/assets/js/libs/_.js

//     Underscore.js 1.3.3

//     (c) 2009-2012 Jeremy Ashkenas, DocumentCloud Inc.

//     Underscore is freely distributable under the MIT license.

//     Portions of Underscore are inspired or borrowed from Prototype,

//     Oliver Steele's Functional, and John Resig's Micro-Templating.

//     For all details and documentation:

//     http://documentcloud.github.com/underscore



(function() {



    // Baseline setup

    // --------------



    // Establish the root object, `window` in the browser, or `global` on the server.

    var root = this;



    // Save the previous value of the `_` variable.

    var previousUnderscore = root._;



    // Establish the object that gets returned to break out of a loop iteration.

    var breaker = {};



    // Save bytes in the minified (but not gzipped) version:

    var ArrayProto = Array.prototype, ObjProto = Object.prototype, FuncProto = Function.prototype;



    // Create quick reference variables for speed access to core prototypes.

    var slice            = ArrayProto.slice,

        unshift          = ArrayProto.unshift,

        toString         = ObjProto.toString,

        hasOwnProperty   = ObjProto.hasOwnProperty;



    // All **ECMAScript 5** native function implementations that we hope to use

    // are declared here.

    var

        nativeForEach      = ArrayProto.forEach,

        nativeMap          = ArrayProto.map,

        nativeReduce       = ArrayProto.reduce,

        nativeReduceRight  = ArrayProto.reduceRight,

        nativeFilter       = ArrayProto.filter,

        nativeEvery        = ArrayProto.every,

        nativeSome         = ArrayProto.some,

        nativeIndexOf      = ArrayProto.indexOf,

        nativeLastIndexOf  = ArrayProto.lastIndexOf,

        nativeIsArray      = Array.isArray,

        nativeKeys         = Object.keys,

        nativeBind         = FuncProto.bind;



    // Create a safe reference to the Underscore object for use below.

    var _ = function(obj) { return new wrapper(obj); };



    // Export the Underscore object for **Node.js**, with

    // backwards-compatibility for the old `require()` API. If we're in

    // the browser, add `_` as a global object via a string identifier,

    // for Closure Compiler "advanced" mode.

    if (typeof exports !== 'undefined') {

        if (typeof module !== 'undefined' && module.exports) {

            exports = module.exports = _;

        }

        exports._ = _;

    } else {

        root['_'] = _;

    }



    // Current version.

    _.VERSION = '1.3.3';



    // Collection Functions

    // --------------------



    // The cornerstone, an `each` implementation, aka `forEach`.

    // Handles objects with the built-in `forEach`, arrays, and raw objects.

    // Delegates to **ECMAScript 5**'s native `forEach` if available.

    var each = _.each = _.forEach = function(obj, iterator, context) {

        if (obj == null) return;

        if (nativeForEach && obj.forEach === nativeForEach) {

            obj.forEach(iterator, context);

        } else if (obj.length === +obj.length) {

            for (var i = 0, l = obj.length; i < l; i++) {

                if (i in obj && iterator.call(context, obj[i], i, obj) === breaker) return;

            }

        } else {

            for (var key in obj) {

                if (_.has(obj, key)) {

                    if (iterator.call(context, obj[key], key, obj) === breaker) return;

                }

            }

        }

    };



    // Return the results of applying the iterator to each element.

    // Delegates to **ECMAScript 5**'s native `map` if available.

    _.map = _.collect = function(obj, iterator, context) {

        var results = [];

        if (obj == null) return results;

        if (nativeMap && obj.map === nativeMap) return obj.map(iterator, context);

        each(obj, function(value, index, list) {

            results[results.length] = iterator.call(context, value, index, list);

        });

        if (obj.length === +obj.length) results.length = obj.length;

        return results;

    };



    // **Reduce** builds up a single result from a list of values, aka `inject`,

    // or `foldl`. Delegates to **ECMAScript 5**'s native `reduce` if available.

    _.reduce = _.foldl = _.inject = function(obj, iterator, memo, context) {

        var initial = arguments.length > 2;

        if (obj == null) obj = [];

        if (nativeReduce && obj.reduce === nativeReduce) {

            if (context) iterator = _.bind(iterator, context);

            return initial ? obj.reduce(iterator, memo) : obj.reduce(iterator);

        }

        each(obj, function(value, index, list) {

            if (!initial) {

                memo = value;

                initial = true;

            } else {

                memo = iterator.call(context, memo, value, index, list);

            }

        });

        if (!initial) throw new TypeError('Reduce of empty array with no initial value');

        return memo;

    };



    // The right-associative version of reduce, also known as `foldr`.

