src/Parser.ts

   1 /**
   2  * @license MIT
   3  */
   4
   5 import { C0 } from './EscapeSequences';
   6 import { IInputHandler } from './Interfaces';
   7 import { CHARSETS, DEFAULT_CHARSET } from './Charsets';
   8
   9 const normalStateHandler: {[key: string]: (parser: Parser, handler: IInputHandler) => void} = {};
  10 normalStateHandler[C0.BEL] = (parser, handler) => handler.bell();
  11 normalStateHandler[C0.LF] = (parser, handler) => handler.lineFeed();
  12 normalStateHandler[C0.VT] = normalStateHandler[C0.LF];
  13 normalStateHandler[C0.FF] = normalStateHandler[C0.LF];
  14 normalStateHandler[C0.CR] = (parser, handler) => handler.carriageReturn();
  15 normalStateHandler[C0.BS] = (parser, handler) => handler.backspace();
  16 normalStateHandler[C0.HT] = (parser, handler) => handler.tab();
  17 normalStateHandler[C0.SO] = (parser, handler) => handler.shiftOut();
  18 normalStateHandler[C0.SI] = (parser, handler) => handler.shiftIn();
  19 normalStateHandler[C0.ESC] = (parser, handler) => parser.setState(ParserState.ESCAPED);
  20
  21 // TODO: Remove terminal when parser owns params and currentParam
  22 const escapedStateHandler: {[key: string]: (parser: Parser, terminal: any) => void} = {};
  23 escapedStateHandler['['] = (parser, terminal) => {
  24   // ESC [ Control Sequence Introducer (CSI  is 0x9b)
  25   terminal.params = [];
  26   terminal.currentParam = 0;
  27   parser.setState(ParserState.CSI_PARAM);
  28 };
  29 escapedStateHandler[']'] = (parser, terminal) => {
  30   // ESC ] Operating System Command (OSC is 0x9d)
  31   terminal.params = [];
  32   terminal.currentParam = 0;
  33   parser.setState(ParserState.OSC);
  34 };
  35 escapedStateHandler['P'] = (parser, terminal) => {
  36   // ESC P Device Control String (DCS is 0x90)
  37   terminal.params = [];
  38   terminal.currentParam = 0;
  39   parser.setState(ParserState.DCS);
  40 };
  41 escapedStateHandler['_'] = (parser, terminal) => {
  42   // ESC _ Application Program Command ( APC is 0x9f).
  43   parser.setState(ParserState.IGNORE);
  44 };
  45 escapedStateHandler['^'] = (parser, terminal) => {
  46   // ESC ^ Privacy Message ( PM is 0x9e).
  47   parser.setState(ParserState.IGNORE);
  48 };
  49 escapedStateHandler['c'] = (parser, terminal) => {
  50   // ESC c Full Reset (RIS).
  51   terminal.reset();
  52 };
  53 escapedStateHandler['E'] = (parser, terminal) => {
  54   // ESC E Next Line ( NEL is 0x85).
  55   terminal.buffer.x = 0;
  56   terminal.index();
  57   parser.setState(ParserState.NORMAL);
  58 };
  59 escapedStateHandler['D'] = (parser, terminal) => {
  60   // ESC D Index ( IND is 0x84).
  61   terminal.index();
  62   parser.setState(ParserState.NORMAL);
  63 };
  64 escapedStateHandler['M'] = (parser, terminal) => {
  65   // ESC M Reverse Index ( RI is 0x8d).
  66   terminal.reverseIndex();
  67   parser.setState(ParserState.NORMAL);
  68 };
  69 escapedStateHandler['%'] = (parser, terminal) => {
  70   // ESC % Select default/utf-8 character set.
