diff --git a/src/state.js b/src/state.js
new file mode 100644
index 0000000000..cb5e4b4fbe
--- /dev/null
+++ b/src/state.js
@@ -0,0 +1,56 @@
+import {reservedWords, keywords} from "./identifier"
+import {types as tt} from "./tokentype"
+
+export default function Parser(options, input, startPos) {
+  this.options = options
+  this.loadPlugins(this.options.plugins)
+  this.sourceFile = this.options.sourceFile || null
+  this.isKeyword = keywords[this.options.ecmaVersion >= 6 ? 6 : 5]
+  this.isReservedWord = reservedWords[this.options.ecmaVersion]
+  this.input = input
+
+  // Set up token state
+
+  // The current position of the tokenizer in the input.
+  if (startPos) {
+    this.pos = startPos;
+    this.lineStart = Math.max(0, this.input.lastIndexOf("\n", startPos));
+    this.curLine = this.input.slice(0, this.lineStart).split(lineBreak).length;
+  } else {
+    this.pos = this.lineStart = 0;
+    this.curLine = 1;
+  }
+
+  // Properties of the current token:
+  // Its type
+  this.type = tt.eof;
+  // For tokens that include more information than their type, the value
+  this.value = null;
+  // Its start and end offset
+  this.start = this.end = this.pos;
+  // And, if locations are used, the {line, column} object
+  // corresponding to those offsets
+  this.startLoc = this.endLoc = null;
+
+  // Position information for the previous token
+  this.lastTokEndLoc = this.lastTokStartLoc = null;
+  this.lastTokStart = this.lastTokEnd = this.pos;
+
+  // The context stack is used to superficially track syntactic
+  // context to predict whether a regular expression is allowed in a
+  // given position.
+  this.context = this.initialContext()
+  this.exprAllowed = true
+
+  // Figure out if it's a module code.
+  this.strict = this.inModule = this.options.sourceType === "module";
+
+  // Flags to track whether we are in a function, a generator.
+  this.inFunction = this.inGenerator = false;
+  // Labels in scope.
+  this.labels = [];
+
+  // If enabled, skip leading hashbang line.
+  if (this.pos === 0 && this.options.allowHashBang && this.input.slice(0, 2) === '#!')
+    this.skipLineComment(2);
+}
diff --git a/src/tokencontext.js b/src/tokencontext.js
new file mode 100644
index 0000000000..870f3f1325
--- /dev/null
+++ b/src/tokencontext.js
@@ -0,0 +1,102 @@
+// The algorithm used to determine whether a regexp can appear at a
+// given point in the program is loosely based on sweet.js' approach.
+// See https://github.com/mozilla/sweet.js/wiki/design
+
+import Parser from "./state"
+import {types as tt} from "./tokentype"
+
+export class TokContext {
+  constructor(token, isExpr, preserveSpace, override) {
+    this.token = token
+    this.isExpr = isExpr
+    this.preserveSpace = preserveSpace
+    this.override = override
+  }
+}
+
+export const types = {
+  b_stat: new TokContext("{", false),
+  b_expr: new TokContext("{", true),
+  b_tmpl: new TokContext("${", true, null, p => p.readTmplToken()),
+  p_stat: new TokContext("(", false),
+  p_expr: new TokContext("(", true),
+  q_tmpl: new TokContext("`", true, true),
+  f_expr: new TokContext("function", true)
+}
+
+const pp = Parser.prototype
+
+pp.initialContext = function() {
+  return [types.b_stat]
+}
+
+pp.braceIsBlock = function(prevType) {
+  var parent;
+  if (prevType === tt.colon && (parent = this.curContext()).token == "{")
+    return !parent.isExpr;
+  if (prevType === tt._return)
+    return lineBreak.test(this.input.slice(this.lastTokEnd, this.start));
+  if (prevType === tt._else || prevType === tt.semi || prevType === tt.eof)
+    return true;
+  if (prevType == tt.braceL)
+    return this.curContext() === types.b_stat;
+  return !this.exprAllowed;
+};
+
+pp.updateContext = function(prevType) {
+  var update, type = this.type;
+  if (type.keyword && prevType == tt.dot)
+    this.exprAllowed = false;
+  else if (update = type.updateContext)
+    update.call(this, prevType);