    // Delegates to **ECMAScript 5**'s native `reduceRight` if available.

    _.reduceRight = _.foldr = function(obj, iterator, memo, context) {

        var initial = arguments.length > 2;

        if (obj == null) obj = [];

        if (nativeReduceRight && obj.reduceRight === nativeReduceRight) {

            if (context) iterator = _.bind(iterator, context);

            return initial ? obj.reduceRight(iterator, memo) : obj.reduceRight(iterator);

        }

        var reversed = _.toArray(obj).reverse();

        if (context && !initial) iterator = _.bind(iterator, context);

        return initial ? _.reduce(reversed, iterator, memo, context) : _.reduce(reversed, iterator);

    };



    // Return the first value which passes a truth test. Aliased as `detect`.

    _.find = _.detect = function(obj, iterator, context) {

        var result;

        any(obj, function(value, index, list) {

            if (iterator.call(context, value, index, list)) {

                result = value;

                return true;

            }

        });

        return result;

    };



    // Return all the elements that pass a truth test.

    // Delegates to **ECMAScript 5**'s native `filter` if available.

    // Aliased as `select`.

    _.filter = _.select = function(obj, iterator, context) {

        var results = [];

        if (obj == null) return results;

        if (nativeFilter && obj.filter === nativeFilter) return obj.filter(iterator, context);

        each(obj, function(value, index, list) {

            if (iterator.call(context, value, index, list)) results[results.length] = value;

        });

        return results;

    };



    // Return all the elements for which a truth test fails.

    _.reject = function(obj, iterator, context) {

        var results = [];

        if (obj == null) return results;

        each(obj, function(value, index, list) {

            if (!iterator.call(context, value, index, list)) results[results.length] = value;

        });

        return results;

    };



    // Determine whether all of the elements match a truth test.

    // Delegates to **ECMAScript 5**'s native `every` if available.

    // Aliased as `all`.

    _.every = _.all = function(obj, iterator, context) {

        var result = true;

        if (obj == null) return result;

        if (nativeEvery && obj.every === nativeEvery) return obj.every(iterator, context);

        each(obj, function(value, index, list) {

            if (!(result = result && iterator.call(context, value, index, list))) return breaker;

        });

        return !!result;

    };



    // Determine if at least one element in the object matches a truth test.

    // Delegates to **ECMAScript 5**'s native `some` if available.

    // Aliased as `any`.

    var any = _.some = _.any = function(obj, iterator, context) {

        iterator || (iterator = _.identity);

        var result = false;

        if (obj == null) return result;

        if (nativeSome && obj.some === nativeSome) return obj.some(iterator, context);

        each(obj, function(value, index, list) {

            if (result || (result = iterator.call(context, value, index, list))) return breaker;

        });

        return !!result;

    };



    // Determine if a given value is included in the array or object using `===`.

    // Aliased as `contains`.

    _.include = _.contains = function(obj, target) {

        var found = false;

        if (obj == null) return found;

        if (nativeIndexOf && obj.indexOf === nativeIndexOf) return obj.indexOf(target) != -1;

        found = any(obj, function(value) {

            return value === target;

        });

        return found;

    };



    // Invoke a method (with arguments) on every item in a collection.

    _.invoke = function(obj, method) {

        var args = slice.call(arguments, 2);

        return _.map(obj, function(value) {

            return (_.isFunction(method) ? method || value : value[method]).apply(value, args);

        });

    };



    // Convenience version of a common use case of `map`: fetching a property.

    _.pluck = function(obj, key) {

        return _.map(obj, function(value){ return value[key]; });

    };



    // Return the maximum element or (element-based computation).

    _.max = function(obj, iterator, context) {

        if (!iterator && _.isArray(obj) && obj[0] === +obj[0]) return Math.max.apply(Math, obj);

        if (!iterator && _.isEmpty(obj)) return -Infinity;

        var result = {computed : -Infinity};

        each(obj, function(value, index, list) {

            var computed = iterator ? iterator.call(context, value, index, list) : value;

            computed >= result.computed && (result = {value : value, computed : computed});

        });

        return result.value;

    };



    // Return the minimum element (or element-based computation).