  71   // @ = default, G = utf-8
  72   terminal.setgLevel(0);
  73   terminal.setgCharset(0, DEFAULT_CHARSET); // US (default)
  74   parser.setState(ParserState.NORMAL);
  75   parser.skipNextChar();
  76 };
  77 escapedStateHandler[C0.CAN] = (parser) => parser.setState(ParserState.NORMAL);
  78
  79 const csiParamStateHandler: {[key: string]: (parser: Parser) => void} = {};
  80 csiParamStateHandler['?'] = (parser) => parser.setPrefix('?');
  81 csiParamStateHandler['>'] = (parser) => parser.setPrefix('>');
  82 csiParamStateHandler['!'] = (parser) => parser.setPrefix('!');
  83 csiParamStateHandler['0'] = (parser) => parser.setParam(parser.getParam() * 10);
  84 csiParamStateHandler['1'] = (parser) => parser.setParam(parser.getParam() * 10 + 1);
  85 csiParamStateHandler['2'] = (parser) => parser.setParam(parser.getParam() * 10 + 2);
  86 csiParamStateHandler['3'] = (parser) => parser.setParam(parser.getParam() * 10 + 3);
  87 csiParamStateHandler['4'] = (parser) => parser.setParam(parser.getParam() * 10 + 4);
  88 csiParamStateHandler['5'] = (parser) => parser.setParam(parser.getParam() * 10 + 5);
  89 csiParamStateHandler['6'] = (parser) => parser.setParam(parser.getParam() * 10 + 6);
  90 csiParamStateHandler['7'] = (parser) => parser.setParam(parser.getParam() * 10 + 7);
  91 csiParamStateHandler['8'] = (parser) => parser.setParam(parser.getParam() * 10 + 8);
  92 csiParamStateHandler['9'] = (parser) => parser.setParam(parser.getParam() * 10 + 9);
  93 csiParamStateHandler['$'] = (parser) => parser.setPostfix('$');
  94 csiParamStateHandler['"'] = (parser) => parser.setPostfix('"');
  95 csiParamStateHandler[' '] = (parser) => parser.setPostfix(' ');
  96 csiParamStateHandler['\''] = (parser) => parser.setPostfix('\'');
  97 csiParamStateHandler[';'] = (parser) => parser.finalizeParam();
  98 csiParamStateHandler[C0.CAN] = (parser) => parser.setState(ParserState.NORMAL);
  99
 100 const csiStateHandler: {[key: string]: (handler: IInputHandler, params: number[], prefix: string, postfix: string, parser: Parser) => void} = {};
 101 csiStateHandler['@'] = (handler, params, prefix) => handler.insertChars(params);
 102 csiStateHandler['A'] = (handler, params, prefix) => handler.cursorUp(params);
 103 csiStateHandler['B'] = (handler, params, prefix) => handler.cursorDown(params);
 104 csiStateHandler['C'] = (handler, params, prefix) => handler.cursorForward(params);
 105 csiStateHandler['D'] = (handler, params, prefix) => handler.cursorBackward(params);
 106 csiStateHandler['E'] = (handler, params, prefix) => handler.cursorNextLine(params);
 107 csiStateHandler['F'] = (handler, params, prefix) => handler.cursorPrecedingLine(params);
 108 csiStateHandler['G'] = (handler, params, prefix) => handler.cursorCharAbsolute(params);
 109 csiStateHandler['H'] = (handler, params, prefix) => handler.cursorPosition(params);
 110 csiStateHandler['I'] = (handler, params, prefix) => handler.cursorForwardTab(params);
 111 csiStateHandler['J'] = (handler, params, prefix) => handler.eraseInDisplay(params);
 112 csiStateHandler['K'] = (handler, params, prefix) => handler.eraseInLine(params);
 113 csiStateHandler['L'] = (handler, params, prefix) => handler.insertLines(params);
 114 csiStateHandler['M'] = (handler, params, prefix) => handler.deleteLines(params);
 115 csiStateHandler['P'] = (handler, params, prefix) => handler.deleteChars(params);
 116 csiStateHandler['S'] = (handler, params, prefix) => handler.scrollUp(params);
 117 csiStateHandler['T'] = (handler, params, prefix) => {
 118   if (params.length < 2 && !prefix) {
 119     handler.scrollDown(params);
 120   }
 121 };
 122 csiStateHandler['X'] = (handler, params, prefix) => handler.eraseChars(params);
 123 csiStateHandler['Z'] = (handler, params, prefix) => handler.cursorBackwardTab(params);
 124 csiStateHandler['`'] = (handler, params, prefix) => handler.charPosAbsolute(params);
 125 csiStateHandler['a'] = (handler, params, prefix) => handler.HPositionRelative(params);
 126 csiStateHandler['b'] = (handler, params, prefix) => handler.repeatPrecedingCharacter(params);
 127 csiStateHandler['c'] = (handler, params, prefix) => handler.sendDeviceAttributes(params);