+  else
+    this.exprAllowed = type.beforeExpr;
+};
+
+// Token-specific context update code
+
+tt.parenR.updateContext = tt.braceR.updateContext = function() {
+  var out = this.context.pop();
+  if (out === types.b_stat && this.curContext() === types.f_expr) {
+    this.context.pop();
+    this.exprAllowed = false;
+  } else if (out === types.b_tmpl) {
+    this.exprAllowed = true;
+  } else {
+    this.exprAllowed = !(out && out.isExpr);
+  }
+};
+
+tt.braceL.updateContext = function(prevType) {
+  this.context.push(this.braceIsBlock(prevType) ? types.b_stat : types.b_expr);
+  this.exprAllowed = true;
+};
+
+tt.dollarBraceL.updateContext = function() {
+  this.context.push(types.b_tmpl);
+  this.exprAllowed = true;
+};
+
+tt.parenL.updateContext = function(prevType) {
+  var statementParens = prevType === tt._if || prevType === tt._for || prevType === tt._with || prevType === tt._while;
+  this.context.push(statementParens ? types.p_stat : types.p_expr);
+  this.exprAllowed = true;
+};
+
+tt.incDec.updateContext = function() {
+  // tokExprAllowed stays unchanged
+};
+
+tt._function.updateContext = function() {
+  if (this.curContext() !== types.b_stat)
+    this.context.push(types.f_expr);
+  this.exprAllowed = false;
+};
+
+tt.backQuote.updateContext = function() {
+  if (this.curContext() === types.q_tmpl)
+    this.context.pop();
+  else
+    this.context.push(types.q_tmpl);
+  this.exprAllowed = false;
+};
diff --git a/src/tokenize.js b/src/tokenize.js
new file mode 100644
index 0000000000..9a2007e15d
--- /dev/null
+++ b/src/tokenize.js
@@ -0,0 +1,724 @@
+import {isIdentifierStart, isIdentifierChar} from "./identifier"
+import {types as tt, keywords as keywordTypes} from "./tokentype"
+import Parser from "./state"
+import "./tokencontext"
+
+// 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(p) {
+    this.type = p.type;
+    this.value = p.value;
+    this.start = p.start;
+    this.end = p.end;
+    if (p.options.locations)
+      this.loc = new SourceLocation(p, p.startLoc, p.endLoc);
+    if (p.options.ranges)
+      this.range = [p.start, p.end];
+  }
+}
+
+// Matches a whole line break (where CRLF is considered a single
+// line break). Used to count lines.
+
+export const lineBreak = /\r\n?|\n|\u2028|\u2029/g
+
+export function isNewLine(code) {
+  return code === 10 || code === 13 || code === 0x2028 || code == 0x2029
+}
+
+// ## Tokenizer
+
+// These are used when `options.locations` is on, for the
+// `startLoc` and `endLoc` properties.
+
+class Position {
+  constructor(line, col) {
+    this.line = line
+    this.column = col
+  }
+
+  offset(n) {
+    return new Position(this.line, this.column + n)
+  }
+}
+
+// Shorthand because we are going to be adding a _lot_ of methods to
+// this.
+const pp = Parser.prototype
+
+pp.extend = function(name, f) {
+  this[name] = f(this[name]);
+};
+
+pp.loadPlugins = function(plugins) {
+  for (var name in plugins) {
+    var plugin = exports.plugins[name];
+    if (!plugin) throw new Error("Plugin '" + name + "' not found");
+    plugin(this, plugins[name]);
+  }
+};
+
+// Move to the next token
+
+pp.next = function() {
+  if (this.options.onToken)
+    this.options.onToken(new Token(this));
+
+  this.lastTokEnd = this.end;
+  this.lastTokStart = this.start;
+  this.lastTokEndLoc = this.endLoc;
+  this.lastTokStartLoc = this.startLoc;
+  this.nextToken();
+};
+
+pp.getToken = function() {
+  this.next();
+  return new Token(this);
+};
+
+// If we're in an ES6 environment, make parsers iterable
+if (typeof Symbol !== "undefined")
+  pp[Symbol.iterator] = function () {
+    var self = this;
+    return {next: function () {
+      var token = self.getToken();
+      return {
+        done: token.type === tt.eof,
+        value: token
+      };
+    }};
+  };
+
+// Toggle strict mode. Re-reads the next number or string to please
+// pedantic tests (`"use strict"; 010;` should fail).
