number;
 *   removeHistoryDuplicates?: boolean;
 *   prompt?: string;
 *   crlfDelay?: number;
 *   escapeCodeTimeout?: number;
 *   tabSize?: number;
 *   signal?: AbortSignal;
 *   }} input
 * @param {Writable} [output]
 * @param {Function} [completer]
 * @param {boolean} [terminal]
 * @returns {Interface}
 */
function createInterface(input, output, completer, terminal) {
  return new Interface(input, output, completer, terminal);
}
 
 
function Interface(input, output, completer, terminal) {
  if (!(this instanceof Interface)) {
    return new Interface(input, output, completer, terminal);
  }
 
  this._sawReturnAt = 0;
  // TODO(BridgeAR): Document this property. The name is not ideal, so we might
  // want to expose an alias and document that instead.
  this.isCompletionEnabled = true;
  this._sawKeyPress = false;
  this._previousKey = null;
  this.escapeCodeTimeout = ESCAPE_CODE_TIMEOUT;
  this.tabSize = 8;
 
  FunctionPrototypeCall(EventEmitter, this);
  let history;
  let historySize;
  let removeHistoryDuplicates = false;
  let crlfDelay;
  let prompt = '> ';
  let signal;
  if (input && input.input) {
    // An options object was given
    output = input.output;
    completer = input.completer;
    terminal = input.terminal;
    history = input.history;
    historySize = input.historySize;
    signal = input.signal;
    if (input.tabSize !== undefined) {
      validateUint32(input.tabSize, 'tabSize', true);
      this.tabSize = input.tabSize;
    }
    removeHistoryDuplicates = input.removeHistoryDuplicates;
    if (input.prompt !== undefined) {
      prompt = input.prompt;
    }
    if (input.escapeCodeTimeout !== undefined) {
      if (NumberIsFinite(input.escapeCodeTimeout)) {
        this.escapeCodeTimeout = input.escapeCodeTimeout;
      } else {
        throw new ERR_INVALID_ARG_VALUE(
          'input.escapeCodeTimeout',
          this.escapeCodeTimeout
        );
      }
    }
 
    if (signal) {
      validateAbortSignal(signal, 'options.signal');
    }
 
    crlfDelay = input.crlfDelay;
    input = input.input;
  }
 
  if (completer !== undefined && typeof completer !== 'function') {
    throw new ERR_INVALID_ARG_VALUE('completer', completer);
  }
 
  if (history === undefined) {
    history = [];
  } else {
    validateArray(history, 'history');
  }
 
  if (historySize === undefined) {
    historySize = kHistorySize;
  }
 
  if (typeof historySize !== 'number' ||
      NumberIsNaN(historySize) ||
      historySize < 0) {
    throw new ERR_INVALID_ARG_VALUE.RangeError('historySize', historySize);
  }
 
  // Backwards compat; check the isTTY prop of the output stream
  //  when `terminal` was not specified
  if (terminal === undefined && !(output === null || output === undefined)) {
    terminal = !!output.isTTY;
  }
 
  const self = this;
 
  this.line = '';
  this[kSubstringSearch] = null;
  this.output = output;
  this.input = input;
  this.history = history;
  this.historySize = historySize;
  this.removeHistoryDuplicates = !!removeHistoryDuplicates;
  this.crlfDelay = crlfDelay ?
    MathMax(kMincrlfDelay, crlfDelay) : kMincrlfDelay;
  // Check arity, 2 - for async, 1 for sync
  if (typeof completer === 'function') {
    this.completer = completer.length === 2 ?
      completer :
      function completerWrapper(v, cb) {
        cb(null, completer(v));
      };
  }
 
  this[kQuestionCancel] = FunctionPrototypeBind(_questionCancel, this);
 
  this.setPrompt(prompt);
 
  this.terminal = !!terminal;
 
  if (process.env.TERM === 'dumb') {
    this._ttyWrite = FunctionPrototypeBind(_ttyWriteDumb, this);
  }
 
  function onerror(err) {
    self.emit('error', err);
  }
 
  function ondata(data) {
    self._normalWrite(data);
  }
 
  function onend() {
    if (typeof self._line_buffer === 'string' &&
        self._line_buffer.length > 0) {
      self.emit('line', self._line_buffer);
    }
    self.close();
  }
 
