var KEYWORDS = array_to_hash([
    "break",
    "case",
    "catch",
    "const",
    "continue",
    "debugger",
    "default",
    "delete",
    "do",
    "else",
    "finally",
    "for",
    "function",
    "if",
    "in",
    "instanceof",
    "new",
    "return",
    "switch",
    "throw",
    "try",
    "typeof",
    "var",
    "void",
    "while",
    "with"
]);

var RESERVED_WORDS = array_to_hash([
    "abstract",
    "boolean",
    "byte",
    "char",
    "class",
    "double",
    "enum",
    "export",
    "extends",
    "final",
    "float",
    "goto",
    "implements",
    "import",
    "int",
    "interface",
    "long",
    "native",
    "package",
    "private",
    "protected",
    "public",
    "short",
    "static",
    "super",
    "synchronized",
    "throws",
    "transient",
    "volatile"
]);

var KEYWORDS_BEFORE_EXPRESSION = array_to_hash([
    "return",
    "new",
    "delete",
    "throw",
    "else",
    "case"
]);

var KEYWORDS_ATOM = array_to_hash([
    "false",
    "null",
    "true"
]);

var OPERATOR_CHARS = array_to_hash(characters("+-*&%=<>!?|~^"));

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;

var OPERATORS = array_to_hash([
    "in",
    "instanceof",
    "typeof",
    "new",
    "void",
    "delete",
    "++",
    "--",
    "+",
    "-",
    "!",
    "~",
    "&",
    "|",
    "^",
    "*",
    "/",
    "%",
    ">>",
    "<<",
    ">>>",
    "<",
    ">",
    "<=",
    ">=",
    "==",
    "===",
    "!=",
    "!==",
    "?",
    "=",
    "+=",
    "-=",
    "/=",
    "*=",
    "%=",
    ">>=",
    "<<=",
    ">>>=",
    "|=",
    "^=",
    "&=",
    "&&",
    "||"
]);

var WHITESPACE_CHARS = array_to_hash(characters(" \u00a0\n\r\t\f\u000b\u200b\u180e\u2000\u2001\u2002\u2003\u2004\u2005\u2006\u2007\u2008\u2009\u200a\u202f\u205f\u3000"));

var PUNC_BEFORE_EXPRESSION = array_to_hash(characters("[{(,.;:"));

var PUNC_CHARS = array_to_hash(characters("[]{}(),;:"));

var REGEXP_MODIFIERS = array_to_hash(characters("gmsiy"));

