// © 2010 Jeremy Ashkenas, DocumentCloud Inc. // Underscore is freely distributable under the terms of the MIT license. // Portions of Underscore are inspired by or borrowed from Prototype.js, // Oliver Steele's Functional, and John Resig's Micro-Templating. // For all details and documentation: // 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 thrown to break out of a loop iteration.
var breaker = typeof StopIteration !== 'undefined' ? StopIteration : '__break__';

// Quick regexp-escaping function, because JS doesn't have a `RegExp.escape()`.
var escapeRegExp = function(s) { return s.replace(/([.*+?^${}()|[\]\/\\])/g, '\\$1'); };

// Save bytes in the minified (but not gzipped) version:
var ArrayProto = Array.prototype, ObjProto = Object.prototype;

// Create quick reference variables for speed access to core prototypes.
var slice                 = ArrayProto.slice,
    unshift               = ArrayProto.unshift,
    toString              = ObjProto.toString,
    hasOwnProperty        = ObjProto.hasOwnProperty,
    propertyIsEnumerable  = ObjProto.propertyIsEnumerable;

// 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;

// Create a safe reference to the Underscore object for use below.
var _ = function(obj) { return new wrapper(obj); };

// Export the Underscore object for **CommonJS**.
if (typeof exports !== 'undefined') exports._ = _;

// Export Underscore to the global scope.
root._ = _;

// Current version.
_.VERSION = '1.1.1';

// Collection Functions
// --------------------

// The cornerstone, an `each` implementation.
// Handles objects implementing `forEach`, arrays, and raw objects.
// Delegates to **ECMAScript 5**'s native `forEach` if available.
var each = _.forEach = function(obj, iterator, context) {
  try {
    if (nativeForEach && obj.forEach === nativeForEach) {
      obj.forEach(iterator, context);
    } else if (_.isNumber(obj.length)) {
      for (var i = 0, l = obj.length; i < l; i++) iterator.call(context, obj[i], i, obj);
    } else {
      for (var key in obj) {
        if (hasOwnProperty.call(obj, key)) iterator.call(context, obj[key], key, obj);
      }
    }
  } catch(e) {
    if (e != breaker) throw e;
  }
  return obj;
};

// Return the results of applying the iterator to each element.
// Delegates to **ECMAScript 5**'s native `map` if available.
_.map = function(obj, iterator, context) {
  if (nativeMap && obj.map === nativeMap) return obj.map(iterator, context);
  var results = [];
  each(obj, function(value, index, list) {
    results[results.length] = iterator.call(context, value, index, list);
  });
  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 = function(obj, iterator, memo, context) {
  if (nativeReduce && obj.reduce === nativeReduce) {
    if (context) iterator = _.bind(iterator, context);
    return obj.reduce(iterator, memo);
  }
  each(obj, function(value, index, list) {
    memo = iterator.call(context, memo, value, index, list);
  });
  return memo;
};

// The right-associative version of reduce, also known as `foldr`. Uses
// Delegates to **ECMAScript 5**'s native reduceRight if available.
_.reduceRight = function(obj, iterator, memo, context) {
  if (nativeReduceRight && obj.reduceRight === nativeReduceRight) {
    if (context) iterator = _.bind(iterator, context);
    return obj.reduceRight(iterator, memo);
  }
  var reversed = _.clone(_.toArray(obj)).reverse();
  return _.reduce(reversed, iterator, memo, context);
};

// Return the first value which passes a truth test.
_.detect = function(obj, iterator, context) {
  var result;
  each(obj, function(value, index, list) {
    if (iterator.call(context, value, index, list)) {
      result = value;
      _.breakLoop();
    }
  });
  return result;
};

// Return all the elements that pass a truth test.
// Delegates to **ECMAScript 5**'s native `filter` if available.
_.filter = function(obj, iterator, context) {
  if (nativeFilter && obj.filter === nativeFilter) return obj.filter(iterator, context);
  var results = [];
  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 = [];
  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.
_.every = function(obj, iterator, context) {
  iterator = iterator || _.identity;
  if (nativeEvery && obj.every === nativeEvery) return obj.every(iterator, context);
  var result = true;
  each(obj, function(value, index, list) {
    if (!(result = result && iterator.call(context, value, index, list))) _.breakLoop();
  });
  return result;
};

// Determine if at least one element in the object matches a truth test.
// Delegates to **ECMAScript 5**'s native `some` if available.
_.some = function(obj, iterator, context) {
  iterator = iterator || _.identity;
  if (nativeSome && obj.some === nativeSome) return obj.some(iterator, context);
  var result = false;
  each(obj, function(value, index, list) {
    if (result = iterator.call(context, value, index, list)) _.breakLoop();
  });
  return result;
};

