babylon/lib/tokenizer/index.js

/* @flow */

"use strict";

var _classCallCheck = require("babel-runtime/helpers/class-call-check")["default"];

var _interopRequireDefault = require("babel-runtime/helpers/interop-require-default")["default"];

exports.__esModule = true;

var _utilIdentifier = require("../util/identifier");

var _types = require("./types");

var _context = require("./context");

var _utilLocation = require("../util/location");

var _utilWhitespace = require("../util/whitespace");

var _state = require("./state");

var _state2 = _interopRequireDefault(_state);

// Object type used to represent tokens. Note that normally, tokens
// simply exist as properties on the parser object. This is only
// used for the onToken callback and the external tokenizer.

/*:: import type { TokenType } from "./types";*/
var Token = function Token(state) {
  _classCallCheck(this, Token);

  this.type = state.type;
  this.value = state.value;
  this.start = state.start;
  this.end = state.end;
  this.loc = new _utilLocation.SourceLocation(state.startLoc, state.endLoc);
}

// ## Tokenizer

;

exports.Token = Token;
function codePointToString(code) {
  // UTF-16 Decoding
  if (code <= 0xFFFF) {
    return String.fromCharCode(code);
  } else {
    return String.fromCharCode((code - 0x10000 >> 10) + 0xD800, (code - 0x10000 & 1023) + 0xDC00);
  }
}

var Tokenizer = (function () {
  function Tokenizer(options, input) {
    _classCallCheck(this, Tokenizer);

    this.state = new _state2["default"]();
    this.state.init(options, input);
  }

  // Move to the next token

  Tokenizer.prototype.next = function next() {
    if (!this.isLookahead) {
      this.state.tokens.push(new Token(this.state));
    }

    this.state.lastTokEnd = this.state.end;
    this.state.lastTokStart = this.state.start;
    this.state.lastTokEndLoc = this.state.endLoc;
    this.state.lastTokStartLoc = this.state.startLoc;
    this.nextToken();
  };

  // TODO

  Tokenizer.prototype.eat = function eat(type) {
    if (this.match(type)) {
      this.next();
      return true;
    } else {
      return false;
    }
  };

  // TODO

  Tokenizer.prototype.match = function match(type) {
    return this.state.type === type;
  };

  // TODO

  Tokenizer.prototype.isKeyword = function isKeyword(word) {
    return _utilIdentifier.isKeyword(word);
  };

  // TODO

  Tokenizer.prototype.lookahead = function lookahead() {
    var old = this.state;
    this.state = old.clone(true);

    this.isLookahead = true;
    this.next();
    this.isLookahead = false;

    var curr = this.state.clone(true);
    this.state = old;
    return curr;
  };

  // Toggle strict mode. Re-reads the next number or string to please
  // pedantic tests (`"use strict"; 010;` should fail).

  Tokenizer.prototype.setStrict = function setStrict(strict) {
    this.state.strict = strict;
    if (!this.match(_types.types.num) && !this.match(_types.types.string)) return;
    this.state.pos = this.state.start;
    while (this.state.pos < this.state.lineStart) {
      this.state.lineStart = this.input.lastIndexOf("\n", this.state.lineStart - 2) + 1;
      --this.state.curLine;
    }
    this.nextToken();
  };

  Tokenizer.prototype.curContext = function curContext() {
    return this.state.context[this.state.context.length - 1];
  };

  // Read a single token, updating the parser object's token-related
  // properties.

  Tokenizer.prototype.nextToken = function nextToken() {
    var curContext = this.curContext();
    if (!curContext || !curContext.preserveSpace) this.skipSpace();

    this.state.containsOctal = false;
    this.state.octalPosition = null;
    this.state.start = this.state.pos;
    this.state.startLoc = this.state.curPosition();
    if (this.state.pos >= this.input.length) return this.finishToken(_types.types.eof);

    if (curContext.override) {
      return curContext.override(this);
    } else {
      return this.readToken(this.fullCharCodeAtPos());
    }
  };

