lodash.js

/*!
 * Lo-Dash v0.4.2 <http://lodash.com>
 * Copyright 2012 John-David Dalton <http://allyoucanleet.com/>
 * Based on Underscore.js 1.3.3, copyright 2009-2012 Jeremy Ashkenas, DocumentCloud Inc.
 * <http://documentcloud.github.com/underscore>
 * Available under MIT license <http://lodash.com/license>
 */
;(function(window, undefined) {
  'use strict';

  /**
   * Used to cache the last `_.templateSettings.evaluate` delimiter to avoid
   * unnecessarily assigning `reEvaluateDelimiter` a new generated regexp.
   * Assigned in `_.template`.
   */
  var lastEvaluateDelimiter;

  /**
   * Used to cache the last template `options.variable` to avoid unnecessarily
   * assigning `reDoubleVariable` a new generated regexp. Assigned in `_.template`.
   */
  var lastVariable;

  /**
   * Used to match potentially incorrect data object references, like `obj.obj`,
   * in compiled templates. Assigned in `_.template`.
   */
  var reDoubleVariable;

  /**
   * Used to match "evaluate" delimiters, including internal delimiters,
   * in template text. Assigned in `_.template`.
   */
  var reEvaluateDelimiter;

  /** Detect free variable `exports` */
  var freeExports = typeof exports == 'object' && exports &&
    (typeof global == 'object' && global && global == global.global && (window = global), exports);

  /** Native prototype shortcuts */
  var ArrayProto = Array.prototype,
      BoolProto = Boolean.prototype,
      ObjectProto = Object.prototype,
      NumberProto = Number.prototype,
      StringProto = String.prototype;

  /** Used to generate unique IDs */
  var idCounter = 0;

  /** Used to restore the original `_` reference in `noConflict` */
  var oldDash = window._;

  /** Used to detect delimiter values that should be processed by `tokenizeEvaluate` */
  var reComplexDelimiter = /[-+=!~*%&^<>|{(\/]|\[\D|\b(?:delete|in|instanceof|new|typeof|void)\b/;

  /** Used to match empty string literals in compiled template source */
  var reEmptyStringLeading = /\b__p \+= '';/g,
      reEmptyStringMiddle = /\b(__p \+=) '' \+/g,
      reEmptyStringTrailing = /(__e\(.*?\)|\b__t\)) \+\n'';/g;

  /** Used to match regexp flags from their coerced string values */
  var reFlags = /\w*$/;

  /** Used to insert the data object variable into compiled template source */
  var reInsertVariable = /(?:__e|__t = )\(\s*(?![\d\s"']|this\.)/g;

  /** Used to detect if a method is native */
  var reNative = RegExp('^' +
    (ObjectProto.valueOf + '')
      .replace(/[.*+?^=!:${}()|[\]\/\\]/g, '\\$&')
      .replace(/valueOf|for [^\]]+/g, '.+?') + '$'
  );

  /** Used to match tokens in template text */
  var reToken = /__token__(\d+)/g;

  /** Used to match unescaped characters in strings for inclusion in HTML */
  var reUnescapedHtml = /[&<"']/g;

  /** Used to match unescaped characters in compiled string literals */
  var reUnescapedString = /['\n\r\t\u2028\u2029\\]/g;

  /** Used to fix the JScript [[DontEnum]] bug */
  var shadowed = [
    'constructor', 'hasOwnProperty', 'isPrototypeOf', 'propertyIsEnumerable',
    'toLocaleString', 'toString', 'valueOf'
  ];

  /** Used to make template sourceURLs easier to identify */
  var templateCounter = 0;

  /** Used to replace template delimiters */
  var token = '__token__';

  /** Used to store tokenized template text snippets */
  var tokenized = [];

  /** Native method shortcuts */
  var concat = ArrayProto.concat,
      hasOwnProperty = ObjectProto.hasOwnProperty,
      push = ArrayProto.push,
      propertyIsEnumerable = ObjectProto.propertyIsEnumerable,
      slice = ArrayProto.slice,
      toString = ObjectProto.toString;

  /* Native method shortcuts for methods with the same name as other `lodash` methods */
  var nativeBind = reNative.test(nativeBind = slice.bind) && nativeBind,
      nativeIsArray = reNative.test(nativeIsArray = Array.isArray) && nativeIsArray,
      nativeIsFinite = window.isFinite,
      nativeKeys = reNative.test(nativeKeys = Object.keys) && nativeKeys;

  /** `Object#toString` result shortcuts */
  var argsClass = '[object Arguments]',
      arrayClass = '[object Array]',
      boolClass = '[object Boolean]',
      dateClass = '[object Date]',
      funcClass = '[object Function]',
      numberClass = '[object Number]',
      objectClass = '[object Object]',
      regexpClass = '[object RegExp]',
      stringClass = '[object String]';

  /** Timer shortcuts */
  var clearTimeout = window.clearTimeout,
      setTimeout = window.setTimeout;

  /**
   * Detect the JScript [[DontEnum]] bug:
   * In IE < 9 an objects own properties, shadowing non-enumerable ones, are
   * made non-enumerable as well.
   */
  var hasDontEnumBug = !propertyIsEnumerable.call({ 'valueOf': 0 }, 'valueOf');

  /** Detect if an `arguments` object's [[Class]] is unresolvable (Firefox < 4, IE < 9) */
  var noArgsClass = !isArguments(arguments);

  /** Detect if `Array#slice` cannot be used to convert strings to arrays (Opera < 10.52) */
  var noArraySliceOnStrings = slice.call('x')[0] != 'x';

  /**
   * Detect lack of support for accessing string characters by index:
   * IE < 8 can't access characters by index and IE 8 can only access
   * characters by index on string literals.
   */
  var noCharByIndex = ('x'[0] + Object('x')[0]) != 'xx';

  /** Detect if a node's [[Class]] is unresolvable (IE < 9) */
  var noNodeClass = toString.call(window.document || {}) == objectClass;

  /* Detect if `Function#bind` exists and is inferred to be fast (all but V8) */
  var isBindFast = nativeBind && /\n|Opera/.test(nativeBind + toString.call(window.opera));

  /* Detect if `Object.keys` exists and is inferred to be fast (IE, Opera, V8) */
  var isKeysFast = nativeKeys && /^.+$|true/.test(nativeKeys + !!window.attachEvent);

  /** Detect if sourceURL syntax is usable without erroring */
  try {
    // The JS engine in Adobe products, like InDesign, will throw a syntax error
    // when it encounters a single line comment beginning with the `@` symbol.
    // The JS engine in Narwhal will generate the function `function anonymous(){//}`
    // and throw a syntax error. In IE, `@` symbols are part of its non-standard
    // conditional compilation support. The `@cc_on` statement activates its
    // support while the trailing `!` induces a syntax error to exlude it.
    // See http://msdn.microsoft.com/en-us/library/121hztk3(v=vs.94).aspx
    var useSourceURL = (Function('//@cc_on!')(), true);
  } catch(e){ }

  /** Used to identify object classifications that are array-like */
  var arrayLikeClasses = {};
  arrayLikeClasses[boolClass] = arrayLikeClasses[dateClass] = arrayLikeClasses[funcClass] =
  arrayLikeClasses[numberClass] = arrayLikeClasses[objectClass] = arrayLikeClasses[regexpClass] = false;
  arrayLikeClasses[argsClass] = arrayLikeClasses[arrayClass] = arrayLikeClasses[stringClass] = true;

  /** Used to identify object classifications that `_.clone` supports */
  var cloneableClasses = {};
  cloneableClasses[argsClass] = cloneableClasses[funcClass] = false;
  cloneableClasses[arrayClass] = cloneableClasses[boolClass] = cloneableClasses[dateClass] =
  cloneableClasses[numberClass] = cloneableClasses[objectClass] = cloneableClasses[regexpClass] =
  cloneableClasses[stringClass] = true;

  /**
   * Used to escape characters for inclusion in HTML.
   * The `>` and `/` characters don't require escaping in HTML and have no
   * special meaning unless they're part of a tag or an unquoted attribute value
   * http://mathiasbynens.be/notes/ambiguous-ampersands (semi-related fun fact)
   */
  var htmlEscapes = {
    '&': '&amp;',
    '<': '&lt;',
    '"': '&quot;',
    "'": '&#x27;'
  };

  /** Used to determine if values are of the language type Object */
  var objectTypes = {
    'boolean': false,
    'function': true,
    'object': true,
    'number': false,
    'string': false,
    'undefined': false,
    'unknown': true
  };

  /** Used to escape characters for inclusion in compiled string literals */
  var stringEscapes = {
    '\\': '\\',
    "'": "'",
    '\n': 'n',
    '\r': 'r',
    '\t': 't',
    '\u2028': 'u2028',
    '\u2029': 'u2029'
  };

  /*--------------------------------------------------------------------------*/

  /**
   * The `lodash` function.
   *
   * @name _
   * @constructor
   * @param {Mixed} value The value to wrap in a `LoDash` instance.
   * @returns {Object} Returns a `LoDash` instance.
   */
  function lodash(value) {
    // allow invoking `lodash` without the `new` operator
    return new LoDash(value);
  }

  /**
   * Creates a `LoDash` instance that wraps a value to allow chaining.
   *
   * @private
   * @constructor
   * @param {Mixed} value The value to wrap.
   */
  function LoDash(value) {
    // exit early if already wrapped
    if (value && value._wrapped) {
      return value;
    }
    this._wrapped = value;
  }

  /**
   * By default, Lo-Dash uses embedded Ruby (ERB) style template delimiters,
   * change the following template settings to use alternative delimiters.
   *
   * @static
   * @memberOf _
   * @type Object
   */
  lodash.templateSettings = {

    /**
     * Used to detect `data` property values to be HTML-escaped.
     *
     * @static
     * @memberOf _.templateSettings
     * @type RegExp
     */
    'escape': /<%-([\s\S]+?)%>/g,

    /**
     * Used to detect code to be evaluated.
     *
     * @static
     * @memberOf _.templateSettings
     * @type RegExp
     */
    'evaluate': /<%([\s\S]+?)%>/g,

    /**
     * Used to detect `data` property values to inject.
     *
     * @static
     * @memberOf _.templateSettings
     * @type RegExp
     */
    'interpolate': /<%=([\s\S]+?)%>/g,

    /**
     * Used to reference the data object in the template text.
     *
     * @static
     * @memberOf _.templateSettings
     * @type String
     */
    'variable': 'obj'
  };

  /*--------------------------------------------------------------------------*/

  /**
   * The template used to create iterator functions.
   *
   * @private
   * @param {Obect} data The data object used to populate the text.
   * @returns {String} Returns the interpolated text.
   */
  var iteratorTemplate = template(
    // conditional strict mode
   '<% if (useStrict) { %>\'use strict\';\n<% } %>' +

    // the `iteratee` may be reassigned by the `top` snippet
    'var index, value, iteratee = <%= firstArg %>, ' +
    // assign the `result` variable an initial value
    'result<% if (init) { %> = <%= init %><% } %>;\n' +
    // add code to exit early or do so if the first argument is falsey
    '<%= exit %>;\n' +
    // add code after the exit snippet but before the iteration branches
    '<%= top %>;\n' +

    // the following branch is for iterating arrays and array-like objects
    '<% if (arrayBranch) { %>' +
    'var length = iteratee.length; index = -1;' +
    '  <% if (objectBranch) { %>\nif (length === length >>> 0) {<% } %>' +

    // add support for accessing string characters by index if needed
    '  <% if (noCharByIndex) { %>\n' +
    '  if (toString.call(iteratee) == stringClass) {\n' +
    '    iteratee = iteratee.split(\'\')\n' +
    '  }' +
    '  <% } %>\n' +

    '  <%= arrayBranch.beforeLoop %>;\n' +
    '  while (++index < length) {\n' +
    '    value = iteratee[index];\n' +
    '    <%= arrayBranch.inLoop %>\n' +
    '  }' +
    '  <% if (objectBranch) { %>\n}<% } %>' +
    '<% } %>' +

    // the following branch is for iterating an object's own/inherited properties
    '<% if (objectBranch) { %>' +
    '  <% if (arrayBranch) { %>\nelse {<% } %>' +
    '  <% if (!hasDontEnumBug) { %>\n' +
    '  var skipProto = typeof iteratee == \'function\' && \n' +
    '    propertyIsEnumerable.call(iteratee, \'prototype\');\n' +
    '  <% } %>' +

    // iterate own properties using `Object.keys` if it's fast
    '  <% if (isKeysFast && useHas) { %>\n' +
    '  var ownIndex = -1,\n' +
    '      ownProps = nativeKeys(iteratee),\n' +
    '      length = ownProps.length;\n\n' +
    '  <%= objectBranch.beforeLoop %>;\n' +
    '  while (++ownIndex < length) {\n' +
    '    index = ownProps[ownIndex];\n' +
    '    if (!(skipProto && index == \'prototype\')) {\n' +
    '      value = iteratee[index];\n' +
    '      <%= objectBranch.inLoop %>\n' +
    '    }\n' +
    '  }' +

    // else using a for-in loop
    '  <% } else { %>\n' +
    '  <%= objectBranch.beforeLoop %>;\n' +
    '  for (index in iteratee) {' +
    '    <% if (hasDontEnumBug) { %>\n' +
    '    <%   if (useHas) { %>if (hasOwnProperty.call(iteratee, index)) {\n  <% } %>' +
    '    value = iteratee[index];\n' +
    '    <%= objectBranch.inLoop %>;\n' +
    '    <%   if (useHas) { %>}<% } %>' +
    '    <% } else { %>\n' +

    // Firefox < 3.6, Opera > 9.50 - Opera < 11.60, and Safari < 5.1
    // (if the prototype or a property on the prototype has been set)
    // incorrectly sets a function's `prototype` property [[Enumerable]]
    // value to `true`. Because of this Lo-Dash standardizes on skipping
    // the the `prototype` property of functions regardless of its
    // [[Enumerable]] value.
    '    if (!(skipProto && index == \'prototype\')<% if (useHas) { %> &&\n' +
    '        hasOwnProperty.call(iteratee, index)<% } %>) {\n' +
    '      value = iteratee[index];\n' +
    '      <%= objectBranch.inLoop %>\n' +
    '    }' +
    '    <% } %>\n' +
    '  }' +
    '  <% } %>' +

    // Because IE < 9 can't set the `[[Enumerable]]` attribute of an
    // existing property and the `constructor` property of a prototype
    // defaults to non-enumerable, Lo-Dash skips the `constructor`
    // property when it infers it's iterating over a `prototype` object.
    '  <% if (hasDontEnumBug) { %>\n\n' +
    '  var ctor = iteratee.constructor;\n' +
    '    <% for (var k = 0; k < 7; k++) { %>\n' +
    '  index = \'<%= shadowed[k] %>\';\n' +
    '  if (<%' +
    '      if (shadowed[k] == \'constructor\') {' +
    '        %>!(ctor && ctor.prototype === iteratee) && <%' +
    '      } %>hasOwnProperty.call(iteratee, index)) {\n' +
    '    value = iteratee[index];\n' +
    '    <%= objectBranch.inLoop %>\n' +
    '  }' +
    '    <% } %>' +
    '  <% } %>' +
    '  <% if (arrayBranch) { %>\n}<% } %>' +
    '<% } %>\n' +