    _.min = function(obj, iterator, context) {

        if (!iterator && _.isArray(obj) && obj[0] === +obj[0]) return Math.min.apply(Math, obj);

        if (!iterator && _.isEmpty(obj)) return Infinity;

        var result = {computed : Infinity};

        each(obj, function(value, index, list) {

            var computed = iterator ? iterator.call(context, value, index, list) : value;

            computed < result.computed && (result = {value : value, computed : computed});

        });

        return result.value;

    };



    // Shuffle an array.

    _.shuffle = function(obj) {

        var shuffled = [], rand;

        each(obj, function(value, index, list) {

            rand = Math.floor(Math.random() * (index + 1));

            shuffled[index] = shuffled[rand];

            shuffled[rand] = value;

        });

        return shuffled;

    };



    // Sort the object's values by a criterion produced by an iterator.

    _.sortBy = function(obj, val, context) {

        var iterator = _.isFunction(val) ? val : function(obj) { return obj[val]; };

        return _.pluck(_.map(obj, function(value, index, list) {

            return {

                value : value,

                criteria : iterator.call(context, value, index, list)

            };

        }).sort(function(left, right) {

                var a = left.criteria, b = right.criteria;

                if (a === void 0) return 1;

                if (b === void 0) return -1;

                return a < b ? -1 : a > b ? 1 : 0;

            }), 'value');

    };



    // Groups the object's values by a criterion. Pass either a string attribute

    // to group by, or a function that returns the criterion.

    _.groupBy = function(obj, val) {

        var result = {};

        var iterator = _.isFunction(val) ? val : function(obj) { return obj[val]; };

        each(obj, function(value, index) {

            var key = iterator(value, index);

            (result[key] || (result[key] = [])).push(value);

        });

        return result;

    };



    // Use a comparator function to figure out at what index an object should

    // be inserted so as to maintain order. Uses binary search.

    _.sortedIndex = function(array, obj, iterator) {

        iterator || (iterator = _.identity);

        var low = 0, high = array.length;

        while (low < high) {

            var mid = (low + high) >> 1;

            iterator(array[mid]) < iterator(obj) ? low = mid + 1 : high = mid;

        }

        return low;

    };



    // Safely convert anything iterable into a real, live array.

    _.toArray = function(obj) {

        if (!obj)                                     return [];

        if (_.isArray(obj))                           return slice.call(obj);

        if (_.isArguments(obj))                       return slice.call(obj);

        if (obj.toArray && _.isFunction(obj.toArray)) return obj.toArray();

        return _.values(obj);

    };



    // Return the number of elements in an object.

    _.size = function(obj) {

        return _.isArray(obj) ? obj.length : _.keys(obj).length;

    };



    // Array Functions

    // ---------------



    // Get the first element of an array. Passing **n** will return the first N

    // values in the array. Aliased as `head` and `take`. The **guard** check

    // allows it to work with `_.map`.

    _.first = _.head = _.take = function(array, n, guard) {

        return (n != null) && !guard ? slice.call(array, 0, n) : array[0];

    };



    // Returns everything but the last entry of the array. Especcialy useful on

    // the arguments object. Passing **n** will return all the values in

    // the array, excluding the last N. The **guard** check allows it to work with

    // `_.map`.

    _.initial = function(array, n, guard) {

        return slice.call(array, 0, array.length - ((n == null) || guard ? 1 : n));

    };



    // Get the last element of an array. Passing **n** will return the last N

    // values in the array. The **guard** check allows it to work with `_.map`.

    _.last = function(array, n, guard) {

        if ((n != null) && !guard) {

            return slice.call(array, Math.max(array.length - n, 0));

        } else {

            return array[array.length - 1];

        }

    };



    // Returns everything but the first entry of the array. Aliased as `tail`.

    // Especially useful on the arguments object. Passing an **index** will return

    // the rest of the values in the array from that index onward. The **guard**

    // check allows it to work with `_.map`.

    _.rest = _.tail = function(array, index, guard) {

        return slice.call(array, (index == null) || guard ? 1 : index);

    };



    // Trim out all falsy values from an array.

    _.compact = function(array) {

        return _.filter(array, function(value){ return !!value; });

    };



    // Return a completely flattened version of an array.

    _.flatten = function(array, shallow) {

        return _.reduce(array, function(memo, value) {

            if (_.isArray(value)) return memo.concat(shallow ? value : _.flatten(value));

            memo[memo.length] = value;

            return memo;

        }, []);

    };



    // Return a version of the array that does not contain the specified value(s).

    _.without = function(array) {

        return _.difference(array, slice.call(arguments, 1));

    };



    // Produce a duplicate-free version of the array. If the array has already

    // been sorted, you have the option of using a faster algorithm.