  Tokenizer.prototype.readToken = function readToken(code) {
    // Identifier or keyword. '\uXXXX' sequences are allowed in
    // identifiers, so '\' also dispatches to that.
    if (_utilIdentifier.isIdentifierStart(code, true) || code === 92 /* '\' */) {
        return this.readWord();
      } else {
      return this.getTokenFromCode(code);
    }
  };

  Tokenizer.prototype.fullCharCodeAtPos = function fullCharCodeAtPos() {
    var code = this.input.charCodeAt(this.state.pos);
    if (code <= 0xd7ff || code >= 0xe000) return code;

    var next = this.input.charCodeAt(this.state.pos + 1);
    return (code << 10) + next - 0x35fdc00;
  };

  Tokenizer.prototype.pushComment = function pushComment(block, text, start, end, startLoc, endLoc) {
    var comment = {
      type: block ? "CommentBlock" : "CommentLine",
      value: text,
      start: start,
      end: end,
      loc: new _utilLocation.SourceLocation(startLoc, endLoc)
    };

    if (!this.isLookahead) {
      this.state.tokens.push(comment);
      this.state.comments.push(comment);
    }

    this.addComment(comment);
  };

  Tokenizer.prototype.skipBlockComment = function skipBlockComment() {
    var startLoc = this.state.curPosition();
    var start = this.state.pos,
        end = this.input.indexOf("*/", this.state.pos += 2);
    if (end === -1) this.raise(this.state.pos - 2, "Unterminated comment");

    this.state.pos = end + 2;
    _utilWhitespace.lineBreakG.lastIndex = start;
    var match = undefined;
    while ((match = _utilWhitespace.lineBreakG.exec(this.input)) && match.index < this.state.pos) {
      ++this.state.curLine;
      this.state.lineStart = match.index + match[0].length;
    }

    this.pushComment(true, this.input.slice(start + 2, end), start, this.state.pos, startLoc, this.state.curPosition());
  };

  Tokenizer.prototype.skipLineComment = function skipLineComment(startSkip) {
    var start = this.state.pos;
    var startLoc = this.state.curPosition();
    var ch = this.input.charCodeAt(this.state.pos += startSkip);
    while (this.state.pos < this.input.length && ch !== 10 && ch !== 13 && ch !== 8232 && ch !== 8233) {
      ++this.state.pos;
      ch = this.input.charCodeAt(this.state.pos);
    }

    this.pushComment(false, this.input.slice(start + startSkip, this.state.pos), start, this.state.pos, startLoc, this.state.curPosition());
  };

  // Called at the start of the parse and after every token. Skips
  // whitespace and comments, and.

  Tokenizer.prototype.skipSpace = function skipSpace() {
    loop: while (this.state.pos < this.input.length) {
      var ch = this.input.charCodeAt(this.state.pos);
      switch (ch) {
        case 32:case 160:
          // ' '
          ++this.state.pos;
          break;

        case 13:
          if (this.input.charCodeAt(this.state.pos + 1) === 10) {
            ++this.state.pos;
          }

        case 10:case 8232:case 8233:
          ++this.state.pos;
          ++this.state.curLine;
          this.state.lineStart = this.state.pos;
          break;

        case 47:
          // '/'
          switch (this.input.charCodeAt(this.state.pos + 1)) {
            case 42:
              // '*'
              this.skipBlockComment();
              break;

            case 47:
              this.skipLineComment(2);
              break;

            default:
              break loop;
          }
          break;

        default:
          if (ch > 8 && ch < 14 || ch >= 5760 && _utilWhitespace.nonASCIIwhitespace.test(String.fromCharCode(ch))) {
            ++this.state.pos;
          } else {
            break loop;
          }
      }
    }
  };

  // Called at the end of every token. Sets `end`, `val`, and
  // maintains `context` and `exprAllowed`, and skips the space after
  // the token, so that the next one's `start` will point at the
  // right position.