// Determine if a given value is included in the array or object using `===`.
_.include = function(obj, target) {
  if (nativeIndexOf && obj.indexOf === nativeIndexOf) return obj.indexOf(target) != -1;
  var found = false;
  each(obj, function(value) {
    if (found = value === target) _.breakLoop();
  });
  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 (method ? value[method] : value).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)) return Math.max.apply(Math, obj);
  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)) return Math.min.apply(Math, obj);
  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;
};

// Sort the object's values by a criterion produced by an iterator.
_.sortBy = function(obj, iterator, context) {
  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;
    return a < b ? -1 : a > b ? 1 : 0;
  }), 'value');
};

// 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(iterable) {
  if (!iterable)                return [];
  if (iterable.toArray)         return iterable.toArray();
  if (_.isArray(iterable))      return iterable;
  if (_.isArguments(iterable))  return slice.call(iterable);
  return _.values(iterable);
};

// Return the number of elements in an object.
_.size = function(obj) {
  return _.toArray(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`. The **guard** check allows it to work
// with `_.map`.
_.first = function(array, n, guard) {
  return n && !guard ? slice.call(array, 0, n) : array[0];
};

// 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 = function(array, index, guard) {
  return slice.call(array, _.isUndefined(index) || guard ? 1 : index);
};

// Get the last element of an array.
_.last = function(array) {
  return array[array.length - 1];
};

// 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) {
  return _.reduce(array, function(memo, value) {
    if (_.isArray(value)) return memo.concat(_.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) {
  var values = slice.call(arguments, 1);
  return _.filter(array, function(value){ return !_.include(values, value); });
};

// Produce a duplicate-free version of the array. If the array has already
// been sorted, you have the option of using a faster algorithm.
_.uniq = function(array, isSorted) {
  return _.reduce(array, function(memo, el, i) {
    if (0 == i || (isSorted === true ? _.last(memo) != el : !_.include(memo, el))) memo[memo.length] = el;
    return memo;
  }, []);
};

// Produce an array that contains every item shared between all the
// passed-in arrays.
_.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;
    });
  });
};

// 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 occurence 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.
_.indexOf = function(array, item) {
  if (nativeIndexOf && array.indexOf === nativeIndexOf) return array.indexOf(item);
  for (var i = 0, l = array.length; i < l; i++) if (array[i] === item) return i;
  return -1;
};

// Delegates to **ECMAScript 5**'s native `lastIndexOf` if available.
_.lastIndexOf = function(array, item) {
  if (nativeLastIndexOf && array.lastIndexOf === nativeLastIndexOf) return array.lastIndexOf(item);
  var i = array.length;
  while (i--) if (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) {
  var a     = slice.call(arguments);
  var solo  = a.length <= 1;
  var start = solo ? 0 : a[0], stop = solo ? a[0] : a[1], step = a[2] || 1;
  var len   = Math.ceil((stop - start) / step);
  if (len <= 0) return [];
  var range = new Array(len);
  for (var i = start, idx = 0; true; i += step) {
    if ((step > 0 ? i - stop : stop - i) >= 0) return range;
    range[idx++] = i;
  }
};

// Function Functions
// ------------------

// Create a function bound to a given object (assigning `this`, and arguments,
// optionally). Binding with arguments is also known as `curry`.
_.bind = function(func, obj) {
  var args = slice.call(arguments, 2);
  return function() {
    return func.apply(obj || {}, args.concat(slice.call(arguments)));
  };
};

// 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 key in memo ? 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(func, 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 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));
    return wrapper.apply(wrapper, 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 = slice.call(arguments);
  return function() {
    var args = slice.call(arguments);
    for (var i=funcs.length-1; i >= 0; i--) {
      args = [funcs[i].apply(this, args)];
    }
    return args[0];
  };
};

// Object Functions
// ----------------

// Retrieve the names of an object's properties.
// Delegates to **ECMAScript 5**'s native `Object.keys`
_.keys = nativeKeys || function(obj) {
  if (_.isArray(obj)) return _.range(0, obj.length);
  var keys = [];
  for (var key in obj) if (hasOwnProperty.call(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.
_.functions = function(obj) {
  return _.filter(_.keys(obj), function(key){ return _.isFunction(obj[key]); }).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;
};

// Create a (shallow-cloned) duplicate of an object.
_.clone = function(obj) {
  if (_.isArray(obj)) return obj.slice(0);
  return _.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;
};