    // Aliased as `unique`.

    _.uniq = _.unique = function(array, isSorted, iterator) {

        var initial = iterator ? _.map(array, iterator) : array;

        var results = [];

        // The `isSorted` flag is irrelevant if the array only contains two elements.

        if (array.length < 3) isSorted = true;

        _.reduce(initial, function (memo, value, index) {

            if (isSorted ? _.last(memo) !== value || !memo.length : !_.include(memo, value)) {

                memo.push(value);

                results.push(array[index]);

            }

            return memo;

        }, []);

        return results;

    };



    // Produce an array that contains the union: each distinct element from all of

    // the passed-in arrays.

    _.union = function() {

        return _.uniq(_.flatten(arguments, true));

    };



    // Produce an array that contains every item shared between all the

    // passed-in arrays. (Aliased as "intersect" for back-compat.)

    _.intersection = _.intersect = function(array) {

        var rest = slice.call(arguments, 1);

        return _.filter(_.uniq(array), function(item) {

            return _.every(rest, function(other) {

                return _.indexOf(other, item) >= 0;

            });

        });

    };



    // Take the difference between one array and a number of other arrays.

    // Only the elements present in just the first array will remain.

    _.difference = function(array) {

        var rest = _.flatten(slice.call(arguments, 1), true);

        return _.filter(array, function(value){ return !_.include(rest, value); });

    };



    // Zip together multiple lists into a single array -- elements that share

    // an index go together.

    _.zip = function() {

        var args = slice.call(arguments);

        var length = _.max(_.pluck(args, 'length'));

        var results = new Array(length);

        for (var i = 0; i < length; i++) results[i] = _.pluck(args, "" + i);

        return results;

    };



    // If the browser doesn't supply us with indexOf (I'm looking at you, **MSIE**),

    // we need this function. Return the position of the first occurrence of an

    // item in an array, or -1 if the item is not included in the array.

    // Delegates to **ECMAScript 5**'s native `indexOf` if available.

    // If the array is large and already in sort order, pass `true`

    // for **isSorted** to use binary search.

    _.indexOf = function(array, item, isSorted) {

        if (array == null) return -1;

        var i, l;

        if (isSorted) {

            i = _.sortedIndex(array, item);

            return array[i] === item ? i : -1;

        }

        if (nativeIndexOf && array.indexOf === nativeIndexOf) return array.indexOf(item);

        for (i = 0, l = array.length; i < l; i++) if (i in array && array[i] === item) return i;

        return -1;

    };



    // Delegates to **ECMAScript 5**'s native `lastIndexOf` if available.

    _.lastIndexOf = function(array, item) {

        if (array == null) return -1;

        if (nativeLastIndexOf && array.lastIndexOf === nativeLastIndexOf) return array.lastIndexOf(item);

        var i = array.length;

        while (i--) if (i in array && array[i] === item) return i;

        return -1;

    };



    // Generate an integer Array containing an arithmetic progression. A port of

    // the native Python `range()` function. See

    // [the Python documentation](http://docs.python.org/library/functions.html#range).

    _.range = function(start, stop, step) {

        if (arguments.length <= 1) {

            stop = start || 0;

            start = 0;

        }

        step = arguments[2] || 1;



        var len = Math.max(Math.ceil((stop - start) / step), 0);

        var idx = 0;

        var range = new Array(len);



        while(idx < len) {

            range[idx++] = start;

            start += step;

        }



        return range;

    };



    // Function (ahem) Functions

    // ------------------



    // Reusable constructor function for prototype setting.

    var ctor = function(){};



    // Create a function bound to a given object (assigning `this`, and arguments,

    // optionally). Binding with arguments is also known as `curry`.

    // Delegates to **ECMAScript 5**'s native `Function.bind` if available.

    // We check for `func.bind` first, to fail fast when `func` is undefined.

    _.bind = function bind(func, context) {

        var bound, args;

        if (func.bind === nativeBind && nativeBind) return nativeBind.apply(func, slice.call(arguments, 1));

        if (!_.isFunction(func)) throw new TypeError;

        args = slice.call(arguments, 2);

        return bound = function() {

            if (!(this instanceof bound)) return func.apply(context, args.concat(slice.call(arguments)));

            ctor.prototype = func.prototype;

            var self = new ctor;

            var result = func.apply(self, args.concat(slice.call(arguments)));

            if (Object(result) === result) return result;

            return self;

        };

    };



    // Bind all of an object's methods to that object. Useful for ensuring that

    // all callbacks defined on an object belong to it.

