text: /* @noflow */
  /* eslint max-len: 0 */
  /* eslint indent: 0 */
  
  import type { TokenType } from "./types";
  import { isIdentifierStart, isIdentifierChar, isKeyword } from "../util/identifier";
  import { types as tt, keywords as keywordTypes } from "./types";
  import { types as ct } from "./context";
  import { SourceLocation } from "../util/location";
  import { lineBreak, lineBreakG, isNewLine, nonASCIIwhitespace } from "../util/whitespace";
  import State from "./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.
  
  export class Token {
    constructor(state) {
      this.type = state.type;
      this.value = state.value;
      this.start = state.start;
      this.end = state.end;
      this.loc = new SourceLocation(state.startLoc, state.endLoc);
    }
  
    type: TokenType;
    value: any;
    start: number;
    end: number;
    loc: SourceLocation;
  }
  
  // ## Tokenizer
  
  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);
    }
  }
  
  export default class Tokenizer {
    constructor(options, input) {
      this.state = new State;
      this.state.init(options, input);
    }
  
    // Move to the next token
  
    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
  
    eat(type) {
      if (this.match(type)) {
        this.next();
        return true;
      } else {
        return false;
      }
    }
  
    // TODO
  
    match(type) {
      return this.state.type === type;
    }
  
    // TODO
  
    isKeyword(word) {
      return isKeyword(word);
    }
  
    // TODO
  
    lookahead() {
      let old = this.state;
      this.state = old.clone(true);
  
      this.isLookahead = true;
      this.next();
      this.isLookahead = false;
  
      let 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).
  
    setStrict(strict) {
      this.state.strict = strict;
      if (!this.match(tt.num) && !this.match(tt.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();
    }
  
    curContext() {
      return this.state.context[this.state.context.length - 1];
    }
  
    // Read a single token, updating the parser object's token-related
    // properties.
  
    nextToken() {
      let 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(tt.eof);
  
      if (curContext.override) {
        return curContext.override(this);
      } else {
        return this.readToken(this.fullCharCodeAtPos());
      }
    }
  
    readToken(code) {
      // Identifier or keyword. '\uXXXX' sequences are allowed in
      // identifiers, so '\' also dispatches to that.
      if (isIdentifierStart(code) || code === 92 /* '\' */) {
        return this.readWord();
      } else {
        return this.getTokenFromCode(code);
      }
    }
  
    fullCharCodeAtPos() {
      let code = this.input.charCodeAt(this.state.pos);
      if (code <= 0xd7ff || code >= 0xe000) return code;
  
      let next = this.input.charCodeAt(this.state.pos + 1);
      return (code << 10) + next - 0x35fdc00;
    }
  
    pushComment(block, text, start, end, startLoc, endLoc) {
      let comment = {
        type: block ? "CommentBlock" : "CommentLine",
        value: text,
        start: start,
        end: end,
        loc: new SourceLocation(startLoc, endLoc)
      };
  
      if (!this.isLookahead) {
        this.state.tokens.push(comment);
        this.state.comments.push(comment);
      }
  
      this.addComment(comment);
    }
  
    skipBlockComment() {
      let startLoc = this.state.curPosition();
      let 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;
      lineBreakG.lastIndex = start;
      let match;
      while ((match = 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());
    }
  
    skipLineComment(startSkip) {
      let start = this.state.pos;
      let startLoc = this.state.curPosition();
      let 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.
  
    skipSpace() {
      loop: while (this.state.pos < this.input.length) {
        let 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 && 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.
  
    finishToken(type, val) {
      this.state.end = this.state.pos;
      this.state.endLoc = this.state.curPosition();
      let 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.
    //
    readToken_dot() {
      let next = this.input.charCodeAt(this.state.pos + 1);
      if (next >= 48 && next <= 57) {
        return this.readNumber(true);
      }
  
      let next2 = this.input.charCodeAt(this.state.pos + 2);
      if (next === 46 && next2 === 46) { // 46 = dot '.'
        this.state.pos += 3;
        return this.finishToken(tt.ellipsis);
      } else {
        ++this.state.pos;
        return this.finishToken(tt.dot);
      }
    }
  
    readToken_slash() { // '/'
      if (this.state.exprAllowed) {
        ++this.state.pos;
        return this.readRegexp();
      }
  
      let next = this.input.charCodeAt(this.state.pos + 1);
      if (next === 61) {
        return this.finishOp(tt.assign, 2);
      } else {
        return this.finishOp(tt.slash, 1);
      }
    }
  