 128 csiStateHandler['d'] = (handler, params, prefix) => handler.linePosAbsolute(params);
 129 csiStateHandler['e'] = (handler, params, prefix) => handler.VPositionRelative(params);
 130 csiStateHandler['f'] = (handler, params, prefix) => handler.HVPosition(params);
 131 csiStateHandler['g'] = (handler, params, prefix) => handler.tabClear(params);
 132 csiStateHandler['h'] = (handler, params, prefix) => handler.setMode(params);
 133 csiStateHandler['l'] = (handler, params, prefix) => handler.resetMode(params);
 134 csiStateHandler['m'] = (handler, params, prefix) => handler.charAttributes(params);
 135 csiStateHandler['n'] = (handler, params, prefix) => handler.deviceStatus(params);
 136 csiStateHandler['p'] = (handler, params, prefix) => {
 137   switch (prefix) {
 138     case '!': handler.softReset(params); break;
 139   }
 140 };
 141 csiStateHandler['q'] = (handler, params, prefix, postfix) => {
 142   if (postfix === ' ') {
 143     handler.setCursorStyle(params);
 144   }
 145 };
 146 csiStateHandler['r'] = (handler, params) => handler.setScrollRegion(params);
 147 csiStateHandler['s'] = (handler, params) => handler.saveCursor(params);
 148 csiStateHandler['u'] = (handler, params) => handler.restoreCursor(params);
 149 csiStateHandler[C0.CAN] = (handler, params, prefix, postfix, parser) => parser.setState(ParserState.NORMAL);
 150
 151 enum ParserState {
 152   NORMAL = 0,
 153   ESCAPED = 1,
 154   CSI_PARAM = 2,
 155   CSI = 3,
 156   OSC = 4,
 157   CHARSET = 5,
 158   DCS = 6,
 159   IGNORE = 7
 160 }
 161
 162 /**
 163  * The terminal's parser, all input into the terminal goes through the parser
 164  * which parses and defers the actual input handling the the IInputHandler
 165  * specified in the constructor.
 166  */
 167 export class Parser {
 168   private _state: ParserState;
 169   private _position: number;
 170
 171   // TODO: Remove terminal when handler can do everything
 172   constructor(
 173     private _inputHandler: IInputHandler,
 174     private _terminal: any
 175   ) {
 176     this._state = ParserState.NORMAL;
 177   }
 178
 179   /**
 180    * Parse and handle data.
 181    *
 182    * @param data The data to parse.
 183    */
 184   public parse(data: string): ParserState {
 185     let l = data.length, j, cs, ch, code, low;
 186
 187     if (this._terminal.debug) {
 188       this._terminal.log('data: ' + data);
 189     }
 190
 191     this._position = 0;
 192     // apply leftover surrogate high from last write
 193     if (this._terminal.surrogate_high) {
 194       data = this._terminal.surrogate_high + data;
 195       this._terminal.surrogate_high = '';
 196     }
 197
 198     for (; this._position < l; this._position++) {
 199       ch = data[this._position];
 200
 201       // FIXME: higher chars than 0xa0 are not allowed in escape sequences
 202       //        --> maybe move to default
 203       code = data.charCodeAt(this._position);
 204       if (0xD800 <= code && code <= 0xDBFF) {
 205         // we got a surrogate high
 206         // get surrogate low (next 2 bytes)
 207         low = data.charCodeAt(this._position + 1);
 208         if (isNaN(low)) {
 209           // end of data stream, save surrogate high
 210           this._terminal.surrogate_high = ch;
 211           continue;
 212         }
 213         code = ((code - 0xD800) * 0x400) + (low - 0xDC00) + 0x10000;
 214         ch += data.charAt(this._position + 1);
 215       }
 216       // surrogate low - already handled above
 217       if (0xDC00 <= code && code <= 0xDFFF)
 218         continue;
 219
 220       switch (this._state) {
 221         case ParserState.NORMAL:
 222           if (ch in normalStateHandler) {
 223             normalStateHandler[ch](this, this._inputHandler);
 224           } else {
 225             this._inputHandler.addChar(ch, code);
 226           }
 227           break;
 228         case ParserState.ESCAPED:
 229           if (ch in escapedStateHandler) {
 230             escapedStateHandler[ch](this, this._terminal);
 231             // Skip switch as it was just handled
 232             break;
 233           }
 234           switch (ch) {
 235
 236             // ESC (,),*,+,-,. Designate G0-G2 Character Set.