    // add code to the bottom of the iteration function
    '<%= bottom %>;\n' +
    // finally, return the `result`
    'return result'
  );

  /**
   * Reusable iterator options shared by
   * `every`, `filter`, `find`, `forEach`, `forIn`, `forOwn`, `groupBy`, `map`,
   * `reject`, `some`, and `sortBy`.
   */
  var baseIteratorOptions = {
    'args': 'collection, callback, thisArg',
    'init': 'collection',
    'top':
      'if (!callback) {\n' +
      '  callback = identity\n' +
      '}\n' +
      'else if (thisArg) {\n' +
      '  callback = iteratorBind(callback, thisArg)\n' +
      '}',
    'inLoop': 'callback(value, index, collection)'
  };

  /** Reusable iterator options for `countBy`, `groupBy`, and `sortBy` */
  var countByIteratorOptions = {
    'init': '{}',
    'top':
      'var prop;\n' +
      'if (typeof callback != \'function\') {\n' +
      '  var valueProp = callback;\n' +
      '  callback = function(value) { return value[valueProp] }\n' +
      '}\n' +
      'else if (thisArg) {\n' +
      '  callback = iteratorBind(callback, thisArg)\n' +
      '}',
    'inLoop':
      'prop = callback(value, index, collection);\n' +
      '(hasOwnProperty.call(result, prop) ? result[prop]++ : result[prop] = 1)'
  };

  /** Reusable iterator options for `every` and `some` */
  var everyIteratorOptions = {
    'init': 'true',
    'inLoop': 'if (!callback(value, index, collection)) return !result'
  };

  /** Reusable iterator options for `defaults` and `extend` */
  var extendIteratorOptions = {
    'useHas': false,
    'useStrict': false,
    'args': 'object',
    'init': 'object',
    'top':
      'for (var iterateeIndex = 1, length = arguments.length; iterateeIndex < length; iterateeIndex++) {\n' +
      '  iteratee = arguments[iterateeIndex];\n' +
      (hasDontEnumBug ? '  if (iteratee) {' : ''),
    'inLoop': 'result[index] = value',
    'bottom': (hasDontEnumBug ? '  }\n' : '') + '}'
  };

  /** Reusable iterator options for `filter`, `reject`, and `where` */
  var filterIteratorOptions = {
    'init': '[]',
    'inLoop': 'callback(value, index, collection) && result.push(value)'
  };

  /** Reusable iterator options for `find`, `forEach`, `forIn`, and `forOwn` */
  var forEachIteratorOptions = {
    'top': 'if (thisArg) callback = iteratorBind(callback, thisArg)'
  };

  /** Reusable iterator options for `forIn` and `forOwn` */
  var forOwnIteratorOptions = {
    'inLoop': {
      'object': baseIteratorOptions.inLoop
    }
  };

  /** Reusable iterator options for `invoke`, `map`, `pluck`, and `sortBy` */
  var mapIteratorOptions = {
    'init': '',
    'exit': 'if (!collection) return []',
    'beforeLoop': {
      'array':  'result = Array(length)',
      'object': 'result = ' + (isKeysFast ? 'Array(length)' : '[]')
    },
    'inLoop': {
      'array':  'result[index] = callback(value, index, collection)',
      'object': 'result' + (isKeysFast ? '[ownIndex] = ' : '.push') + '(callback(value, index, collection))'
    }
  };

  /*--------------------------------------------------------------------------*/

  /**
   * Creates a new function optimized for searching large arrays for a given `value`,
   * starting at `fromIndex`, using strict equality for comparisons, i.e. `===`.
   *
   * @private
   * @param {Array} array The array to search.
   * @param {Mixed} value The value to search for.
   * @param {Number} [fromIndex=0] The index to start searching from.
   * @param {Number} [largeSize=30] The length at which an array is considered large.
   * @returns {Boolean} Returns `true` if `value` is found, else `false`.
   */
  function cachedContains(array, fromIndex, largeSize) {
    fromIndex || (fromIndex = 0);

    var length = array.length,
        isLarge = (length - fromIndex) >= (largeSize || 30),
        cache = isLarge ? {} : array;

    if (isLarge) {
      // init value cache
      var key,
          index = fromIndex - 1;

      while (++index < length) {
        // manually coerce `value` to string because `hasOwnProperty`, in some
        // older versions of Firefox, coerces objects incorrectly
        key = array[index] + '';
        (hasOwnProperty.call(cache, key) ? cache[key] : (cache[key] = [])).push(array[index]);
      }
    }
    return function(value) {
      if (isLarge) {
        var key = value + '';
        return hasOwnProperty.call(cache, key) && indexOf(cache[key], value) > -1;
      }
      return indexOf(cache, value, fromIndex) > -1;
    }
  }

  /**
   * Creates compiled iteration functions. The iteration function will be created
   * to iterate over only objects if the first argument of `options.args` is
   * "object" or `options.inLoop.array` is falsey.
   *
   * @private
   * @param {Object} [options1, options2, ...] The compile options objects.
   *
   *  useHas - A boolean to specify whether or not to use `hasOwnProperty` checks
   *   in the object loop.
   *
   *  useStrict - A boolean to specify whether or not to include the ES5
   *   "use strict" directive.
   *
   *  args - A string of comma separated arguments the iteration function will
   *   accept.
   *
   *  init - A string to specify the initial value of the `result` variable.
   *
   *  exit - A string of code to use in place of the default exit-early check
   *   of `if (!arguments[0]) return result`.
   *
   *  top - A string of code to execute after the exit-early check but before
   *   the iteration branches.
   *
   *  beforeLoop - A string or object containing an "array" or "object" property
   *   of code to execute before the array or object loops.
   *
   *  inLoop - A string or object containing an "array" or "object" property
   *   of code to execute in the array or object loops.
   *
   *  bottom - A string of code to execute after the iteration branches but
   *   before the `result` is returned.
   *
   * @returns {Function} Returns the compiled function.
   */
  function createIterator() {
    var object,
        prop,
        value,
        index = -1,
        length = arguments.length;

    // merge options into a template data object
    var data = {
      'bottom': '',
      'exit': '',
      'init': '',
      'top': '',
      'arrayBranch': { 'beforeLoop': '' },
      'objectBranch': { 'beforeLoop': '' }
    };

    while (++index < length) {
      object = arguments[index];
      for (prop in object) {
        value = (value = object[prop]) == null ? '' : value;
        // keep this regexp explicit for the build pre-process
        if (/beforeLoop|inLoop/.test(prop)) {
          if (typeof value == 'string') {
            value = { 'array': value, 'object': value };
          }
          data.arrayBranch[prop] = value.array;
          data.objectBranch[prop] = value.object;
        } else {
          data[prop] = value;
        }
      }
    }
    // set additional template `data` values
    var args = data.args,
        firstArg = /^[^,]+/.exec(args)[0];

    data.firstArg = firstArg;
    data.hasDontEnumBug = hasDontEnumBug;
    data.isKeysFast = isKeysFast;
    data.shadowed = shadowed;
    data.useHas = data.useHas !== false;
    data.useStrict = data.useStrict !== false;

    if (!('noCharByIndex' in data)) {
      data.noCharByIndex = noCharByIndex;
    }
    if (!data.exit) {
      data.exit = 'if (!' + firstArg + ') return result';
    }
    if (firstArg != 'collection' || !data.arrayBranch.inLoop) {
      data.arrayBranch = null;
    }
    // create the function factory
    var factory = Function(
        'arrayClass, arrayLikeClasses, ArrayProto, bind, compareAscending, concat, ' +
        'forIn, funcClass, hasOwnProperty, identity, indexOf, isArguments, iteratorBind, ' +
        'objectTypes, nativeKeys, propertyIsEnumerable, slice, stringClass, toString',
      'return function(' + args + ') {\n' + iteratorTemplate(data) + '\n}'
    );
    // return the compiled function
    return factory(
      arrayClass, arrayLikeClasses, ArrayProto, bind, compareAscending, concat,
      forIn, funcClass, hasOwnProperty, identity, indexOf, isArguments, iteratorBind,
      objectTypes, nativeKeys, propertyIsEnumerable, slice, stringClass, toString
    );
  }

  /**
   * Used by `sortBy` to compare transformed values of `collection`, sorting
   * them in ascending order.
   *
   * @private
   * @param {Object} a The object to compare to `b`.
   * @param {Object} b The object to compare to `a`.
   * @returns {Number} Returns `-1` if `a` < `b`, `0` if `a` == `b`, or `1` if `a` > `b`.
   */
  function compareAscending(a, b) {
    a = a.criteria;
    b = b.criteria;

    if (a === undefined) {
      return 1;
    }
    if (b === undefined) {
      return -1;
    }
    return a < b ? -1 : a > b ? 1 : 0;
  }

  /**
   * Used by `template` to replace tokens with their corresponding code snippets.
   *
   * @private
   * @param {String} match The matched token.
   * @param {String} index The `tokenized` index of the code snippet.
   * @returns {String} Returns the code snippet.
   */
  function detokenize(match, index) {
    return tokenized[index];
  }

  /**
   * Used by `template` to escape characters for inclusion in compiled
   * string literals.
   *
   * @private
   * @param {String} match The matched character to escape.
   * @returns {String} Returns the escaped character.
   */
  function escapeStringChar(match) {
    return '\\' + stringEscapes[match];
  }

  /**
   * Used by `escape` to escape characters for inclusion in HTML.
   *
   * @private
   * @param {String} match The matched character to escape.
   * @returns {String} Returns the escaped character.
   */
  function escapeHtmlChar(match) {
    return htmlEscapes[match];
  }

  /**
   * Creates a new function that, when called, invokes `func` with the `this`
   * binding of `thisArg` and the arguments (value, index, object).
   *
   * @private
   * @param {Function} func The function to bind.
   * @param {Mixed} [thisArg] The `this` binding of `func`.
   * @returns {Function} Returns the new bound function.
   */
  function iteratorBind(func, thisArg) {
    return function(value, index, object) {
      return func.call(thisArg, value, index, object);
    };
  }

  /**
   * A no-operation function.
   *
   * @private
   */
  function noop() {
    // no operation performed
  }

  /**
   * A shim implementation of `Object.keys` that produces an array of the given
   * object's own enumerable property names.
   *
   * @private
   * @param {Object} object The object to inspect.
   * @returns {Array} Returns a new array of property names.
   */
  var shimKeys = createIterator({
    'args': 'object',
    'exit': 'if (!(object && objectTypes[typeof object])) throw TypeError()',
    'init': '[]',
    'inLoop': 'result.push(index)'
  });

  /**
   * Used by `template` to replace "escape" template delimiters with tokens.
   *
   * @private
   * @param {String} match The matched template delimiter.
   * @param {String} value The delimiter value.
   * @returns {String} Returns a token.
   */
  function tokenizeEscape(match, value) {
    if (reComplexDelimiter.test(value)) {
      return '<e%-' + value + '%>';
    }
    var index = tokenized.length;
    tokenized[index] = "' +\n__e(" + value + ") +\n'";
    return token + index;
  }

  /**
   * Used by `template` to replace "evaluate" template delimiters, or complex
   * "escape" and "interpolate" delimiters, with tokens.
   *
   * @private
   * @param {String} match The matched template delimiter.
   * @param {String} escapeValue The complex "escape" delimiter value.
   * @param {String} interpolateValue The complex "interpolate" delimiter value.
   * @param {String} [evaluateValue] The "evaluate" delimiter value.
   * @returns {String} Returns a token.
   */
  function tokenizeEvaluate(match, escapeValue, interpolateValue, evaluateValue) {
    var index = tokenized.length;
    if (escapeValue) {
      tokenized[index] = "' +\n__e(" + escapeValue + ") +\n'";
    } else if (evaluateValue) {
      tokenized[index] = "';\n" + evaluateValue + ";\n__p += '";
    } else if (interpolateValue) {
      tokenized[index] = "' +\n((__t = (" + interpolateValue + ")) == null ? '' : __t) +\n'";
    }
    return token + index;
  }

  /**
   * Used by `template` to replace "interpolate" template delimiters with tokens.
   *
   * @private
   * @param {String} match The matched template delimiter.
   * @param {String} value The delimiter value.
   * @returns {String} Returns a token.
   */
  function tokenizeInterpolate(match, value) {
    if (reComplexDelimiter.test(value)) {
      return '<e%=' + value + '%>';
    }
    var index = tokenized.length;
    tokenized[index] = "' +\n((__t = (" + value + ")) == null ? '' : __t) +\n'";
    return token + index;
  }

  /*--------------------------------------------------------------------------*/

  /**
   * Create a clone of `value`. If `deep` is `true`, all nested objects, excluding
   * functons and `arguments` objects, will be cloned otherwise they will be
   * assigned by reference.
   *
   * @static
   * @memberOf _
   * @category Objects
   * @param {Mixed} value The value to clone.
   * @param {Boolean} deep A flag to indicate a deep clone.
   * @param {Object} [guard] Internally used to allow this method to work with
   *  others like `_.map` without using their callback `index` argument for `deep`.
   * @param {Array} [stack=[]] Internally used to keep track of traversed objects
   *  to avoid circular references.
   * @param {Boolean} thorough Internally used to indicate whether or not to perform
   *  a more thorough clone of non-object values.
   * @returns {Mixed} Returns the cloned `value`.
   * @example
   *
   * var stooges = [
   *   { 'name': 'moe', 'age': 40 },
   *   { 'name': 'larry', 'age': 50 },
   *   { 'name': 'curly', 'age': 60 }
   * ];
   *
   * _.clone({ 'name': 'moe' });
   * // => { 'name': 'moe' }
   *
   * var shallow = _.clone(stooges);
   * shallow[0] === stooges[0];
   * // => true
   *
   * var deep = _.clone(stooges, true);
   * shallow[0] === stooges[0];
   * // => false
   */
  function clone(value, deep, guard, stack, thorough) {
    if (value == null) {
      return value;
    }
    var isObj = typeof value == 'object';
    stack || (stack = []);

    if (guard) {
      deep = false;
    }
    // avoid slower checks on non-objects
    if (thorough == null) {
      // primitives passed from iframes use the primary document's native prototypes
      thorough = !!(BoolProto.clone || NumberProto.clone || StringProto.clone);
    }
    // use custom `clone` method if available
    if ((isObj || thorough) && value.clone && toString.call(value.clone) == funcClass) {
      return value.clone(deep);
    }
    // inspect [[Class]]
    if (isObj) {
      // don't clone `arguments` objects, functions, or non-object Objects
      var className = toString.call(value);
      if (!cloneableClasses[className] || (noArgsClass && isArguments(value))) {
        return value;
      }

      var useCtor,
          ctor = value.constructor,
          isArr = className == arrayClass;

      if (className == objectClass) {
        // IE < 9 presents DOM nodes as `Object` objects except they have `toString`
        // methods that are `typeof` "string" and still can coerce nodes to strings
        isObj = !noNodeClass || !(typeof value.toString != 'function' && typeof (value + '') == 'string');

        if (isObj) {
          // check that the constructor is `Object` because `Object instanceof Object` is `true`
          useCtor = toString.call(ctor) == funcClass;
          isObj = !useCtor || ctor instanceof ctor;
        }
        if (isObj) {
          // An object's own properties are iterated before inherited properties.
          // If the last iterated key belongs to an object's own property then
          // there are no inherited enumerable properties.
          forIn(value, function(objValue, objKey) { isObj = objKey; });
          isObj = isObj == true || hasOwnProperty.call(value, isObj);
        }
      }
    }
    // shallow clone
    if (!isObj || !deep) {
      // don't clone functions
      return isObj
        ? (isArr ? slice.call(value) : extend({}, value))
        : value;
    }

    switch (className) {
      case boolClass:
        return new ctor(value == true);

      case dateClass:
        return new ctor(+value);

      case numberClass:
      case stringClass:
        return new ctor(value);

      case regexpClass:
        return ctor(value.source, reFlags.exec(value));
    }

    // check for circular references and return corresponding clone
    var length = stack.length;
    while (length--) {
      if (stack[length].value == value) {
        return stack[length].clone;
      }
    }