  Tokenizer.prototype.finishToken = function finishToken(type, val) {
    this.state.end = this.state.pos;
    this.state.endLoc = this.state.curPosition();
    var prevType = this.state.type;
    this.state.type = type;
    this.state.value = val;

    this.updateContext(prevType);
  };

  // ### Token reading

  // This is the function that is called to fetch the next token. It
  // is somewhat obscure, because it works in character codes rather
  // than characters, and because operator parsing has been inlined
  // into it.
  //
  // All in the name of speed.
  //

  Tokenizer.prototype.readToken_dot = function readToken_dot() {
    var next = this.input.charCodeAt(this.state.pos + 1);
    if (next >= 48 && next <= 57) {
      return this.readNumber(true);
    }

    var next2 = this.input.charCodeAt(this.state.pos + 2);
    if (next === 46 && next2 === 46) {
      // 46 = dot '.'
      this.state.pos += 3;
      return this.finishToken(_types.types.ellipsis);
    } else {
      ++this.state.pos;
      return this.finishToken(_types.types.dot);
    }
  };

  Tokenizer.prototype.readToken_slash = function readToken_slash() {
    // '/'
    if (this.state.exprAllowed) {
      ++this.state.pos;
      return this.readRegexp();
    }

    var next = this.input.charCodeAt(this.state.pos + 1);
    if (next === 61) {
      return this.finishOp(_types.types.assign, 2);
    } else {
      return this.finishOp(_types.types.slash, 1);
    }
  };

  Tokenizer.prototype.readToken_mult_modulo = function readToken_mult_modulo(code) {
    // '%*'
    var type = code === 42 ? _types.types.star : _types.types.modulo;
    var width = 1;
    var next = this.input.charCodeAt(this.state.pos + 1);

    if (next === 42 && this.hasPlugin("exponentiationOperator")) {
      // '*'
      width++;
      next = this.input.charCodeAt(this.state.pos + 2);
      type = _types.types.exponent;
    }

    if (next === 61) {
      width++;
      type = _types.types.assign;
    }

    return this.finishOp(type, width);
  };

  Tokenizer.prototype.readToken_pipe_amp = function readToken_pipe_amp(code) {
    // '|&'
    var next = this.input.charCodeAt(this.state.pos + 1);
    if (next === code) return this.finishOp(code === 124 ? _types.types.logicalOR : _types.types.logicalAND, 2);
    if (next === 61) return this.finishOp(_types.types.assign, 2);
    return this.finishOp(code === 124 ? _types.types.bitwiseOR : _types.types.bitwiseAND, 1);
  };

  Tokenizer.prototype.readToken_caret = function readToken_caret() {
    // '^'
    var next = this.input.charCodeAt(this.state.pos + 1);
    if (next === 61) {
      return this.finishOp(_types.types.assign, 2);
    } else {
      return this.finishOp(_types.types.bitwiseXOR, 1);
    }
  };

  Tokenizer.prototype.readToken_plus_min = function readToken_plus_min(code) {
    // '+-'
    var next = this.input.charCodeAt(this.state.pos + 1);

    if (next === code) {
      if (next === 45 && this.input.charCodeAt(this.state.pos + 2) === 62 && _utilWhitespace.lineBreak.test(this.input.slice(this.state.lastTokEnd, this.state.pos))) {
        // A `-->` line comment
        this.skipLineComment(3);
        this.skipSpace();
        return this.nextToken();
      }
      return this.finishOp(_types.types.incDec, 2);
    }

    if (next === 61) {
      return this.finishOp(_types.types.assign, 2);
    } else {
      return this.finishOp(_types.types.plusMin, 1);
    }
  };

  Tokenizer.prototype.readToken_lt_gt = function readToken_lt_gt(code) {
    // '<>'
    var next = this.input.charCodeAt(this.state.pos + 1);
    var size = 1;

    if (next === code) {
      size = code === 62 && this.input.charCodeAt(this.state.pos + 2) === 62 ? 3 : 2;
      if (this.input.charCodeAt(this.state.pos + size) === 61) return this.finishOp(_types.types.assign, size + 1);
      return this.finishOp(_types.types.bitShift, size);
    }

    if (next === 33 && code === 60 && this.input.charCodeAt(this.state.pos + 2) === 45 && this.input.charCodeAt(this.state.pos + 3) === 45) {
      if (this.inModule) this.unexpected();
      // `<!--`, an XML-style comment that should be interpreted as a line comment
      this.skipLineComment(4);
      this.skipSpace();
      return this.nextToken();
    }

    if (next === 61) {
      size = this.input.charCodeAt(this.state.pos + 2) === 61 ? 3 : 2;
    }

    return this.finishOp(_types.types.relational, size);
  };