/* -----[ Tokenizer ]----- */

// regexps adapted from http://xregexp.com/plugins/#unicode
var UNICODE = {
    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-\\u0523\\u0531-\\u0556\\u0559\\u0561-\\u0587\\u05D0-\\u05EA\\u05F0-\\u05F2\\u0621-\\u064A\\u066E\\u066F\\u0671-\\u06D3\\u06D5\\u06E5\\u06E6\\u06EE\\u06EF\\u06FA-\\u06FC\\u06FF\\u0710\\u0712-\\u072F\\u074D-\\u07A5\\u07B1\\u07CA-\\u07EA\\u07F4\\u07F5\\u07FA\\u0904-\\u0939\\u093D\\u0950\\u0958-\\u0961\\u0971\\u0972\\u097B-\\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\\u0D05-\\u0D0C\\u0D0E-\\u0D10\\u0D12-\\u0D28\\u0D2A-\\u0D39\\u0D3D\\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\\u0EDD\\u0F00\\u0F40-\\u0F47\\u0F49-\\u0F6C\\u0F88-\\u0F8B\\u1000-\\u102A\\u103F\\u1050-\\u1055\\u105A-\\u105D\\u1061\\u1065\\u1066\\u106E-\\u1070\\u1075-\\u1081\\u108E\\u10A0-\\u10C5\\u10D0-\\u10FA\\u10FC\\u1100-\\u1159\\u115F-\\u11A2\\u11A8-\\u11F9\\u1200-\\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-\\u1676\\u1681-\\u169A\\u16A0-\\u16EA\\u1700-\\u170C\\u170E-\\u1711\\u1720-\\u1731\\u1740-\\u1751\\u1760-\\u176C\\u176E-\\u1770\\u1780-\\u17B3\\u17D7\\u17DC\\u1820-\\u1877\\u1880-\\u18A8\\u18AA\\u1900-\\u191C\\u1950-\\u196D\\u1970-\\u1974\\u1980-\\u19A9\\u19C1-\\u19C7\\u1A00-\\u1A16\\u1B05-\\u1B33\\u1B45-\\u1B4B\\u1B83-\\u1BA0\\u1BAE\\u1BAF\\u1C00-\\u1C23\\u1C4D-\\u1C4F\\u1C5A-\\u1C7D\\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-\\u2094\\u2102\\u2107\\u210A-\\u2113\\u2115\\u2119-\\u211D\\u2124\\u2126\\u2128\\u212A-\\u212D\\u212F-\\u2139\\u213C-\\u213F\\u2145-\\u2149\\u214E\\u2183\\u2184\\u2C00-\\u2C2E\\u2C30-\\u2C5E\\u2C60-\\u2C6F\\u2C71-\\u2C7D\\u2C80-\\u2CE4\\u2D00-\\u2D25\\u2D30-\\u2D65\\u2D6F\\u2D80-\\u2D96\\u2DA0-\\u2DA6\\u2DA8-\\u2DAE\\u2DB0-\\u2DB6\\u2DB8-\\u2DBE\\u2DC0-\\u2DC6\\u2DC8-\\u2DCE\\u2DD0-\\u2DD6\\u2DD8-\\u2DDE\\u2E2F\\u3005\\u3006\\u3031-\\u3035\\u303B\\u303C\\u3041-\\u3096\\u309D-\\u309F\\u30A1-\\u30FA\\u30FC-\\u30FF\\u3105-\\u312D\\u3131-\\u318E\\u31A0-\\u31B7\\u31F0-\\u31FF\\u3400\\u4DB5\\u4E00\\u9FC3\\uA000-\\uA48C\\uA500-\\uA60C\\uA610-\\uA61F\\uA62A\\uA62B\\uA640-\\uA65F\\uA662-\\uA66E\\uA67F-\\uA697\\uA717-\\uA71F\\uA722-\\uA788\\uA78B\\uA78C\\uA7FB-\\uA801\\uA803-\\uA805\\uA807-\\uA80A\\uA80C-\\uA822\\uA840-\\uA873\\uA882-\\uA8B3\\uA90A-\\uA925\\uA930-\\uA946\\uAA00-\\uAA28\\uAA40-\\uAA42\\uAA44-\\uAA4B\\uAC00\\uD7A3\\uF900-\\uFA2D\\uFA30-\\uFA6A\\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]"),
    non_spacing_mark: new RegExp("[\\u0300-\\u036F\\u0483-\\u0487\\u0591-\\u05BD\\u05BF\\u05C1\\u05C2\\u05C4\\u05C5\\u05C7\\u0610-\\u061A\\u064B-\\u065E\\u0670\\u06D6-\\u06DC\\u06DF-\\u06E4\\u06E7\\u06E8\\u06EA-\\u06ED\\u0711\\u0730-\\u074A\\u07A6-\\u07B0\\u07EB-\\u07F3\\u0816-\\u0819\\u081B-\\u0823\\u0825-\\u0827\\u0829-\\u082D\\u0900-\\u0902\\u093C\\u0941-\\u0948\\u094D\\u0951-\\u0955\\u0962\\u0963\\u0981\\u09BC\\u09C1-\\u09C4\\u09CD\\u09E2\\u09E3\\u0A01\\u0A02\\u0A3C\\u0A41\\u0A42\\u0A47\\u0A48\\u0A4B-\\u0A4D\\u0A51\\u0A70\\u0A71\\u0A75\\u0A81\\u0A82\\u0ABC\\u0AC1-\\u0AC5\\u0AC7\\u0AC8\\u0ACD\\u0AE2\\u0AE3\\u0B01\\u0B3C\\u0B3F\\u0B41-\\u0B44\\u0B4D\\u0B56\\u0B62\\u0B63\\u0B82\\u0BC0\\u0BCD\\u0C3E-\\u0C40\\u0C46-\\u0C48\\u0C4A-\\u0C4D\\u0C55\\u0C56\\u0C62\\u0C63\\u0CBC\\u0CBF\\u0CC6\\u0CCC\\u0CCD\\u0CE2\\u0CE3\\u0D41-\\u0D44\\u0D4D\\u0D62\\u0D63\\u0DCA\\u0DD2-\\u0DD4\\u0DD6\\u0E31\\u0E34-\\u0E3A\\u0E47-\\u0E4E\\u0EB1\\u0EB4-\\u0EB9\\u0EBB\\u0EBC\\u0EC8-\\u0ECD\\u0F18\\u0F19\\u0F35\\u0F37\\u0F39\\u0F71-\\u0F7E\\u0F80-\\u0F84\\u0F86\\u0F87\\u0F90-\\u0F97\\u0F99-\\u0FBC\\u0FC6\\u102D-\\u1030\\u1032-\\u1037\\u1039\\u103A\\u103D\\u103E\\u1058\\u1059\\u105E-\\u1060\\u1071-\\u1074\\u1082\\u1085\\u1086\\u108D\\u109D\\u135F\\u1712-\\u1714\\u1732-\\u1734\\u1752\\u1753\\u1772\\u1773\\u17B7-\\u17BD\\u17C6\\u17C9-\\u17D3\\u17DD\\u180B-\\u180D\\u18A9\\u1920-\\u1922\\u1927\\u1928\\u1932\\u1939-\\u193B\\u1A17\\u1A18\\u1A56\\u1A58-\\u1A5E\\u1A60\\u1A62\\u1A65-\\u1A6C\\u1A73-\\u1A7C\\u1A7F\\u1B00-\\u1B03\\u1B34\\u1B36-\\u1B3A\\u1B3C\\u1B42\\u1B6B-\\u1B73\\u1B80\\u1B81\\u1BA2-\\u1BA5\\u1BA8\\u1BA9\\u1C2C-\\u1C33\\u1C36\\u1C37\\u1CD0-\\u1CD2\\u1CD4-\\u1CE0\\u1CE2-\\u1CE8\\u1CED\\u1DC0-\\u1DE6\\u1DFD-\\u1DFF\\u20D0-\\u20DC\\u20E1\\u20E5-\\u20F0\\u2CEF-\\u2CF1\\u2DE0-\\u2DFF\\u302A-\\u302F\\u3099\\u309A\\uA66F\\uA67C\\uA67D\\uA6F0\\uA6F1\\uA802\\uA806\\uA80B\\uA825\\uA826\\uA8C4\\uA8E0-\\uA8F1\\uA926-\\uA92D\\uA947-\\uA951\\uA980-\\uA982\\uA9B3\\uA9B6-\\uA9B9\\uA9BC\\uAA29-\\uAA2E\\uAA31\\uAA32\\uAA35\\uAA36\\uAA43\\uAA4C\\uAAB0\\uAAB2-\\uAAB4\\uAAB7\\uAAB8\\uAABE\\uAABF\\uAAC1\\uABE5\\uABE8\\uABED\\uFB1E\\uFE00-\\uFE0F\\uFE20-\\uFE26]"),
    space_combining_mark: new RegExp("[\\u0903\\u093E-\\u0940\\u0949-\\u094C\\u094E\\u0982\\u0983\\u09BE-\\u09C0\\u09C7\\u09C8\\u09CB\\u09CC\\u09D7\\u0A03\\u0A3E-\\u0A40\\u0A83\\u0ABE-\\u0AC0\\u0AC9\\u0ACB\\u0ACC\\u0B02\\u0B03\\u0B3E\\u0B40\\u0B47\\u0B48\\u0B4B\\u0B4C\\u0B57\\u0BBE\\u0BBF\\u0BC1\\u0BC2\\u0BC6-\\u0BC8\\u0BCA-\\u0BCC\\u0BD7\\u0C01-\\u0C03\\u0C41-\\u0C44\\u0C82\\u0C83\\u0CBE\\u0CC0-\\u0CC4\\u0CC7\\u0CC8\\u0CCA\\u0CCB\\u0CD5\\u0CD6\\u0D02\\u0D03\\u0D3E-\\u0D40\\u0D46-\\u0D48\\u0D4A-\\u0D4C\\u0D57\\u0D82\\u0D83\\u0DCF-\\u0DD1\\u0DD8-\\u0DDF\\u0DF2\\u0DF3\\u0F3E\\u0F3F\\u0F7F\\u102B\\u102C\\u1031\\u1038\\u103B\\u103C\\u1056\\u1057\\u1062-\\u1064\\u1067-\\u106D\\u1083\\u1084\\u1087-\\u108C\\u108F\\u109A-\\u109C\\u17B6\\u17BE-\\u17C5\\u17C7\\u17C8\\u1923-\\u1926\\u1929-\\u192B\\u1930\\u1931\\u1933-\\u1938\\u19B0-\\u19C0\\u19C8\\u19C9\\u1A19-\\u1A1B\\u1A55\\u1A57\\u1A61\\u1A63\\u1A64\\u1A6D-\\u1A72\\u1B04\\u1B35\\u1B3B\\u1B3D-\\u1B41\\u1B43\\u1B44\\u1B82\\u1BA1\\u1BA6\\u1BA7\\u1BAA\\u1C24-\\u1C2B\\u1C34\\u1C35\\u1CE1\\u1CF2\\uA823\\uA824\\uA827\\uA880\\uA881\\uA8B4-\\uA8C3\\uA952\\uA953\\uA983\\uA9B4\\uA9B5\\uA9BA\\uA9BB\\uA9BD-\\uA9C0\\uAA2F\\uAA30\\uAA33\\uAA34\\uAA4D\\uAA7B\\uABE3\\uABE4\\uABE6\\uABE7\\uABE9\\uABEA\\uABEC]"),
    connector_punctuation: new RegExp("[\\u005F\\u203F\\u2040\\u2054\\uFE33\\uFE34\\uFE4D-\\uFE4F\\uFF3F]")
};