  function ontermend() {
    if (typeof self.line === 'string' && self.line.length > 0) {
      self.emit('line', self.line);
    }
    self.close();
  }
 
  function onkeypress(s, key) {
    self._ttyWrite(s, key);
    if (key && key.sequence) {
      // If the key.sequence is half of a surrogate pair
      // (>= 0xd800 and <= 0xdfff), refresh the line so
      // the character is displayed appropriately.
      const ch = StringPrototypeCodePointAt(key.sequence, 0);
      if (ch >= 0xd800 && ch <= 0xdfff)
        self._refreshLine();
    }
  }
 
  function onresize() {
    self._refreshLine();
  }
 
  this[kLineObjectStream] = undefined;
 
  input.on('error', onerror);
 
  if (!this.terminal) {
    function onSelfCloseWithoutTerminal() {
      input.removeListener('data', ondata);
      input.removeListener('error', onerror);
      input.removeListener('end', onend);
    }
 
    input.on('data', ondata);
    input.on('end', onend);
    self.once('close', onSelfCloseWithoutTerminal);
    this._decoder = new StringDecoder('utf8');
  } else {
    function onSelfCloseWithTerminal() {
      input.removeListener('keypress', onkeypress);
      input.removeListener('error', onerror);
      input.removeListener('end', ontermend);
      if (output !== null && output !== undefined) {
        output.removeListener('resize', onresize);
      }
    }
 
    emitKeypressEvents(input, this);
 
    // `input` usually refers to stdin
    input.on('keypress', onkeypress);
    input.on('end', ontermend);
 
    this._setRawMode(true);
    this.terminal = true;
 
    // Cursor position on the line.
    this.cursor = 0;
 
    this.historyIndex = -1;
 
    if (output !== null && output !== undefined)
      output.on('resize', onresize);
 
    self.once('close', onSelfCloseWithTerminal);
  }
 
  if (signal) {
    const onAborted = () => self.close();
    if (signal.aborted) {
      process.nextTick(onAborted);
    } else {
      signal.addEventListener('abort', onAborted, { once: true });
      self.once('close', () => signal.removeEventListener('abort', onAborted));
    }
  }
 
  // Current line
  this.line = '';
 
  input.resume();
}
 
ObjectSetPrototypeOf(Interface.prototype, EventEmitter.prototype);
ObjectSetPrototypeOf(Interface, EventEmitter);
 
ObjectDefineProperty(Interface.prototype, 'columns', {
  configurable: true,
  enumerable: true,
  get: function() {
    if (this.output && this.output.columns)
      return this.output.columns;
    return Infinity;
  }
});
 
/**
 * Sets the prompt written to the output.
 * @param {string} prompt
 * @returns {void}
 */
Interface.prototype.setPrompt = function(prompt) {
  this._prompt = prompt;
};
 
/**
 * Returns the current prompt used by `rl.prompt()`.
 * @returns {string}
 */
Interface.prototype.getPrompt = function() {
  return this._prompt;
};
 
 
Interface.prototype._setRawMode = function(mode) {
  const wasInRawMode = this.input.isRaw;
 
  if (typeof this.input.setRawMode === 'function') {
    this.input.setRawMode(mode);
  }
 
  return wasInRawMode;
};
 
/**
 * Writes the configured `prompt` to a new line in `output`.
 * @param {boolean} [preserveCursor]
 * @returns {void}
 */
Interface.prototype.prompt = function(preserveCursor) {
  if (this.paused) this.resume();
  if (this.terminal && process.env.TERM !== 'dumb') {
    if (!preserveCursor) this.cursor = 0;
    this._refreshLine();
  } else {
    this._writeToOutput(this._prompt);
  }
};
 
