query.js

define(["dojo/_base/kernel",
	"dojo/_base/lang"
], function(kernel, lang){
	var query = function( /*Object*/ obj, /*String*/ expr, /*Object*/ arg){
		// summary:
		//		Perform jsonPath query `expr` on javascript object or json string `obj`
		// obj:
		//		object || json string to perform query on
		// expr:
		//		jsonPath expression (string) to be evaluated
		// arg:
		//		{} special arguments.
		//
		//		- resultType: "VALUE"||"BOTH"||"PATH"} (defaults to value)
		//		- evalType: "RESULT"||"ITEM"} (defaults to ?)

		if(!arg){
			arg = {};
		}

		var strs = [];

		function _str(i){
			return strs[i];
		}
		var _strName = _str.name;
		if(arg.resultType == "PATH" && arg.evalType == "RESULT"){
			throw Error("RESULT based evaluation not supported with PATH based results");
		}
		var P = {
			resultType: arg.resultType || "VALUE",
			normalize: function(expr){
				var subx = [];
				expr = expr.replace(/'([^']|'')*'/g, function(t){
					return _strName + "(" + (strs.push(eval(t)) - 1) + ")";
				});
				var ll = -1;
				while(ll != subx.length){
					ll = subx.length; //TODO: Do expression syntax checking
					expr = expr.replace(/(\??\([^\(\)]*\))/g, function($0){
						return "#" + (subx.push($0) - 1);
					});
				}
				expr = expr.replace(/[\['](#[0-9]+)[\]']/g, '[$1]')
					.replace(/'?\.'?|\['?/g, ";")
					.replace(/;;;|;;/g, ";..;")
					.replace(/;$|'?\]|'$/g, "");
				ll = -1;
				while(ll != expr){
					ll = expr;
					expr = expr.replace(/#([0-9]+)/g, function($0, $1){
						return subx[$1];
					});
				}
				return expr.split(";");
			},
			asPaths: function(paths){
				var i, j, p, x, n;
				for(j = 0; j < paths.length; j++){
					p = "$";
					x = paths[j];
					for(i = 1, n = x.length; i < n; i++){
						p += /^[0-9*]+$/.test(x[i]) ? ("[" + x[i] + "]") : ("['" + x[i] + "']");
					}
					paths[j] = p;
				}
				return paths;
			},
			exec: function(locs, val, rb){
				var path = ['$'];
				var result = rb ? val : [val];
				var paths = [path];

				function add(v, p, def){
					if(v && v.hasOwnProperty(p) && P.resultType != "VALUE"){
						paths.push(path.concat([p]));
					}
					if(def){
						result = v[p];
					}else if(v && v.hasOwnProperty(p)){
						result.push(v[p]);
					}
				}

				function desc(v){
					result.push(v);
					paths.push(path);
					P.walk(v, function(i){
						if(typeof v[i] === "object"){
							var oldPath = path;
							path = path.concat(i);
							desc(v[i]);
							path = oldPath;
						}
					});
				}

				function slice(loc, val){
					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, 10);
							end = parseInt($2 || end, 10);
							step = parseInt($3 || step, 10);
						});
						start = (start < 0) ? Math.max(0, start + len) : Math.min(len, start);
						end = (end < 0) ? Math.max(0, end + len) : Math.min(len, end);
						var i;
						for(i = start; i < end; i += step){
							add(val, i);
						}
					}
				}

				function repStr(str, loc){
					var i = loc.match(/^_str\(([0-9]+)\)$/);
					return i ? strs[i[1]] : str;
				}

				function oper(val, loc){
					if(/^\(.*?\)$/.test(loc)){ // [(expr)]
						add(val, P.eval(loc, val), rb);
					}else if(loc === "*"){
						P.walk(val, rb && val instanceof Array ? // if it is result based, there is no point to just return the same array
							function(i){
								P.walk(val[i], function(j){
									add(val[i], j);
								});
							} :
							function(i){
								add(val, i);
							});
					}else if(loc === ".."){
						desc(val);
					}else if(/,/.test(loc)){ // [name1,name2,...]
						var s, n, i;
						for(s = loc.split(/'?,'?/), i = 0, n = s.length; i < n; i++){
							add(val, repStr(s[i], loc));
						}
					}else if(/^\?\(.*?\)$/.test(loc)){ // [?(expr)]
						P.walk(val, function(i){
							if(P.eval(loc.replace(/^\?\((.*?)\)$/, "$1"), val[i])){
								add(val, i);
							}
						});
					}else if(/^(-?[0-9]*):(-?[0-9]*):?([0-9]*)$/.test(loc)){ // [start:end:step]  python slice syntax
						slice(loc, val);
					}else{
						loc = repStr(loc, loc);
						if(rb && val instanceof Array && !/^[0-9*]+$/.test(loc)){
							P.walk(val, function(i){
								add(val[i], loc);
							});
						}else{
							add(val, loc, rb);
						}
					}

				}
				var loc, valPaths;
				while(locs.length){
					loc = locs.shift();
					if((val = result) === null || val === undefined){
						return val;
					}
					result = [];
					valPaths = paths;
					paths = [];
					if(rb){
						oper(val, loc);
					}else{
						P.walk(val, function(i){
							path = valPaths[i] || path;
							oper(val[i], loc);
						});
					}
				}
				if(P.resultType == "BOTH"){
					paths = P.asPaths(paths);
					var newResult = [];
					var i;
					for(i = 0; i < paths.length; i++){
						newResult.push({
							path: paths[i],
							value: result[i]
						});
					}
					return newResult;
				}
				return P.resultType == "PATH" ? P.asPaths(paths) : result;
			},
			walk: function(val, f){
				var i, n, m;
				if(val instanceof Array){
					for(i = 0, n = val.length; i < n; i++){
						if(i in val){
							f(i);
						}
					}
				}else if(typeof val === "object"){
					for(m in val){
						if(val.hasOwnProperty(m)){
							f(m);
						}
					}
				}
			},
			"eval": function(x, v){
				try {
					return obj && v && eval(x.replace(/@/g, "v"));
				} catch (e){
					throw new SyntaxError("jsonPath: " + e.message + ": " + x.replace(/@/g, "v").replace(/\^/g, "_a"));
				}
			}
		};

		if(expr && obj){
			return P.exec(P.normalize(expr).slice(1), obj, arg.evalType == "RESULT");
		}

		return false;

	};

	if(!kernel.isAsync){
		var obj = lang.getObject("dojox.jsonPath", true);
		obj.query = query;
	}

	return query;

});