  Tokenizer.prototype.readToken_eq_excl = function readToken_eq_excl(code) {
    // '=!'
    var next = this.input.charCodeAt(this.state.pos + 1);
    if (next === 61) return this.finishOp(_types.types.equality, this.input.charCodeAt(this.state.pos + 2) === 61 ? 3 : 2);
    if (code === 61 && next === 62) {
      // '=>'
      this.state.pos += 2;
      return this.finishToken(_types.types.arrow);
    }
    return this.finishOp(code === 61 ? _types.types.eq : _types.types.prefix, 1);
  };

  Tokenizer.prototype.getTokenFromCode = function getTokenFromCode(code) {
    switch (code) {
      // The interpretation of a dot depends on whether it is followed
      // by a digit or another two dots.
      case 46:
        // '.'
        return this.readToken_dot();

      // Punctuation tokens.
      case 40:
        ++this.state.pos;return this.finishToken(_types.types.parenL);
      case 41:
        ++this.state.pos;return this.finishToken(_types.types.parenR);
      case 59:
        ++this.state.pos;return this.finishToken(_types.types.semi);
      case 44:
        ++this.state.pos;return this.finishToken(_types.types.comma);
      case 91:
        ++this.state.pos;return this.finishToken(_types.types.bracketL);
      case 93:
        ++this.state.pos;return this.finishToken(_types.types.bracketR);
      case 123:
        ++this.state.pos;return this.finishToken(_types.types.braceL);
      case 125:
        ++this.state.pos;return this.finishToken(_types.types.braceR);

      case 58:
        if (this.hasPlugin("functionBind") && this.input.charCodeAt(this.state.pos + 1) === 58) {
          return this.finishOp(_types.types.doubleColon, 2);
        } else {
          ++this.state.pos;
          return this.finishToken(_types.types.colon);
        }

      case 63:
        ++this.state.pos;return this.finishToken(_types.types.question);
      case 64:
        ++this.state.pos;return this.finishToken(_types.types.at);

      case 96:
        // '`'
        ++this.state.pos;
        return this.finishToken(_types.types.backQuote);

      case 48:
        // '0'
        var next = this.input.charCodeAt(this.state.pos + 1);
        if (next === 120 || next === 88) return this.readRadixNumber(16); // '0x', '0X' - hex number
        if (next === 111 || next === 79) return this.readRadixNumber(8); // '0o', '0O' - octal number
        if (next === 98 || next === 66) return this.readRadixNumber(2); // '0b', '0B' - binary number
      // Anything else beginning with a digit is an integer, octal
      // number, or float.
      case 49:case 50:case 51:case 52:case 53:case 54:case 55:case 56:case 57:
        // 1-9
        return this.readNumber(false);

      // Quotes produce strings.
      case 34:case 39:
        // '"', "'"
        return this.readString(code);

      // Operators are parsed inline in tiny state machines. '=' (61) is
      // often referred to. `finishOp` simply skips the amount of
      // characters it is given as second argument, and returns a token
      // of the type given by its first argument.

      case 47:
        // '/'
        return this.readToken_slash();

      case 37:case 42:
        // '%*'
        return this.readToken_mult_modulo(code);

      case 124:case 38:
        // '|&'
        return this.readToken_pipe_amp(code);

      case 94:
        // '^'
        return this.readToken_caret();

      case 43:case 45:
        // '+-'
        return this.readToken_plus_min(code);

      case 60:case 62:
        // '<>'
        return this.readToken_lt_gt(code);

      case 61:case 33:
        // '=!'
        return this.readToken_eq_excl(code);

      case 126:
        // '~'
        return this.finishOp(_types.types.prefix, 1);
    }

    this.raise(this.state.pos, "Unexpected character '" + codePointToString(code) + "'");
  };