+
+pp.setStrict = function(strict) {
+  this.strict = strict;
+  if (this.type !== tt.num && this.type !== tt.string) return;
+  this.pos = this.start;
+  if (this.options.locations) {
+    while (this.pos < this.lineStart) {
+      this.lineStart = this.input.lastIndexOf("\n", this.lineStart - 2) + 1;
+      --this.curLine;
+    }
+  }
+  this.nextToken();
+};
+
+pp.curContext = function() {
+  return this.context[this.context.length - 1];
+};
+
+// Read a single token, updating the parser object's token-related
+// properties.
+
+pp.nextToken = function() {
+  let curContext = this.curContext()
+  if (!curContext || !curContext.preserveSpace) this.skipSpace()
+
+  this.start = this.pos
+  if (this.options.locations) this.startLoc = this.curPosition()
+  if (this.pos >= this.input.length) return this.finishToken(tt.eof)
+
+  if (curContext.override) return curContext.override(this)
+  else this.readToken(this.fullCharCodeAtPos())
+}
+
+pp.readToken = function(code) {
+  // Identifier or keyword. '\uXXXX' sequences are allowed in
+  // identifiers, so '\' also dispatches to that.
+  if (isIdentifierStart(code, this.options.ecmaVersion >= 6) || code === 92 /* '\' */)
+    return this.readWord();
+
+  return this.getTokenFromCode(code);
+};
+
+pp.fullCharCodeAtPos = function() {
+  var code = this.input.charCodeAt(this.pos);
+  if (code <= 0xd7ff || code >= 0xe000) return code;
+  var next = this.input.charCodeAt(this.pos + 1);
+  return (code << 10) + next - 0x35fdc00;
+};
+
+pp.skipBlockComment = function() {
+  var startLoc = this.options.onComment && this.options.locations && this.curPosition();
+  var start = this.pos, end = this.input.indexOf("*/", this.pos += 2);
+  if (end === -1) this.raise(this.pos - 2, "Unterminated comment");
+  this.pos = end + 2;
+  if (this.options.locations) {
+    lineBreak.lastIndex = start;
+    var match;
+    while ((match = lineBreak.exec(this.input)) && match.index < this.pos) {
+      ++this.curLine;
+      this.lineStart = match.index + match[0].length;
+    }
+  }
+  if (this.options.onComment)
+    this.options.onComment(true, this.input.slice(start + 2, end), start, this.pos,
+                           startLoc, this.options.locations && this.curPosition());
+};
+
+pp.skipLineComment = function(startSkip) {
+  var start = this.pos;
+  var startLoc = this.options.onComment && this.options.locations && this.curPosition();
+  var ch = this.input.charCodeAt(this.pos+=startSkip);
+  while (this.pos < this.input.length && ch !== 10 && ch !== 13 && ch !== 8232 && ch !== 8233) {
+    ++this.pos;
+    ch = this.input.charCodeAt(this.pos);
+  }
+  if (this.options.onComment)
+    this.options.onComment(false, this.input.slice(start + startSkip, this.pos), start, this.pos,
+                           startLoc, this.options.locations && this.curPosition());
+};
+
+// Called at the start of the parse and after every token. Skips
+// whitespace and comments, and.
+
+pp.skipSpace = function() {
+  while (this.pos < this.input.length) {
+    var ch = this.input.charCodeAt(this.pos);
+    if (ch === 32) { // ' '
+      ++this.pos;
+    } else if (ch === 13) {
+      ++this.pos;
+      var next = this.input.charCodeAt(this.pos);
+      if (next === 10) {
+        ++this.pos;
+      }
+      if (this.options.locations) {
+        ++this.curLine;
+        this.lineStart = this.pos;
+      }
+    } else if (ch === 10 || ch === 8232 || ch === 8233) {
+      ++this.pos;
+      if (this.options.locations) {
+        ++this.curLine;
+        this.lineStart = this.pos;
+      }
+    } else if (ch > 8 && ch < 14) {
+      ++this.pos;
+    } else if (ch === 47) { // '/'
+      var next = this.input.charCodeAt(this.pos + 1);
+      if (next === 42) { // '*'
+        this.skipBlockComment();
+      } else if (next === 47) { // '/'
+        this.skipLineComment(2);
+      } else break;
+    } else if (ch === 160) { // '\xa0'
+      ++this.pos;
+    } else if (ch >= 5760 && nonASCIIwhitespace.test(String.fromCharCode(ch))) {
+      ++this.pos;
+    } else {
+      break;
+    }
+  }
+};
+
+pp.curPosition = function() {
+  return new Position(this.curLine, this.pos - this.lineStart);
+};
+
+// 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.