function is_letter(ch) {
    return UNICODE.letter.test(ch);
};

function is_digit(ch) {
    ch = ch.charCodeAt(0);
    return ch >= 48 && ch <= 57; //XXX: find out if "UnicodeDigit" means something else than 0..9
};

function is_alphanumeric_char(ch) {
    return is_digit(ch) || is_letter(ch);
};

function is_unicode_combining_mark(ch) {
    return UNICODE.non_spacing_mark.test(ch) || UNICODE.space_combining_mark.test(ch);
};

function is_unicode_connector_punctuation(ch) {
    return UNICODE.connector_punctuation.test(ch);
};

function is_identifier(name) {
    return /^[a-z_$][a-z0-9_$]*$/i.test(name)
        && name != "this"
        && !HOP(KEYWORDS_ATOM, name)
        && !HOP(RESERVED_WORDS, name)
        && !HOP(KEYWORDS, name);
};

function is_identifier_start(ch) {
    return ch == "$" || ch == "_" || is_letter(ch);
};

function is_identifier_char(ch) {
    return is_identifier_start(ch)
        || is_unicode_combining_mark(ch)
        || is_digit(ch)
        || is_unicode_connector_punctuation(ch)
        || ch == "\u200c" // zero-width non-joiner <ZWNJ>
        || ch == "\u200d" // zero-width joiner <ZWJ> (in my ECMA-262 PDF, this is also 200c)
    ;
};