  Tokenizer.prototype.finishOp = function finishOp(type, size) {
    var str = this.input.slice(this.state.pos, this.state.pos + size);
    this.state.pos += size;
    return this.finishToken(type, str);
  };

  Tokenizer.prototype.readRegexp = function readRegexp() {
    var escaped = undefined,
        inClass = undefined,
        start = this.state.pos;
    for (;;) {
      if (this.state.pos >= this.input.length) this.raise(start, "Unterminated regular expression");
      var ch = this.input.charAt(this.state.pos);
      if (_utilWhitespace.lineBreak.test(ch)) {
        this.raise(start, "Unterminated regular expression");
      }
      if (escaped) {
        escaped = false;
      } else {
        if (ch === "[") {
          inClass = true;
        } else if (ch === "]" && inClass) {
          inClass = false;
        } else if (ch === "/" && !inClass) {
          break;
        }
        escaped = ch === "\\";
      }
      ++this.state.pos;
    }
    var content = this.input.slice(start, this.state.pos);
    ++this.state.pos;
    // Need to use `readWord1` because '\uXXXX' sequences are allowed
    // here (don't ask).
    var mods = this.readWord1();
    if (mods) {
      var validFlags = /^[gmsiyu]*$/;
      if (!validFlags.test(mods)) this.raise(start, "Invalid regular expression flag");
    }
    return this.finishToken(_types.types.regexp, {
      pattern: content,
      flags: mods
    });
  };

  // Read an integer in the given radix. Return null if zero digits
  // were read, the integer value otherwise. When `len` is given, this
  // will return `null` unless the integer has exactly `len` digits.

  Tokenizer.prototype.readInt = function readInt(radix, len) {
    var start = this.state.pos,
        total = 0;
    for (var i = 0, e = len == null ? Infinity : len; i < e; ++i) {
      var code = this.input.charCodeAt(this.state.pos),
          val = undefined;
      if (code >= 97) {
        val = code - 97 + 10; // a
      } else if (code >= 65) {
          val = code - 65 + 10; // A
        } else if (code >= 48 && code <= 57) {
            val = code - 48; // 0-9
          } else {
              val = Infinity;
            }
      if (val >= radix) break;
      ++this.state.pos;
      total = total * radix + val;
    }
    if (this.state.pos === start || len != null && this.state.pos - start !== len) return null;

    return total;
  };

  Tokenizer.prototype.readRadixNumber = function readRadixNumber(radix) {
    this.state.pos += 2; // 0x
    var val = this.readInt(radix);
    if (val == null) this.raise(this.state.start + 2, "Expected number in radix " + radix);
    if (_utilIdentifier.isIdentifierStart(this.fullCharCodeAtPos())) this.raise(this.state.pos, "Identifier directly after number");
    return this.finishToken(_types.types.num, val);
  };

  // Read an integer, octal integer, or floating-point number.

  Tokenizer.prototype.readNumber = function readNumber(startsWithDot) {
    var start = this.state.pos,
        isFloat = false,
        octal = this.input.charCodeAt(this.state.pos) === 48;
    if (!startsWithDot && this.readInt(10) === null) this.raise(start, "Invalid number");
    var next = this.input.charCodeAt(this.state.pos);
    if (next === 46) {
      // '.'
      ++this.state.pos;
      this.readInt(10);
      isFloat = true;
      next = this.input.charCodeAt(this.state.pos);
    }
    if (next === 69 || next === 101) {
      // 'eE'
      next = this.input.charCodeAt(++this.state.pos);
      if (next === 43 || next === 45) ++this.state.pos; // '+-'
      if (this.readInt(10) === null) this.raise(start, "Invalid number");
      isFloat = true;
    }
    if (_utilIdentifier.isIdentifierStart(this.fullCharCodeAtPos())) this.raise(this.state.pos, "Identifier directly after number");

    var str = this.input.slice(start, this.state.pos),
        val = undefined;
    if (isFloat) {
      val = parseFloat(str);
    } else if (!octal || str.length === 1) {
      val = parseInt(str, 10);
    } else if (/[89]/.test(str) || this.state.strict) {
      this.raise(start, "Invalid number");
    } else {
      val = parseInt(str, 8);
    }
    return this.finishToken(_types.types.num, val);
  };

  // Read a string value, interpreting backslash-escapes.

