text: /*
  * @Author: detailyang
  * @Date:   2016-04-25 00:18:09
  * @Last Modified by:   detailyang
  * @Last Modified time: 2016-04-26 00:51:26
  */
  
  
  var EX_EOF = {};
  var PUNC_CHARS = array_to_hash(characters("[]{}(),;:"));
  var OPERATORS = array_to_hash([
      "in",
      "instanceof",
      "typeof",
      "new",
      "void",
      "delete",
      "++",
      "--",
      "+",
      "-",
      "!",
      "~",
      "&",
      "|",
      "^",
      "*",
      "/",
      "%",
      ">>",
      "<<",
      ">>>",
      "<",
      ">",
      "<=",
      ">=",
      "==",
      "===",
      "!=",
      "!==",
      "?",
      "=",
      "+=",
      "-=",
      "/=",
      "*=",
      "%=",
      ">>=",
      "<<=",
      ">>>=",
      "|=",
      "^=",
      "&=",
      "&&",
      "||"
  ]);
  var PUNC_BEFORE_EXPRESSION = array_to_hash(characters("[{(,.;:"));
  var UNICODE = {  // Unicode 6.1
      letter: new RegExp("[\\u0041-\\u005A\\u0061-\\u007A\\u00AA\\u00B5\\u00BA\\u00C0-\\u00D6\\u00D8-\\u00F6\\u00F8-\\u02C1\\u02C6-\\u02D1\\u02E0-\\u02E4\\u02EC\\u02EE\\u0370-\\u0374\\u0376\\u0377\\u037A-\\u037D\\u0386\\u0388-\\u038A\\u038C\\u038E-\\u03A1\\u03A3-\\u03F5\\u03F7-\\u0481\\u048A-\\u0527\\u0531-\\u0556\\u0559\\u0561-\\u0587\\u05D0-\\u05EA\\u05F0-\\u05F2\\u0620-\\u064A\\u066E\\u066F\\u0671-\\u06D3\\u06D5\\u06E5\\u06E6\\u06EE\\u06EF\\u06FA-\\u06FC\\u06FF\\u0710\\u0712-\\u072F\\u074D-\\u07A5\\u07B1\\u07CA-\\u07EA\\u07F4\\u07F5\\u07FA\\u0800-\\u0815\\u081A\\u0824\\u0828\\u0840-\\u0858\\u08A0\\u08A2-\\u08AC\\u0904-\\u0939\\u093D\\u0950\\u0958-\\u0961\\u0971-\\u0977\\u0979-\\u097F\\u0985-\\u098C\\u098F\\u0990\\u0993-\\u09A8\\u09AA-\\u09B0\\u09B2\\u09B6-\\u09B9\\u09BD\\u09CE\\u09DC\\u09DD\\u09DF-\\u09E1\\u09F0\\u09F1\\u0A05-\\u0A0A\\u0A0F\\u0A10\\u0A13-\\u0A28\\u0A2A-\\u0A30\\u0A32\\u0A33\\u0A35\\u0A36\\u0A38\\u0A39\\u0A59-\\u0A5C\\u0A5E\\u0A72-\\u0A74\\u0A85-\\u0A8D\\u0A8F-\\u0A91\\u0A93-\\u0AA8\\u0AAA-\\u0AB0\\u0AB2\\u0AB3\\u0AB5-\\u0AB9\\u0ABD\\u0AD0\\u0AE0\\u0AE1\\u0B05-\\u0B0C\\u0B0F\\u0B10\\u0B13-\\u0B28\\u0B2A-\\u0B30\\u0B32\\u0B33\\u0B35-\\u0B39\\u0B3D\\u0B5C\\u0B5D\\u0B5F-\\u0B61\\u0B71\\u0B83\\u0B85-\\u0B8A\\u0B8E-\\u0B90\\u0B92-\\u0B95\\u0B99\\u0B9A\\u0B9C\\u0B9E\\u0B9F\\u0BA3\\u0