    // init cloned object
    length = value.length;
    var result = isArr ? ctor(length) : (useCtor ? new ctor : {});

    // add current clone and original value to the stack of traversed objects
    stack.push({ 'clone': result, 'value': value });

    // recursively populate clone (susceptible to call stack limits)
    if (isArr) {
      var index = -1;
      while (++index < length) {
        result[index] = clone(value[index], deep, null, stack, thorough);
      }
    } else {
      forOwn(value, function(objValue, key) {
        result[key] = clone(objValue, deep, null, stack, thorough);
      });
    }
    return result;
  }

  /**
   * Assigns enumerable properties of the default object(s) to the `destination`
   * object for all `destination` properties that resolve to `null`/`undefined`.
   * Once a property is set, additional defaults of the same property will be
   * ignored.
   *
   * @static
   * @memberOf _
   * @category Objects
   * @param {Object} object The destination object.
   * @param {Object} [default1, default2, ...] The default objects.
   * @returns {Object} Returns the `object`.
   * @example
   *
   * var iceCream = { 'flavor': 'chocolate' };
   * _.defaults(iceCream, { 'flavor': 'vanilla', 'sprinkles': 'rainbow' });
   * // => { 'flavor': 'chocolate', 'sprinkles': 'rainbow' }
   */
  var defaults = createIterator(extendIteratorOptions, {
    'inLoop': 'if (result[index] == null) ' + extendIteratorOptions.inLoop
  });

  /**
   * Creates a shallow clone of `object` excluding the specified properties.
   * Property names may be specified as individual arguments or as arrays of
   * property names.
   *
   * @static
   * @memberOf _
   * @category Objects
   * @param {Object} object The source object.
   * @param {Object} [prop1, prop2, ...] The properties to drop.
   * @returns {Object} Returns an object without the dropped properties.
   * @example
   *
   * _.drop({ 'name': 'moe', 'age': 40, 'userid': 'moe1' }, 'userid');
   * // => { 'name': 'moe', 'age': 40 }
   */
  var drop = createIterator({
    'useHas': false,
    'args': 'object',
    'init': '{}',
    'top': 'var props = concat.apply(ArrayProto, arguments)',
    'inLoop': 'if (indexOf(props, index) < 0) result[index] = value'
  });

  /**
   * Assigns enumerable properties of the source object(s) to the `destination`
   * object. Subsequent sources will overwrite propery assignments of previous
   * sources.
   *
   * @static
   * @memberOf _
   * @category Objects
   * @param {Object} object The destination object.
   * @param {Object} [source1, source2, ...] The source objects.
   * @returns {Object} Returns the `object`.
   * @example
   *
   * _.extend({ 'name': 'moe' }, { 'age': 40 });
   * // => { 'name': 'moe', 'age': 40 }
   */
  var extend = createIterator(extendIteratorOptions);

  /**
   * Iterates over `object`'s own and inherited enumerable properties, executing
   * the `callback` for each property. The `callback` is bound to `thisArg` and
   * invoked with 3 arguments; (value, key, object).
   *
   * @static
   * @memberOf _
   * @category Objects
   * @param {Object} object The object to iterate over.
   * @param {Function} callback The function called per iteration.
   * @param {Mixed} [thisArg] The `this` binding for the callback.
   * @returns {Object} Returns the `object`.
   * @example
   *
   * function Dog(name) {
   *   this.name = name;
   * }
   *
   * Dog.prototype.bark = function() {
   *   alert('Woof, woof!');
   * };
   *
   * _.forIn(new Dog('Dagny'), function(value, key) {
   *   alert(key);
   * });
   * // => alerts 'name' and 'bark' (order is not guaranteed)
   */
  var forIn = createIterator(baseIteratorOptions, forEachIteratorOptions, forOwnIteratorOptions, {
    'useHas': false
  });

  /**
   * Iterates over `object`'s own enumerable properties, executing the `callback`
   * for each property. The `callback` is bound to `thisArg` and invoked with 3
   * arguments; (value, key, object).
   *
   * @static
   * @memberOf _
   * @category Objects
   * @param {Object} object The object to iterate over.
   * @param {Function} callback The function called per iteration.
   * @param {Mixed} [thisArg] The `this` binding for the callback.
   * @returns {Object} Returns the `object`.
   * @example
   *
   * _.forOwn({ '0': 'zero', '1': 'one', 'length': 2 }, function(num, key) {
   *   alert(key);
   * });
   * // => alerts '0', '1', and 'length' (order is not guaranteed)
   */
  var forOwn = createIterator(baseIteratorOptions, forEachIteratorOptions, forOwnIteratorOptions);

  /**
   * Creates a sorted array of all enumerable properties, own and inherited,
   * of `object` that have function values.
   *
   * @static
   * @memberOf _
   * @alias methods
   * @category Objects
   * @param {Object} object The object to inspect.
   * @returns {Array} Returns a new array of property names that have function values.
   * @example
   *
   * _.functions(_);
   * // => ['all', 'any', 'bind', 'bindAll', 'clone', 'compact', 'compose', ...]
   */
  var functions = createIterator({
    'useHas': false,
    'args': 'object',
    'init': '[]',
    'inLoop': 'if (toString.call(value) == funcClass) result.push(index)',
    'bottom': 'result.sort()'
  });

  /**
   * Checks if the specified object `property` exists and is a direct property,
   * instead of an inherited property.
   *
   * @static
   * @memberOf _
   * @category Objects
   * @param {Object} object The object to check.
   * @param {String} property The property to check for.
   * @returns {Boolean} Returns `true` if key is a direct property, else `false`.
   * @example
   *
   * _.has({ 'a': 1, 'b': 2, 'c': 3 }, 'b');
   * // => true
   */
  function has(object, property) {
    return hasOwnProperty.call(object, property);
  }

  /**
   * Checks if `value` is an `arguments` object.
   *
   * @static
   * @memberOf _
   * @category Objects
   * @param {Mixed} value The value to check.
   * @returns {Boolean} Returns `true` if the `value` is an `arguments` object, else `false`.
   * @example
   *
   * (function() { return _.isArguments(arguments); })(1, 2, 3);
   * // => true
   *
   * _.isArguments([1, 2, 3]);
   * // => false
   */
  function isArguments(value) {
    return toString.call(value) == argsClass;
  }
  // fallback for browsers that can't detect `arguments` objects by [[Class]]
  if (noArgsClass) {
    isArguments = function(value) {
      return !!(value && hasOwnProperty.call(value, 'callee'));
    };
  }

  /**
   * Checks if `value` is an array.
   *
   * @static
   * @memberOf _
   * @category Objects
   * @param {Mixed} value The value to check.
   * @returns {Boolean} Returns `true` if the `value` is an array, else `false`.
   * @example
   *
   * (function() { return _.isArray(arguments); })();
   * // => false
   *
   * _.isArray([1, 2, 3]);
   * // => true
   */
  var isArray = nativeIsArray || function(value) {
    return toString.call(value) == arrayClass;
  };

  /**
   * Checks if `value` is a boolean (`true` or `false`) value.
   *
   * @static
   * @memberOf _
   * @category Objects
   * @param {Mixed} value The value to check.
   * @returns {Boolean} Returns `true` if the `value` is a boolean value, else `false`.
   * @example
   *
   * _.isBoolean(null);
   * // => false
   */
  function isBoolean(value) {
    return value === true || value === false || toString.call(value) == boolClass;
  }

  /**
   * Checks if `value` is a date.
   *
   * @static
   * @memberOf _
   * @category Objects
   * @param {Mixed} value The value to check.
   * @returns {Boolean} Returns `true` if the `value` is a date, else `false`.
   * @example
   *
   * _.isDate(new Date);
   * // => true
   */
  function isDate(value) {
    return toString.call(value) == dateClass;
  }

  /**
   * Checks if `value` is a DOM element.
   *
   * @static
   * @memberOf _
   * @category Objects
   * @param {Mixed} value The value to check.
   * @returns {Boolean} Returns `true` if the `value` is a DOM element, else `false`.
   * @example
   *
   * _.isElement(document.body);
   * // => true
   */
  function isElement(value) {
    return !!(value && value.nodeType == 1);
  }

  /**
   * Checks if `value` is empty. Arrays, strings, or `arguments` objects with a
   * length of `0` and objects with no own enumerable properties are considered
   * "empty".
   *
   * @static
   * @memberOf _
   * @category Objects
   * @param {Array|Object|String} value The value to inspect.
   * @returns {Boolean} Returns `true` if the `value` is empty, else `false`.
   * @example
   *
   * _.isEmpty([1, 2, 3]);
   * // => false
   *
   * _.isEmpty({});
   * // => true
   *
   * _.isEmpty('');
   * // => true
   */
  var isEmpty = createIterator({
    'args': 'value',
    'init': 'true',
    'top':
      'if (arrayLikeClasses[toString.call(value)]' +
        (noArgsClass ? ' || isArguments(value)' : '') +
      ') return !value.length',
    'inLoop': {
      'object': 'return false'
    }
  });

  /**
   * Performs a deep comparison between two values to determine if they are
   * equivalent to each other.
   *
   * @static
   * @memberOf _
   * @category Objects
   * @param {Mixed} a The value to compare.
   * @param {Mixed} b The other value to compare.
   * @param {Array} [stack=[]] Internally used to keep track of traversed objects
   *  to avoid circular references.
   * @param {Boolean} thorough Internally used to indicate whether or not to perform
   *  a more thorough comparison of non-object values.
   * @returns {Boolean} Returns `true` if the values are equvalent, else `false`.
   * @example
   *
   * var moe = { 'name': 'moe', 'luckyNumbers': [13, 27, 34] };
   * var clone = { 'name': 'moe', 'luckyNumbers': [13, 27, 34] };
   *
   * moe == clone;
   * // => false
   *
   * _.isEqual(moe, clone);
   * // => true
   */
  function isEqual(a, b, stack, thorough) {
    stack || (stack = []);

    // a strict comparison is necessary because `null == undefined`
    if (a == null || b == null) {
      return a === b;
    }
    // avoid slower checks on non-objects
    if (thorough == null) {
      // primitives passed from iframes use the primary document's native prototypes
      thorough = !!(BoolProto.isEqual || NumberProto.isEqual || StringProto.isEqual);
    }
    if (objectTypes[typeof a] || objectTypes[typeof b] || thorough) {
      // unwrap any LoDash wrapped values
      if (a._chain) {
        a = a._wrapped;
      }
      if (b._chain) {
        b = b._wrapped;
      }
      // use custom `isEqual` method if available
      if (a.isEqual && toString.call(a.isEqual) == funcClass) {
        return a.isEqual(b);
      }
      if (b.isEqual && toString.call(b.isEqual) == funcClass) {
        return b.isEqual(a);
      }
    }
    // exit early for identical values
    if (a === b) {
      // treat `+0` vs. `-0` as not equal
      return a !== 0 || (1 / a == 1 / b);
    }
    // compare [[Class]] names
    var className = toString.call(a);
    if (className != toString.call(b)) {
      return false;
    }
    switch (className) {
      case boolClass:
      case dateClass:
        // coerce dates and booleans to numbers, dates to milliseconds and booleans
        // to `1` or `0`, treating invalid dates coerced to `NaN` as not equal
        return +a == +b;

      case numberClass:
        // treat `NaN` vs. `NaN` as equal
        return a != +a
          ? b != +b
          // but treat `+0` vs. `-0` as not equal
          : (a == 0 ? (1 / a == 1 / b) : a == +b);

      case regexpClass:
      case stringClass:
        // coerce regexes to strings (http://es5.github.com/#x15.10.6.4)
        // treat string primitives and their corresponding object instances as equal
        return a == b + '';
    }
    // exit early, in older browsers, if `a` is array-like but not `b`
    var isArr = arrayLikeClasses[className];
    if (noArgsClass && !isArr && (isArr = isArguments(a)) && !isArguments(b)) {
      return false;
    }
    // exit for functions and DOM nodes
    if (!isArr && (className != objectClass || (noNodeClass && (
        (typeof a.toString != 'function' && typeof (a + '') == 'string') ||
        (typeof b.toString != 'function' && typeof (b + '') == 'string'))))) {
      return false;
    }

    // assume cyclic structures are equal
    // the algorithm for detecting cyclic structures is adapted from ES 5.1
    // section 15.12.3, abstract operation `JO` (http://es5.github.com/#x15.12.3)
    var length = stack.length;
    while (length--) {
      if (stack[length] == a) {
        return true;
      }
    }

    var index = -1,
        result = true,
        size = 0;

    // add `a` to the stack of traversed objects
    stack.push(a);

    // recursively compare objects and arrays (susceptible to call stack limits)
    if (isArr) {
      // compare 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--) {
          if (!(result = isEqual(a[size], b[size], stack, thorough))) {
            break;
          }
        }
      }
      return result;
    }

    var ctorA = a.constructor,
        ctorB = b.constructor;

    // non `Object` object instances with different constructors are not equal
    if (ctorA != ctorB && !(
          toString.call(ctorA) == funcClass && ctorA instanceof ctorA &&
          toString.call(ctorB) == funcClass && ctorB instanceof ctorB
        )) {
      return false;
    }
    // deep compare objects
    for (var prop in a) {
      if (hasOwnProperty.call(a, prop)) {
        // count the number of properties.
        size++;
        // deep compare each property value.
        if (!(hasOwnProperty.call(b, prop) && isEqual(a[prop], b[prop], stack, thorough))) {
          return false;
        }
      }
    }
    // ensure both objects have the same number of properties
    for (prop in b) {
      // The JS engine in Adobe products, like InDesign, has a bug that causes
      // `!size--` to throw an error so it must be wrapped in parentheses.
      // https://github.com/documentcloud/underscore/issues/355
      if (hasOwnProperty.call(b, prop) && !(size--)) {
        // `size` will be `-1` if `b` has more properties than `a`
        return false;
      }
    }
    // handle JScript [[DontEnum]] bug
    if (hasDontEnumBug) {
      while (++index < 7) {
        prop = shadowed[index];
        if (hasOwnProperty.call(a, prop) &&
            !(hasOwnProperty.call(b, prop) && isEqual(a[prop], b[prop], stack, thorough))) {
          return false;
        }
      }
    }
    return true;
  }