/**
 * Displays `query` by writing it to the `output`.
 * @param {string} query
 * @param {{ signal?: AbortSignal; }} [options]
 * @param {Function} cb
 * @returns {void}
 */
Interface.prototype.question = function(query, options, cb) {
  cb = typeof options === 'function' ? options : cb;
  options = typeof options === 'object' && options !== null ? options : {};
 
  if (options.signal) {
    if (options.signal.aborted) {
      return;
    }
 
    options.signal.addEventListener('abort', () => {
      this[kQuestionCancel]();
    }, { once: true });
  }
 
  if (typeof cb === 'function') {
    if (this._questionCallback) {
      this.prompt();
    } else {
      this._oldPrompt = this._prompt;
      this.setPrompt(query);
      this._questionCallback = cb;
      this.prompt();
    }
  }
};
 
Interface.prototype.question[promisify.custom] = function(query, options) {
  options = typeof options === 'object' && options !== null ? options : {};
 
  if (options.signal && options.signal.aborted) {
    return PromiseReject(new AbortError());
  }
 
  return new Promise((resolve, reject) => {
    this.question(query, options, resolve);
 
    if (options.signal) {
      options.signal.addEventListener('abort', () => {
        reject(new AbortError());
      }, { once: true });
    }
  });
};
 
function _questionCancel() {
  if (this._questionCallback) {
    this._questionCallback = null;
    this.setPrompt(this._oldPrompt);
    this.clearLine();
  }
}
 
 
Interface.prototype._onLine = function(line) {
  if (this._questionCallback) {
    const cb = this._questionCallback;
    this._questionCallback = null;
    this.setPrompt(this._oldPrompt);
    cb(line);
  } else {
    this.emit('line', line);
  }
};
 
Interface.prototype._writeToOutput = function _writeToOutput(stringToWrite) {
  validateString(stringToWrite, 'stringToWrite');
 
  if (this.output !== null && this.output !== undefined) {
    this.output.write(stringToWrite);
  }
};
 
Interface.prototype._addHistory = function() {
  if (this.line.length === 0) return '';
 
  // If the history is disabled then return the line
  if (this.historySize === 0) return this.line;
 
  // If the trimmed line is empty then return the line
  if (StringPrototypeTrim(this.line).length === 0) return this.line;
 
  if (this.history.length === 0 || this.history[0] !== this.line) {
    if (this.removeHistoryDuplicates) {
      // Remove older history line if identical to new one
      const dupIndex = ArrayPrototypeIndexOf(this.history, this.line);
      if (dupIndex !== -1) ArrayPrototypeSplice(this.history, dupIndex, 1);
    }
 
    ArrayPrototypeUnshift(this.history, this.line);
 
    // Only store so many
    if (this.history.length > this.historySize) ArrayPrototypePop(this.history);
  }
 
  this.historyIndex = -1;
 
  // The listener could change the history object, possibly
  // to remove the last added entry if it is sensitive and should
  // not be persisted in the history, like a password
  const line = this.history[0];
 
  // Emit history event to notify listeners of update
  this.emit('history', this.history);
 
  return line;
};
 
 
Interface.prototype._refreshLine = function() {
  // line length
  const line = this._prompt + this.line;
  const dispPos = this._getDisplayPos(line);
  const lineCols = dispPos.cols;
  const lineRows = dispPos.rows;
 
  // cursor position
  const cursorPos = this.getCursorPos();
 
  // First move to the bottom of the current line, based on cursor pos
  const prevRows = this.prevRows || 0;
  if (prevRows > 0) {
    moveCursor(this.output, 0, -prevRows);
  }
 
  // Cursor to left edge.
  cursorTo(this.output, 0);
  // erase data
  clearScreenDown(this.output);
 
  // Write the prompt and the current buffer content.
  this._writeToOutput(line);
 
  // Force terminal to allocate a new line
  if (lineCols === 0) {
    this._writeToOutput(' ');
  }
 
  // Move cursor to original position.
  cursorTo(this.output, cursorPos.cols);
 
  const diff = lineRows - cursorPos.rows;
  if (diff > 0) {
    moveCursor(this.output, 0, -diff);
  }
 
  this.prevRows = cursorPos.rows;
};
 
/**
 * Closes the `readline.Interface` instance.
 * @returns {void}
 */
Interface.prototype.close = function() {
  if (this.closed) return;
  this.pause();
  if (this.terminal) {
    this._setRawMode(false);
  }
  this.closed = true;
  this.emit('close');
};
 