BA4\\u0BA8-\\u0BAA\\u0BAE-\\u0BB9\\u0BD0\\u0C05-\\u0C0C\\u0C0E-\\u0C10\\u0C12-\\u0C28\\u0C2A-\\u0C33\\u0C35-\\u0C39\\u0C3D\\u0C58\\u0C59\\u0C60\\u0C61\\u0C85-\\u0C8C\\u0C8E-\\u0C90\\u0C92-\\u0CA8\\u0CAA-\\u0CB3\\u0CB5-\\u0CB9\\u0CBD\\u0CDE\\u0CE0\\u0CE1\\u0CF1\\u0CF2\\u0D05-\\u0D0C\\u0D0E-\\u0D10\\u0D12-\\u0D3A\\u0D3D\\u0D4E\\u0D60\\u0D61\\u0D7A-\\u0D7F\\u0D85-\\u0D96\\u0D9A-\\u0DB1\\u0DB3-\\u0DBB\\u0DBD\\u0DC0-\\u0DC6\\u0E01-\\u0E30\\u0E32\\u0E33\\u0E40-\\u0E46\\u0E81\\u0E82\\u0E84\\u0E87\\u0E88\\u0E8A\\u0E8D\\u0E94-\\u0E97\\u0E99-\\u0E9F\\u0EA1-\\u0EA3\\u0EA5\\u0EA7\\u0EAA\\u0EAB\\u0EAD-\\u0EB0\\u0EB2\\u0EB3\\u0EBD\\u0EC0-\\u0EC4\\u0EC6\\u0EDC-\\u0EDF\\u0F00\\u0F40-\\u0F47\\u0F49-\\u0F6C\\u0F88-\\u0F8C\\u1000-\\u102A\\u103F\\u1050-\\u1055\\u105A-\\u105D\\u1061\\u1065\\u1066\\u106E-\\u1070\\u1075-\\u1081\\u108E\\u10A0-\\u10C5\\u10C7\\u10CD\\u10D0-\\u10FA\\u10FC-\\u1248\\u124A-\\u124D\\u1250-\\u1256\\u1258\\u125A-\\u125D\\u1260-\\u1288\\u128A-\\u128D\\u1290-\\u12B0\\u12B2-\\u12B5\\u12B8-\\u12BE\\u12C0\\u12C2-\\u12C5\\u12C8-\\u12D6\\u12D8-\\u1310\\u1312-\\u1315\\u1318-\\u135A\\u1380-\\u138F\\u13A0-\\u13F4\\u1401-\\u166C\\u166F-\\u167F\\u1681-\\u169A\\u16A0-\\u16EA\\u16EE-\\u16F0\\u1700-\\u170C\\u170E-\\u1711\\u1720-\\u1731\\u1740-\\u1751\\u1760-\\u176C\\u176E-\\u1770\\u1780-\\u17B3\\u17D7\\u17DC\\u1820-\\u1877\\u1880-\\u18A8\\u18AA\\u18B0-\\u18F5\\u1900-\\u191C\\u1950-\\u196D\\u1970-\\u1974\\u1980-\\u19AB\\u19C1-\\u19C7\\u1A00-\\u1A16\\u1A20-\\u1A54\\u1AA7\\u1B05-\\u1B33\\u1B45-\\u1B4B\\u1B83-\\u1BA0\\u1BAE\\u1BAF\\u1BBA-\\u1BE5\\u1C00-\\u1C23\\u1C4D-\\u1C4F\\u1C5A-\\u1C7D\\u1CE9-\\u1CEC\\u1CEE-\\u1CF1\\u1CF5\\u1CF6\\u1D00-\\u1DBF\\u1E00-\\u1F15\\u1F18-\\u1F1D\\u1F20-\\u1F45\\u1F48-\\u1F4D\\u1F50-\\u1F57\\u1F59\\u1F5B\\u1F5D\\u1F5F-\\u1F7D\\u1F80-\\u1FB4\\u1FB6-\\u1FBC\\u1FBE\\u1FC2-\\u1FC4\\u1FC6-\\u1FCC\\u1FD0-\\u1FD3\\u1FD6-\\u1FDB\\u1FE0-\\u1FEC\\u1FF2-\\u1FF4\\u1FF6-\\u1FFC\\u2071\\u207F\\u2090-\\u209C\\u2102\\u2107\\u210A-\\u2113\\u2115\\u2119-\\u211D\\u2124\\u2126\\u2128\\u212A-\\u212D\\u212F-\\u2139\\u213C-\\u213F\\u2145-\\u2149\\u214E\\u2160-\\u2188\\u2C00-\\u2C2E\\u2C30-\\u2C5E\\u2C60-\\u2CE4\\u2CEB-\\u2CEE\\u2CF2\\u2CF3\\u2D00-\\u2D25\\u2D27\\u2D2D\\u2D30-\\u2D67\\u2D6F\\u2D80-\\u2D96\\