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);
    }
};

function JS_Parse_Error(message, line, col, pos) {
    this.message = message;
    this.line = line + 1;
    this.col = col + 1;
    this.pos = pos + 1;
    this.stack = new Error().stack;
};

JS_Parse_Error.prototype.toString = function() {
    return this.message + " (line: " + this.line + ", col: " + this.col + ", pos: " + this.pos + ")" + "\n\n" + this.stack;
};

function js_error(message, line, col, pos) {
    console.log("***", message);
    console.log("*** LINE:", line, "COL:", col, "POS:", pos);
    throw new JS_Parse_Error(message, line, col, pos);
};

function is_token(token, type, val) {
    return token.type == type && (val == null || token.value == val);
};

var EX_EOF = {};

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 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 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 new AST_Token(ret);
    };

    function skip_whitespace() {
        while (HOP(WHITESPACE_CHARS, peek()))
            next();
    };

    function read_while(pred) {
        var ret = "", ch = peek(), i = 0;
        while (ch && pred(ch, i++)) {
            ret += next();
            ch = peek();
        }
        return ret;
    };

    function parse_error(err) {
        js_error(err, S.tokline, S.tokcol, S.tokpos);
    };

    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 read_escaped_char(in_string) {
        var ch = next(true, in_string);
        switch (ch) {
          case "n" : return "\n";
          case "r" : return "\r";
          case "t" : return "\t";
          case "b" : return "\b";
          case "v" : return "\u000b";
          case "f" : return "\f";
          case "0" : return "\0";
          case "x" : return String.fromCharCode(hex_bytes(2));
          case "u" : return String.fromCharCode(hex_bytes(4));
          case "\n": return "";
          default  : return ch;
        }
    };

    function hex_bytes(n) {
        var num = 0;
        for (; n > 0; --n) {
            var digit = parseInt(next(true), 16);
            if (isNaN(digit))
                parse_error("Invalid hex-character pattern in string");
            num = (num << 4) | digit;
        }
        return num;
    };

    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;
                ret += ch;
            }
            return token("string", ret);
        });
    };

    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 read_name() {
        var backslash = false, name = "", ch, escaped = false, hex;
        while ((ch = peek()) != null) {
            if (!backslash) {
                if (ch == "\\") escaped = backslash = true, next();
                else if (is_identifier_char(ch)) name += next();
                else break;
            }
            else {
                if (ch != "u") parse_error("Expecting UnicodeEscapeSequence -- uXXXX");
                ch = read_escaped_char();
                if (!is_identifier_char(ch)) parse_error("Unicode char: " + ch.charCodeAt(0) + " is not valid in identifier");
                name += ch;
                backslash = false;
            }
        }
        if (HOP(KEYWORDS, name) && escaped) {
            hex = name.charCodeAt(0).toString(16).toUpperCase();
            name = "\\u" + "0000".substr(hex.length) + hex + name.slice(1);
        }
        return name;
    };

    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 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 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 handle_dot() {
        next();
        return is_digit(peek())
            ? read_num(".")
            : token("punc", ".");
    };

    function read_word() {
        var word = read_name();
        return HOP(KEYWORDS_ATOM, word)
            ? token("atom", word)
            : !HOP(KEYWORDS, word)
            ? token("name", word)
            : HOP(OPERATORS, word)
            ? token("operator", word)
            : token("keyword", word);
    };

    function with_eof_error(eof_error, cont) {
        try {
            return cont();
        } catch(ex) {
            if (ex === EX_EOF) parse_error(eof_error);
            else throw ex;
        }
    };

    function next_token(force_regexp) {
        if (force_regexp != null)
            return read_regexp(force_regexp);
        skip_whitespace();
        start_token();
        var ch = peek();
        if (!ch) return token("eof");
        if (is_digit(ch)) return read_num();
        if (ch == '"' || ch == "'") return read_string();
        if (HOP(PUNC_CHARS, ch)) return token("punc", next());
        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 + "'");
    };

    next_token.context = function(nc) {
        if (nc) S = nc;
        return S;
    };

    return next_token;

};