/**
 * Pauses the `input` stream.
 * @returns {void | Interface}
 */
Interface.prototype.pause = function() {
  if (this.paused) return;
  this.input.pause();
  this.paused = true;
  this.emit('pause');
  return this;
};
 
/**
 * Resumes the `input` stream if paused.
 * @returns {void | Interface}
 */
Interface.prototype.resume = function() {
  if (!this.paused) return;
  this.input.resume();
  this.paused = false;
  this.emit('resume');
  return this;
};
 
/**
 * Writes either `data` or a `key` sequence identified by
 * `key` to the `output`.
 * @param {string} d
 * @param {{
 *   ctrl?: boolean;
 *   meta?: boolean;
 *   shift?: boolean;
 *   name?: string;
 *   }} [key]
 * @returns {void}
 */
Interface.prototype.write = function(d, key) {
  if (this.paused) this.resume();
  if (this.terminal) {
    this._ttyWrite(d, key);
  } else {
    this._normalWrite(d);
  }
};
 
Interface.prototype._normalWrite = function(b) {
  if (b === undefined) {
    return;
  }
  let string = this._decoder.write(b);
  if (this._sawReturnAt &&
      DateNow() - this._sawReturnAt <= this.crlfDelay) {
    string = StringPrototypeReplace(string, /^\n/, '');
    this._sawReturnAt = 0;
  }
 
  // Run test() on the new string chunk, not on the entire line buffer.
  const newPartContainsEnding = RegExpPrototypeTest(lineEnding, string);
 
  if (this._line_buffer) {
    string = this._line_buffer + string;
    this._line_buffer = null;
  }
  if (newPartContainsEnding) {
    this._sawReturnAt = StringPrototypeEndsWith(string, '\r') ? DateNow() : 0;
 
    // Got one or more newlines; process into "line" events
    const lines = StringPrototypeSplit(string, lineEnding);
    // Either '' or (conceivably) the unfinished portion of the next line
    string = ArrayPrototypePop(lines);
    this._line_buffer = string;
    for (let n = 0; n < lines.length; n++)
      this._onLine(lines[n]);
  } else if (string) {
    // No newlines this time, save what we have for next time
    this._line_buffer = string;
  }
};
 
Interface.prototype._insertString = function(c) {
  if (this.cursor < this.line.length) {
    const beg = StringPrototypeSlice(this.line, 0, this.cursor);
    const end = StringPrototypeSlice(this.line, this.cursor, this.line.length);
    this.line = beg + c + end;
    this.cursor += c.length;
    this._refreshLine();
  } else {
    this.line += c;
    this.cursor += c.length;
 
    if (this.getCursorPos().cols === 0) {
      this._refreshLine();
    } else {
      this._writeToOutput(c);
    }
  }
};
 
Interface.prototype._tabComplete = function(lastKeypressWasTab) {
  this.pause();
  const string = StringPrototypeSlice(this.line, 0, this.cursor);
  this.completer(string, (err, value) => {
    this.resume();
 
    if (err) {
      this._writeToOutput(`Tab completion error: ${inspect(err)}`);
      return;
    }
 
    // Result and the text that was completed.
    const { 0: completions, 1: completeOn } = value;
 
    if (!completions || completions.length === 0) {
      return;
    }
 
    // If there is a common prefix to all matches, then apply that portion.
    const prefix = commonPrefix(ArrayPrototypeFilter(completions,
                                                     (e) => e !== ''));
    if (prefix.length > completeOn.length) {
      this._insertString(StringPrototypeSlice(prefix, completeOn.length));
      return;
    }
 
    if (!lastKeypressWasTab) {
      return;
    }
 
    // Apply/show completions.
    const completionsWidth = ArrayPrototypeMap(completions,
                                               (e) => getStringWidth(e));
    const width = MathMaxApply(completionsWidth) + 2; // 2 space padding
    let maxColumns = MathFloor(this.columns / width) || 1;
    if (maxColumns === Infinity) {
      maxColumns = 1;
    }
    let output = '\r\n';
    let lineIndex = 0;
    let whitespace = 0;
    for (let i = 0; i < completions.length; i++) {
      const completion = completions[i];
      if (completion === '' || lineIndex === maxColumns) {
        output += '\r\n';
        lineIndex = 0;
        whitespace = 0;
      } else {
        output += StringPrototypeRepeat(' ', whitespace);
      }
      if (completion !== '') {
        output += completion;
        whitespace = width - completionsWidth[i];
        lineIndex++;
      } else {
        output += '\r\n';
      }
    }
    if (lineIndex !== 0) {
      output += '\r\n\r\n';
    }
    this._writeToOutput(output);
    this._refreshLine();
  });
};
 