u2DA0-\\u2DA6\\u2DA8-\\u2DAE\\u2DB0-\\u2DB6\\u2DB8-\\u2DBE\\u2DC0-\\u2DC6\\u2DC8-\\u2DCE\\u2DD0-\\u2DD6\\u2DD8-\\u2DDE\\u2E2F\\u3005-\\u3007\\u3021-\\u3029\\u3031-\\u3035\\u3038-\\u303C\\u3041-\\u3096\\u309D-\\u309F\\u30A1-\\u30FA\\u30FC-\\u30FF\\u3105-\\u312D\\u3131-\\u318E\\u31A0-\\u31BA\\u31F0-\\u31FF\\u3400-\\u4DB5\\u4E00-\\u9FCC\\uA000-\\uA48C\\uA4D0-\\uA4FD\\uA500-\\uA60C\\uA610-\\uA61F\\uA62A\\uA62B\\uA640-\\uA66E\\uA67F-\\uA697\\uA6A0-\\uA6EF\\uA717-\\uA71F\\uA722-\\uA788\\uA78B-\\uA78E\\uA790-\\uA793\\uA7A0-\\uA7AA\\uA7F8-\\uA801\\uA803-\\uA805\\uA807-\\uA80A\\uA80C-\\uA822\\uA840-\\uA873\\uA882-\\uA8B3\\uA8F2-\\uA8F7\\uA8FB\\uA90A-\\uA925\\uA930-\\uA946\\uA960-\\uA97C\\uA984-\\uA9B2\\uA9CF\\uAA00-\\uAA28\\uAA40-\\uAA42\\uAA44-\\uAA4B\\uAA60-\\uAA76\\uAA7A\\uAA80-\\uAAAF\\uAAB1\\uAAB5\\uAAB6\\uAAB9-\\uAABD\\uAAC0\\uAAC2\\uAADB-\\uAADD\\uAAE0-\\uAAEA\\uAAF2-\\uAAF4\\uAB01-\\uAB06\\uAB09-\\uAB0E\\uAB11-\\uAB16\\uAB20-\\uAB26\\uAB28-\\uAB2E\\uABC0-\\uABE2\\uAC00-\\uD7A3\\uD7B0-\\uD7C6\\uD7CB-\\uD7FB\\uF900-\\uFA6D\\uFA70-\\uFAD9\\uFB00-\\uFB06\\uFB13-\\uFB17\\uFB1D\\uFB1F-\\uFB28\\uFB2A-\\uFB36\\uFB38-\\uFB3C\\uFB3E\\uFB40\\uFB41\\uFB43\\uFB44\\uFB46-\\uFBB1\\uFBD3-\\uFD3D\\uFD50-\\uFD8F\\uFD92-\\uFDC7\\uFDF0-\\uFDFB\\uFE70-\\uFE74\\uFE76-\\uFEFC\\uFF21-\\uFF3A\\uFF41-\\uFF5A\\uFF66-\\uFFBE\\uFFC2-\\uFFC7\\uFFCA-\\uFFCF\\uFFD2-\\uFFD7\\uFFDA-\\uFFDC]"),
      combining_mark: new RegExp("[\\u0300-\\u036F\\u0483-\\u0487\\u0591-\\u05BD\\u05BF\\u05C1\\u05C2\\u05C4\\u05C5\\u05C7\\u0610-\\u061A\\u064B-\\u065F\\u0670\\u06D6-\\u06DC\\u06DF-\\u06E4\\u06E7\\u06E8\\u06EA-\\u06ED\\u0711\\u0730-\\u074A\\u07A6-\\u07B0\\u07EB-\\u07F3\\u0816-\\u0819\\u081B-\\u0823\\u0825-\\u0827\\u0829-\\u082D\\u0859-\\u085B\\u08E4-\\u08FE\\u0900-\\u0903\\u093A-\\u093C\\u093E-\\u094F\\u0951-\\u0957\\u0962\\u0963\\u0981-\\u0983\\u09BC\\u09BE-\\u09C4\\u09C7\\u09C8\\u09CB-\\u09CD\\u09D7\\u09E2\\u09E3\\u0A01-\\u0A03\\u0A3C\\u0A3E-\\u0A42\\u0A47\\u0A48\\u0A4B-\\u0A4D\\u0A51\\u0A70\\u0A71\\u0A75\\u0A81-\\u0A83\\u0ABC\\u0ABE-\\u0AC5\\u0AC7-\\u0AC9\\u0ACB-\\u0ACD\\u0AE2\\u0AE3\\u0B01-\\u0B03\\u0B3C\\u0B3E-\\u0B44\\u0B47\\u0B48\\u0B4B-\\u0B4D\\u0B56\\u0B57\\u0B62\\u0B63\\u0B82\\u0BBE-\\u0BC2\\u0BC6-\\u0BC8\\u0BCA-\\u0BCD\\u0BD7\\u0