    _.bindAll = function(obj) {

        var funcs = slice.call(arguments, 1);

        if (funcs.length == 0) funcs = _.functions(obj);

        each(funcs, function(f) { obj[f] = _.bind(obj[f], obj); });

        return obj;

    };



    // Memoize an expensive function by storing its results.

    _.memoize = function(func, hasher) {

        var memo = {};

        hasher || (hasher = _.identity);

        return function() {

            var key = hasher.apply(this, arguments);

            return _.has(memo, key) ? memo[key] : (memo[key] = func.apply(this, arguments));

        };

    };



    // Delays a function for the given number of milliseconds, and then calls

    // it with the arguments supplied.

    _.delay = function(func, wait) {

        var args = slice.call(arguments, 2);

        return setTimeout(function(){ return func.apply(null, args); }, wait);

    };



    // Defers a function, scheduling it to run after the current call stack has

    // cleared.

    _.defer = function(func) {

        return _.delay.apply(_, [func, 1].concat(slice.call(arguments, 1)));

    };



    // Returns a function, that, when invoked, will only be triggered at most once

    // during a given window of time.

    _.throttle = function(func, wait) {

        var context, args, timeout, throttling, more, result;

        var whenDone = _.debounce(function(){ more = throttling = false; }, wait);

        return function() {

            context = this; args = arguments;

            var later = function() {

                timeout = null;

                if (more) func.apply(context, args);

                whenDone();

            };

            if (!timeout) timeout = setTimeout(later, wait);

            if (throttling) {

                more = true;

            } else {

                result = func.apply(context, args);

            }

            whenDone();

            throttling = true;

            return result;

        };

    };



    // Returns a function, that, as long as it continues to be invoked, will not

    // be triggered. The function will be called after it stops being called for

    // N milliseconds. If `immediate` is passed, trigger the function on the

    // leading edge, instead of the trailing.

    _.debounce = function(func, wait, immediate) {

        var timeout;

        return function() {

            var context = this, args = arguments;

            var later = function() {

                timeout = null;

                if (!immediate) func.apply(context, args);

            };

            if (immediate && !timeout) func.apply(context, args);

            clearTimeout(timeout);

            timeout = setTimeout(later, wait);

        };

    };



    // Returns a function that will be executed at most one time, no matter how

    // often you call it. Useful for lazy initialization.

    _.once = function(func) {

        var ran = false, memo;

        return function() {

            if (ran) return memo;

            ran = true;

            return memo = func.apply(this, arguments);

        };

    };



    // Returns the first function passed as an argument to the second,

    // allowing you to adjust arguments, run code before and after, and

    // conditionally execute the original function.

    _.wrap = function(func, wrapper) {

        return function() {

            var args = [func].concat(slice.call(arguments, 0));

            return wrapper.apply(this, args);

        };

    };



    // Returns a function that is the composition of a list of functions, each

    // consuming the return value of the function that follows.

    _.compose = function() {

        var funcs = arguments;

        return function() {

            var args = arguments;

            for (var i = funcs.length - 1; i >= 0; i--) {

                args = [funcs[i].apply(this, args)];

            }

            return args[0];

        };

    };



    // Returns a function that will only be executed after being called N times.

    _.after = function(times, func) {

        if (times <= 0) return func();

        return function() {

            if (--times < 1) { return func.apply(this, arguments); }

        };

    };



    // Object Functions

    // ----------------



    // Retrieve the names of an object's properties.

    // Delegates to **ECMAScript 5**'s native `Object.keys`

    _.keys = nativeKeys || function(obj) {

        if (obj !== Object(obj)) throw new TypeError('Invalid object');

        var keys = [];

        for (var key in obj) if (_.has(obj, key)) keys[keys.length] = key;

        return keys;

    };



    // Retrieve the values of an object's properties.

    _.values = function(obj) {

        return _.map(obj, _.identity);

    };



    // Return a sorted list of the function names available on the object.

    // Aliased as `methods`

    _.functions = _.methods = function(obj) {

        var names = [];

        for (var key in obj) {

            if (_.isFunction(obj[key])) names.push(key);

        }

        return names.sort();

    };



    // Extend a given object with all the properties in passed-in object(s).

    _.extend = function(obj) {

        each(slice.call(arguments, 1), function(source) {

            for (var prop in source) {

                obj[prop] = source[prop];

            }

        });

        return obj;

    };



    // Return a copy of the object only containing the whitelisted properties.