    readToken_mult_modulo(code) { // '%*'
      let type = code === 42 ? tt.star : tt.modulo;
      let width = 1;
      let next = this.input.charCodeAt(this.state.pos + 1);
  
      if (next === 42 && this.hasPlugin("exponentiationOperator")) { // '*'
        width++;
        next = this.input.charCodeAt(this.state.pos + 2);
        type = tt.exponent;
      }
  
      if (next === 61) {
        width++;
        type = tt.assign;
      }
  
      return this.finishOp(type, width);
    }
  
    readToken_pipe_amp(code) { // '|&'
      let next = this.input.charCodeAt(this.state.pos + 1);
      if (next === code) return this.finishOp(code === 124 ? tt.logicalOR : tt.logicalAND, 2);
      if (next === 61) return this.finishOp(tt.assign, 2);
      return this.finishOp(code === 124 ? tt.bitwiseOR : tt.bitwiseAND, 1);
    }
  
    readToken_caret() { // '^'
      let next = this.input.charCodeAt(this.state.pos + 1);
      if (next === 61) {
        return this.finishOp(tt.assign, 2);
      } else {
        return this.finishOp(tt.bitwiseXOR, 1);
      }
    }
  
    readToken_plus_min(code) { // '+-'
      let next = this.input.charCodeAt(this.state.pos + 1);
  
      if (next === code) {
        if (next === 45 && this.input.charCodeAt(this.state.pos + 2) === 62 && 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(tt.incDec, 2);
      }
  
      if (next === 61) {
        return this.finishOp(tt.assign, 2);
      } else {
        return this.finishOp(tt.plusMin, 1);
      }
    }
  
    readToken_lt_gt(code) { // '<>'
      let next = this.input.charCodeAt(this.state.pos + 1);
      let 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(tt.assign, size + 1);
        return this.finishOp(tt.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 = 2;
      }
  
      return this.finishOp(tt.relational, size);
    }
  
    readToken_eq_excl(code) { // '=!'
      let next = this.input.charCodeAt(this.state.pos + 1);
      if (next === 61) return this.finishOp(tt.equality, this.input.charCodeAt(this.state.pos + 2) === 61 ? 3 : 2);
      if (code === 61 && next === 62) { // '=>'
        this.state.pos += 2;
        return this.finishToken(tt.arrow);
      }
      return this.finishOp(code === 61 ? tt.eq : tt.prefix, 1);
    }
  
    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(tt.parenL);
        case 41: ++this.state.pos; return this.finishToken(tt.parenR);
        case 59: ++this.state.pos; return this.finishToken(tt.semi);
        case 44: ++this.state.pos; return this.finishToken(tt.comma);
        case 91: ++this.state.pos; return this.finishToken(tt.bracketL);
        case 93: ++this.state.pos; return this.finishToken(tt.bracketR);
        case 123: ++this.state.pos; return this.finishToken(tt.braceL);
        case 125: ++this.state.pos; return this.finishToken(tt.braceR);
  
        case 58:
          if (this.hasPlugin("functionBind") && this.input.charCodeAt(this.state.pos + 1) === 58) {
            return this.finishOp(tt.doubleColon, 2);
          } else {
            ++this.state.pos;
            return this.finishToken(tt.colon);
          }
  
        case 63: ++this.state.pos; return this.finishToken(tt.question);
        case 64: ++this.state.pos; return this.finishToken(tt.at);
  
        case 96: // '`'
          ++this.state.pos;
          return this.finishToken(tt.backQuote);
  
        case 48: // '0'
          let 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(tt.prefix, 1);
      }
  
      this.raise(this.state.pos, `Unexpected character '${codePointToString(code)}'`);
    }
  
    finishOp(type, size) {
      let str = this.input.slice(this.state.pos, this.state.pos + size);
      this.state.pos += size;
      return this.finishToken(type, str);
    }
  
    readRegexp() {
      let escaped, inClass, start = this.state.pos;
      for (;;) {
        if (this.state.pos >= this.input.length) this.raise(start, "Unterminated regular expression");
        let ch = this.input.charAt(this.state.pos);
        if (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;
      }
      let content = this.input.slice(start, this.state.pos);
      ++this.state.pos;
      // Need to use `readWord1` because '\uXXXX' sequences are allowed
      // here (don't ask).
      let mods = this.readWord1();
      if (mods) {
        let validFlags = /^[gmsiyu]*$/;
        if (!validFlags.test(mods)) this.raise(start, "Invalid regular expression flag");
      }
      return this.finishToken(tt.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.
  