 237             case '(': // <-- this seems to get all the attention
 238             case ')':
 239             case '*':
 240             case '+':
 241             case '-':
 242             case '.':
 243               switch (ch) {
 244                 case '(':
 245                   this._terminal.gcharset = 0;
 246                   break;
 247                 case ')':
 248                   this._terminal.gcharset = 1;
 249                   break;
 250                 case '*':
 251                   this._terminal.gcharset = 2;
 252                   break;
 253                 case '+':
 254                   this._terminal.gcharset = 3;
 255                   break;
 256                 case '-':
 257                   this._terminal.gcharset = 1;
 258                   break;
 259                 case '.':
 260                   this._terminal.gcharset = 2;
 261                   break;
 262               }
 263               this._state = ParserState.CHARSET;
 264               break;
 265
 266             // Designate G3 Character Set (VT300).
 267             // A = ISO Latin-1 Supplemental.
 268             // Not implemented.
 269             case '/':
 270               this._terminal.gcharset = 3;
 271               this._state = ParserState.CHARSET;
 272               this._position--;
 273               break;
 274
 275             // ESC N
 276             // Single Shift Select of G2 Character Set
 277             // ( SS2 is 0x8e). This affects next character only.
 278             case 'N':
 279               break;
 280             // ESC O
 281             // Single Shift Select of G3 Character Set
 282             // ( SS3 is 0x8f). This affects next character only.
 283             case 'O':
 284               break;
 285             // ESC n
 286             // Invoke the G2 Character Set as GL (LS2).
 287             case 'n':
 288               this._terminal.setgLevel(2);
 289               break;
 290             // ESC o
 291             // Invoke the G3 Character Set as GL (LS3).
 292             case 'o':
 293               this._terminal.setgLevel(3);
 294               break;
 295             // ESC |
 296             // Invoke the G3 Character Set as GR (LS3R).
 297             case '|':
 298               this._terminal.setgLevel(3);
 299               break;
 300             // ESC }
 301             // Invoke the G2 Character Set as GR (LS2R).
 302             case '}':
 303               this._terminal.setgLevel(2);
 304               break;
 305             // ESC ~
 306             // Invoke the G1 Character Set as GR (LS1R).
 307             case '~':
 308               this._terminal.setgLevel(1);
 309               break;
 310
 311             // ESC 7 Save Cursor (DECSC).
 312             case '7':
 313               this._inputHandler.saveCursor();
 314               this._state = ParserState.NORMAL;
 315               break;
 316
 317             // ESC 8 Restore Cursor (DECRC).
 318             case '8':
 319               this._inputHandler.restoreCursor();
 320               this._state = ParserState.NORMAL;
 321               break;
 322
 323             // ESC # 3 DEC line height/width
 324             case '#':
 325               this._state = ParserState.NORMAL;
 326               this._position++;
 327               break;
 328
 329             // ESC H Tab Set (HTS is 0x88).
 330             case 'H':
 331               this._terminal.tabSet();
 332               this._state = ParserState.NORMAL;
 333               break;
 334
 335             // ESC = Application Keypad (DECKPAM).
 336             case '=':
 337               this._terminal.log('Serial port requested application keypad.');
 338               this._terminal.applicationKeypad = true;
 339               this._terminal.viewport.syncScrollArea();
 340               this._state = ParserState.NORMAL;
 341               break;
 342
 343             // ESC > Normal Keypad (DECKPNM).
 344             case '>':
 345               this._terminal.log('Switching back to normal keypad.');
 346               this._terminal.applicationKeypad = false;
 347               this._terminal.viewport.syncScrollArea();
 348               this._state = ParserState.NORMAL;
 349               break;
 350
 351             default:
 352               this._state = ParserState.NORMAL;
 353               this._terminal.error('Unknown ESC control: %s.', ch);
 354               break;
 355           }
 356           break;
 357
 358         case ParserState.CHARSET:
 359           if (ch in CHARSETS) {
 360             cs = CHARSETS[ch];
 361             if (ch === '/') { // ISOLatin is actually /A
 362               this.skipNextChar();
 363             }
 364           } else {
 365             cs = DEFAULT_CHARSET;
 366           }
 367           this._terminal.setgCharset(this._terminal.gcharset, cs);
 368           this._terminal.gcharset = null;
 369           this._state = ParserState.NORMAL;
 370           break;
 371
 372         case ParserState.OSC:
 373           // OSC Ps ; Pt ST
 374           // OSC Ps ; Pt BEL
 375           //   Set Text Parameters.