/* -----[ Parser (constants) ]----- */

var UNARY_PREFIX = array_to_hash([
    "typeof",
    "void",
    "delete",
    "--",
    "++",
    "!",
    "~",
    "-",
    "+"
]);

var UNARY_POSTFIX = array_to_hash([ "--", "++" ]);

var ASSIGNMENT = (function(a, ret, i){
    while (i < a.length) {
        ret[a[i]] = a[i];
        i++;
    }
    return ret;
})(
    [ "=", "+=", "-=", "/=", "*=", "%=", ">>=", "<<=", ">>>=", "|=", "^=", "&=" ],
    {},
    0
);

var PRECEDENCE = (function(a, ret){
    for (var i = 0, n = 1; i < a.length; ++i, ++n) {
        var b = a[i];
        for (var j = 0; j < b.length; ++j) {
            ret[b[j]] = n;
        }
    }
    return ret;
})(
    [
        ["||"],
        ["&&"],
        ["|"],
        ["^"],
        ["&"],
        ["==", "===", "!=", "!=="],
        ["<", ">", "<=", ">=", "in", "instanceof"],
        [">>", "<<", ">>>"],
        ["+", "-"],
        ["*", "/", "%"]
    ],
    {}
);

var STATEMENTS_WITH_LABELS = array_to_hash([ "for", "do", "while", "switch" ]);

var ATOMIC_START_TOKEN = array_to_hash([ "atom", "num", "string", "regexp", "name" ]);

/* -----[ Parser ]----- */

function parse($TEXT, exigent_mode) {

    var S = {
        input         : typeof $TEXT == "string" ? tokenizer($TEXT, true) : $TEXT,
        token         : null,
        prev          : null,
        peeked        : null,
        in_function   : 0,
        in_directives : true,
        in_loop       : 0,
        labels        : []
    };

    S.token = next();

    function is(type, value) {
        return is_token(S.token, type, value);
    };

    function peek() { return S.peeked || (S.peeked = S.input()); };

    function next() {
        S.prev = S.token;
        if (S.peeked) {
            S.token = S.peeked;
            S.peeked = null;
        } else {
            S.token = S.input();
        }
        S.in_directives = S.in_directives && (
            S.token.type == "string" || is("punc", ";")
        );
        return S.token;
    };

    function prev() {
        return S.prev;
    };

    function croak(msg, line, col, pos) {
        var ctx = S.input.context();
        js_error(msg,
                 line != null ? line : ctx.tokline,
                 col != null ? col : ctx.tokcol,
                 pos != null ? pos : ctx.tokpos);
    };

    function token_error(token, msg) {
        croak(msg, token.line, token.col);
    };

    function unexpected(token) {
        if (token == null)
            token = S.token;
        token_error(token, "Unexpected token: " + token.type + " (" + token.value + ")");
    };

    function expect_token(type, val) {
        if (is(type, val)) {
            return next();
        }
        token_error(S.token, "Unexpected token " + S.token.type + " «" + S.token.value + "»" + ", expected " + type + " «" + val + "»");
    };

    function expect(punc) { return expect_token("punc", punc); };

    function can_insert_semicolon() {
        return !exigent_mode && (
            S.token.nlb || is("eof") || is("punc", "}")
        );
    };

    function semicolon() {
        if (is("punc", ";")) next();
        else if (!can_insert_semicolon()) unexpected();
    };

    function parenthesised() {
        expect("(");
        var exp = expression();
        expect(")");
        return exp;
    };

    function embed_tokens(parser) {
        return function() {
            var start = S.token;
            var expr = parser.apply(this, arguments);
            var end = prev();
            expr.start = start;
            expr.end = end;
            return expr;
        };
    };

    var statement = embed_tokens(function() {
        if (is("operator", "/") || is("operator", "/=")) {
            S.peeked = null;
            S.token = S.input(S.token.value.substr(1)); // force regexp
        }
        switch (S.token.type) {
          case "string":
            var dir = S.in_directives, stat = simple_statement();
            // XXXv2: decide how to fix directives
            // if (dir && stat instanceof AST_String && !is("punc", ","))
            //     return new AST_Directive({ value: stat.value });
            return stat;
          case "num":
          case "regexp":
          case "operator":
          case "atom":
            return simple_statement();

          case "name":
            return is_token(peek(), "punc", ":")
                ? labeled_statement()
                : simple_statement();

          case "punc":
            switch (S.token.value) {
              case "{":
                return block_(false);
              case "[":
              case "(":
                return simple_statement();
              case ";":
                next();
                return new AST_EmptyStatement();
              default:
                unexpected();
            }

          case "keyword":
            switch (prog1(S.token.value, next)) {
              case "break":
                return break_cont(AST_Break);

              case "continue":
                return break_cont(AST_Continue);

              case "debugger":
                semicolon();
                return new AST_Debugger();

              case "do":
                return new AST_Do({
                    body      : in_loop(statement),
                    condition : (expect_token("keyword", "while"), prog1(parenthesised, semicolon))
                });

              case "while":
                return new AST_While({
                    condition : parenthesised(),
                    body      : in_loop(statement)
                });

              case "for":
                return for_();

              case "function":
                return function_(true);

              case "if":
                return if_();

              case "return":
                if (S.in_function == 0)
                    croak("'return' outside of function");
                return new AST_Return({
                    value: ( is("punc", ";")
                             ? (next(), null)
                             : can_insert_semicolon()
                             ? null
                             : prog1(expression, semicolon) )
                });