+
+pp.finishToken = function(type, val) {
+  this.end = this.pos;
+  if (this.options.locations) this.endLoc = this.curPosition();
+  var prevType = this.type;
+  this.type = type;
+  this.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.
+//
+pp.readToken_dot = function() {
+  var next = this.input.charCodeAt(this.pos + 1);
+  if (next >= 48 && next <= 57) return this.readNumber(true);
+  var next2 = this.input.charCodeAt(this.pos + 2);
+  if (this.options.ecmaVersion >= 6 && next === 46 && next2 === 46) { // 46 = dot '.'
+    this.pos += 3;
+    return this.finishToken(tt.ellipsis);
+  } else {
+    ++this.pos;
+    return this.finishToken(tt.dot);
+  }
+};
+
+pp.readToken_slash = function() { // '/'
+  var next = this.input.charCodeAt(this.pos + 1);
+  if (this.exprAllowed) {++this.pos; return this.readRegexp();}
+  if (next === 61) return this.finishOp(tt.assign, 2);
+  return this.finishOp(tt.slash, 1);
+};
+
+pp.readToken_mult_modulo = function(code) { // '%*'
+  var next = this.input.charCodeAt(this.pos + 1);
+  if (next === 61) return this.finishOp(tt.assign, 2);
+  return this.finishOp(code === 42 ? tt.star : tt.modulo, 1);
+};
+
+pp.readToken_pipe_amp = function(code) { // '|&'
+  var next = this.input.charCodeAt(this.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);
+};
+
+pp.readToken_caret = function() { // '^'
+  var next = this.input.charCodeAt(this.pos + 1);
+  if (next === 61) return this.finishOp(tt.assign, 2);
+  return this.finishOp(tt.bitwiseXOR, 1);
+};
+
+pp.readToken_plus_min = function(code) { // '+-'
+  var next = this.input.charCodeAt(this.pos + 1);
+  if (next === code) {
+    if (next == 45 && this.input.charCodeAt(this.pos + 2) == 62 &&
+        lineBreak.test(this.input.slice(this.lastTokEnd, this.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);
+  return this.finishOp(tt.plusMin, 1);
+};
+
+pp.readToken_lt_gt = function(code) { // '<>'
+  var next = this.input.charCodeAt(this.pos + 1);
+  var size = 1;
+  if (next === code) {
+    size = code === 62 && this.input.charCodeAt(this.pos + 2) === 62 ? 3 : 2;
+    if (this.input.charCodeAt(this.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.pos + 2) == 45 &&
+      this.input.charCodeAt(this.pos + 3) == 45) {
+    if (this.inModule) 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.pos + 2) === 61 ? 3 : 2;
+  return this.finishOp(tt.relational, size);
+};
+
+pp.readToken_eq_excl = function(code) { // '=!'