  Tokenizer.prototype.readCodePoint = function readCodePoint() {
    var ch = this.input.charCodeAt(this.state.pos),
        code = undefined;

    if (ch === 123) {
      var codePos = ++this.state.pos;
      code = this.readHexChar(this.input.indexOf("}", this.state.pos) - this.state.pos);
      ++this.state.pos;
      if (code > 0x10FFFF) this.raise(codePos, "Code point out of bounds");
    } else {
      code = this.readHexChar(4);
    }
    return code;
  };

  Tokenizer.prototype.readString = function readString(quote) {
    var out = "",
        chunkStart = ++this.state.pos;
    for (;;) {
      if (this.state.pos >= this.input.length) this.raise(this.state.start, "Unterminated string constant");
      var ch = this.input.charCodeAt(this.state.pos);
      if (ch === quote) break;
      if (ch === 92) {
        // '\'
        out += this.input.slice(chunkStart, this.state.pos);
        out += this.readEscapedChar(false);
        chunkStart = this.state.pos;
      } else {
        if (_utilWhitespace.isNewLine(ch)) this.raise(this.state.start, "Unterminated string constant");
        ++this.state.pos;
      }
    }
    out += this.input.slice(chunkStart, this.state.pos++);
    return this.finishToken(_types.types.string, out);
  };

  // Reads template string tokens.

  Tokenizer.prototype.readTmplToken = function readTmplToken() {
    var out = "",
        chunkStart = this.state.pos;
    for (;;) {
      if (this.state.pos >= this.input.length) this.raise(this.state.start, "Unterminated template");
      var ch = this.input.charCodeAt(this.state.pos);
      if (ch === 96 || ch === 36 && this.input.charCodeAt(this.state.pos + 1) === 123) {
        // '`', '${'
        if (this.state.pos === this.state.start && this.match(_types.types.template)) {
          if (ch === 36) {
            this.state.pos += 2;
            return this.finishToken(_types.types.dollarBraceL);
          } else {
            ++this.state.pos;
            return this.finishToken(_types.types.backQuote);
          }
        }
        out += this.input.slice(chunkStart, this.state.pos);
        return this.finishToken(_types.types.template, out);
      }
      if (ch === 92) {
        // '\'
        out += this.input.slice(chunkStart, this.state.pos);
        out += this.readEscapedChar(true);
        chunkStart = this.state.pos;
      } else if (_utilWhitespace.isNewLine(ch)) {
        out += this.input.slice(chunkStart, this.state.pos);
        ++this.state.pos;
        switch (ch) {
          case 13:
            if (this.input.charCodeAt(this.state.pos) === 10) ++this.state.pos;
          case 10:
            out += "\n";
            break;
          default:
            out += String.fromCharCode(ch);
            break;
        }
        ++this.state.curLine;
        this.state.lineStart = this.state.pos;
        chunkStart = this.state.pos;
      } else {
        ++this.state.pos;
      }
    }
  };

  // Used to read escaped characters

  Tokenizer.prototype.readEscapedChar = function readEscapedChar(inTemplate) {
    var ch = this.input.charCodeAt(++this.state.pos);
    ++this.state.pos;
    switch (ch) {
      case 110:
        return "\n"; // 'n' -> '\n'
      case 114:
        return "\r"; // 'r' -> '\r'
      case 120:
        return String.fromCharCode(this.readHexChar(2)); // 'x'
      case 117:
        return codePointToString(this.readCodePoint()); // 'u'
      case 116:
        return "\t"; // 't' -> '\t'
      case 98:
        return "\b"; // 'b' -> '\b'
      case 118:
        return "\u000b"; // 'v' -> '\u000b'
      case 102:
        return "\f"; // 'f' -> '\f'
      case 13:
        if (this.input.charCodeAt(this.state.pos) === 10) ++this.state.pos; // '\r\n'
      case 10:
        // ' \n'
        this.state.lineStart = this.state.pos;
        ++this.state.curLine;
        return "";
      default:
        if (ch >= 48 && ch <= 55) {
          var octalStr = this.input.substr(this.state.pos - 1, 3).match(/^[0-7]+/)[0];
          var octal = parseInt(octalStr, 8);
          if (octal > 255) {
            octalStr = octalStr.slice(0, -1);
            octal = parseInt(octalStr, 8);
          }
          if (octal > 0) {
            if (!this.state.containsOctal) {
              this.state.containsOctal = true;
              this.state.octalPosition = this.state.pos - 2;
            }
            if (this.state.strict || inTemplate) {
              this.raise(this.state.pos - 2, "Octal literal in strict mode");
            }
          }
          this.state.pos += octalStr.length - 1;
          return String.fromCharCode(octal);
        }
        return String.fromCharCode(ch);
    }
  };