Interface.prototype._wordLeft = function() {
  if (this.cursor > 0) {
    // Reverse the string and match a word near beginning
    // to avoid quadratic time complexity
    const leading = StringPrototypeSlice(this.line, 0, this.cursor);
    const reversed = ArrayPrototypeJoin(
      ArrayPrototypeReverse(ArrayFrom(leading)), '');
    const match = StringPrototypeMatch(reversed, /^\s*(?:[^\w\s]+|\w+)?/);
    this._moveCursor(-match[0].length);
  }
};
 
 
Interface.prototype._wordRight = function() {
  if (this.cursor < this.line.length) {
    const trailing = StringPrototypeSlice(this.line, this.cursor);
    const match = StringPrototypeMatch(trailing, /^(?:\s+|[^\w\s]+|\w+)\s*/);
    this._moveCursor(match[0].length);
  }
};
 
Interface.prototype._deleteLeft = function() {
  if (this.cursor > 0 && this.line.length > 0) {
    // The number of UTF-16 units comprising the character to the left
    const charSize = charLengthLeft(this.line, this.cursor);
    this.line = StringPrototypeSlice(this.line, 0, this.cursor - charSize) +
                StringPrototypeSlice(this.line, this.cursor, this.line.length);
 
    this.cursor -= charSize;
    this._refreshLine();
  }
};
 
 
Interface.prototype._deleteRight = function() {
  if (this.cursor < this.line.length) {
    // The number of UTF-16 units comprising the character to the left
    const charSize = charLengthAt(this.line, this.cursor);
    this.line = StringPrototypeSlice(this.line, 0, this.cursor) +
      StringPrototypeSlice(this.line, this.cursor + charSize, this.line.length);
    this._refreshLine();
  }
};
 
 
Interface.prototype._deleteWordLeft = function() {
  if (this.cursor > 0) {
    // Reverse the string and match a word near beginning
    // to avoid quadratic time complexity
    let leading = StringPrototypeSlice(this.line, 0, this.cursor);
    const reversed = ArrayPrototypeJoin(
      ArrayPrototypeReverse(ArrayFrom(leading)), '');
    const match = StringPrototypeMatch(reversed, /^\s*(?:[^\w\s]+|\w+)?/);
    leading = StringPrototypeSlice(leading, 0,
                                   leading.length - match[0].length);
    this.line = leading + StringPrototypeSlice(this.line, this.cursor,
                                               this.line.length);
    this.cursor = leading.length;
    this._refreshLine();
  }
};
 
 
Interface.prototype._deleteWordRight = function() {
  if (this.cursor < this.line.length) {
    const trailing = StringPrototypeSlice(this.line, this.cursor);
    const match = StringPrototypeMatch(trailing, /^(?:\s+|\W+|\w+)\s*/);
    this.line = StringPrototypeSlice(this.line, 0, this.cursor) +
                StringPrototypeSlice(trailing, match[0].length);
    this._refreshLine();
  }
};
 
 
Interface.prototype._deleteLineLeft = function() {
  this.line = StringPrototypeSlice(this.line, this.cursor);
  this.cursor = 0;
  this._refreshLine();
};
 
 
Interface.prototype._deleteLineRight = function() {
  this.line = StringPrototypeSlice(this.line, 0, this.cursor);
  this._refreshLine();
};
 
 
Interface.prototype.clearLine = function() {
  this._moveCursor(+Infinity);
  this._writeToOutput('\r\n');
  this.line = '';
  this.cursor = 0;
  this.prevRows = 0;
};
 