+  var next = this.input.charCodeAt(this.pos + 1);
+  if (next === 61) return this.finishOp(tt.equality, this.input.charCodeAt(this.pos + 2) === 61 ? 3 : 2);
+  if (code === 61 && next === 62 && this.options.ecmaVersion >= 6) { // '=>'
+    this.pos += 2;
+    return this.finishToken(tt.arrow);
+  }
+  return this.finishOp(code === 61 ? tt.eq : tt.prefix, 1);
+};
+
+pp.getTokenFromCode = function(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.pos; return this.finishToken(tt.parenL);
+  case 41: ++this.pos; return this.finishToken(tt.parenR);
+  case 59: ++this.pos; return this.finishToken(tt.semi);
+  case 44: ++this.pos; return this.finishToken(tt.comma);
+  case 91: ++this.pos; return this.finishToken(tt.bracketL);
+  case 93: ++this.pos; return this.finishToken(tt.bracketR);
+  case 123: ++this.pos; return this.finishToken(tt.braceL);
+  case 125: ++this.pos; return this.finishToken(tt.braceR);
+  case 58: ++this.pos; return this.finishToken(tt.colon);
+  case 63: ++this.pos; return this.finishToken(tt.question);
+
+  case 96: // '`'
+    if (this.options.ecmaVersion < 6) break;
+    ++this.pos;
+    return this.finishToken(tt.backQuote);
+
+  case 48: // '0'
+    var next = this.input.charCodeAt(this.pos + 1);
+    if (next === 120 || next === 88) return this.readRadixNumber(16); // '0x', '0X' - hex number
+    if (this.options.ecmaVersion >= 6) {
+      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.pos, "Unexpected character '" + codePointToString(code) + "'");
+};
+
+pp.finishOp = function(type, size) {
+  var str = this.input.slice(this.pos, this.pos + size);
+  this.pos += size;
+  return this.finishToken(type, str);
+};
+
+var regexpUnicodeSupport = false;
+try { new RegExp("\uffff", "u"); regexpUnicodeSupport = true; }
+catch(e) {}
+
+// Parse a regular expression. Some context-awareness is necessary,
+// since a '/' inside a '[]' set does not end the expression.
+
+pp.readRegexp = function() {
+  var content = "", escaped, inClass, start = this.pos;
+  for (;;) {
+    if (this.pos >= this.input.length) this.raise(start, "Unterminated regular expression");
+    var ch = this.input.charAt(this.pos);
+    if (lineBreak.test(ch)) this.raise(start, "Unterminated regular expression");
+    if (!escaped) {
+      if (ch === "[") inClass = true;
+      else if (ch === "]" && inClass) inClass = false;
+      else if (ch === "/" && !inClass) break;
+      escaped = ch === "\\";
+    } else escaped = false;
+    ++this.pos;
+  }
+  var content = this.input.slice(start, this.pos);
+  ++this.pos;
+  // Need to use `readWord1` because '\uXXXX' sequences are allowed
+  // here (don't ask).
+  var mods = this.readWord1();
+  var tmp = content;
+  if (mods) {
+    var validFlags = /^[gmsiy]*$/;
+    if (this.options.ecmaVersion >= 6) validFlags = /^[gmsiyu]*$/;
+    if (!validFlags.test(mods)) this.raise(start, "Invalid regular expression flag");
+    if (mods.indexOf('u') >= 0 && !regexpUnicodeSupport) {
+      // Replace each astral symbol and every Unicode escape sequence that
+      // possibly represents an astral symbol or a paired surrogate with a
+      // single ASCII symbol to avoid throwing on regular expressions that
+      // are only valid in combination with the `/u` flag.
+      // Note: replacing with the ASCII symbol `x` might cause false
+      // negatives in unlikely scenarios. For example, `[\u{61}-b]` is a
+      // perfectly valid pattern that is equivalent to `[a-b]`, but it would
+      // be replaced by `[x-b]` which throws an error.
+      tmp = tmp.replace(/\\u([a-fA-F0-9]{4})|\\u\{([0-9a-fA-F]+)\}|[\uD800-\uDBFF][\uDC00-\uDFFF]/g, "x")
+    }
+  }
+  // Detect invalid regular expressions.
+  try {
+    new RegExp(tmp);
+  } catch (e) {
+    if (e instanceof SyntaxError) this.raise(start, "Error parsing regular expression: " + e.message);
+    this.raise(e);
+  }
+  // Get a regular expression object for this pattern-flag pair, or `null` in
+  // case the current environment doesn't support the flags it uses.
+  try {
+    var value = new RegExp(content, mods);
+  } catch (err) {
+    value = null;
+  }
+  return this.finishToken(tt.regexp, {pattern: content, flags: mods, value: value});
+};
+
+// 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.
+
+pp.readInt = function(radix, len) {
+  var start = this.pos, total = 0;
+  for (var i = 0, e = len == null ? Infinity : len; i < e; ++i) {
+    var code = this.input.charCodeAt(this.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.pos;
+    total = total * radix + val;
+  }
+  if (this.pos === start || len != null && this.pos - start !== len) return null;
+
+  return total;
+};
+
+pp.readRadixNumber = function(radix) {
+  this.pos += 2; // 0x
+  var val = this.readInt(radix);
+  if (val == null) this.raise(this.start + 2, "Expected number in radix " + radix);
+  if (isIdentifierStart(this.fullCharCodeAtPos())) this.raise(this.pos, "Identifier directly after number");
+  return this.finishToken(tt.num, val);
+};
+
+// Read an integer, octal integer, or floating-point number.