  /**
   * Checks if `value` is a finite number.
   * Note: This is not the same as native `isFinite`, which will return true for
   * booleans and other values. See http://es5.github.com/#x15.1.2.5.
   *
   * @deprecated
   * @static
   * @memberOf _
   * @category Objects
   * @param {Mixed} value The value to check.
   * @returns {Boolean} Returns `true` if the `value` is a finite number, else `false`.
   * @example
   *
   * _.isFinite(-101);
   * // => true
   *
   * _.isFinite('10');
   * // => false
   *
   * _.isFinite(Infinity);
   * // => false
   */
  function isFinite(value) {
    return nativeIsFinite(value) && toString.call(value) == numberClass;
  }

  /**
   * Checks if `value` is a function.
   *
   * @static
   * @memberOf _
   * @category Objects
   * @param {Mixed} value The value to check.
   * @returns {Boolean} Returns `true` if the `value` is a function, else `false`.
   * @example
   *
   * _.isFunction(''.concat);
   * // => true
   */
  function isFunction(value) {
    return toString.call(value) == funcClass;
  }

  /**
   * Checks if `value` is the language type of Object.
   * (e.g. arrays, functions, objects, regexes, `new Number(0)`, and `new String('')`)
   *
   * @static
   * @memberOf _
   * @category Objects
   * @param {Mixed} value The value to check.
   * @returns {Boolean} Returns `true` if the `value` is an object, else `false`.
   * @example
   *
   * _.isObject({});
   * // => true
   *
   * _.isObject(1);
   * // => false
   */
  function isObject(value) {
    // check if the value is the ECMAScript language type of Object
    // http://es5.github.com/#x8
    return value && objectTypes[typeof value];
  }

  /**
   * Checks if `value` is `NaN`.
   * Note: This is not the same as native `isNaN`, which will return true for
   * `undefined` and other values. See http://es5.github.com/#x15.1.2.4.
   *
   * @deprecated
   * @static
   * @memberOf _
   * @category Objects
   * @param {Mixed} value The value to check.
   * @returns {Boolean} Returns `true` if the `value` is `NaN`, else `false`.
   * @example
   *
   * _.isNaN(NaN);
   * // => true
   *
   * _.isNaN(new Number(NaN));
   * // => true
   *
   * isNaN(undefined);
   * // => true
   *
   * _.isNaN(undefined);
   * // => false
   */
  function isNaN(value) {
    // `NaN` as a primitive is the only value that is not equal to itself
    // (perform the [[Class]] check first to avoid errors with some host objects in IE)
    return toString.call(value) == numberClass && value != +value
  }

  /**
   * Checks if `value` is `null`.
   *
   * @deprecated
   * @static
   * @memberOf _
   * @category Objects
   * @param {Mixed} value The value to check.
   * @returns {Boolean} Returns `true` if the `value` is `null`, else `false`.
   * @example
   *
   * _.isNull(null);
   * // => true
   *
   * _.isNull(undefined);
   * // => false
   */
  function isNull(value) {
    return value === null;
  }

  /**
   * Checks if `value` is a number.
   *
   * @static
   * @memberOf _
   * @category Objects
   * @param {Mixed} value The value to check.
   * @returns {Boolean} Returns `true` if the `value` is a number, else `false`.
   * @example
   *
   * _.isNumber(8.4 * 5;
   * // => true
   */
  function isNumber(value) {
    return toString.call(value) == numberClass;
  }

  /**
   * Checks if `value` is a regular expression.
   *
   * @static
   * @memberOf _
   * @category Objects
   * @param {Mixed} value The value to check.
   * @returns {Boolean} Returns `true` if the `value` is a regular expression, else `false`.
   * @example
   *
   * _.isRegExp(/moe/);
   * // => true
   */
  function isRegExp(value) {
    return toString.call(value) == regexpClass;
  }

  /**
   * Checks if `value` is a string.
   *
   * @static
   * @memberOf _
   * @category Objects
   * @param {Mixed} value The value to check.
   * @returns {Boolean} Returns `true` if the `value` is a string, else `false`.
   * @example
   *
   * _.isString('moe');
   * // => true
   */
  function isString(value) {
    return toString.call(value) == stringClass;
  }

  /**
   * Checks if `value` is `undefined`.
   *
   * @deprecated
   * @static
   * @memberOf _
   * @category Objects
   * @param {Mixed} value The value to check.
   * @returns {Boolean} Returns `true` if the `value` is `undefined`, else `false`.
   * @example
   *
   * _.isUndefined(void 0);
   * // => true
   */
  function isUndefined(value) {
    return value === undefined;
  }

  /**
   * Creates an array composed of the own enumerable property names of `object`.
   *
   * @static
   * @memberOf _
   * @category Objects
   * @param {Object} object The object to inspect.
   * @returns {Array} Returns a new array of property names.
   * @example
   *
   * _.keys({ 'one': 1, 'two': 2, 'three': 3 });
   * // => ['one', 'two', 'three'] (order is not guaranteed)
   */
  var keys = !nativeKeys ? shimKeys : function(object) {
    // avoid iterating over the `prototype` property
    return typeof object == 'function' && propertyIsEnumerable.call(object, 'prototype')
      ? shimKeys(object)
      : nativeKeys(object);
  };

  /**
   * Creates a shallow clone of `object` composed of the specified properties.
   * Property names may be specified as individual arguments or as arrays of
   * property names.
   *
   * @static
   * @memberOf _
   * @category Objects
   * @param {Object} object The source object.
   * @param {Object} [prop1, prop2, ...] The properties to pick.
   * @returns {Object} Returns an object composed of the picked properties.
   * @example
   *
   * _.pick({ 'name': 'moe', 'age': 40, 'userid': 'moe1' }, 'name', 'age');
   * // => { 'name': 'moe', 'age': 40 }
   */
  function pick(object) {
    var prop,
        index = 0,
        props = concat.apply(ArrayProto, arguments),
        length = props.length,
        result = {};

    // start `index` at `1` to skip `object`
    while (++index < length) {
      prop = props[index];
      if (prop in object) {
        result[prop] = object[prop];
      }
    }
    return result;
  }

  /**
   * Gets the size of `value` by returning `value.length` if `value` is an
   * array, string, or `arguments` object. If `value` is an object, size is
   * determined by returning the number of own enumerable properties it has.
   *
   * @deprecated
   * @static
   * @memberOf _
   * @category Objects
   * @param {Array|Object|String} value The value to inspect.
   * @returns {Number} Returns `value.length` or number of own enumerable properties.
   * @example
   *
   * _.size([1, 2]);
   * // => 2
   *
   * _.size({ 'one': 1, 'two': 2, 'three': 3 });
   * // => 3
   *
   * _.size('curly');
   * // => 5
   */
  function size(value) {
    if (!value) {
      return 0;
    }
    return arrayLikeClasses[toString.call(value)] || (noArgsClass && isArguments(value))
      ? value.length
      : keys(value).length;
  }

  /**
   * Creates an array composed of the own enumerable property values of `object`.
   *
   * @static
   * @memberOf _
   * @category Objects
   * @param {Object} object The object to inspect.
   * @returns {Array} Returns a new array of property values.
   * @example
   *
   * _.values({ 'one': 1, 'two': 2, 'three': 3 });
   * // => [1, 2, 3]
   */
  var values = createIterator({
    'args': 'object',
    'init': '[]',
    'inLoop': 'result.push(value)'
  });

  /*--------------------------------------------------------------------------*/

  /**
   * Checks if a given `target` element is present in a `collection` using strict
   * equality for comparisons, i.e. `===`.
   *
   * @static
   * @memberOf _
   * @alias include
   * @category Collections
   * @param {Array|Object|String} collection The collection to iterate over.
   * @param {Mixed} target The value to check for.
   * @returns {Boolean} Returns `true` if the `target` element is found, else `false`.
   * @example
   *
   * _.contains([1, 2, 3], 3);
   * // => true
   *
   * _.contains({ 'name': 'moe', 'age': 40 }, 'moe');
   * // => true
   *
   * _.contains('curly', 'ur');
   * // => true
   */
  var contains = createIterator({
    'args': 'collection, target',
    'init': 'false',
    'noCharByIndex': false,
    'beforeLoop': {
      'array': 'if (toString.call(iteratee) == stringClass) return collection.indexOf(target) > -1'
    },
    'inLoop': 'if (value === target) return true'
  });

  /**
   * Creates an object composed of keys returned from running each element of
   * `collection` through a `callback`. The corresponding value of each key is
   * the number of times the key was returned by `callback`. The `callback` is
   * bound to `thisArg` and invoked with 3 arguments; (value, index|key, collection).
   * The `callback` argument may also be the name of a property to count by (e.g. 'length').
   *
   * @static
   * @memberOf _
   * @category Collections
   * @param {Array|Object|String} collection The collection to iterate over.
   * @param {Function|String} callback The function called per iteration or
   *  property name to count by.
   * @param {Mixed} [thisArg] The `this` binding for the callback.
   * @returns {Object} Returns the composed aggregate object.
   * @example
   *
   * _.countBy([4.3, 6.1, 6.4], function(num) { return Math.floor(num); });
   * // => { '4': 1, '6': 2 }
   *
   * _.countBy([4.3, 6.1, 6.4], function(num) { return this.floor(num); }, Math);
   * // => { '4': 1, '6': 2 }
   *
   * _.countBy(['one', 'two', 'three'], 'length');
   * // => { '3': 2, '5': 1 }
   */
  var countBy = createIterator(baseIteratorOptions, countByIteratorOptions);

  /**
   * Checks if the `callback` returns a truthy value for **all** elements of a
   * `collection`. The `callback` is bound to `thisArg` and invoked with 3
   * arguments; (value, index|key, collection).
   *
   * @static
   * @memberOf _
   * @alias all
   * @category Collections
   * @param {Array|Object|String} collection The collection to iterate over.
   * @param {Function} [callback=identity] The function called per iteration.
   * @param {Mixed} [thisArg] The `this` binding for the callback.
   * @returns {Boolean} Returns `true` if all elements pass the callback check, else `false`.
   * @example
   *
   * _.every([true, 1, null, 'yes'], Boolean);
   * // => false
   */
  var every = createIterator(baseIteratorOptions, everyIteratorOptions);

  /**
   * Examines each element in a `collection`, returning an array of all elements
   * the `callback` returns truthy for. The `callback` is bound to `thisArg` and
   * invoked with 3 arguments; (value, index|key, collection).
   *
   * @static
   * @memberOf _
   * @alias select
   * @category Collections
   * @param {Array|Object|String} collection The collection to iterate over.
   * @param {Function} [callback=identity] The function called per iteration.
   * @param {Mixed} [thisArg] The `this` binding for the callback.
   * @returns {Array} Returns a new array of elements that passed callback check.
   * @example
   *
   * var evens = _.filter([1, 2, 3, 4, 5, 6], function(num) { return num % 2 == 0; });
   * // => [2, 4, 6]
   */
  var filter = createIterator(baseIteratorOptions, filterIteratorOptions);

  /**
   * Examines each element in a `collection`, returning the first one the `callback`
   * returns truthy for. The function returns as soon as it finds an acceptable
   * element, and does not iterate over the entire `collection`. The `callback` is
   * bound to `thisArg` and invoked with 3 arguments; (value, index|key, collection).
   *
   * @static
   * @memberOf _
   * @alias detect
   * @category Collections
   * @param {Array|Object|String} collection The collection to iterate over.
   * @param {Function} callback The function called per iteration.
   * @param {Mixed} [thisArg] The `this` binding for the callback.
   * @returns {Mixed} Returns the element that passed the callback check, else `undefined`.
   * @example
   *
   * var even = _.find([1, 2, 3, 4, 5, 6], function(num) { return num % 2 == 0; });
   * // => 2
   */
  var find = createIterator(baseIteratorOptions, forEachIteratorOptions, {
    'init': '',
    'inLoop': 'if (callback(value, index, collection)) return value'
  });

  /**
   * Iterates over a `collection`, executing the `callback` for each element in
   * the `collection`. The `callback` is bound to `thisArg` and invoked with 3
   * arguments; (value, index|key, collection).
   *
   * @static
   * @memberOf _
   * @alias each
   * @category Collections
   * @param {Array|Object|String} collection The collection to iterate over.
   * @param {Function} callback The function called per iteration.
   * @param {Mixed} [thisArg] The `this` binding for the callback.
   * @returns {Array|Object} Returns the `collection`.
   * @example
   *
   * _([1, 2, 3]).forEach(alert).join(',');
   * // => alerts each number and returns '1,2,3'
   *
   * _.forEach({ 'one': 1, 'two': 2, 'three': 3 }, alert);
   * // => alerts each number (order is not guaranteed)
   */
  var forEach = createIterator(baseIteratorOptions, forEachIteratorOptions);

  /**
   * Creates an object composed of keys returned from running each element of
   * `collection` through a `callback`. The corresponding value of each key is an
   * array of elements passed to `callback` that returned the key. The `callback`
   * is bound to `thisArg` and invoked with 3 arguments; (value, index|key, collection).
   * The `callback` argument may also be the name of a property to count by (e.g. 'length').
   *
   * @static
   * @memberOf _
   * @category Collections
   * @param {Array|Object|String} collection The collection to iterate over.
   * @param {Function|String} callback The function called per iteration or
   *  property name to group by.
   * @param {Mixed} [thisArg] The `this` binding for the callback.
   * @returns {Object} Returns the composed aggregate object.
   * @example
   *
   * _.groupBy([4.2, 6.1, 6.4], function(num) { return Math.floor(num); });
   * // => { '4': [4.2], '6': [6.1, 6.4] }
   *
   * _.groupBy([4.2, 6.1, 6.4], function(num) { return this.floor(num); }, Math);
   * // => { '4': [4.2], '6': [6.1, 6.4] }
   *
   * _.groupBy(['one', 'two', 'three'], 'length');
   * // => { '3': ['one', 'two'], '5': ['three'] }
   */
  var groupBy = createIterator(baseIteratorOptions, countByIteratorOptions, {
    'inLoop':
      'prop = callback(value, index, collection);\n' +
      '(hasOwnProperty.call(result, prop) ? result[prop] : result[prop] = []).push(value)'
  });

