/* JSONPath 0.8.5 - XPath for JSON
 *
 * Copyright (c) 2007 Stefan Goessner (goessner.net)
 * Licensed under the MIT (MIT-LICENSE.txt) licence.
 *
 * Proposal of Chris Zyp goes into version 0.9.x
 * Issue 7 resolved
 */
function jsonPath(obj, expr, arg) {
    var P = {
        resultType: arg && arg.resultType || "VALUE",
        result: [],
        normalize: function(expr) {
            var subx = [];
            return expr.replace(/[\['](\??\(.*?\))[\]']|\['(.*?)'\]/g, function($0,$1,$2){return "[#"+(subx.push($1||$2)-1)+"]";})  /* http://code.google.com/p/jsonpath/issues/detail?id=4 */
                .replace(/'?\.'?|\['?/g, ";")
                .replace(/;;;|;;/g, ";..;")
                .replace(/;$|'?\]|'$/g, "")
                .replace(/#([0-9]+)/g, function($0,$1){return subx[$1];});
        },
        asPath: function(path) {
            var x = path.split(";"), p = "$";
            for (var i=1,n=x.length; i<n; i++)
                p += /^[0-9*]+$/.test(x[i]) ? ("["+x[i]+"]") : ("['"+x[i]+"']");
            return p;
        },
        store: function(p, v) {
            if (p) P.result[P.result.length] = P.resultType == "PATH" ? P.asPath(p) : v;
            return !!p;
        },
        trace: function(expr, val, path) {
            if (expr !== "") {
                var x = expr.split(";"), loc = x.shift();
                x = x.join(";");
                if (val && val.hasOwnProperty(loc))
                    P.trace(x, val[loc], path + ";" + loc);
                else if (loc === "*")
                    P.walk(loc, x, val, path, function(m,l,x,v,p) { P.trace(m+";"+x,v,p); });
                else if (loc === "..") {
                    P.trace(x, val, path);
                    P.walk(loc, x, val, path, function(m,l,x,v,p) { typeof v[m] === "object" && P.trace("..;"+x,v[m],p+";"+m); });
                }
                else if (/^\(.*?\)$/.test(loc)) // [(expr)]
                    P.trace(P.eval(loc, val, path.substr(path.lastIndexOf(";")+1))+";"+x, val, path);
                else if (/^\?\(.*?\)$/.test(loc)) // [?(expr)]
                    P.walk(loc, x, val, path, function(m,l,x,v,p) { if (P.eval(l.replace(/^\?\((.*?)\)$/,"$1"), v instanceof Array ? v[m] : v, m)) P.trace(m+";"+x,v,p); }); // issue 5 resolved
                else if (/^(-?[0-9]*):(-?[0-9]*):?([0-9]*)$/.test(loc)) // [start:end:step]  phyton slice syntax
                    P.slice(loc, x, val, path);
                else if (/,/.test(loc)) { // [name1,name2,...]
                    for (var s=loc.split(/'?,'?/),i=0,n=s.length; i<n; i++)
                        P.trace(s[i]+";"+x, val, path);
                }
            }
            else
                P.store(path, val);
        },
        walk: function(loc, expr, val, path, f) {
            if (val instanceof Array) {
                for (var i=0,n=val.length; i<n; i++)
                    if (i in val)
                        f(i,loc,expr,val,path);
            }
            else if (typeof val === "object") {
                for (var m in val)
                    if (val.hasOwnProperty(m))
                        f(m,loc,expr,val,path);
            }
        },
        slice: function(loc, expr, val, path) {
            if (val instanceof Array) {
                var len=val.length, start=0, end=len, step=1;
                loc.replace(/^(-?[0-9]*):(-?[0-9]*):?(-?[0-9]*)$/g, function($0,$1,$2,$3){start=parseInt($1||start);end=parseInt($2||end);step=parseInt($3||step);});
                start = (start < 0) ? Math.max(0,start+len) : Math.min(len,start);
                end   = (end < 0)   ? Math.max(0,end+len)   : Math.min(len,end);
                for (var i=start; i<end; i+=step)
                    P.trace(i+";"+expr, val, path);
            }
        },
        eval: function(x, _v, _vname) {
            try { return $ && _v && eval(x.replace(/(^|[^\\])@/g, "$1_v").replace(/\\@/g, "@")); }  // issue 7 : resolved ..
            catch(e) { throw new SyntaxError("jsonPath: " + e.message + ": " + x.replace(/(^|[^\\])@/g, "$1_v").replace(/\\@/g, "@")); }  // issue 7 : resolved ..
        }
    };

    var $ = obj;
    if (expr && obj && (P.resultType == "VALUE" || P.resultType == "PATH")) {
        P.trace(P.normalize(expr).replace(/^\$;?/,""), obj, "$");  // issue 6 resolved
        return P.result.length ? P.result : false;
    }
}