 
Interface.prototype._line = function() {
  const line = this._addHistory();
  this.clearLine();
  this._onLine(line);
};
 
// TODO(BridgeAR): Add underscores to the search part and a red background in
// case no match is found. This should only be the visual part and not the
// actual line content!
// TODO(BridgeAR): In case the substring based search is active and the end is
// reached, show a comment how to search the history as before. E.g., using
// <ctrl> + N. Only show this after two/three UPs or DOWNs, not on the first
// one.
Interface.prototype._historyNext = function() {
  if (this.historyIndex >= 0) {
    const search = this[kSubstringSearch] || '';
    let index = this.historyIndex - 1;
    while (index >= 0 &&
           (!StringPrototypeStartsWith(this.history[index], search) ||
             this.line === this.history[index])) {
      index--;
    }
    if (index === -1) {
      this.line = search;
    } else {
      this.line = this.history[index];
    }
    this.historyIndex = index;
    this.cursor = this.line.length; // Set cursor to end of line.
    this._refreshLine();
  }
};
 
Interface.prototype._historyPrev = function() {
  if (this.historyIndex < this.history.length && this.history.length) {
    const search = this[kSubstringSearch] || '';
    let index = this.historyIndex + 1;
    while (index < this.history.length &&
           (!StringPrototypeStartsWith(this.history[index], search) ||
             this.line === this.history[index])) {
      index++;
    }
    if (index === this.history.length) {
      this.line = search;
    } else {
      this.line = this.history[index];
    }
    this.historyIndex = index;
    this.cursor = this.line.length; // Set cursor to end of line.
    this._refreshLine();
  }
};
 
// Returns the last character's display position of the given string
Interface.prototype._getDisplayPos = function(str) {
  let offset = 0;
  const col = this.columns;
  let rows = 0;
  str = stripVTControlCharacters(str);
  for (const char of new SafeStringIterator(str)) {
    if (char === '\n') {
      // Rows must be incremented by 1 even if offset = 0 or col = +Infinity.
      rows += MathCeil(offset / col) || 1;
      offset = 0;
      continue;
    }
    // Tabs must be aligned by an offset of the tab size.
    if (char === '\t') {
      offset += this.tabSize - (offset % this.tabSize);
      continue;
    }
    const width = getStringWidth(char);
    if (width === 0 || width === 1) {
      offset += width;
    } else { // width === 2
      if ((offset + 1) % col === 0) {
        offset++;
      }
      offset += 2;
    }
  }
  const cols = offset % col;
  rows += (offset - cols) / col;
  return { cols, rows };
};
 
/**
 * Returns the real position of the cursor in relation
 * to the input prompt + string.
 * @returns {{
 *   rows: number;
 *   cols: number;
 *   }}
 */
Interface.prototype.getCursorPos = function() {
  const strBeforeCursor = this._prompt +
                          StringPrototypeSlice(this.line, 0, this.cursor);
  return this._getDisplayPos(strBeforeCursor);
};
Interface.prototype._getCursorPos = Interface.prototype.getCursorPos;
 
// This function moves cursor dx places to the right
// (-dx for left) and refreshes the line if it is needed.
Interface.prototype._moveCursor = function(dx) {
  if (dx === 0) {
    return;
  }
  const oldPos = this.getCursorPos();
  this.cursor += dx;
 
  // Bounds check
  if (this.cursor < 0) {
    this.cursor = 0;
  } else if (this.cursor > this.line.length) {
    this.cursor = this.line.length;
  }
 
  const newPos = this.getCursorPos();
 
  // Check if cursor stayed on the line.
  if (oldPos.rows === newPos.rows) {
    const diffWidth = newPos.cols - oldPos.cols;
    moveCursor(this.output, diffWidth, 0);
  } else {
    this._refreshLine();
  }
};
 
function _ttyWriteDumb(s, key) {
  key = key || {};
 
  if (key.name === 'escape') return;
 
  if (this._sawReturnAt && key.name !== 'enter')
    this._sawReturnAt = 0;
 
  if (key.ctrl) {
    if (key.name === 'c') {
      if (this.listenerCount('SIGINT') > 0) {
        this.emit('SIGINT');
      } else {
        // This readline instance is finished
        this.close();
      }
 
