added getPathValue utility helper

lib/utils/getPathValue.js

@@ -0,0 +1,102 @@
+/**
+ * Chai - getPathValue utility
+ * Copyright(c) 2012 Jake Luer <jake@alogicalparadox.com>
+ * @see https://github.com/logicalparadox/filtr
+ * MIT Licensed
+ */
+
+/**
+ * # .getPathValue(path, object)
+ *
+ * This allows the retrieval of values in an
+ * object given a string path.
+ *
+ *     var obj = {
+ *         prop1: {
+ *             arr: ['a', 'b', 'c']
+ *           , str: 'Hello'
+ *         }
+ *       , prop2: {
+ *             arr: [ { nested: 'Universe' } ]
+ *           , str: 'Hello again!'
+ *         }
+ *     }
+ *
+ * The following would be the results.
+ *
+ *     getPathValue('prop1.str', obj); // Hello
+ *     getPathValue('prop1.att[2]', obj); // b
+ *     getPathValue('prop2.arr[0].nested', obj); // Universe
+ *
+ * @param {String} path
+ * @param {Object} object
+ * @returns {Object} value or `undefined`
+ * @api public
+ */
+
+var getPathValue = module.exports = function (path, obj) {
+  var parsed = parsePath(path);
+  return _getPathValue(parsed, obj);
+};
+
+/*!
+ * ## parsePath(path)
+ *
+ * Helper function used to parse string object
+ * paths. Use in conjunction with `_getPathValue`.
+ *
+ *      var parsed = parsePath('myobject.property.subprop');
+ *
+ * ### Paths:
+ *
+ * * Can be as near infinitely deep and nested
+ * * Arrays are also valid using the formal `myobject.document[3].property`.
+ *
+ * @param {String} path
+ * @returns {Object} parsed
+ * @api private
+ */
+
+function parsePath (path) {
+  var parts = path.split('.').filter(Boolean);
+  return parts.map(function (value) {
+    var re = /([A-Za-z0-9]+)\[(\d+)\]$/
+      , mArr = re.exec(value)
+      , val;
+    if (mArr) val = { p: mArr[1], i: parseFloat(mArr[2]) };
+    return val || value;
+  });
+};
+
+/**
+ * ## _getPathValue(parsed, obj)
+ *
+ * Helper companion function for `.parsePath` that returns
+ * the value located at the parsed address.
+ *
+ *      var value = getPathValue(parsed, obj);
+ *
+ * @param {Object} parsed definition from `parsePath`.
+ * @param {Object} object to search against
+ * @returns {Object|Undefined} value
+ * @api private
+ */
+
+function _getPathValue (parsed, obj) {
+  var tmp = obj
+    , res;
+  for (var i = 0, l = parsed.length; i < l; i++) {
+    var part = parsed[i];
+    if (tmp) {
+      if ('object' === typeof part && tmp[part.p]) {
+        tmp = tmp[part.p][part.i];
+      } else {
+        tmp = tmp[part];
+      }
+      if (i == (l - 1)) res = tmp;
+    } else {
+      res = undefined;
+    }
+  }
+  return res;
+};

lib/utils/index.js

@@ -21,3 +21,9 @@ exports.inspect = require('./inspect');
  */
 
 exports.eql = require('./eql');
+
+/*!
+ * Deep path value
+ */
+
+exports.getPathValue = require('./getPathValue');