    _.pick = function(obj) {

        var result = {};

        each(_.flatten(slice.call(arguments, 1)), function(key) {

            if (key in obj) result[key] = obj[key];

        });

        return result;

    };



    // Fill in a given object with default properties.

    _.defaults = function(obj) {

        each(slice.call(arguments, 1), function(source) {

            for (var prop in source) {

                if (obj[prop] == null) obj[prop] = source[prop];

            }

        });

        return obj;

    };



    // Create a (shallow-cloned) duplicate of an object.

    _.clone = function(obj) {

        if (!_.isObject(obj)) return obj;

        return _.isArray(obj) ? obj.slice() : _.extend({}, obj);

    };



    // Invokes interceptor with the obj, and then returns obj.

    // The primary purpose of this method is to "tap into" a method chain, in

    // order to perform operations on intermediate results within the chain.

    _.tap = function(obj, interceptor) {

        interceptor(obj);

        return obj;

    };



    // Internal recursive comparison function.

    function eq(a, b, stack) {

        // Identical objects are equal. `0 === -0`, but they aren't identical.

        // See the Harmony `egal` proposal: http://wiki.ecmascript.org/doku.php?id=harmony:egal.

        if (a === b) return a !== 0 || 1 / a == 1 / b;

        // A strict comparison is necessary because `null == undefined`.

        if (a == null || b == null) return a === b;

        // Unwrap any wrapped objects.

        if (a._chain) a = a._wrapped;

        if (b._chain) b = b._wrapped;

        // Invoke a custom `isEqual` method if one is provided.

        if (a.isEqual && _.isFunction(a.isEqual)) return a.isEqual(b);

        if (b.isEqual && _.isFunction(b.isEqual)) return b.isEqual(a);

        // Compare `[[Class]]` names.

        var className = toString.call(a);

        if (className != toString.call(b)) return false;

        switch (className) {

            // Strings, numbers, dates, and booleans are compared by value.

            case '[object String]':

                // Primitives and their corresponding object wrappers are equivalent; thus, `"5"` is

                // equivalent to `new String("5")`.

                return a == String(b);

            case '[object Number]':

                // `NaN`s are equivalent, but non-reflexive. An `egal` comparison is performed for

                // other numeric values.

                return a != +a ? b != +b : (a == 0 ? 1 / a == 1 / b : a == +b);

            case '[object Date]':

            case '[object Boolean]':

                // Coerce dates and booleans to numeric primitive values. Dates are compared by their

                // millisecond representations. Note that invalid dates with millisecond representations

                // of `NaN` are not equivalent.

                return +a == +b;

            // RegExps are compared by their source patterns and flags.

            case '[object RegExp]':

                return a.source == b.source &&

                    a.global == b.global &&

                    a.multiline == b.multiline &&

                    a.ignoreCase == b.ignoreCase;

        }

        if (typeof a != 'object' || typeof b != 'object') return false;

        // Assume equality for cyclic structures. The algorithm for detecting cyclic

        // structures is adapted from ES 5.1 section 15.12.3, abstract operation `JO`.

        var length = stack.length;

        while (length--) {

            // Linear search. Performance is inversely proportional to the number of

            // unique nested structures.

            if (stack[length] == a) return true;

        }

        // Add the first object to the stack of traversed objects.

        stack.push(a);

        var size = 0, result = true;

        // Recursively compare objects and arrays.

        if (className == '[object Array]') {

            // Compare array lengths to determine if a deep comparison is necessary.

            size = a.length;

            result = size == b.length;

            if (result) {

                // Deep compare the contents, ignoring non-numeric properties.

                while (size--) {

                    // Ensure commutative equality for sparse arrays.

                    if (!(result = size in a == size in b && eq(a[size], b[size], stack))) break;

                }

            }

        } else {

            // Objects with different constructors are not equivalent.

            if ('constructor' in a != 'constructor' in b || a.constructor != b.constructor) return false;

            // Deep compare objects.

            for (var key in a) {

                if (_.has(a, key)) {

                    // Count the expected number of properties.

                    size++;

                    // Deep compare each member.

                    if (!(result = _.has(b, key) && eq(a[key], b[key], stack))) break;

                }

            }

            // Ensure that both objects contain the same number of properties.

            if (result) {

                for (key in b) {

                    if (_.has(b, key) && !(size--)) break;

                }

                result = !size;

            }

        }

        // Remove the first object from the stack of traversed objects.

        stack.pop();

        return result;

    }



    // Perform a deep comparison to check if two objects are equal.