 376           if (ch === C0.ESC || ch === C0.BEL) {
 377             if (ch === C0.ESC) this._position++;
 378
 379             this._terminal.params.push(this._terminal.currentParam);
 380
 381             switch (this._terminal.params[0]) {
 382               case 0:
 383               case 1:
 384               case 2:
 385                 if (this._terminal.params[1]) {
 386                   this._terminal.title = this._terminal.params[1];
 387                   this._terminal.handleTitle(this._terminal.title);
 388                 }
 389                 break;
 390               case 3:
 391                 // set X property
 392                 break;
 393               case 4:
 394               case 5:
 395                 // change dynamic colors
 396                 break;
 397               case 10:
 398               case 11:
 399               case 12:
 400               case 13:
 401               case 14:
 402               case 15:
 403               case 16:
 404               case 17:
 405               case 18:
 406               case 19:
 407                 // change dynamic ui colors
 408                 break;
 409               case 46:
 410                 // change log file
 411                 break;
 412               case 50:
 413                 // dynamic font
 414                 break;
 415               case 51:
 416                 // emacs shell
 417                 break;
 418               case 52:
 419                 // manipulate selection data
 420                 break;
 421               case 104:
 422               case 105:
 423               case 110:
 424               case 111:
 425               case 112:
 426               case 113:
 427               case 114:
 428               case 115:
 429               case 116:
 430               case 117:
 431               case 118:
 432                 // reset colors
 433                 break;
 434             }
 435
 436             this._terminal.params = [];
 437             this._terminal.currentParam = 0;
 438             this._state = ParserState.NORMAL;
 439           } else {
 440             if (!this._terminal.params.length) {
 441               if (ch >= '0' && ch <= '9') {
 442                 this._terminal.currentParam =
 443                   this._terminal.currentParam * 10 + ch.charCodeAt(0) - 48;
 444               } else if (ch === ';') {
 445                 this._terminal.params.push(this._terminal.currentParam);
 446                 this._terminal.currentParam = '';
 447               }
 448             } else {
 449               this._terminal.currentParam += ch;
 450             }
 451           }
 452           break;
 453
 454         case ParserState.CSI_PARAM:
 455           if (ch in csiParamStateHandler) {
 456             csiParamStateHandler[ch](this);
 457             break;
 458           }
 459           this.finalizeParam();
 460           // Fall through the CSI as this character should be the CSI code.
 461           this._state = ParserState.CSI;
 462
 463         case ParserState.CSI:
 464           if (ch in csiStateHandler) {
 465             if (this._terminal.debug) {
 466               this._terminal.log(`CSI ${this._terminal.prefix ? this._terminal.prefix : ''} ${this._terminal.params ? this._terminal.params.join(';') : ''} ${this._terminal.postfix ? this._terminal.postfix : ''} ${ch}`);
 467             }
 468             csiStateHandler[ch](this._inputHandler, this._terminal.params, this._terminal.prefix, this._terminal.postfix, this);
 469           } else {
 470             this._terminal.error('Unknown CSI code: %s.', ch);
 471           }
 472
 473           this._state = ParserState.NORMAL;
 474           this._terminal.prefix = '';
 475           this._terminal.postfix = '';
 476           break;
 477
 478         case ParserState.DCS:
 479           if (ch === C0.ESC || ch === C0.BEL) {
 480             if (ch === C0.ESC) this._position++;
 481             let pt;
 482             let valid: boolean;
 483
 484             switch (this._terminal.prefix) {
 485               // User-Defined Keys (DECUDK).
 486               case '':
 487                 break;
 488
 489               // Request Status String (DECRQSS).