C01-\\u0C03\\u0C3E-\\u0C44\\u0C46-\\u0C48\\u0C4A-\\u0C4D\\u0C55\\u0C56\\u0C62\\u0C63\\u0C82\\u0C83\\u0CBC\\u0CBE-\\u0CC4\\u0CC6-\\u0CC8\\u0CCA-\\u0CCD\\u0CD5\\u0CD6\\u0CE2\\u0CE3\\u0D02\\u0D03\\u0D3E-\\u0D44\\u0D46-\\u0D48\\u0D4A-\\u0D4D\\u0D57\\u0D62\\u0D63\\u0D82\\u0D83\\u0DCA\\u0DCF-\\u0DD4\\u0DD6\\u0DD8-\\u0DDF\\u0DF2\\u0DF3\\u0E31\\u0E34-\\u0E3A\\u0E47-\\u0E4E\\u0EB1\\u0EB4-\\u0EB9\\u0EBB\\u0EBC\\u0EC8-\\u0ECD\\u0F18\\u0F19\\u0F35\\u0F37\\u0F39\\u0F3E\\u0F3F\\u0F71-\\u0F84\\u0F86\\u0F87\\u0F8D-\\u0F97\\u0F99-\\u0FBC\\u0FC6\\u102B-\\u103E\\u1056-\\u1059\\u105E-\\u1060\\u1062-\\u1064\\u1067-\\u106D\\u1071-\\u1074\\u1082-\\u108D\\u108F\\u109A-\\u109D\\u135D-\\u135F\\u1712-\\u1714\\u1732-\\u1734\\u1752\\u1753\\u1772\\u1773\\u17B4-\\u17D3\\u17DD\\u180B-\\u180D\\u18A9\\u1920-\\u192B\\u1930-\\u193B\\u19B0-\\u19C0\\u19C8\\u19C9\\u1A17-\\u1A1B\\u1A55-\\u1A5E\\u1A60-\\u1A7C\\u1A7F\\u1B00-\\u1B04\\u1B34-\\u1B44\\u1B6B-\\u1B73\\u1B80-\\u1B82\\u1BA1-\\u1BAD\\u1BE6-\\u1BF3\\u1C24-\\u1C37\\u1CD0-\\u1CD2\\u1CD4-\\u1CE8\\u1CED\\u1CF2-\\u1CF4\\u1DC0-\\u1DE6\\u1DFC-\\u1DFF\\u20D0-\\u20DC\\u20E1\\u20E5-\\u20F0\\u2CEF-\\u2CF1\\u2D7F\\u2DE0-\\u2DFF\\u302A-\\u302F\\u3099\\u309A\\uA66F\\uA674-\\uA67D\\uA69F\\uA6F0\\uA6F1\\uA802\\uA806\\uA80B\\uA823-\\uA827\\uA880\\uA881\\uA8B4-\\uA8C4\\uA8E0-\\uA8F1\\uA926-\\uA92D\\uA947-\\uA953\\uA980-\\uA983\\uA9B3-\\uA9C0\\uAA29-\\uAA36\\uAA43\\uAA4C\\uAA4D\\uAA7B\\uAAB0\\uAAB2-\\uAAB4\\uAAB7\\uAAB8\\uAABE\\uAABF\\uAAC1\\uAAEB-\\uAAEF\\uAAF5\\uAAF6\\uABE3-\\uABEA\\uABEC\\uABED\\uFB1E\\uFE00-\\uFE0F\\uFE20-\\uFE26]"),
      connector_punctuation: new RegExp("[\\u005F\\u203F\\u2040\\u2054\\uFE33\\uFE34\\uFE4D-\\uFE4F\\uFF3F]"),
      digit: new RegExp("[\\u0030-\\u0039\\u0660-\\u0669\\u06F0-\\u06F9\\u07C0-\\u07C9\\u0966-\\u096F\\u09E6-\\u09EF\\u0A66-\\u0A6F\\u0AE6-\\u0AEF\\u0B66-\\u0B6F\\u0BE6-\\u0BEF\\u0C66-\\u0C6F\\u0CE6-\\u0CEF\\u0D66-\\u0D6F\\u0E50-\\u0E59\\u0ED0-\\u0ED9\\u0F20-\\u0F29\\u1040-\\u1049\\u1090-\\u1099\\u17E0-\\u17E9\\u1810-\\u1819\\u1946-\\u194F\\u19D0-\\u19D9\\u1A80-\\u1A89\\u1A90-\\u1A99\\u1B50-\\u1B59\\u1BB0-\\u1BB9\\u1C40-\\u1C49\\u1C50-\\u1C59\\uA620-\\uA629\\uA8D0-\\uA8D9\\uA900-\\uA909\\uA9D0-\\uA9D9\\uAA50-\\uAA59\\uABF0-\\uABF9\\uFF10-\\uFF19]")
  };
  