  /**
   * Invokes the method named by `methodName` on each element in the `collection`.
   * Additional arguments will be passed to each invoked method. If `methodName`
   * is a function it will be invoked for, and `this` bound to, each element
   * in the `collection`.
   *
   * @static
   * @memberOf _
   * @category Collections
   * @param {Array|Object|String} collection The collection to iterate over.
   * @param {Function|String} methodName The name of the method to invoke or
   *  the function invoked per iteration.
   * @param {Mixed} [arg1, arg2, ...] Arguments to invoke the method with.
   * @returns {Array} Returns a new array of values returned from each invoked method.
   * @example
   *
   * _.invoke([[5, 1, 7], [3, 2, 1]], 'sort');
   * // => [[1, 5, 7], [1, 2, 3]]
   *
   * _.invoke([123, 456], String.prototype.split, '');
   * // => [['1', '2', '3'], ['4', '5', '6']]
   */
  var invoke = createIterator(mapIteratorOptions, {
    'args': 'collection, methodName',
    'top':
      'var args = slice.call(arguments, 2),\n' +
      '    isFunc = typeof methodName == \'function\'',
    'inLoop': {
      'array':
        'result[index] = (isFunc ? methodName : value[methodName])' +
        '.apply(value, args)',
      'object':
        'result' + (isKeysFast ? '[ownIndex] = ' : '.push') +
        '((isFunc ? methodName : value[methodName]).apply(value, args))'
    }
  });

  /**
   * Creates a new array of values by running each element in the `collection`
   * through a `callback`. The `callback` is bound to `thisArg` and invoked with
   * 3 arguments; (value, index|key, collection).
   *
   * @static
   * @memberOf _
   * @alias collect
   * @category Collections
   * @param {Array|Object|String} collection The collection to iterate over.
   * @param {Function} [callback=identity] The function called per iteration.
   * @param {Mixed} [thisArg] The `this` binding for the callback.
   * @returns {Array} Returns a new array of elements returned by the callback.
   * @example
   *
   * _.map([1, 2, 3], function(num) { return num * 3; });
   * // => [3, 6, 9]
   *
   * _.map({ 'one': 1, 'two': 2, 'three': 3 }, function(num) { return num * 3; });
   * // => [3, 6, 9] (order is not guaranteed)
   */
  var map = createIterator(baseIteratorOptions, mapIteratorOptions);

  /**
   * Retrieves the value of a specified property from all elements in
   * the `collection`.
   *
   * @static
   * @memberOf _
   * @category Collections
   * @param {Array|Object|String} collection The collection to iterate over.
   * @param {String} property The property to pluck.
   * @returns {Array} Returns a new array of property values.
   * @example
   *
   * var stooges = [
   *   { 'name': 'moe', 'age': 40 },
   *   { 'name': 'larry', 'age': 50 },
   *   { 'name': 'curly', 'age': 60 }
   * ];
   *
   * _.pluck(stooges, 'name');
   * // => ['moe', 'larry', 'curly']
   */
  var pluck = createIterator(mapIteratorOptions, {
    'args': 'collection, property',
    'inLoop': {
      'array':  'result[index] = value[property]',
      'object': 'result' + (isKeysFast ? '[ownIndex] = ' : '.push') + '(value[property])'
    }
  });

  /**
   * Boils down a `collection` to a single value. The initial state of the
   * reduction is `accumulator` and each successive step of it should be returned
   * by the `callback`. The `callback` is bound to `thisArg` and invoked with 4
   * arguments; for arrays they are (accumulator, value, index|key, collection).
   *
   * @static
   * @memberOf _
   * @alias foldl, inject
   * @category Collections
   * @param {Array|Object|String} collection The collection to iterate over.
   * @param {Function} callback The function called per iteration.
   * @param {Mixed} [accumulator] Initial value of the accumulator.
   * @param {Mixed} [thisArg] The `this` binding for the callback.
   * @returns {Mixed} Returns the accumulated value.
   * @example
   *
   * var sum = _.reduce([1, 2, 3], function(memo, num) { return memo + num; });
   * // => 6
   */
  var reduce = createIterator({
    'args': 'collection, callback, accumulator, thisArg',
    'init': 'accumulator',
    'top':
      'var noaccum = arguments.length < 3;\n' +
      'if (thisArg) callback = iteratorBind(callback, thisArg)',
    'beforeLoop': {
      'array': 'if (noaccum) result = collection[++index]'
    },
    'inLoop': {
      'array':
        'result = callback(result, value, index, collection)',
      'object':
        'result = noaccum\n' +
        '  ? (noaccum = false, value)\n' +
        '  : callback(result, value, index, collection)'
    }
  });

  /**
   * The right-associative version of `_.reduce`.
   *
   * @static
   * @memberOf _
   * @alias foldr
   * @category Collections
   * @param {Array|Object|String} collection The collection to iterate over.
   * @param {Function} callback The function called per iteration.
   * @param {Mixed} [accumulator] Initial value of the accumulator.
   * @param {Mixed} [thisArg] The `this` binding for the callback.
   * @returns {Mixed} Returns the accumulated value.
   * @example
   *
   * var list = [[0, 1], [2, 3], [4, 5]];
   * var flat = _.reduceRight(list, function(a, b) { return a.concat(b); }, []);
   * // => [4, 5, 2, 3, 0, 1]
   */
  function reduceRight(collection, callback, accumulator, thisArg) {
    if (!collection) {
      return accumulator;
    }

    var length = collection.length,
        noaccum = arguments.length < 3;

    if(thisArg) {
      callback = iteratorBind(callback, thisArg);
    }
    if (length === length >>> 0) {
      var iteratee = noCharByIndex && toString.call(collection) == stringClass
        ? collection.split('')
        : collection;

      if (length && noaccum) {
        accumulator = iteratee[--length];
      }
      while (length--) {
        accumulator = callback(accumulator, iteratee[length], length, collection);
      }
      return accumulator;
    }

    var prop,
        props = keys(collection);

    length = props.length;
    if (length && noaccum) {
      accumulator = collection[props[--length]];
    }
    while (length--) {
      prop = props[length];
      accumulator = callback(accumulator, collection[prop], prop, collection);
    }
    return accumulator;
  }

  /**
   * The opposite of `_.filter`, this method returns the values of a
   * `collection` that `callback` does **not** return truthy for.
   *
   * @static
   * @memberOf _
   * @category Collections
   * @param {Array|Object|String} collection The collection to iterate over.
   * @param {Function} [callback=identity] The function called per iteration.
   * @param {Mixed} [thisArg] The `this` binding for the callback.
   * @returns {Array} Returns a new array of elements that did **not** pass the callback check.
   * @example
   *
   * var odds = _.reject([1, 2, 3, 4, 5, 6], function(num) { return num % 2 == 0; });
   * // => [1, 3, 5]
   */
  var reject = createIterator(baseIteratorOptions, filterIteratorOptions, {
    'inLoop': '!' + filterIteratorOptions.inLoop
  });

  /**
   * Checks if the `callback` returns a truthy value for **any** element of a
   * `collection`. The function returns as soon as it finds passing value, and
   * does not iterate over the entire `collection`. The `callback` is bound to
   * `thisArg` and invoked with 3 arguments; (value, index|key, collection).
   *
   * @static
   * @memberOf _
   * @alias any
   * @category Collections
   * @param {Array|Object|String} collection The collection to iterate over.
   * @param {Function} [callback=identity] The function called per iteration.
   * @param {Mixed} [thisArg] The `this` binding for the callback.
   * @returns {Boolean} Returns `true` if any element passes the callback check, else `false`.
   * @example
   *
   * _.some([null, 0, 'yes', false]);
   * // => true
   */
  var some = createIterator(baseIteratorOptions, everyIteratorOptions, {
    'init': 'false',
    'inLoop': everyIteratorOptions.inLoop.replace('!', '')
  });

  /**
   * Creates a new sorted array, sorted in ascending order by the results of
   * running each element of `collection` through a `callback`. The `callback` is
   * bound to `thisArg` and invoked with 3 arguments; (value, index|key, collection).
   * The `callback` argument may also be the name of a property to sort by (e.g. 'length').
   *
   * @static
   * @memberOf _
   * @category Collections
   * @param {Array|Object|String} collection The collection to iterate over.
   * @param {Function|String} callback The function called per iteration or
   *  property name to sort by.
   * @param {Mixed} [thisArg] The `this` binding for the callback.
   * @returns {Array} Returns a new array of sorted elements.
   * @example
   *
   * _.sortBy([1, 2, 3], function(num) { return Math.sin(num); });
   * // => [3, 1, 2]
   *
   * _.sortBy([1, 2, 3], function(num) { return this.sin(num); }, Math);
   * // => [3, 1, 2]
   *
   * _.sortBy(['larry', 'brendan', 'moe'], 'length');
   * // => ['moe', 'larry', 'brendan']
   */
  var sortBy = createIterator(baseIteratorOptions, countByIteratorOptions, mapIteratorOptions, {
    'inLoop': {
      'array':
        'result[index] = {\n' +
        '  criteria: callback(value, index, collection),\n' +
        '  value: value\n' +
        '}',
      'object':
        'result' + (isKeysFast ? '[ownIndex] = ' : '.push') + '({\n' +
        '  criteria: callback(value, index, collection),\n' +
        '  value: value\n' +
        '})'
    },
    'bottom':
      'result.sort(compareAscending);\n' +
      'length = result.length;\n' +
      'while (length--) {\n' +
      '  result[length] = result[length].value\n' +
      '}'
  });

  /**
   * Converts the `collection`, into an array. Useful for converting the
   * `arguments` object.
   *
   * @static
   * @memberOf _
   * @category Collections
   * @param {Array|Object|String} collection The collection to convert.
   * @returns {Array} Returns the new converted array.
   * @example
   *
   * (function() { return _.toArray(arguments).slice(1); })(1, 2, 3, 4);
   * // => [2, 3, 4]
   */
  function toArray(collection) {
    if (!collection) {
      return [];
    }
    if (collection.toArray && toString.call(collection.toArray) == funcClass) {
      return collection.toArray();
    }
    var length = collection.length;
    if (length === length >>> 0) {
      return (noArraySliceOnStrings ? toString.call(collection) == stringClass : typeof collection == 'string')
        ? collection.split('')
        : slice.call(collection);
    }
    return values(collection);
  }

  /**
   * Examines each element in a `collection`, returning an array of all elements
   * that contain the given `properties`.
   *
   * @static
   * @memberOf _
   * @category Collections
   * @param {Array|Object|String} collection The collection to iterate over.
   * @param {Object} properties The object of properties/values to filter by.
   * @returns {Array} Returns a new array of elements that contain the given `properties`.
   * @example
   *
   * var stooges = [
   *   { 'name': 'moe', 'age': 40 },
   *   { 'name': 'larry', 'age': 50 },
   *   { 'name': 'curly', 'age': 60 }
   * ];
   *
   * _.where(stooges, { 'age': 40 });
   * // => [{ 'name': 'moe', 'age': 40 }]
   */
  var where = createIterator(filterIteratorOptions, {
    'args': 'collection, properties',
    'top':
      'var pass, prop, propIndex, props = [];\n' +
      'forIn(properties, function(value, prop) { props.push(prop) });\n' +
      'var propsLength = props.length',
    'inLoop':
      'for (pass = true, propIndex = 0; propIndex < propsLength; propIndex++) {\n' +
      '  prop = props[propIndex];\n' +
      '  if (!(pass = value[prop] === properties[prop])) break\n' +
      '}\n' +
      'if (pass) result.push(value)'
  });

  /*--------------------------------------------------------------------------*/

  /**
   * Creates a new array with all falsey values of `array` removed. The values
   * `false`, `null`, `0`, `""`, `undefined` and `NaN` are all falsey.
   *
   * @static
   * @memberOf _
   * @category Arrays
   * @param {Array} array The array to compact.
   * @returns {Array} Returns a new filtered array.
   * @example
   *
   * _.compact([0, 1, false, 2, '', 3]);
   * // => [1, 2, 3]
   */
  function compact(array) {
    var result = [];
    if (!array) {
      return result;
    }
    var index = -1,
        length = array.length;

    while (++index < length) {
      if (array[index]) {
        result.push(array[index]);
      }
    }
    return result;
  }

  /**
   * Creates a new array of `array` elements not present in the other arrays
   * using strict equality for comparisons, i.e. `===`.
   *
   * @static
   * @memberOf _
   * @category Arrays
   * @param {Array} array The array to process.
   * @param {Array} [array1, array2, ...] Arrays to check.
   * @returns {Array} Returns a new array of `array` elements not present in the
   *  other arrays.
   * @example
   *
   * _.difference([1, 2, 3, 4, 5], [5, 2, 10]);
   * // => [1, 3, 4]
   */
  function difference(array) {
    var result = [];
    if (!array) {
      return result;
    }
    var index = -1,
        length = array.length,
        flattened = concat.apply(result, arguments),
        contains = cachedContains(flattened, length);

    while (++index < length) {
      if (!contains(array[index])) {
        result.push(array[index]);
      }
    }
    return result;
  }

  /**
   * Gets the first element of the `array`. Pass `n` to return the first `n`
   * elements of the `array`.
   *
   * @static
   * @memberOf _
   * @alias head, take
   * @category Arrays
   * @param {Array} array The array to query.
   * @param {Number} [n] The number of elements to return.
   * @param {Object} [guard] Internally used to allow this method to work with
   *  others like `_.map` without using their callback `index` argument for `n`.
   * @returns {Mixed} Returns the first element or an array of the first `n`
   *  elements of `array`.
   * @example
   *
   * _.first([5, 4, 3, 2, 1]);
   * // => 5
   */
  function first(array, n, guard) {
    if (array) {
      return (n == null || guard) ? array[0] : slice.call(array, 0, n);
    }
  }

  /**
   * Flattens a nested array (the nesting can be to any depth). If `shallow` is
   * truthy, `array` will only be flattened a single level.
   *
   * @static
   * @memberOf _
   * @category Arrays
   * @param {Array} array The array to compact.
   * @param {Boolean} shallow A flag to indicate only flattening a single level.
   * @returns {Array} Returns a new flattened array.
   * @example
   *
   * _.flatten([1, [2], [3, [[4]]]]);
   * // => [1, 2, 3, 4];
   *
   * _.flatten([1, [2], [3, [[4]]]], true);
   * // => [1, 2, 3, [[4]]];
   */
  function flatten(array, shallow) {
    var result = [];
    if (!array) {
      return result;
    }
    var value,
        index = -1,
        length = array.length;

    while (++index < length) {
      value = array[index];
      if (isArray(value)) {
        push.apply(result, shallow ? value : flatten(value));
      } else {
        result.push(value);
      }
    }
    return result;
  }

  /**
   * Gets the index at which the first occurrence of `value` is found using
   * strict equality for comparisons, i.e. `===`. If the `array` is already
   * sorted, passing `true` for `isSorted` will run a faster binary search.
   *
   * @static
   * @memberOf _
   * @category Arrays
   * @param {Array} array The array to search.
   * @param {Mixed} value The value to search for.
   * @param {Boolean|Number} [fromIndex=0] The index to start searching from or
   *  `true` to perform a binary search on a sorted `array`.
   * @returns {Number} Returns the index of the matched value or `-1`.
   * @example
   *
   * _.indexOf([1, 2, 3, 1, 2, 3], 2);
   * // => 1
   *
   * _.indexOf([1, 2, 3, 1, 2, 3], 2, 3);
   * // => 4
   *
   * _.indexOf([1, 1, 2, 2, 3, 3], 2, true);
   * // => 2
   */
  function indexOf(array, value, fromIndex) {
    if (!array) {
      return -1;
    }
    var index = -1,
        length = array.length;

    if (fromIndex) {
      if (typeof fromIndex == 'number') {
        index = (fromIndex < 0 ? Math.max(0, length + fromIndex) : fromIndex) - 1;
      } else {
        index = sortedIndex(array, value);
        return array[index] === value ? index : -1;
      }
    }
    while (++index < length) {
      if (array[index] === value) {
        return index;
      }
    }
    return -1;
  }