  // Used to read character escape sequences ('\x', '\u', '\U').

  Tokenizer.prototype.readHexChar = function readHexChar(len) {
    var codePos = this.state.pos;
    var n = this.readInt(16, len);
    if (n === null) this.raise(codePos, "Bad character escape sequence");
    return n;
  };

  // Read an identifier, and return it as a string. Sets `this.state.containsEsc`
  // to whether the word contained a '\u' escape.
  //
  // Incrementally adds only escaped chars, adding other chunks as-is
  // as a micro-optimization.

  Tokenizer.prototype.readWord1 = function readWord1() {
    this.state.containsEsc = false;
    var word = "",
        first = true,
        chunkStart = this.state.pos;
    while (this.state.pos < this.input.length) {
      var ch = this.fullCharCodeAtPos();
      if (_utilIdentifier.isIdentifierChar(ch, true)) {
        this.state.pos += ch <= 0xffff ? 1 : 2;
      } else if (ch === 92) {
        // "\"
        this.state.containsEsc = true;

        word += this.input.slice(chunkStart, this.state.pos);
        var escStart = this.state.pos;

        if (this.input.charCodeAt(++this.state.pos) !== 117) {
          // "u"
          this.raise(this.state.pos, "Expecting Unicode escape sequence \\uXXXX");
        }

        ++this.state.pos;
        var esc = this.readCodePoint();
        if (!(first ? _utilIdentifier.isIdentifierStart : _utilIdentifier.isIdentifierChar)(esc, true)) {
          this.raise(escStart, "Invalid Unicode escape");
        }

        word += codePointToString(esc);
        chunkStart = this.state.pos;
      } else {
        break;
      }
      first = false;
    }
    return word + this.input.slice(chunkStart, this.state.pos);
  };

  // Read an identifier or keyword token. Will check for reserved
  // words when necessary.

  Tokenizer.prototype.readWord = function readWord() {
    var word = this.readWord1();
    var type = _types.types.name;
    if (!this.state.containsEsc && this.isKeyword(word)) {
      type = _types.keywords[word];
    }
    return this.finishToken(type, word);
  };

  Tokenizer.prototype.braceIsBlock = function braceIsBlock(prevType) {
    if (prevType === _types.types.colon) {
      var _parent = this.curContext();
      if (_parent === _context.types.b_stat || _parent === _context.types.b_expr) {
        return !_parent.isExpr;
      }
    }

    if (prevType === _types.types._return) {
      return _utilWhitespace.lineBreak.test(this.input.slice(this.state.lastTokEnd, this.state.start));
    }

    if (prevType === _types.types._else || prevType === _types.types.semi || prevType === _types.types.eof || prevType === _types.types.parenR) {
      return true;
    }

    if (prevType === _types.types.braceL) {
      return this.curContext() === _context.types.b_stat;
    }

    return !this.state.exprAllowed;
  };

  Tokenizer.prototype.updateContext = function updateContext(prevType) {
    var update = undefined,
        type = this.state.type;
    if (type.keyword && prevType === _types.types.dot) {
      this.state.exprAllowed = false;
    } else if (update = type.updateContext) {
      update.call(this, prevType);
    } else {
      this.state.exprAllowed = type.beforeExpr;
    }
  };

  return Tokenizer;
})();

exports["default"] = Tokenizer;