  function is_letter(ch) {
      return UNICODE.letter.test(ch);
  };
  
  function is_digit(ch) {
      ch = ch.charCodeAt(0);
      return ch >= 48 && ch <= 57;
  };
  
  var RE_HEX_NUMBER = /^0x[0-9a-f]+$/i;
  var RE_OCT_NUMBER = /^0[0-7]+$/;
  var RE_DEC_NUMBER = /^\d*\.?\d*(?:e[+-]?\d*(?:\d\.?|\.?\d)\d*)?$/i;
  
  function is_alphanumeric_char(ch) {
      return is_digit(ch) || is_letter(ch);
  };
  
  function parse_js_number(num) {
      if (RE_HEX_NUMBER.test(num)) {
          return parseInt(num.substr(2), 16);
      } else if (RE_OCT_NUMBER.test(num)) {
          return parseInt(num.substr(1), 8);
      } else if (RE_DEC_NUMBER.test(num)) {
          return parseFloat(num);
      }
  };
  
  module.exports = function Tokenizer($TEXT) {
      var S = {
          text            : $TEXT.replace(/\r\n?|[\n\u2028\u2029]/g, "\n").replace(/^\uFEFF/, ''),
          pos             : 0,
          tokpos          : 0,
          line            : 0,
          tokline         : 0,
          col             : 0,
          tokcol          : 0,
          newline_before  : false,
          regex_allowed   : false,
          comments_before : []
      };
  