  /**
   * Gets all but the last element of `array`. Pass `n` to exclude the last `n`
   * elements from the result.
   *
   * @static
   * @memberOf _
   * @category Arrays
   * @param {Array} array The array to query.
   * @param {Number} [n] The number of elements to return.
   * @param {Object} [guard] Internally used to allow this method to work with
   *  others like `_.map` without using their callback `index` argument for `n`.
   * @returns {Array} Returns all but the last element or `n` elements of `array`.
   * @example
   *
   * _.initial([3, 2, 1]);
   * // => [3, 2]
   */
  function initial(array, n, guard) {
    if (!array) {
      return [];
    }
    return slice.call(array, 0, -((n == null || guard) ? 1 : n));
  }

  /**
   * Computes the intersection of all the passed-in arrays.
   *
   * @static
   * @memberOf _
   * @category Arrays
   * @param {Array} [array1, array2, ...] Arrays to process.
   * @returns {Array} Returns a new array of unique elements, in order, that are
   *  present in **all** of the arrays.
   * @example
   *
   * _.intersection([1, 2, 3], [101, 2, 1, 10], [2, 1]);
   * // => [1, 2]
   */
  function intersection(array) {
    var result = [];
    if (!array) {
      return result;
    }
    var value,
        index = -1,
        length = array.length,
        others = slice.call(arguments, 1),
        cache = [];

    while (++index < length) {
      value = array[index];
      if (indexOf(result, value) < 0 &&
          every(others, function(other, index) {
            return (cache[index] || (cache[index] = cachedContains(other)))(value);
          })) {
        result.push(value);
      }
    }
    return result;
  }

  /**
   * Gets the last element of the `array`. Pass `n` to return the lasy `n`
   * elementsvof the `array`.
   *
   * @static
   * @memberOf _
   * @category Arrays
   * @param {Array} array The array to query.
   * @param {Number} [n] The number of elements to return.
   * @param {Object} [guard] Internally used to allow this method to work with
   *  others like `_.map` without using their callback `index` argument for `n`.
   * @returns {Mixed} Returns the last element or an array of the last `n`
   *  elements of `array`.
   * @example
   *
   * _.last([3, 2, 1]);
   * // => 1
   */
  function last(array, n, guard) {
    if (array) {
      var length = array.length;
      return (n == null || guard) ? array[length - 1] : slice.call(array, -n || length);
    }
  }

  /**
   * Gets the index at which the last occurrence of `value` is found using
   * strict equality for comparisons, i.e. `===`.
   *
   * @static
   * @memberOf _
   * @category Arrays
   * @param {Array} array The array to search.
   * @param {Mixed} value The value to search for.
   * @param {Number} [fromIndex=array.length-1] The index to start searching from.
   * @returns {Number} Returns the index of the matched value or `-1`.
   * @example
   *
   * _.lastIndexOf([1, 2, 3, 1, 2, 3], 2);
   * // => 4
   *
   * _.lastIndexOf([1, 2, 3, 1, 2, 3], 2, 3);
   * // => 1
   */
  function lastIndexOf(array, value, fromIndex) {
    if (!array) {
      return -1;
    }
    var index = array.length;
    if (fromIndex && typeof fromIndex == 'number') {
      index = (fromIndex < 0 ? Math.max(0, index + fromIndex) : Math.min(fromIndex, index - 1)) + 1;
    }
    while (index--) {
      if (array[index] === value) {
        return index;
      }
    }
    return -1;
  }

  /**
   * Retrieves the maximum value of an `array`. If `callback` is passed,
   * it will be executed for each value in the `array` to generate the
   * criterion by which the value is ranked. The `callback` is bound to
   * `thisArg` and invoked with 3 arguments; (value, index, array).
   *
   * @static
   * @memberOf _
   * @category Arrays
   * @param {Array} array The array to iterate over.
   * @param {Function} [callback] The function called per iteration.
   * @param {Mixed} [thisArg] The `this` binding for the callback.
   * @returns {Mixed} Returns the maximum value.
   * @example
   *
   * var stooges = [
   *   { 'name': 'moe', 'age': 40 },
   *   { 'name': 'larry', 'age': 50 },
   *   { 'name': 'curly', 'age': 60 }
   * ];
   *
   * _.max(stooges, function(stooge) { return stooge.age; });
   * // => { 'name': 'curly', 'age': 60 };
   */
  function max(array, callback, thisArg) {
    var computed = -Infinity,
        result = computed;

    if (!array) {
      return result;
    }
    var current,
        index = -1,
        length = array.length;

    if (!callback) {
      while (++index < length) {
        if (array[index] > result) {
          result = array[index];
        }
      }
      return result;
    }
    if (thisArg) {
      callback = iteratorBind(callback, thisArg);
    }
    while (++index < length) {
      current = callback(array[index], index, array);
      if (current > computed) {
        computed = current;
        result = array[index];
      }
    }
    return result;
  }

  /**
   * Retrieves the minimum value of an `array`. If `callback` is passed,
   * it will be executed for each value in the `array` to generate the
   * criterion by which the value is ranked. The `callback` is bound to `thisArg`
   * and invoked with 3 arguments; (value, index, array).
   *
   * @static
   * @memberOf _
   * @category Arrays
   * @param {Array} array The array to iterate over.
   * @param {Function} [callback] The function called per iteration.
   * @param {Mixed} [thisArg] The `this` binding for the callback.
   * @returns {Mixed} Returns the minimum value.
   * @example
   *
   * _.min([10, 5, 100, 2, 1000]);
   * // => 2
   */
  function min(array, callback, thisArg) {
    var computed = Infinity,
        result = computed;

    if (!array) {
      return result;
    }
    var current,
        index = -1,
        length = array.length;

    if (!callback) {
      while (++index < length) {
        if (array[index] < result) {
          result = array[index];
        }
      }
      return result;
    }
    if (thisArg) {
      callback = iteratorBind(callback, thisArg);
    }
    while (++index < length) {
      current = callback(array[index], index, array);
      if (current < computed) {
        computed = current;
        result = array[index];
      }
    }
    return result;
  }

  /**
   * Creates an array of numbers (positive and/or negative) progressing from
   * `start` up to but not including `stop`. This method is a port of Python's
   * `range()` function. See http://docs.python.org/library/functions.html#range.
   *
   * @static
   * @memberOf _
   * @category Arrays
   * @param {Number} [start=0] The start of the range.
   * @param {Number} end The end of the range.
   * @param {Number} [step=1] The value to increment or descrement by.
   * @returns {Array} Returns a new range array.
   * @example
   *
   * _.range(10);
   * // => [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
   *
   * _.range(1, 11);
   * // => [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
   *
   * _.range(0, 30, 5);
   * // => [0, 5, 10, 15, 20, 25]
   *
   * _.range(0, -10, -1);
   * // => [0, -1, -2, -3, -4, -5, -6, -7, -8, -9]
   *
   * _.range(0);
   * // => []
   */
  function range(start, end, step) {
    start = +start || 0;
    step = +step || 1;

    if (end == null) {
      end = start;
      start = 0;
    }
    // use `Array(length)` so V8 will avoid the slower "dictionary" mode
    // http://www.youtube.com/watch?v=XAqIpGU8ZZk#t=16m27s
    var index = -1,
        length = Math.max(0, Math.ceil((end - start) / step)),
        result = Array(length);

    while (++index < length) {
      result[index] = start;
      start += step;
    }
    return result;
  }

  /**
   * The opposite of `_.initial`, this method gets all but the first value of
   * `array`. Pass `n` to exclude the first `n` values from the result.
   *
   * @static
   * @memberOf _
   * @alias tail
   * @category Arrays
   * @param {Array} array The array to query.
   * @param {Number} [n] The number of elements to return.
   * @param {Object} [guard] Internally used to allow this method to work with
   *  others like `_.map` without using their callback `index` argument for `n`.
   * @returns {Array} Returns all but the first value or `n` values of `array`.
   * @example
   *
   * _.rest([3, 2, 1]);
   * // => [2, 1]
   */
  function rest(array, n, guard) {
    if (!array) {
      return [];
    }
    return slice.call(array, (n == null || guard) ? 1 : n);
  }

  /**
   * Creates a new array of shuffled `array` values, using a version of the
   * Fisher-Yates shuffle. See http://en.wikipedia.org/wiki/Fisher-Yates_shuffle.
   *
   * @static
   * @memberOf _
   * @category Arrays
   * @param {Array} array The array to shuffle.
   * @returns {Array} Returns a new shuffled array.
   * @example
   *
   * _.shuffle([1, 2, 3, 4, 5, 6]);
   * // => [4, 1, 6, 3, 5, 2]
   */
  function shuffle(array) {
    if (!array) {
      return [];
    }
    var rand,
        index = -1,
        length = array.length,
        result = Array(length);

    while (++index < length) {
      rand = Math.floor(Math.random() * (index + 1));
      result[index] = result[rand];
      result[rand] = array[index];
    }
    return result;
  }

  /**
   * Uses a binary search to determine the smallest index at which the `value`
   * should be inserted into `array` in order to maintain the sort order of the
   * sorted `array`. If `callback` is passed, it will be executed for `value` and
   * each element in `array` to compute their sort ranking. The `callback` is
   * bound to `thisArg` and invoked with 1 argument; (value).
   *
   * @static
   * @memberOf _
   * @category Arrays
   * @param {Array} array The array to iterate over.
   * @param {Mixed} value The value to evaluate.
   * @param {Function} [callback=identity] The function called per iteration.
   * @param {Mixed} [thisArg] The `this` binding for the callback.
   * @returns {Number} Returns the index at which the value should be inserted
   *  into `array`.
   * @example
   *
   * _.sortedIndex([20, 30, 40], 35);
   * // => 2
   *
   * var dict = {
   *   'wordToNumber': { 'twenty': 20, 'thirty': 30, 'thirty-five': 35, 'fourty': 40 }
   * };
   *
   * _.sortedIndex(['twenty', 'thirty', 'fourty'], 'thirty-five', function(word) {
   *   return dict.wordToNumber[word];
   * });
   * // => 2
   *
   * _.sortedIndex(['twenty', 'thirty', 'fourty'], 'thirty-five', function(word) {
   *   return this.wordToNumber[word];
   * }, dict);
   * // => 2
   */
  function sortedIndex(array, value, callback, thisArg) {
    if (!array) {
      return 0;
    }
    var mid,
        low = 0,
        high = array.length;

    if (callback) {
      if (thisArg) {
        callback = bind(callback, thisArg);
      }
      value = callback(value);
      while (low < high) {
        mid = (low + high) >>> 1;
        callback(array[mid]) < value ? low = mid + 1 : high = mid;
      }
    } else {
      while (low < high) {
        mid = (low + high) >>> 1;
        array[mid] < value ? low = mid + 1 : high = mid;
      }
    }
    return low;
  }

  /**
   * Computes the union of the passed-in arrays.
   *
   * @static
   * @memberOf _
   * @category Arrays
   * @param {Array} [array1, array2, ...] Arrays to process.
   * @returns {Array} Returns a new array of unique values, in order, that are
   *  present in one or more of the arrays.
   * @example
   *
   * _.union([1, 2, 3], [101, 2, 1, 10], [2, 1]);
   * // => [1, 2, 3, 101, 10]
   */
  function union() {
    var index = -1,
        result = [],
        flattened = concat.apply(result, arguments),
        length = flattened.length;

    while (++index < length) {
      if (indexOf(result, flattened[index]) < 0) {
        result.push(flattened[index]);
      }
    }
    return result;
  }

  /**
   * Creates a duplicate-value-free version of the `array` using strict equality
   * for comparisons, i.e. `===`. If the `array` is already sorted, passing `true`
   * for `isSorted` will run a faster algorithm. If `callback` is passed, each
   * element of `array` is passed through a callback` before uniqueness is computed.
   * The `callback` is bound to `thisArg` and invoked with 3 arguments; (value, index, array).
   *
   * @static
   * @memberOf _
   * @alias unique
   * @category Arrays
   * @param {Array} array The array to process.
   * @param {Boolean} [isSorted=false] A flag to indicate that the `array` is already sorted.
   * @param {Function} [callback=identity] The function called per iteration.
   * @param {Mixed} [thisArg] The `this` binding for the callback.
   * @returns {Array} Returns a duplicate-value-free array.
   * @example
   *
   * _.uniq([1, 2, 1, 3, 1]);
   * // => [1, 2, 3]
   *
   * _.uniq([1, 1, 2, 2, 3], true);
   * // => [1, 2, 3]
   *
   * _.uniq([1, 2, 1.5, 3, 2.5], function(num) { return Math.floor(num); });
   * // => [1, 2, 3]
   *
   * _.uniq([1, 2, 1.5, 3, 2.5], function(num) { return this.floor(num); }, Math);
   * // => [1, 2, 3]
   */
  function uniq(array, isSorted, callback, thisArg) {
    var result = [];
    if (!array) {
      return result;
    }
    var computed,
        index = -1,
        length = array.length,
        seen = [];

    // juggle arguments
    if (typeof isSorted == 'function') {
      thisArg = callback;
      callback = isSorted;
      isSorted = false;
    }
    if (!callback) {
      callback = identity;
    } else if (thisArg) {
      callback = iteratorBind(callback, thisArg);
    }
    while (++index < length) {
      computed = callback(array[index], index, array);
      if (isSorted
            ? !index || seen[seen.length - 1] !== computed
            : indexOf(seen, computed) < 0
          ) {
        seen.push(computed);
        result.push(array[index]);
      }
    }
    return result;
  }

  /**
   * Creates a new array with all occurrences of the passed values removed using
   * strict equality for comparisons, i.e. `===`.
   *
   * @static
   * @memberOf _
   * @category Arrays
   * @param {Array} array The array to filter.
   * @param {Mixed} [value1, value2, ...] Values to remove.
   * @returns {Array} Returns a new filtered array.
   * @example
   *
   * _.without([1, 2, 1, 0, 3, 1, 4], 0, 1);
   * // => [2, 3, 4]
   */
  function without(array) {
    var result = [];
    if (!array) {
      return result;
    }
    var index = -1,
        length = array.length,
        contains = cachedContains(arguments, 1, 20);

    while (++index < length) {
      if (!contains(array[index])) {
        result.push(array[index]);
      }
    }
    return result;
  }