    _.isEqual = function(a, b) {

        return eq(a, b, []);

    };



    // Is a given array, string, or object empty?

    // An "empty" object has no enumerable own-properties.

    _.isEmpty = function(obj) {

        if (obj == null) return true;

        if (_.isArray(obj) || _.isString(obj)) return obj.length === 0;

        for (var key in obj) if (_.has(obj, key)) return false;

        return true;

    };



    // Is a given value a DOM element?

    _.isElement = function(obj) {

        return !!(obj && obj.nodeType == 1);

    };



    // Is a given value an array?

    // Delegates to ECMA5's native Array.isArray

    _.isArray = nativeIsArray || function(obj) {

        return toString.call(obj) == '[object Array]';

    };



    // Is a given variable an object?

    _.isObject = function(obj) {

        return obj === Object(obj);

    };



    // Is a given variable an arguments object?

    _.isArguments = function(obj) {

        return toString.call(obj) == '[object Arguments]';

    };

    if (!_.isArguments(arguments)) {

        _.isArguments = function(obj) {

            return !!(obj && _.has(obj, 'callee'));

        };

    }



    // Is a given value a function?

    _.isFunction = function(obj) {

        return toString.call(obj) == '[object Function]';

    };



    // Is a given value a string?

    _.isString = function(obj) {

        return toString.call(obj) == '[object String]';

    };



    // Is a given value a number?

    _.isNumber = function(obj) {

        return toString.call(obj) == '[object Number]';

    };



    // Is a given object a finite number?

    _.isFinite = function(obj) {

        return _.isNumber(obj) && isFinite(obj);

    };



    // Is the given value `NaN`?

    _.isNaN = function(obj) {

        // `NaN` is the only value for which `===` is not reflexive.

        return obj !== obj;

    };



    // Is a given value a boolean?

    _.isBoolean = function(obj) {

        return obj === true || obj === false || toString.call(obj) == '[object Boolean]';

    };



    // Is a given value a date?

    _.isDate = function(obj) {

        return toString.call(obj) == '[object Date]';

    };



    // Is the given value a regular expression?

    _.isRegExp = function(obj) {

        return toString.call(obj) == '[object RegExp]';

    };



    // Is a given value equal to null?

    _.isNull = function(obj) {

        return obj === null;

    };



    // Is a given variable undefined?

    _.isUndefined = function(obj) {

        return obj === void 0;

    };



    // Has own property?

    _.has = function(obj, key) {

        return hasOwnProperty.call(obj, key);

    };



    // Utility Functions

    // -----------------



    // Run Underscore.js in *noConflict* mode, returning the `_` variable to its

    // previous owner. Returns a reference to the Underscore object.

    _.noConflict = function() {

        root._ = previousUnderscore;

        return this;

    };



    // Keep the identity function around for default iterators.

    _.identity = function(value) {

        return value;

    };



    // Run a function **n** times.

    _.times = function (n, iterator, context) {

        for (var i = 0; i < n; i++) iterator.call(context, i);

    };



    // Escape a string for HTML interpolation.

    _.escape = function(string) {

        return (''+string).replace(/&/g, '&amp;').replace(/</g, '&lt;').replace(/>/g, '&gt;').replace(/"/g, '&quot;').replace(/'/g, '&#x27;').replace(/\//g,'&#x2F;');

    };



    // If the value of the named property is a function then invoke it;

    // otherwise, return it.

    _.result = function(object, property) {

        if (object == null) return null;

        var value = object[property];

        return _.isFunction(value) ? value.call(object) : value;

    };



    // Add your own custom functions to the Underscore object, ensuring that

    // they're correctly added to the OOP wrapper as well.

    _.mixin = function(obj) {

        each(_.functions(obj), function(name){

            addToWrapper(name, _[name] = obj[name]);

        });

    };



    // Generate a unique integer id (unique within the entire client session).

    // Useful for temporary DOM ids.

    var idCounter = 0;

    _.uniqueId = function(prefix) {

        var id = idCounter++;

        return prefix ? prefix + id : id;

    };



    // By default, Underscore uses ERB-style template delimiters, change the

    // following template settings to use alternative delimiters.