              case "switch":
                return new AST_Switch({
                    expression : parenthesised(),
                    body       : switch_block_()
                });

              case "throw":
                if (S.token.nlb)
                    croak("Illegal newline after 'throw'");
                return new AST_Throw({
                    value: prog1(expression, semicolon)
                });

              case "try":
                return try_();

              case "var":
                return prog1(var_, semicolon);

              case "const":
                return prog1(const_, semicolon);

              case "with":
                return new AST_With({
                    expression : parenthesised(),
                    body       : statement()
                });

              default:
                unexpected();
            }
        }
    });

    function labeled_statement() {
        var label = as_symbol(AST_Label);
        if (find_if(function(l){ return l.name == label.name }, S.labels)) {
            // ECMA-262, 12.12: An ECMAScript program is considered
            // syntactically incorrect if it contains a
            // LabelledStatement that is enclosed by a
            // LabelledStatement with the same Identifier as label.
            croak("Label " + label.name + " defined twice");
        }
        expect(":");
        S.labels.push(label);
        var start = S.token, stat = statement();
        S.labels.pop();
        return new AST_LabeledStatement({ statement: stat, label: label });
    };

    function simple_statement() {
        return new AST_SimpleStatement({ body: prog1(expression, semicolon) });
    };

    function break_cont(type) {
        var label = null;
        if (!can_insert_semicolon()) {
            label = as_symbol(AST_LabelRef, true);
        }
        if (label != null) {
            if (!find_if(function(l){ return l.name == label.name }, S.labels))
                croak("Undefined label " + label.name);
        }
        else if (S.in_loop == 0)
            croak(type.TYPE + " not inside a loop or switch");
        semicolon();
        return new type({ label: label });
    };

    function for_() {
        expect("(");
        var init = null;
        if (!is("punc", ";")) {
            init = is("keyword", "var")
                ? (next(), var_(true))
                : expression(true, true);
            if (is("operator", "in")) {
                if (init instanceof AST_Var && init.definitions.length > 1)
                    croak("Only one variable declaration allowed in for..in loop");
                next();
                return for_in(init);
            }
        }
        return regular_for(init);
    };

    function regular_for(init) {
        expect(";");
        var test = is("punc", ";") ? null : expression();
        expect(";");
        var step = is("punc", ")") ? null : expression();
        expect(")");
        return new AST_For({
            init      : init,
            condition : test,
            step      : step,
            body      : in_loop(statement)
        });
    };

    function for_in(init) {
        var lhs = init instanceof AST_Var ? init.definitions[0].name : null;
        var obj = expression();
        expect(")");
        return new AST_ForIn({
            init   : init,
            name   : lhs,
            object : obj,
            body   : in_loop(statement)
        });
    };

    var function_ = function(in_statement) {
        var name = is("name") ? as_symbol(in_statement
                                          ? AST_SymbolDefun
                                          : AST_SymbolLambda) : null;
        if (in_statement && !name)
            unexpected();
        expect("(");
        var ctor = in_statement ? AST_Defun : AST_Function;
        return new ctor({
            name: name,
            argnames: (function(first, a){
                while (!is("punc", ")")) {
                    if (first) first = false; else expect(",");
                    a.push(as_symbol(AST_SymbolFunarg));
                }
                next();
                return a;
            })(true, []),
            body: embed_tokens(function(){
                ++S.in_function;
                var loop = S.in_loop;
                var labels = S.labels;
                S.in_directives = true;
                S.in_loop = 0;
                S.labels = [];
                var a = block_(true);
                --S.in_function;
                S.in_loop = loop;
                S.labels = labels;
                return a;
            })()
        });
    };

    function if_() {
        var cond = parenthesised(), body = statement(), belse = null;
        if (is("keyword", "else")) {
            next();
            belse = statement();
        }
        return new AST_If({
            condition   : cond,
            consequent  : body,
            alternative : belse
        });
    };

    function block_(required) {
        var start = S.token;
        expect("{");
        var a = [];
        while (!is("punc", "}")) {
            if (is("eof")) unexpected();
            a.push(statement());
        }
        var end = S.token;
        next();
        return new AST_BlockStatement({
            required : required,
            start    : start,
            body     : a,
            end      : end
        });
    };

    var switch_block_ = embed_tokens(curry(in_loop, function(){
        expect("{");
        var a = [], cur = null, branch = null, start = S.token;
        while (!is("punc", "}")) {
            if (is("eof")) unexpected();
            if (is("keyword", "case")) {
                if (branch) branch.end = prev();
                cur = [];
                branch = new AST_Case({
                    start      : prog1(S.token, next),
                    expression : expression(),
                    body       : cur
                });
                a.push(branch);
                expect(":");
            }
            else if (is("keyword", "default")) {
                if (branch) branch.end = prev();
                cur = [];
                branch = new AST_Default({
                    start : prog1(S.token, next, curry(expect, ":")),
                    body  : cur
                })
                a.push(branch);
            }
            else {
                if (!cur) unexpected();
                cur.push(statement());
            }
        }
        if (branch) branch.end = prev();
        var end = S.token;
        next();
        return new AST_SwitchBlock({
            required : true,
            start    : start,
            body     : a,
            end      : end
        });
    }));