  /**
   * Merges the elements of each array at their corresponding indexes. Useful for
   * separate data sources that are coordinated through matching array indexes.
   * For a matrix of nested arrays, `_.zip.apply(...)` can transpose the matrix
   * in a similar fashion.
   *
   * @static
   * @memberOf _
   * @category Arrays
   * @param {Array} [array1, array2, ...] Arrays to process.
   * @returns {Array} Returns a new array of merged arrays.
   * @example
   *
   * _.zip(['moe', 'larry', 'curly'], [30, 40, 50], [true, false, false]);
   * // => [['moe', 30, true], ['larry', 40, false], ['curly', 50, false]]
   */
  function zip(array) {
    if (!array) {
      return [];
    }
    var index = -1,
        length = max(pluck(arguments, 'length')),
        result = Array(length);

    while (++index < length) {
      result[index] = pluck(arguments, index);
    }
    return result;
  }

  /**
   * Merges an array of `keys` and an array of `values` into a single object.
   *
   * @static
   * @memberOf _
   * @category Arrays
   * @param {Array} keys The array of keys.
   * @param {Array} [values=[]] The array of values.
   * @returns {Object} Returns an object composed of the given keys and
   *  corresponding values.
   * @example
   *
   * _.zipObject(['moe', 'larry', 'curly'], [30, 40, 50]);
   * // => { 'moe': 30, 'larry': 40, 'curly': 50 }
   */
  function zipObject(keys, values) {
    if (!keys) {
      return {};
    }
    var index = -1,
        length = keys.length,
        result = {};

    values || (values = []);
    while (++index < length) {
      result[keys[index]] = values[index];
    }
    return result;
  }

  /*--------------------------------------------------------------------------*/

  /**
   * Creates a new function that is restricted to executing only after it is
   * called `n` times.
   *
   * @static
   * @memberOf _
   * @category Functions
   * @param {Number} n The number of times the function must be called before
   * it is executed.
   * @param {Function} func The function to restrict.
   * @returns {Function} Returns the new restricted function.
   * @example
   *
   * var renderNotes = _.after(notes.length, render);
   * _.forEach(notes, function(note) {
   *   note.asyncSave({ 'success': renderNotes });
   * });
   * // `renderNotes` is run once, after all notes have saved
   */
  function after(n, func) {
    if (n < 1) {
      return func();
    }
    return function() {
      if (--n < 1) {
        return func.apply(this, arguments);
      }
    };
  }

  /**
   * Creates a new function that, when called, invokes `func` with the `this`
   * binding of `thisArg` and prepends any additional `bind` arguments to those
   * passed to the bound function. Lazy defined methods may be bound by passing
   * the object they are bound to as `func` and the method name as `thisArg`.
   *
   * @static
   * @memberOf _
   * @category Functions
   * @param {Function|Object} func The function to bind or the object the method belongs to.
   * @param {Mixed} [thisArg] The `this` binding of `func` or the method name.
   * @param {Mixed} [arg1, arg2, ...] Arguments to be partially applied.
   * @returns {Function} Returns the new bound function.
   * @example
   *
   * // basic bind
   * var func = function(greeting) {
   *   return greeting + ' ' + this.name;
   * };
   *
   * func = _.bind(func, { 'name': 'moe' }, 'hi');
   * func();
   * // => 'hi moe'
   *
   * // lazy bind
   * var object = {
   *   'name': 'moe',
   *   'greet': function(greeting) {
   *     return greeting + ' ' + this.name;
   *   }
   * };
   *
   * var func = _.bind(object, 'greet', 'hi');
   * func();
   * // => 'hi moe'
   *
   * object.greet = function(greeting) {
   *   return greeting + ', ' + this.name + '!';
   * };
   *
   * func();
   * // => 'hi, moe!'
   */
  function bind(func, thisArg) {
    var methodName,
        isFunc = toString.call(func) == funcClass;

    // juggle arguments
    if (!isFunc) {
      methodName = thisArg;
      thisArg = func;
    }
    // use `Function#bind` if it exists and is fast
    // (in V8 `Function#bind` is slower except when partially applied)
    else if (isBindFast || (nativeBind && arguments.length > 2)) {
      return nativeBind.call.apply(nativeBind, arguments);
    }

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

    function bound() {
      // `Function#bind` spec
      // http://es5.github.com/#x15.3.4.5
      var args = arguments,
          thisBinding = thisArg;

      if (!isFunc) {
        func = thisArg[methodName];
      }
      if (partialArgs.length) {
        args = args.length
          ? concat.apply(partialArgs, args)
          : partialArgs;
      }
      if (this instanceof bound) {
        // get `func` instance if `bound` is invoked in a `new` expression
        noop.prototype = func.prototype;
        thisBinding = new noop;

        // mimic the constructor's `return` behavior
        // http://es5.github.com/#x13.2.2
        var result = func.apply(thisBinding, args);
        return result && objectTypes[typeof result]
          ? result
          : thisBinding
      }
      return func.apply(thisBinding, args);
    }
    return bound;
  }

  /**
   * Binds methods on `object` to `object`, overwriting the existing method.
   * If no method names are provided, all the function properties of `object`
   * will be bound.
   *
   * @static
   * @memberOf _
   * @category Functions
   * @param {Object} object The object to bind and assign the bound methods to.
   * @param {String} [methodName1, methodName2, ...] Method names on the object to bind.
   * @returns {Object} Returns the `object`.
   * @example
   *
   * var buttonView = {
   *  'label': 'lodash',
   *  'onClick': function() { alert('clicked: ' + this.label); }
   * };
   *
   * _.bindAll(buttonView);
   * jQuery('#lodash_button').on('click', buttonView.onClick);
   * // => When the button is clicked, `this.label` will have the correct value
   */
  var bindAll = createIterator({
    'useHas': false,
    'useStrict': false,
    'args': 'object',
    'init': 'object',
    'top':
      'var funcs = arguments,\n' +
      '    length = funcs.length;\n' +
      'if (length > 1) {\n' +
      '  for (var index = 1; index < length; index++)\n' +
      '    result[funcs[index]] = bind(result[funcs[index]], result);\n' +
      '  return result\n' +
      '}',
    'inLoop':
      'if (toString.call(result[index]) == funcClass)' +
      ' result[index] = bind(result[index], result)'
  });

  /**
   * Creates a new function that is the composition of the passed functions,
   * where each function consumes the return value of the function that follows.
   * In math terms, composing the functions `f()`, `g()`, and `h()` produces `f(g(h()))`.
   *
   * @static
   * @memberOf _
   * @category Functions
   * @param {Function} [func1, func2, ...] Functions to compose.
   * @returns {Function} Returns the new composed function.
   * @example
   *
   * var greet = function(name) { return 'hi: ' + name; };
   * var exclaim = function(statement) { return statement + '!'; };
   * var welcome = _.compose(exclaim, greet);
   * welcome('moe');
   * // => 'hi: moe!'
   */
  function compose() {
    var funcs = arguments;
    return function() {
      var args = arguments,
          length = funcs.length;

      while (length--) {
        args = [funcs[length].apply(this, args)];
      }
      return args[0];
    };
  }

  /**
   * Creates a new function that will delay the execution of `func` until after
   * `wait` milliseconds have elapsed since the last time it was invoked. Pass
   * `true` for `immediate` to cause debounce to invoke `func` on the leading,
   * instead of the trailing, edge of the `wait` timeout. Subsequent calls to
   * the debounced function will return the result of the last `func` call.
   *
   * @static
   * @memberOf _
   * @category Functions
   * @param {Function} func The function to debounce.
   * @param {Number} wait The number of milliseconds to delay.
   * @param {Boolean} immediate A flag to indicate execution is on the leading
   *  edge of the timeout.
   * @returns {Function} Returns the new debounced function.
   * @example
   *
   * var lazyLayout = _.debounce(calculateLayout, 300);
   * jQuery(window).on('resize', lazyLayout);
   */
  function debounce(func, wait, immediate) {
    var args,
        result,
        thisArg,
        timeoutId;

    function delayed() {
      timeoutId = null;
      if (!immediate) {
        func.apply(thisArg, args);
      }
    }

    return function() {
      var isImmediate = immediate && !timeoutId;
      args = arguments;
      thisArg = this;

      clearTimeout(timeoutId);
      timeoutId = setTimeout(delayed, wait);

      if (isImmediate) {
        result = func.apply(thisArg, args);
      }
      return result;
    };
  }

  /**
   * Executes the `func` function after `wait` milliseconds. Additional arguments
   * will be passed to `func` when it is invoked.
   *
   * @static
   * @memberOf _
   * @category Functions
   * @param {Function} func The function to delay.
   * @param {Number} wait The number of milliseconds to delay execution.
   * @param {Mixed} [arg1, arg2, ...] Arguments to invoke the function with.
   * @returns {Number} Returns the `setTimeout` timeout id.
   * @example
   *
   * var log = _.bind(console.log, console);
   * _.delay(log, 1000, 'logged later');
   * // => 'logged later' (Appears after one second.)
   */
  function delay(func, wait) {
    var args = slice.call(arguments, 2);
    return setTimeout(function() { return func.apply(undefined, args); }, wait);
  }

  /**
   * Defers executing the `func` function until the current call stack has cleared.
   * Additional arguments will be passed to `func` when it is invoked.
   *
   * @static
   * @memberOf _
   * @category Functions
   * @param {Function} func The function to defer.
   * @param {Mixed} [arg1, arg2, ...] Arguments to invoke the function with.
   * @returns {Number} Returns the `setTimeout` timeout id.
   * @example
   *
   * _.defer(function() { alert('deferred'); });
   * // returns from the function before `alert` is called
   */
  function defer(func) {
    var args = slice.call(arguments, 1);
    return setTimeout(function() { return func.apply(undefined, args); }, 1);
  }

  /**
   * Creates a new function that memoizes the result of `func`. If `resolver` is
   * passed, it will be used to determine the cache key for storing the result
   * based on the arguments passed to the memoized function. By default, the first
   * argument passed to the memoized function is used as the cache key.
   *
   * @static
   * @memberOf _
   * @category Functions
   * @param {Function} func The function to have its output memoized.
   * @param {Function} [resolver] A function used to resolve the cache key.
   * @returns {Function} Returns the new memoizing function.
   * @example
   *
   * var fibonacci = _.memoize(function(n) {
   *   return n < 2 ? n : fibonacci(n - 1) + fibonacci(n - 2);
   * });
   */
  function memoize(func, resolver) {
    var cache = {};
    return function() {
      var prop = resolver ? resolver.apply(this, arguments) : arguments[0];
      return hasOwnProperty.call(cache, prop)
        ? cache[prop]
        : (cache[prop] = func.apply(this, arguments));
    };
  }

  /**
   * Creates a new function that is restricted to one execution. Repeat calls to
   * the function will return the value of the first call.
   *
   * @static
   * @memberOf _
   * @category Functions
   * @param {Function} func The function to restrict.
   * @returns {Function} Returns the new restricted function.
   * @example
   *
   * var initialize = _.once(createApplication);
   * initialize();
   * initialize();
   * // Application is only created once.
   */
  function once(func) {
    var result,
        ran = false;

    return function() {
      if (ran) {
        return result;
      }
      ran = true;
      result = func.apply(this, arguments);
      return result;
    };
  }

  /**
   * Creates a new function that, when called, invokes `func` with any additional
   * `partial` arguments prepended to those passed to the new function. This method
   * is similar `bind`, except it does **not** alter the `this` binding.
   *
   * @static
   * @memberOf _
   * @category Functions
   * @param {Function} func The function to partially apply arguments to.
   * @param {Mixed} [arg1, arg2, ...] Arguments to be partially applied.
   * @returns {Function} Returns the new partially applied function.
   * @example
   *
   * var greet = function(greeting, name) { return greeting + ': ' + name; };
   * var hi = _.partial(greet, 'hi');
   * hi('moe');
   * // => 'hi: moe'
   */
  function partial(func) {
    var args = slice.call(arguments, 1),
        argsLength = args.length;

    return function() {
      var result,
          others = arguments;

      if (others.length) {
        args.length = argsLength;
        push.apply(args, others);
      }
      result = args.length == 1 ? func.call(this, args[0]) : func.apply(this, args);
      args.length = argsLength;
      return result;
    };
  }

  /**
   * Creates a new function that, when executed, will only call the `func`
   * function at most once per every `wait` milliseconds. If the throttled
   * function is invoked more than once during the `wait` timeout, `func` will
   * also be called on the trailing edge of the timeout. Subsequent calls to the
   * throttled function will return the result of the last `func` call.
   *
   * @static
   * @memberOf _
   * @category Functions
   * @param {Function} func The function to throttle.
   * @param {Number} wait The number of milliseconds to throttle executions to.
   * @returns {Function} Returns the new throttled function.
   * @example
   *
   * var throttled = _.throttle(updatePosition, 100);
   * jQuery(window).on('scroll', throttled);
   */
  function throttle(func, wait) {
    var args,
        result,
        thisArg,
        timeoutId,
        lastCalled = 0;

    function trailingCall() {
      lastCalled = new Date;
      timeoutId = null;
      func.apply(thisArg, args);
    }

    return function() {
      var now = new Date,
          remain = wait - (now - lastCalled);

      args = arguments;
      thisArg = this;

      if (remain <= 0) {
        lastCalled = now;
        result = func.apply(thisArg, args);
      }
      else if (!timeoutId) {
        timeoutId = setTimeout(trailingCall, remain);
      }
      return result;
    };
  }

  /**
   * Creates a new function that passes `value` to the `wrapper` function as its
   * first argument. Additional arguments passed to the new function are appended
   * to those passed to the `wrapper` function.
   *
   * @static
   * @memberOf _
   * @category Functions
   * @param {Mixed} value The value to wrap.
   * @param {Function} wrapper The wrapper function.
   * @returns {Function} Returns the new function.
   * @example
   *
   * var hello = function(name) { return 'hello: ' + name; };
   * hello = _.wrap(hello, function(func) {
   *   return 'before, ' + func('moe') + ', after';
   * });
   * hello();
   * // => 'before, hello: moe, after'
   */
  function wrap(value, wrapper) {
    return function() {
      var args = [value];
      if (arguments.length) {
        push.apply(args, arguments);
      }
      return wrapper.apply(this, args);
    };
  }

  /*--------------------------------------------------------------------------*/

  /**
   * Escapes a string for inclusion in HTML, replacing `&`, `<`, `"`, and `'`
   * characters.
   *
   * @static
   * @memberOf _
   * @category Utilities
   * @param {String} string The string to escape.
   * @returns {String} Returns the escaped string.
   * @example
   *
   * _.escape('Curly, Larry & Moe');
   * // => "Curly, Larry &amp; Moe"
   */
  function escape(string) {
    return string == null ? '' : (string + '').replace(reUnescapedHtml, escapeHtmlChar);
  }

  /**
   * This function returns the first argument passed to it.
   * Note: It is used throughout Lo-Dash as a default callback.
   *
   * @static
   * @memberOf _
   * @category Utilities
   * @param {Mixed} value Any value.
   * @returns {Mixed} Returns `value`.
   * @example
   *
   * var moe = { 'name': 'moe' };
   * moe === _.identity(moe);
   * // => true
   */
  function identity(value) {
    return value;
  }