// Perform a deep comparison to check if two objects are equal.
_.isEqual = function(a, b) {
  // Check object identity.
  if (a === b) return true;
  // Different types?
  var atype = typeof(a), btype = typeof(b);
  if (atype != btype) return false;
  // Basic equality test (watch out for coercions).
  if (a == b) return true;
  // One is falsy and the other truthy.
  if ((!a && b) || (a && !b)) return false;
  // One of them implements an isEqual()?
  if (a.isEqual) return a.isEqual(b);
  // Check dates' integer values.
  if (_.isDate(a) && _.isDate(b)) return a.getTime() === b.getTime();
  // Both are NaN?
  if (_.isNaN(a) && _.isNaN(b)) return false;
  // Compare regular expressions.
  if (_.isRegExp(a) && _.isRegExp(b))
    return a.source     === b.source &&
           a.global     === b.global &&
           a.ignoreCase === b.ignoreCase &&
           a.multiline  === b.multiline;
  // If a is not an object by this point, we can't handle it.
  if (atype !== 'object') return false;
  // Check for different array lengths before comparing contents.
  if (a.length && (a.length !== b.length)) return false;
  // Nothing else worked, deep compare the contents.
  var aKeys = _.keys(a), bKeys = _.keys(b);
  // Different object sizes?
  if (aKeys.length != bKeys.length) return false;
  // Recursive comparison of contents.
  for (var key in a) if (!(key in b) || !_.isEqual(a[key], b[key])) return false;
  return true;
};

// Is a given array or object empty?
_.isEmpty = function(obj) {
  if (_.isArray(obj) || _.isString(obj)) return obj.length === 0;
  for (var key in obj) if (hasOwnProperty.call(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 !!(obj && obj.concat && obj.unshift && !obj.callee);
};

// Is a given variable an arguments object?
_.isArguments = function(obj) {
  return !!(obj && obj.callee);
};

// Is a given value a function?
_.isFunction = function(obj) {
  return !!(obj && obj.constructor && obj.call && obj.apply);
};

// Is a given value a string?
_.isString = function(obj) {
  return !!(obj === '' || (obj && obj.charCodeAt && obj.substr));
};

// Is a given value a number?
_.isNumber = function(obj) {
  return (obj === +obj) || (toString.call(obj) === '[object Number]');
};

// Is a given value a boolean?
_.isBoolean = function(obj) {
  return obj === true || obj === false;
};

// Is a given value a date?
_.isDate = function(obj) {
  return !!(obj && obj.getTimezoneOffset && obj.setUTCFullYear);
};

// Is the given value a regular expression?
_.isRegExp = function(obj) {
  return !!(obj && obj.test && obj.exec && (obj.ignoreCase || obj.ignoreCase === false));
};

// Is the given value NaN -- this one is interesting. NaN != NaN, and
// isNaN(undefined) == true, so we make sure it's a number first.
_.isNaN = function(obj) {
  return _.isNumber(obj) && isNaN(obj);
};

// Is a given value equal to null?
_.isNull = function(obj) {
  return obj === null;
};

// Is a given variable undefined?
_.isUndefined = function(obj) {
  return typeof obj == 'undefined';
};

// 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);
};

// Break out of the middle of an iteration.
_.breakLoop = function() {
  throw breaker;
};

// 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
};

// 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(str, data) {
  var c  = _.templateSettings;
  var tmpl = 'var __p=[],print=function(){__p.push.apply(__p,arguments);};' +
    'with(obj||{}){__p.push(\'' +
    str.replace(/'/g, "\\'")
       .replace(c.interpolate, function(match, code) {
         return "'," + code.replace(/\\'/g, "'") + ",'";
       })
       .replace(c.evaluate || null, function(match, code) {
         return "');" + code.replace(/\\'/g, "'")
                            .replace(/[\r\n\t]/g, ' ') + "__p.push('";
       })
       .replace(/\r/g, '\\r')
       .replace(/\n/g, '\\n')
       .replace(/\t/g, '\\t')
       + "');}return __p.join('');";
  var func = new Function('obj', tmpl);
  return data ? func(data) : func;
};

// Aliases:
// --------

_.each     = _.forEach;
_.foldl    = _.inject       = _.reduce;
_.foldr    = _.reduceRight;
_.select   = _.filter;
_.all      = _.every;
_.any      = _.some;
_.contains = _.include;
_.head     = _.first;
_.tail     = _.rest;
_.methods  = _.functions;

// 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; };

// 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() {
    method.apply(this._wrapped, arguments);
    return result(this._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;
};

})();