      function peek() { return S.text.charAt(S.pos); };
      function next(signal_eof, in_string) {
          var ch = S.text.charAt(S.pos++);
          if (signal_eof && !ch)
              throw EX_EOF;
          if (ch == "\n") {
              S.newline_before = S.newline_before || !in_string;
              ++S.line;
              S.col = 0;
          } else {
              ++S.col;
          }
          return ch;
      };
  
      function start_token() {
          S.tokline = S.line;
          S.tokcol = S.col;
          S.tokpos = S.pos;
      };
  
      function token(type, value, is_comment) {
          S.regex_allowed = ((type == "operator" && !HOP(UNARY_POSTFIX, value)) ||
                             (type == "keyword" && HOP(KEYWORDS_BEFORE_EXPRESSION, value)) ||
                             (type == "punc" && HOP(PUNC_BEFORE_EXPRESSION, value)));
          var ret = {
              type   : type,
              value  : value,
              line   : S.tokline,
              col    : S.tokcol,
              pos    : S.tokpos,
              endpos : S.pos,
              nlb    : S.newline_before
          };
          if (!is_comment) {
              ret.comments_before = S.comments_before;
              S.comments_before = [];
              // make note of any newlines in the comments that came before
              for (var i = 0, len = ret.comments_before.length; i < len; i++) {
                  ret.nlb = ret.nlb || ret.comments_before[i].nlb;
              }
          }
          S.newline_before = false;
          return ret;
      };
  
      function read_while(pred) {
          var ret = "", ch = peek(), i = 0;
          while (ch && pred(ch, i++)) {
              ret += next();
              ch = peek();
          }
          return ret;
      };
  
      function read_string() {
          return with_eof_error("Unterminated string constant", function(){
              var quote = next(), ret = "";
              for (;;) {
                  var ch = next(true);
                  if (ch == "\\") {
                      // read OctalEscapeSequence (XXX: deprecated if "strict mode")
                      // https://github.com/mishoo/UglifyJS/issues/178
                      var octal_len = 0, first = null;
                      ch = read_while(function(ch){
                          if (ch >= "0" && ch <= "7") {
                              if (!first) {
                                  first = ch;
                                  return ++octal_len;
                              }
                              else if (first <= "3" && octal_len <= 2) return ++octal_len;
                              else if (first >= "4" && octal_len <= 1) return ++octal_len;
                          }
                          return false;
                      });
                      if (octal_len > 0) ch = String.fromCharCode(parseInt(ch, 8));
                      else ch = read_escaped_char(true);
                  }
                  else if (ch == quote) break;
                  else if (ch == "\n") throw EX_EOF;
                  ret += ch;
              }
              return token("string", ret);
          });
      };
  
      function with_eof_error(eof_error, cont) {
          try {
              return cont();
          } catch(ex) {
              if (ex === EX_EOF) parse_error(eof_error);
              else throw ex;
          }
      };
  
      function read_num(prefix) {
          var has_e = false, after_e = false, has_x = false, has_dot = prefix == ".";
          var num = read_while(function(ch, i){
              if (ch == "x" || ch == "X") {
                  if (has_x) return false;
                  return has_x = true;
              }
              if (!has_x && (ch == "E" || ch == "e")) {
                  if (has_e) return false;
                  return has_e = after_e = true;
              }
              if (ch == "-") {
                  if (after_e || (i == 0 && !prefix)) return true;
                  return false;
              }
              if (ch == "+") return after_e;
              after_e = false;
              if (ch == ".") {
                  if (!has_dot && !has_x && !has_e)
                      return has_dot = true;
                  return false;
              }
              return is_alphanumeric_char(ch);
          });
          if (prefix)
              num = prefix + num;
          var valid = parse_js_number(num);
          if (!isNaN(valid)) {
              return token("num", valid);
          } else {
              parse_error("Invalid syntax: " + num);
          }
      };
  