    readInt(radix, len) {
      let start = this.state.pos, total = 0;
      for (let i = 0, e = len == null ? Infinity : len; i < e; ++i) {
        let code = this.input.charCodeAt(this.state.pos), val;
        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;
    }
  
    readRadixNumber(radix) {
      this.state.pos += 2; // 0x
      let val = this.readInt(radix);
      if (val == null) this.raise(this.state.start + 2, "Expected number in radix " + radix);
      if (isIdentifierStart(this.fullCharCodeAtPos())) this.raise(this.state.pos, "Identifier directly after number");
      return this.finishToken(tt.num, val);
    }
  
    // Read an integer, octal integer, or floating-point number.
  
    readNumber(startsWithDot) {
      let 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");
      let 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 (isIdentifierStart(this.fullCharCodeAtPos())) this.raise(this.state.pos, "Identifier directly after number");
  
      let str = this.input.slice(start, this.state.pos), val;
      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(tt.num, val);
    }
  
    // Read a string value, interpreting backslash-escapes.
  
    readCodePoint() {
      let ch = this.input.charCodeAt(this.state.pos), code;
  
      if (ch === 123) {
        let 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;
    }
  
    readString(quote) {
      let out = "", chunkStart = ++this.state.pos;
      for (;;) {
        if (this.state.pos >= this.input.length) this.raise(this.state.start, "Unterminated string constant");
        let 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 (isNewLine(ch)) this.raise(this.state.start, "Unterminated string constant");
          ++this.state.pos;
        }
      }
      out += this.input.slice(chunkStart, this.state.pos++);
      return this.finishToken(tt.string, out);
    }
  
    // Reads template string tokens.
  
    readTmplToken() {
      let out = "", chunkStart = this.state.pos;
      for (;;) {
        if (this.state.pos >= this.input.length) this.raise(this.state.start, "Unterminated template");
        let 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(tt.template)) {
            if (ch === 36) {
              this.state.pos += 2;
              return this.finishToken(tt.dollarBraceL);
            } else {
              ++this.state.pos;
              return this.finishToken(tt.backQuote);
            }
          }
          out += this.input.slice(chunkStart, this.state.pos);
          return this.finishToken(tt.template, out);
        }
        if (ch === 92) { // '\'
          out += this.input.slice(chunkStart, this.state.pos);
          out += this.readEscapedChar(true);
          chunkStart = this.state.pos;
        } else if (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
  
    readEscapedChar(inTemplate) {
      let 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) {
            let octalStr = this.input.substr(this.state.pos - 1, 3).match(/^[0-7]+/)[0];
            let 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').
  
    readHexChar(len) {
      let codePos = this.state.pos;
      let 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.
  
    readWord1() {
      this.state.containsEsc = false;
      let word = "", first = true, chunkStart = this.state.pos;
      while (this.state.pos < this.input.length) {
        let ch = this.fullCharCodeAtPos();
        if (isIdentifierChar(ch)) {
          this.state.pos += ch <= 0xffff ? 1 : 2;
        } else if (ch === 92) { // "\"
          this.state.containsEsc = true;
  
          word += this.input.slice(chunkStart, this.state.pos);
          let 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;
          let esc = this.readCodePoint();
          if (!(first ? isIdentifierStart : 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.
  
    readWord() {
      let word = this.readWord1();
      let type = tt.name;
      if (!this.state.containsEsc && this.isKeyword(word)) {
        type = keywordTypes[word];
      }
      return this.finishToken(type, word);
    }
  
    braceIsBlock(prevType) {
      if (prevType === tt.colon) {
        let parent = this.curContext();
        if (parent === ct.b_stat || parent === ct.b_expr) {
          return !parent.isExpr;
        }
      }
  
      if (prevType === tt._return) {
        return lineBreak.test(this.input.slice(this.state.lastTokEnd, this.state.start));
      }
  
      if (prevType === tt._else || prevType === tt.semi || prevType === tt.eof || prevType === tt.parenR) {
        return true;
      }
  
      if (prevType === tt.braceL) {
        return this.curContext() === ct.b_stat;
      }
  
      return !this.state.exprAllowed;
    }
  
    updateContext(prevType) {
      let update, type = this.state.type;
      if (type.keyword && prevType === tt.dot) {
        this.state.exprAllowed = false;
      } else if (update = type.updateContext) {
        update.call(this, prevType);
      } else {
        this.state.exprAllowed = type.beforeExpr;
      }
    }
  }
  