+
+pp.readNumber = function(startsWithDot) {
+  var start = this.pos, isFloat = false, octal = this.input.charCodeAt(this.pos) === 48;
+  if (!startsWithDot && this.readInt(10) === null) this.raise(start, "Invalid number");
+  if (this.input.charCodeAt(this.pos) === 46) {
+    ++this.pos;
+    this.readInt(10);
+    isFloat = true;
+  }
+  var next = this.input.charCodeAt(this.pos);
+  if (next === 69 || next === 101) { // 'eE'
+    next = this.input.charCodeAt(++this.pos);
+    if (next === 43 || next === 45) ++this.pos; // '+-'
+    if (this.readInt(10) === null) this.raise(start, "Invalid number");
+    isFloat = true;
+  }
+  if (isIdentifierStart(this.fullCharCodeAtPos())) this.raise(this.pos, "Identifier directly after number");
+
+  var str = this.input.slice(start, this.pos), val;
+  if (isFloat) val = parseFloat(str);
+  else if (!octal || str.length === 1) val = parseInt(str, 10);
+  else if (/[89]/.test(str) || this.strict) this.raise(start, "Invalid number");
+  else val = parseInt(str, 8);
+  return this.finishToken(tt.num, val);
+};
+
+// Read a string value, interpreting backslash-escapes.
+
+pp.readCodePoint = function() {
+  var ch = this.input.charCodeAt(this.pos), code;
+
+  if (ch === 123) {
+    if (this.options.ecmaVersion < 6) this.unexpected();
+    ++this.pos;
+    code = this.readHexChar(this.input.indexOf('}', this.pos) - this.pos);
+    ++this.pos;
+    if (code > 0x10FFFF) this.unexpected();
+  } else {
+    code = this.readHexChar(4);
+  }
+  return code;
+};
+
+function codePointToString(code) {
+  // UTF-16 Decoding
+  if (code <= 0xFFFF) return String.fromCharCode(code);
+  return String.fromCharCode(((code - 0x10000) >> 10) + 0xD800,
+                             ((code - 0x10000) & 1023) + 0xDC00);
+}
+
+pp.readString = function(quote) {
+  var out = "", chunkStart = ++this.pos;
+  for (;;) {
+    if (this.pos >= this.input.length) this.raise(this.start, "Unterminated string constant");
+    var ch = this.input.charCodeAt(this.pos);
+    if (ch === quote) break;
+    if (ch === 92) { // '\'
+      out += this.input.slice(chunkStart, this.pos);
+      out += this.readEscapedChar();
+      chunkStart = this.pos;
+    } else {
+      if (isNewLine(ch)) this.raise(this.start, "Unterminated string constant");
+      ++this.pos;
+    }
+  }
+  out += this.input.slice(chunkStart, this.pos++);
+  return this.finishToken(tt.string, out);
+};
+
+// Reads template string tokens.