      function handle_dot() {
          next();
          return is_digit(peek())
              ? read_num(".")
              : token("punc", ".");
      };
  
      function eof() {
          return !S.peek();
      };
  
      function find(what, signal_eof) {
          var pos = S.text.indexOf(what, S.pos);
          if (signal_eof && pos == -1) throw EX_EOF;
          return pos;
      };
  
      function read_line_comment() {
          next();
          var i = find("\n"), ret;
          if (i == -1) {
              ret = S.text.substr(S.pos);
              S.pos = S.text.length;
          } else {
              ret = S.text.substring(S.pos, i);
              S.pos = i;
          }
          return token("comment1", ret, true);
      };
  
      function read_multiline_comment() {
          next();
          return with_eof_error("Unterminated multiline comment", function(){
              var i = find("*/", true),
              text = S.text.substring(S.pos, i);
              S.pos = i + 2;
              S.line += text.split("\n").length - 1;
              S.newline_before = S.newline_before || text.indexOf("\n") >= 0;
  
              // https://github.com/mishoo/UglifyJS/issues/#issue/100
              if (/^@cc_on/i.test(text)) {
                  warn("WARNING: at line " + S.line);
                  warn("*** Found \"conditional comment\": " + text);
                  warn("*** UglifyJS DISCARDS ALL COMMENTS.  This means your code might no longer work properly in Internet Explorer.");
              }
  
              return token("comment2", text, true);
          });
      };
  
  
      function handle_slash() {
          next();
          var regex_allowed = S.regex_allowed;
          switch (peek()) {
            case "/":
              S.comments_before.push(read_line_comment());
              S.regex_allowed = regex_allowed;
              return next_token();
            case "*":
              S.comments_before.push(read_multiline_comment());
              S.regex_allowed = regex_allowed;
              return next_token();
          }
          return S.regex_allowed ? read_regexp("") : read_operator("/");
      };
  
      function read_operator(prefix) {
          function grow(op) {
              if (!peek()) return op;
              var bigger = op + peek();
              if (HOP(OPERATORS, bigger)) {
                  next();
                  return grow(bigger);
              } else {
                  return op;
              }
          };
          return token("operator", grow(prefix || next()));
      };
  
      function read_regexp(regexp) {
          return with_eof_error("Unterminated regular expression", function(){
              var prev_backslash = false, ch, in_class = false;
              while ((ch = next(true))) if (prev_backslash) {
                  regexp += "\\" + ch;
                  prev_backslash = false;
              } else if (ch == "[") {
                  in_class = true;
                  regexp += ch;
              } else if (ch == "]" && in_class) {
                  in_class = false;
                  regexp += ch;
              } else if (ch == "/" && !in_class) {
                  break;
              } else if (ch == "\\") {
                  prev_backslash = true;
              } else {
                  regexp += ch;
              }
              var mods = read_name();
              return token("regexp", [ regexp, mods ]);
          });
      };
  
      function next_token(force_regexp) {
          start_token();
          var ch = peek();
          if (!ch) return token("eof");
          if (ch == '"' || ch == "'") {
              var x = read_string();
              return x;
          }
          if (is_digit(ch)) return read_num();
          if (HOP(PUNC_CHARS, ch)) return token("punc", next());
          if (ch == ".") return handle_dot();
          if (ch == "/") return handle_slash();
          next();
          return token('test');
          // if (ch == ".") return handle_dot();
          // if (ch == "/") return handle_slash();
          // if (HOP(OPERATOR_CHARS, ch)) return read_operator();
          // if (ch == "\\" || is_identifier_start(ch)) return read_word();
          // parse_error("Unexpected character '" + ch + "'");
      };
  
      return next_token;
  }
  
  
  function HOP(obj, prop) {
      return Object.prototype.hasOwnProperty.call(obj, prop);
  };
  
  function array_to_hash(a) {
      var ret = {};
      for (var i = 0; i < a.length; ++i)
          ret[a[i]] = true;
      return ret;
  };
  
  function characters(str) {
      return str.split("");
  };