    _.templateSettings = {

        evaluate    : /<%([\s\S]+?)%>/g,

        interpolate : /<%=([\s\S]+?)%>/g,

        escape      : /<%-([\s\S]+?)%>/g

    };



    // When customizing `templateSettings`, if you don't want to define an

    // interpolation, evaluation or escaping regex, we need one that is

    // guaranteed not to match.

    var noMatch = /.^/;



    // Certain characters need to be escaped so that they can be put into a

    // string literal.

    var escapes = {

        '\\': '\\',

        "'": "'",

        'r': '\r',

        'n': '\n',

        't': '\t',

        'u2028': '\u2028',

        'u2029': '\u2029'

    };



    for (var p in escapes) escapes[escapes[p]] = p;

    var escaper = /\\|'|\r|\n|\t|\u2028|\u2029/g;

    var unescaper = /\\(\\|'|r|n|t|u2028|u2029)/g;



    // Within an interpolation, evaluation, or escaping, remove HTML escaping

    // that had been previously added.

    var unescape = function(code) {

        return code.replace(unescaper, function(match, escape) {

            return escapes[escape];

        });

    };



    // JavaScript micro-templating, similar to John Resig's implementation.

    // Underscore templating handles arbitrary delimiters, preserves whitespace,

    // and correctly escapes quotes within interpolated code.

    _.template = function(text, data, settings) {

        settings = _.defaults(settings || {}, _.templateSettings);



        // Compile the template source, taking care to escape characters that

        // cannot be included in a string literal and then unescape them in code

        // blocks.

        var source = "__p+='" + text

            .replace(escaper, function(match) {

                return '\\' + escapes[match];

            })

            .replace(settings.escape || noMatch, function(match, code) {

                return "'+\n_.escape(" + unescape(code) + ")+\n'";

            })

            .replace(settings.interpolate || noMatch, function(match, code) {

                return "'+\n(" + unescape(code) + ")+\n'";

            })

            .replace(settings.evaluate || noMatch, function(match, code) {

                return "';\n" + unescape(code) + "\n;__p+='";

            }) + "';\n";



        // If a variable is not specified, place data values in local scope.

        if (!settings.variable) source = 'with(obj||{}){\n' + source + '}\n';



        source = "var __p='';" +

            "var print=function(){__p+=Array.prototype.join.call(arguments, '')};\n" +

            source + "return __p;\n";



        var render = new Function(settings.variable || 'obj', '_', source);

        if (data) return render(data, _);

        var template = function(data) {

            return render.call(this, data, _);

        };



        // Provide the compiled function source as a convenience for build time

        // precompilation.

        template.source = 'function(' + (settings.variable || 'obj') + '){\n' +

            source + '}';



        return template;

    };



    // Add a "chain" function, which will delegate to the wrapper.

    _.chain = function(obj) {

        return _(obj).chain();

    };



    // The OOP Wrapper

    // ---------------



    // If Underscore is called as a function, it returns a wrapped object that

    // can be used OO-style. This wrapper holds altered versions of all the

    // underscore functions. Wrapped objects may be chained.

    var wrapper = function(obj) { this._wrapped = obj; };



    // Expose `wrapper.prototype` as `_.prototype`

    _.prototype = wrapper.prototype;



    // Helper function to continue chaining intermediate results.

    var result = function(obj, chain) {

        return chain ? _(obj).chain() : obj;

    };



    // A method to easily add functions to the OOP wrapper.

    var addToWrapper = function(name, func) {

        wrapper.prototype[name] = function() {

            var args = slice.call(arguments);

            unshift.call(args, this._wrapped);

            return result(func.apply(_, args), this._chain);

        };

    };



    // Add all of the Underscore functions to the wrapper object.

    _.mixin(_);



    // Add all mutator Array functions to the wrapper.

    each(['pop', 'push', 'reverse', 'shift', 'sort', 'splice', 'unshift'], function(name) {

        var method = ArrayProto[name];

        wrapper.prototype[name] = function() {

            var wrapped = this._wrapped;

            method.apply(wrapped, arguments);

            var length = wrapped.length;

            if ((name == 'shift' || name == 'splice') && length === 0) delete wrapped[0];

            return result(wrapped, this._chain);

        };

    });



    // Add all accessor Array functions to the wrapper.

    each(['concat', 'join', 'slice'], function(name) {

        var method = ArrayProto[name];

        wrapper.prototype[name] = function() {

            return result(method.apply(this._wrapped, arguments), this._chain);

        };

    });



    // Start chaining a wrapped Underscore object.

    wrapper.prototype.chain = function() {

        this._chain = true;

        return this;

    };



    // Extracts the result from a wrapped and chained object.

    wrapper.prototype.value = function() {

        return this._wrapped;

    };



}).call(this);





_.templateSettings = {

  interpolate : /\{\{(.+?)\}\}/g

};