    function try_() {
        var body = block_(true), bcatch = null, bfinally = null;
        if (is("keyword", "catch")) {
            var start = S.token;
            next();
            expect("(");
            var name = as_symbol(AST_SymbolCatch);
            expect(")");
            bcatch = new AST_Catch({
                start   : start,
                argname : name,
                body    : block_(true),
                end     : prev()
            });
        }
        if (is("keyword", "finally")) {
            var start = S.token;
            next();
            bfinally = new AST_Finally({
                start : start,
                body  : block_(true),
                end   : prev()
            });
        }
        if (!bcatch && !bfinally)
            croak("Missing catch/finally blocks");
        return new AST_Try({
            btry     : body,
            bcatch   : bcatch,
            bfinally : bfinally
        });
    };

    function vardefs(no_in) {
        var a = [];
        for (;;) {
            a.push(new AST_VarDef({
                start : S.token,
                name  : as_symbol(AST_SymbolVar),
                value : is("operator", "=") ? (next(), expression(false, no_in)) : null,
                end   : prev()
            }));
            if (!is("punc", ","))
                break;
            next();
        }
        return a;
    };

    var var_ = function(no_in) {
        return new AST_Var({
            start       : prev(),
            definitions : vardefs(no_in),
            end         : prev()
        });
    };

    var const_ = function() {
        return new AST_Const({
            start       : prev(),
            definitions : vardefs(),
            end         : prev()
        });
    };

    var new_ = function() {
        var start = S.token;
        expect_token("operator", "new");
        var newexp = expr_atom(false), args;
        if (is("punc", "(")) {
            next();
            args = expr_list(")");
        } else {
            args = [];
        }
        return subscripts(new AST_New({
            start      : start,
            expression : newexp,
            args       : args,
            end        : prev()
        }), true);
    };

    function as_atom_node() {
        var tok = S.token, ret;
        switch (tok.type) {
          case "name":
            return as_symbol(AST_SymbolRef);
          case "num":
            ret = new AST_Number({ start: tok, end: tok, value: tok.value });
            break;
          case "string":
            ret = new AST_String({ start: tok, end: tok, value: tok.value });
            break;
          case "regexp":
            ret = new AST_RegExp({ start: tok, end: tok, pattern: tok.value[0], mods: tok.value[1] });
            break;
          case "atom":
            switch (tok.value) {
              case "false":
                ret = new AST_False({ start: tok, end: tok });
                break;
              case "true":
                ret = new AST_True({ start: tok, end: tok });
                break;
              case "null":
                ret = new AST_Null({ start: tok, end: tok });
                break;
            }
            break;
        }
        next();
        return ret;
    };

    var expr_atom = function(allow_calls) {
        if (is("operator", "new")) {
            return new_();
        }
        var start = S.token;
        if (is("punc")) {
            switch (start.value) {
              case "(":
                next();
                var ex = expression();
                ex.start = start;
                ex.end = S.token;
                expect(")");
                return subscripts(ex, allow_calls);
              case "[":
                return subscripts(array_(), allow_calls);
              case "{":
                return subscripts(object_(), allow_calls);
            }
            unexpected();
        }
        if (is("keyword", "function")) {
            next();
            var func = function_(false);
            func.start = start;
            func.end = prev();
            return subscripts(func, allow_calls);
        }
        if (HOP(ATOMIC_START_TOKEN, S.token.type)) {
            return subscripts(as_atom_node(), allow_calls);
        }
        unexpected();
    };

    function expr_list(closing, allow_trailing_comma, allow_empty) {
        var first = true, a = [];
        while (!is("punc", closing)) {
            if (first) first = false; else expect(",");
            if (allow_trailing_comma && is("punc", closing)) break;
            if (is("punc", ",") && allow_empty) {
                a.push(new AST_Undefined({ start: S.token, end: S.token }));
            } else {
                a.push(expression(false));
            }
        }
        next();
        return a;
    };

    var array_ = embed_tokens(function() {
        expect("[");
        return new AST_Array({
            elements: expr_list("]", !exigent_mode, true)
        });
    });

    var object_ = embed_tokens(function() {
        expect("{");
        var first = true, a = [];
        while (!is("punc", "}")) {
            if (first) first = false; else expect(",");
            if (!exigent_mode && is("punc", "}"))
                // allow trailing comma
                break;
            var start = S.token;
            var type = start.type;
            var name = as_property_name();
            if (type == "name" && !is("punc", ":")) {
                if (name == "get") {
                    a.push(new AST_ObjectGetter({
                        start : start,
                        key   : name,
                        value : function_(false),
                        end   : prev()
                    }));
                    continue;
                }
                if (name == "set") {
                    a.push(new AST_ObjectSetter({
                        start : start,
                        key   : name,
                        value : function_(false),
                        end   : prev()
                    }));
                    continue;
                }
            }
            expect(":");
            a.push(new AST_ObjectKeyVal({
                start : start,
                key   : name,
                value : expression(false),
                end   : prev()
            }));
        }
        next();
        return new AST_Object({ properties: a });
    });