 490               // test: echo -e '\eP$q"p\e\\'
 491               case '$q':
 492                 pt = this._terminal.currentParam;
 493                 valid = false;
 494
 495                 switch (pt) {
 496                   // DECSCA
 497                   case '"q':
 498                     pt = '0"q';
 499                     break;
 500
 501                   // DECSCL
 502                   case '"p':
 503                     pt = '61"p';
 504                     break;
 505
 506                   // DECSTBM
 507                   case 'r':
 508                     pt = ''
 509                       + (this._terminal.buffer.scrollTop + 1)
 510                       + ';'
 511                       + (this._terminal.buffer.scrollBottom + 1)
 512                       + 'r';
 513                     break;
 514
 515                   // SGR
 516                   case 'm':
 517                     pt = '0m';
 518                     break;
 519
 520                   default:
 521                     this._terminal.error('Unknown DCS Pt: %s.', pt);
 522                     pt = '';
 523                     break;
 524                 }
 525
 526                 this._terminal.send(C0.ESC + 'P' + +valid + '$r' + pt + C0.ESC + '\\');
 527                 break;
 528
 529               // Set Termcap/Terminfo Data (xterm, experimental).
 530               case '+p':
 531                 break;
 532
 533               // Request Termcap/Terminfo String (xterm, experimental)
 534               // Regular xterm does not even respond to this sequence.
 535               // This can cause a small glitch in vim.
 536               // test: echo -ne '\eP+q6b64\e\\'
 537               case '+q':
 538                 pt = this._terminal.currentParam;
 539                 valid = false;
 540
 541                 this._terminal.send(C0.ESC + 'P' + +valid + '+r' + pt + C0.ESC + '\\');
 542                 break;
 543
 544               default:
 545                 this._terminal.error('Unknown DCS prefix: %s.', this._terminal.prefix);
 546                 break;
 547             }
 548
 549             this._terminal.currentParam = 0;
 550             this._terminal.prefix = '';
 551             this._state = ParserState.NORMAL;
 552           } else if (!this._terminal.currentParam) {
 553             if (!this._terminal.prefix && ch !== '$' && ch !== '+') {
 554               this._terminal.currentParam = ch;
 555             } else if (this._terminal.prefix.length === 2) {
 556               this._terminal.currentParam = ch;
 557             } else {
 558               this._terminal.prefix += ch;
 559             }
 560           } else {
 561             this._terminal.currentParam += ch;
 562           }
 563           break;
 564
 565         case ParserState.IGNORE:
 566           // For PM and APC.
 567           if (ch === C0.ESC || ch === C0.BEL) {
 568             if (ch === C0.ESC) this._position++;
 569             this._state = ParserState.NORMAL;
 570           }
 571           break;
 572       }
 573     }
 574     return this._state;
 575   }
 576
 577   /**
 578    * Set the parser's current parsing state.
 579    *
 580    * @param state The new state.
 581    */
 582   public setState(state: ParserState): void {
 583     this._state = state;
 584   }
 585
 586   /**
 587    * Sets the parsier's current prefix. CSI codes can have prefixes of '?', '>'
 588    * or '!'.
 589    *
 590    * @param prefix The prefix.
 591    */
 592   public setPrefix(prefix: string): void {
 593     this._terminal.prefix = prefix;
 594   }
 595
 596   /**
 597    * Sets the parsier's current prefix. CSI codes can have postfixes of '$',
 598    * '"', ' ', '\''.
 599    *
 600    * @param postfix The postfix.
 601    */
 602   public setPostfix(postfix: string): void {
 603     this._terminal.postfix = postfix;
 604   }
 605
 606   /**
 607    * Sets the parser's current parameter.
 608    *
 609    * @param param the parameter.
 610    */
 611   public setParam(param: number) {
 612     this._terminal.currentParam = param;
 613   }
 614
 615   /**
 616    * Gets the parser's current parameter.
 617    */
 618   public getParam(): number {
 619     return this._terminal.currentParam;
 620   }
 621
 622   /**
 623    * Finalizes the parser's current parameter, adding it to the list of
 624    * parameters and setting the new current parameter to 0.
 625    */
 626   public finalizeParam(): void {
 627     this._terminal.params.push(this._terminal.currentParam);
 628     this._terminal.currentParam = 0;
 629   }
 630
 631   /**
 632    * Tell the parser to skip the next character.
 633    */
 634   public skipNextChar(): void {
 635     this._position++;
 636   }
 637
 638   /**
 639    * Tell the parser to repeat parsing the current character (for example if it
 640    * needs parsing using a different state.
 641    */
 642   // public repeatChar(): void {
 643   //   this._position--;
 644   // }
 645 }