      return;
    } else if (key.name === 'd') {
      this.close();
      return;
    }
  }
 
  switch (key.name) {
    case 'return':  // Carriage return, i.e. \r
      this._sawReturnAt = DateNow();
      this._line();
      break;
 
    case 'enter':
      // When key interval > crlfDelay
      if (this._sawReturnAt === 0 ||
          DateNow() - this._sawReturnAt > this.crlfDelay) {
        this._line();
      }
      this._sawReturnAt = 0;
      break;
 
    default:
      if (typeof s === 'string' && s) {
        this.line += s;
        this.cursor += s.length;
        this._writeToOutput(s);
      }
  }
}
 
// Handle a write from the tty
Interface.prototype._ttyWrite = function(s, key) {
  const previousKey = this._previousKey;
  key = key || {};
  this._previousKey = key;
 
  // Activate or deactivate substring search.
  if ((key.name === 'up' || key.name === 'down') &&
      !key.ctrl && !key.meta && !key.shift) {
    if (this[kSubstringSearch] === null) {
      this[kSubstringSearch] = StringPrototypeSlice(this.line, 0, this.cursor);
    }
  } else if (this[kSubstringSearch] !== null) {
    this[kSubstringSearch] = null;
    // Reset the index in case there's no match.
    if (this.history.length === this.historyIndex) {
      this.historyIndex = -1;
    }
  }
 
  // Ignore escape key, fixes
  // https://github.com/nodejs/node-v0.x-archive/issues/2876.
  if (key.name === 'escape') return;
 
  if (key.ctrl && key.shift) {
    /* Control and shift pressed */
    switch (key.name) {
      // TODO(BridgeAR): The transmitted escape sequence is `\b` and that is
      // identical to <ctrl>-h. It should have a unique escape sequence.
      case 'backspace':
        this._deleteLineLeft();
        break;
 
      case 'delete':
        this._deleteLineRight();
        break;
    }
 
  } else if (key.ctrl) {
    /* Control key pressed */
 
    switch (key.name) {
      case 'c':
        if (this.listenerCount('SIGINT') > 0) {
          this.emit('SIGINT');
        } else {
          // This readline instance is finished
          this.close();
        }
        break;
 
      case 'h': // delete left
        this._deleteLeft();
        break;
 
      case 'd': // delete right or EOF
        if (this.cursor === 0 && this.line.length === 0) {
          // This readline instance is finished
          this.close();
        } else if (this.cursor < this.line.length) {
          this._deleteRight();
        }
        break;
 
      case 'u': // Delete from current to start of line
        this._deleteLineLeft();
        break;
 
      case 'k': // Delete from current to end of line
        this._deleteLineRight();
        break;
 
      case 'a': // Go to the start of the line
        this._moveCursor(-Infinity);
        break;
 
      case 'e': // Go to the end of the line
        this._moveCursor(+Infinity);
        break;
 
      case 'b': // back one character
        this._moveCursor(-charLengthLeft(this.line, this.cursor));
        break;
 
      case 'f': // Forward one character
        this._moveCursor(+charLengthAt(this.line, this.cursor));
        break;
 
      case 'l': // Clear the whole screen
        cursorTo(this.output, 0, 0);
        clearScreenDown(this.output);
        this._refreshLine();
        break;
 
      case 'n': // next history item
        this._historyNext();
        break;
 
      case 'p': // Previous history item
        this._historyPrev();
        break;
 
      case 'z':
        if (process.platform === 'win32') break;
        if (this.listenerCount('SIGTSTP') > 0) {
          this.emit('SIGTSTP');
        } else {
          process.once('SIGCONT', () => {
            // Don't raise events if stream has already been abandoned.
            if (!this.paused) {
              // Stream must be paused and resumed after SIGCONT to catch
              // SIGINT, SIGTSTP, and EOF.
              this.pause();
              this.emit('SIGCONT');
            }
            // Explicitly re-enable "raw mode" and move the cursor to
            // the correct position.
            // See https://github.com/joyent/node/issues/3295.
            this._setRawMode(true);
            this._refreshLine();
          });
          this._setRawMode(false);
          process.kill(process.pid, 'SIGTSTP');
        }
        break;
 