    function as_property_name() {
        switch (S.token.type) {
          case "num":
          case "string":
          case "name":
          case "operator":
          case "keyword":
          case "atom":
            return prog1(S.token.value, next);
          default:
            unexpected();
        }
    };

    function as_name() {
        switch (S.token.type) {
          case "name":
          case "operator":
          case "keyword":
          case "atom":
            return prog1(S.token.value, next);
          default:
            unexpected();
        }
    };

    function as_symbol(type, noerror) {
        if (!is("name")) {
            if (!noerror) croak("Name expected");
            return null;
        }
        var name = S.token.value;
        var sym = new (name == "this" ? AST_This : type)({
            name  : String(S.token.value),
            start : S.token,
            end   : S.token
        });
        next();
        return sym;
    };

    var subscripts = function(expr, allow_calls) {
        var start = expr.start;
        if (is("punc", ".")) {
            next();
            return subscripts(new AST_Dot({
                start      : start,
                expression : expr,
                property   : as_name(),
                end        : prev()
            }), allow_calls);
        }
        if (is("punc", "[")) {
            next();
            var prop = expression();
            expect("]");
            return subscripts(new AST_Sub({
                start      : start,
                expression : expr,
                property   : prop,
                end        : prev()
            }), allow_calls);
        }
        if (allow_calls && is("punc", "(")) {
            next();
            return subscripts(new AST_Call({
                start      : start,
                expression : expr,
                args       : expr_list(")"),
                end        : prev()
            }), true);
        }
        return expr;
    };

    var maybe_unary = function(allow_calls) {
        var start = S.token;
        if (is("operator") && HOP(UNARY_PREFIX, S.token.value)) {
            var ex = make_unary(AST_UnaryPrefix,
                                prog1(S.token.value, next),
                                maybe_unary(allow_calls));
            ex.start = start;
            ex.end = prev();
            return ex;
        }
        var val = expr_atom(allow_calls);
        while (is("operator") && HOP(UNARY_POSTFIX, S.token.value) && !S.token.nlb) {
            val = make_unary(AST_UnaryPostfix, S.token.value, val);
            val.start = start;
            val.end = S.token;
            next();
        }
        return val;
    };

    function make_unary(ctor, op, expr) {
        if ((op == "++" || op == "--") && !is_assignable(expr))
            croak("Invalid use of " + op + " operator");
        return new ctor({ operator: op, expression: expr });
    };

    var expr_op = function(left, min_prec, no_in) {
        var op = is("operator") ? S.token.value : null;
        if (op == "in" && no_in) op = null;
        var prec = op != null ? PRECEDENCE[op] : null;
        if (prec != null && prec > min_prec) {
            next();
            var right = expr_op(maybe_unary(true), prec, no_in);
            return expr_op(new AST_Binary({
                start    : left.start,
                left     : left,
                operator : op,
                right    : right,
                end      : right.end
            }), min_prec, no_in);
        }
        return left;
    };

    function expr_ops(no_in) {
        return expr_op(maybe_unary(true), 0, no_in);
    };

    var maybe_conditional = function(no_in) {
        var start = S.token;
        var expr = expr_ops(no_in);
        if (is("operator", "?")) {
            next();
            var yes = expression(false);
            expect(":");
            return new AST_Conditional({
                start       : start,
                condition   : expr,
                consequent  : yes,
                alternative : expression(false, no_in),
                end         : peek()
            });
        }
        return expr;
    };

    function is_assignable(expr) {
        if (!exigent_mode) return true;
        switch (expr[0]+"") {
          case "dot":
          case "sub":
          case "new":
          case "call":
            return true;
          case "name":
            return expr[1] != "this";
        }
    };

    var maybe_assign = function(no_in) {
        var start = S.token;
        var left = maybe_conditional(no_in), val = S.token.value;
        if (is("operator") && HOP(ASSIGNMENT, val)) {
            if (is_assignable(left)) {
                next();
                return new AST_Assign({
                    start    : start,
                    left     : left,
                    operator : ASSIGNMENT[val],
                    right    : maybe_assign(no_in),
                    end      : peek()
                });
            }
            croak("Invalid assignment");
        }
        return left;
    };

    var expression = function(commas, no_in) {
        if (arguments.length == 0)
            commas = true;
        var start = S.token;
        var expr = maybe_assign(no_in);
        if (commas && is("punc", ",")) {
            next();
            return new AST_Seq({
                start  : start,
                first  : expr,
                second : expression(true, no_in),
                end    : peek()
            });
        }
        return expr;
    };

    function in_loop(cont) {
        ++S.in_loop;
        var ret = cont();
        --S.in_loop;
        return ret;
    };

    return new AST_Toplevel({
        start: S.token,
        body: (function(a){
            while (!is("eof"))
                a.push(statement());
            return a;
        })([]),
        end: prev()
    });

};

var warn = function() {};