+
+pp.readTmplToken = function() {
+  var out = "", chunkStart = this.pos;
+  for (;;) {
+    if (this.pos >= this.input.length) this.raise(this.start, "Unterminated template");
+    var ch = this.input.charCodeAt(this.pos);
+    if (ch === 96 || ch === 36 && this.input.charCodeAt(this.pos + 1) === 123) { // '`', '${'
+      if (this.pos === this.start && this.type === tt.template) {
+        if (ch === 36) {
+          this.pos += 2;
+          return this.finishToken(tt.dollarBraceL);
+        } else {
+          ++this.pos;
+          return this.finishToken(tt.backQuote);
+        }
+      }
+      out += this.input.slice(chunkStart, this.pos);
+      return this.finishToken(tt.template, out);
+    }
+    if (ch === 92) { // '\'
+      out += this.input.slice(chunkStart, this.pos);
+      out += this.readEscapedChar();
+      chunkStart = this.pos;
+    } else if (isNewLine(ch)) {
+      out += this.input.slice(chunkStart, this.pos);
+      ++this.pos;
+      if (ch === 13 && this.input.charCodeAt(this.pos) === 10) {
+        ++this.pos;
+        out += "\n";
+      } else {
+        out += String.fromCharCode(ch);
+      }
+      if (this.options.locations) {
+        ++this.curLine;
+        this.lineStart = this.pos;
+      }
+      chunkStart = this.pos;
+    } else {
+      ++this.pos;
+    }
+  }
+};
+
+// Used to read escaped characters
+
+pp.readEscapedChar = function() {
+  var ch = this.input.charCodeAt(++this.pos);
+  var octal = /^[0-7]+/.exec(this.input.slice(this.pos, this.pos + 3));
+  if (octal) octal = octal[0];
+  while (octal && parseInt(octal, 8) > 255) octal = octal.slice(0, -1);
+  if (octal === "0") octal = null;
+  ++this.pos;
+  if (octal) {
+    if (this.strict) this.raise(this.pos - 2, "Octal literal in strict mode");
+    this.pos += octal.length - 1;
+    return String.fromCharCode(parseInt(octal, 8));
+  } else {
+    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 48: return "\0"; // 0 -> '\0'
+    case 13: if (this.input.charCodeAt(this.pos) === 10) ++this.pos; // '\r\n'
+    case 10: // ' \n'
+      if (this.options.locations) { this.lineStart = this.pos; ++this.curLine; }
+      return "";
+    default: return String.fromCharCode(ch);
+    }
+  }
+};
+
+// Used to read character escape sequences ('\x', '\u', '\U').
+
+pp.readHexChar = function(len) {
+  var n = this.readInt(16, len);
+  if (n === null) this.raise(this.start, "Bad character escape sequence");
+  return n;
+};
+
+// Used to signal to callers of `readWord1` whether the word
+// contained any escape sequences. This is needed because words with
+// escape sequences must not be interpreted as keywords.
+
+var containsEsc;
+
+// Read an identifier, and return it as a string. Sets `containsEsc`
+// to whether the word contained a '\u' escape.
+//
+// Incrementally adds only escaped chars, adding other chunks as-is
+// as a micro-optimization.
+
+pp.readWord1 = function() {
+  containsEsc = false;
+  var word = "", first = true, chunkStart = this.pos;
+  var astral = this.options.ecmaVersion >= 6;
+  while (this.pos < this.input.length) {
+    var ch = this.fullCharCodeAtPos();
+    if (isIdentifierChar(ch, astral)) {
+      this.pos += ch <= 0xffff ? 1 : 2;
+    } else if (ch === 92) { // "\"
+      containsEsc = true;
+      word += this.input.slice(chunkStart, this.pos);
+      var escStart = this.pos;
+      if (this.input.charCodeAt(++this.pos) != 117) // "u"
+        this.raise(this.pos, "Expecting Unicode escape sequence \\uXXXX");
+      ++this.pos;
+      var esc = this.readCodePoint();
+      if (!(first ? isIdentifierStart : isIdentifierChar)(esc, astral))
+        this.raise(escStart, "Invalid Unicode escape");
+      word += codePointToString(esc);
+      chunkStart = this.pos;
+    } else {
+      break;
+    }
+    first = false;
+  }
+  return word + this.input.slice(chunkStart, this.pos);
+};
+
+// Read an identifier or keyword token. Will check for reserved
+// words when necessary.
+
+pp.readWord = function() {
+  var word = this.readWord1();
+  var type = tt.name;
+  if ((this.options.ecmaVersion >= 6 || !containsEsc) && this.isKeyword(word))
+    type = keywordTypes[word];
+  return this.finishToken(type, word);
+};
+
+// This function is used to raise exceptions on parse errors. It
+// takes an offset integer (into the current `input`) to indicate
+// the location of the error, attaches the position to the end
+// of the error message, and then raises a `SyntaxError` with that
+// message.
+
+pp.raise = function(pos, message) {
+  var loc = getLineInfo(this.input, pos);
+  message += " (" + loc.line + ":" + loc.column + ")";
+  var err = new SyntaxError(message);
+  err.pos = pos; err.loc = loc; err.raisedAt = this.pos;
+  throw err;
+};
+
+pp.currentPos = function() {
+  return this.options.locations ? [this.start, this.startLoc] : this.start;
+};