      case 'w': // Delete backwards to a word boundary
      // TODO(BridgeAR): The transmitted escape sequence is `\b` and that is
      // identical to <ctrl>-h. It should have a unique escape sequence.
      // Falls through
      case 'backspace':
        this._deleteWordLeft();
        break;
 
      case 'delete': // Delete forward to a word boundary
        this._deleteWordRight();
        break;
 
      case 'left':
        this._wordLeft();
        break;
 
      case 'right':
        this._wordRight();
        break;
    }
 
  } else if (key.meta) {
    /* Meta key pressed */
 
    switch (key.name) {
      case 'b': // backward word
        this._wordLeft();
        break;
 
      case 'f': // forward word
        this._wordRight();
        break;
 
      case 'd': // delete forward word
      case 'delete':
        this._deleteWordRight();
        break;
 
      case 'backspace': // Delete backwards to a word boundary
        this._deleteWordLeft();
        break;
    }
 
  } else {
    /* No modifier keys used */
 
    // \r bookkeeping is only relevant if a \n comes right after.
    if (this._sawReturnAt && key.name !== 'enter')
      this._sawReturnAt = 0;
 
    switch (key.name) {
      case 'return':  // Carriage return, i.e. \r
        this._sawReturnAt = DateNow();
        this._line();
        break;
 
      case 'enter':
        // When key interval > crlfDelay
        if (this._sawReturnAt === 0 ||
            DateNow() - this._sawReturnAt > this.crlfDelay) {
          this._line();
        }
        this._sawReturnAt = 0;
        break;
 
      case 'backspace':
        this._deleteLeft();
        break;
 
      case 'delete':
        this._deleteRight();
        break;
 
      case 'left':
        // Obtain the code point to the left
        this._moveCursor(-charLengthLeft(this.line, this.cursor));
        break;
 
      case 'right':
        this._moveCursor(+charLengthAt(this.line, this.cursor));
        break;
 
      case 'home':
        this._moveCursor(-Infinity);
        break;
 
      case 'end':
        this._moveCursor(+Infinity);
        break;
 
      case 'up':
        this._historyPrev();
        break;
 
      case 'down':
        this._historyNext();
        break;
 
      case 'tab':
        // If tab completion enabled, do that...
        if (typeof this.completer === 'function' && this.isCompletionEnabled) {
          const lastKeypressWasTab = previousKey && previousKey.name === 'tab';
          this._tabComplete(lastKeypressWasTab);
          break;
        }
      // falls through
      default:
        if (typeof s === 'string' && s) {
          const lines = StringPrototypeSplit(s, /\r\n|\n|\r/);
          for (let i = 0, len = lines.length; i < len; i++) {
            if (i > 0) {
              this._line();
            }
            this._insertString(lines[i]);
          }
        }
    }
  }
};
 
/**
 * Creates an `AsyncIterator` object that iterates through
 * each line in the input stream as a string.
 * @returns {Symbol.AsyncIterator}
 */
Interface.prototype[SymbolAsyncIterator] = function() {
  if (this[kLineObjectStream] === undefined) {
    if (Readable === undefined) {
      Readable = require('stream').Readable;
    }
    const readable = new Readable({
      objectMode: true,
      read: () => {
        this.resume();
      },
      destroy: (err, cb) => {
        this.off('line', lineListener);
        this.off('close', closeListener);
        this.close();
        cb(err);
      }
    });
    const lineListener = (input) => {
      if (!readable.push(input)) {
        // TODO(rexagod): drain to resume flow
        this.pause();
      }
    };
    const closeListener = () => {
      readable.push(null);
    };
    const errorListener = (err) => {
      readable.destroy(err);
    };
    this.on('error', errorListener);
    this.on('line', lineListener);
    this.on('close', closeListener);
    this[kLineObjectStream] = readable;
  }
 
  return this[kLineObjectStream][SymbolAsyncIterator]();
};
 
module.exports = {
  Interface,
  clearLine,
  clearScreenDown,
  createInterface,
  cursorTo,
  emitKeypressEvents,
  moveCursor
};