  /**
   * Adds functions properties of `object` to the `lodash` function and chainable
   * wrapper.
   *
   * @static
   * @memberOf _
   * @category Utilities
   * @param {Object} object The object of function properties to add to `lodash`.
   * @example
   *
   * _.mixin({
   *   'capitalize': function(string) {
   *     return string.charAt(0).toUpperCase() + string.slice(1).toLowerCase();
   *   }
   * });
   *
   * _.capitalize('curly');
   * // => 'Curly'
   *
   * _('larry').capitalize();
   * // => 'Larry'
   */
  function mixin(object) {
    forEach(functions(object), function(methodName) {
      var func = lodash[methodName] = object[methodName];

      LoDash.prototype[methodName] = function() {
        var args = [this._wrapped];
        if (arguments.length) {
          push.apply(args, arguments);
        }
        var result = func.apply(lodash, args);
        if (this._chain) {
          result = new LoDash(result);
          result._chain = true;
        }
        return result;
      };
    });
  }

  /**
   * Reverts the '_' variable to its previous value and returns a reference to
   * the `lodash` function.
   *
   * @static
   * @memberOf _
   * @category Utilities
   * @returns {Function} Returns the `lodash` function.
   * @example
   *
   * var lodash = _.noConflict();
   */
  function noConflict() {
    window._ = oldDash;
    return this;
  }

  /**
   * Resolves the value of `property` on `object`. If `property` is a function
   * it will be invoked and its result returned, else the property value is
   * returned. If `object` is falsey, then `null` is returned.
   *
   * @deprecated
   * @static
   * @memberOf _
   * @category Utilities
   * @param {Object} object The object to inspect.
   * @param {String} property The property to get the result of.
   * @returns {Mixed} Returns the resolved value.
   * @example
   *
   * var object = {
   *   'cheese': 'crumpets',
   *   'stuff': function() {
   *     return 'nonsense';
   *   }
   * };
   *
   * _.result(object, 'cheese');
   * // => 'crumpets'
   *
   * _.result(object, 'stuff');
   * // => 'nonsense'
   */
  function result(object, property) {
    // based on Backbone's private `getValue` function
    // https://github.com/documentcloud/backbone/blob/0.9.2/backbone.js#L1419-1424
    if (!object) {
      return null;
    }
    var value = object[property];
    return toString.call(value) == funcClass ? object[property]() : value;
  }

  /**
   * A micro-templating method that handles arbitrary delimiters, preserves
   * whitespace, and correctly escapes quotes within interpolated code.
   *
   * @static
   * @memberOf _
   * @category Utilities
   * @param {String} text The template text.
   * @param {Obect} data The data object used to populate the text.
   * @param {Object} options The options object.
   * @returns {Function|String} Returns a compiled function when no `data` object
   *  is given, else it returns the interpolated text.
   * @example
   *
   * // using compiled template
   * var compiled = _.template('hello: <%= name %>');
   * compiled({ 'name': 'moe' });
   * // => 'hello: moe'
   *
   * var list = '<% _.forEach(people, function(name) { %> <li><%= name %></li> <% }); %>';
   * _.template(list, { 'people': ['moe', 'curly', 'larry'] });
   * // => '<li>moe</li><li>curly</li><li>larry</li>'
   *
   * var template = _.template('<b><%- value %></b>');
   * template({ 'value': '<script>' });
   * // => '<b>&lt;script></b>'
   *
   * // using `print`
   * var compiled = _.template('<% print("Hello " + epithet); %>');
   * compiled({ 'epithet': 'stooge' });
   * // => 'Hello stooge.'
   *
   * // using custom template settings
   * _.templateSettings = {
   *   'interpolate': /\{\{(.+?)\}\}/g
   * };
   *
   * var template = _.template('Hello {{ name }}!');
   * template({ 'name': 'Mustache' });
   * // => 'Hello Mustache!'
   *
   * // using the `variable` option
   * _.template('<%= data.hasWith %>', { 'hasWith': 'no' }, { 'variable': 'data' });
   * // => 'no'
   *
   * // using the `source` property
   * <script>
   *   JST.project = <%= _.template(jstText).source %>;
   * </script>
   */
  function template(text, data, options) {
    // based on John Resig's `tmpl` implementation
    // http://ejohn.org/blog/javascript-micro-templating/
    // and Laura Doktorova's doT.js
    // https://github.com/olado/doT
    options || (options = {});

    var isEvaluating,
        result,
        escapeDelimiter = options.escape,
        evaluateDelimiter = options.evaluate,
        interpolateDelimiter = options.interpolate,
        settings = lodash.templateSettings,
        variable = options.variable;

    // use default settings if no options object is provided
    if (escapeDelimiter == null) {
      escapeDelimiter = settings.escape;
    }
    if (evaluateDelimiter == null) {
      // use `false` as the fallback value, instead of leaving it `undefined`,
      // so the initial assignment of `reEvaluateDelimiter` will still occur
      evaluateDelimiter = settings.evaluate || false;
    }
    if (interpolateDelimiter == null) {
      interpolateDelimiter = settings.interpolate;
    }

    // tokenize delimiters to avoid escaping them
    if (escapeDelimiter) {
      text = text.replace(escapeDelimiter, tokenizeEscape);
    }
    if (interpolateDelimiter) {
      text = text.replace(interpolateDelimiter, tokenizeInterpolate);
    }
    if (evaluateDelimiter != lastEvaluateDelimiter) {
      // generate `reEvaluateDelimiter` to match `_.templateSettings.evaluate`
      // and internal `<e%- %>`, `<e%= %>` delimiters
      lastEvaluateDelimiter = evaluateDelimiter;
      reEvaluateDelimiter = RegExp(
        '<e%-([\\s\\S]+?)%>|<e%=([\\s\\S]+?)%>' +
        (evaluateDelimiter ? '|' + evaluateDelimiter.source : '')
      , 'g');
    }
    isEvaluating = tokenized.length;
    text = text.replace(reEvaluateDelimiter, tokenizeEvaluate);
    isEvaluating = isEvaluating != tokenized.length;

    // escape characters that cannot be included in string literals and
    // detokenize delimiter code snippets
    text = "__p += '" + text
      .replace(reUnescapedString, escapeStringChar)
      .replace(reToken, detokenize) + "';\n";

    // clear stored code snippets
    tokenized.length = 0;

    // if `options.variable` is not specified and the template contains "evaluate"
    // delimiters, wrap a with-statement around the generated code to add the
    // data object to the top of the scope chain
    if (!variable) {
      variable = settings.variable || lastVariable || 'obj';

      if (isEvaluating) {
        text = 'with (' + variable + ') {\n' + text + '\n}\n';
      }
      else {
        if (variable != lastVariable) {
          // generate `reDoubleVariable` to match references like `obj.obj` inside
          // transformed "escape" and "interpolate" delimiters
          lastVariable = variable;
          reDoubleVariable = RegExp('(\\(\\s*)' + variable + '\\.' + variable + '\\b', 'g');
        }
        // avoid a with-statement by prepending data object references to property names
        text = text
          .replace(reInsertVariable, '$&' + variable + '.')
          .replace(reDoubleVariable, '$1__d');
      }
    }

    // cleanup code by stripping empty strings
    text = ( isEvaluating ? text.replace(reEmptyStringLeading, '') : text)
      .replace(reEmptyStringMiddle, '$1')
      .replace(reEmptyStringTrailing, '$1;');

    // frame code as the function body
    text = 'function(' + variable + ') {\n' +
      variable + ' || (' + variable + ' = {});\n' +
      'var __t, __p = \'\', __e = _.escape' +
      (isEvaluating
        ? ', __j = Array.prototype.join;\n' +
          'function print() { __p += __j.call(arguments, \'\') }\n'
        : ', __d = ' + variable + '.' + variable + ' || ' + variable + ';\n'
      ) +
      text +
      'return __p\n}';

    // add a sourceURL for easier debugging
    // http://www.html5rocks.com/en/tutorials/developertools/sourcemaps/#toc-sourceurl
    if (useSourceURL) {
      text += '\n//@ sourceURL=/lodash/template/source[' + (templateCounter++) + ']';
    }

    try {
      result = Function('_', 'return ' + text)(lodash);
    } catch(e) {
      // defer syntax errors until the compiled template is executed to allow
      // examining the `source` property beforehand and for consistency,
      // because other template related errors occur at execution
      result = function() { throw e; };
    }

    if (data) {
      return result(data);
    }
    // provide the compiled function's source via its `toString` method, in
    // supported environments, or the `source` property as a convenience for
    // build time precompilation
    result.source = text;
    return result;
  }

  /**
   * Executes the `callback` function `n` times. The `callback` is bound to
   * `thisArg` and invoked with 1 argument; (index).
   *
   * @static
   * @memberOf _
   * @category Utilities
   * @param {Number} n The number of times to execute the callback.
   * @param {Function} callback The function called per iteration.
   * @param {Mixed} [thisArg] The `this` binding for the callback.
   * @example
   *
   * _.times(3, function() { genie.grantWish(); });
   * // => calls `genie.grantWish()` 3 times
   *
   * _.times(3, function() { this.grantWish(); }, genie);
   * // => also calls `genie.grantWish()` 3 times
   */
  function times(n, callback, thisArg) {
    var index = -1;
    if (thisArg) {
      while (++index < n) {
        callback.call(thisArg, index);
      }
    } else {
      while (++index < n) {
        callback(index);
      }
    }
  }

  /**
   * Generates a unique id. If `prefix` is passed, the id will be appended to it.
   *
   * @static
   * @memberOf _
   * @category Utilities
   * @param {String} [prefix] The value to prefix the id with.
   * @returns {Number|String} Returns a numeric id if no prefix is passed, else
   *  a string id may be returned.
   * @example
   *
   * _.uniqueId('contact_');
   * // => 'contact_104'
   */
  function uniqueId(prefix) {
    var id = idCounter++;
    return prefix ? prefix + id : id;
  }

  /*--------------------------------------------------------------------------*/

  /**
   * Wraps the value in a `lodash` wrapper object.
   *
   * @static
   * @memberOf _
   * @category Chaining
   * @param {Mixed} value The value to wrap.
   * @returns {Object} Returns the wrapper object.
   * @example
   *
   * var stooges = [
   *   { 'name': 'moe', 'age': 40 },
   *   { 'name': 'larry', 'age': 50 },
   *   { 'name': 'curly', 'age': 60 }
   * ];
   *
   * var youngest = _.chain(stooges)
   *     .sortBy(function(stooge) { return stooge.age; })
   *     .map(function(stooge) { return stooge.name + ' is ' + stooge.age; })
   *     .first()
   *     .value();
   * // => 'moe is 40'
   */
  function chain(value) {
    value = new LoDash(value);
    value._chain = true;
    return value;
  }

  /**
   * Invokes `interceptor` with the `value` as the first argument, and then
   * returns `value`. The purpose of this method is to "tap into" a method chain,
   * in order to perform operations on intermediate results within the chain.
   *
   * @static
   * @memberOf _
   * @category Chaining
   * @param {Mixed} value The value to pass to `interceptor`.
   * @param {Function} interceptor The function to invoke.
   * @returns {Mixed} Returns `value`.
   * @example
   *
   * _.chain([1,2,3,200])
   *  .filter(function(num) { return num % 2 == 0; })
   *  .tap(alert)
   *  .map(function(num) { return num * num })
   *  .value();
   * // => // [2, 200] (alerted)
   * // => [4, 40000]
   */
  function tap(value, interceptor) {
    interceptor(value);
    return value;
  }

  /**
   * Enables method chaining on the wrapper object.
   *
   * @name chain
   * @deprecated
   * @memberOf _
   * @category Chaining
   * @returns {Mixed} Returns the wrapper object.
   * @example
   *
   * _([1, 2, 3]).value();
   * // => [1, 2, 3]
   */
  function wrapperChain() {
    this._chain = true;
    return this;
  }

  /**
   * Extracts the wrapped value.
   *
   * @name value
   * @memberOf _
   * @category Chaining
   * @returns {Mixed} Returns the wrapped value.
   * @example
   *
   * _([1, 2, 3]).value();
   * // => [1, 2, 3]
   */
  function wrapperValue() {
    return this._wrapped;
  }

  /*--------------------------------------------------------------------------*/

  /**
   * The semantic version number.
   *
   * @static
   * @memberOf _
   * @type String
   */
  lodash.VERSION = '0.4.2';

  // assign static methods
  lodash.after = after;
  lodash.bind = bind;
  lodash.bindAll = bindAll;
  lodash.chain = chain;
  lodash.clone = clone;
  lodash.compact = compact;
  lodash.compose = compose;
  lodash.contains = contains;
  lodash.countBy = countBy;
  lodash.debounce = debounce;
  lodash.defaults = defaults;
  lodash.defer = defer;
  lodash.delay = delay;
  lodash.difference = difference;
  lodash.drop = drop;
  lodash.escape = escape;
  lodash.every = every;
  lodash.extend = extend;
  lodash.filter = filter;
  lodash.find = find;
  lodash.first = first;
  lodash.flatten = flatten;
  lodash.forEach = forEach;
  lodash.forIn = forIn;
  lodash.forOwn = forOwn;
  lodash.functions = functions;
  lodash.groupBy = groupBy;
  lodash.has = has;
  lodash.identity = identity;
  lodash.indexOf = indexOf;
  lodash.initial = initial;
  lodash.intersection = intersection;
  lodash.invoke = invoke;
  lodash.isArguments = isArguments;
  lodash.isArray = isArray;
  lodash.isBoolean = isBoolean;
  lodash.isDate = isDate;
  lodash.isElement = isElement;
  lodash.isEmpty = isEmpty;
  lodash.isEqual = isEqual;
  lodash.isFinite = isFinite;
  lodash.isFunction = isFunction;
  lodash.isNaN = isNaN;
  lodash.isNull = isNull;
  lodash.isNumber = isNumber;
  lodash.isObject = isObject;
  lodash.isRegExp = isRegExp;
  lodash.isString = isString;
  lodash.isUndefined = isUndefined;
  lodash.keys = keys;
  lodash.last = last;
  lodash.lastIndexOf = lastIndexOf;
  lodash.map = map;
  lodash.max = max;
  lodash.memoize = memoize;
  lodash.min = min;
  lodash.mixin = mixin;
  lodash.noConflict = noConflict;
  lodash.once = once;
  lodash.partial = partial;
  lodash.pick = pick;
  lodash.pluck = pluck;
  lodash.range = range;
  lodash.reduce = reduce;
  lodash.reduceRight = reduceRight;
  lodash.reject = reject;
  lodash.rest = rest;
  lodash.result = result;
  lodash.shuffle = shuffle;
  lodash.size = size;
  lodash.some = some;
  lodash.sortBy = sortBy;
  lodash.sortedIndex = sortedIndex;
  lodash.tap = tap;
  lodash.template = template;
  lodash.throttle = throttle;
  lodash.times = times;
  lodash.toArray = toArray;
  lodash.union = union;
  lodash.uniq = uniq;
  lodash.uniqueId = uniqueId;
  lodash.values = values;
  lodash.where = where;
  lodash.without = without;
  lodash.wrap = wrap;
  lodash.zip = zip;
  lodash.zipObject = zipObject;

  // assign aliases
  lodash.all = every;
  lodash.any = some;
  lodash.collect = map;
  lodash.detect = find;
  lodash.each = forEach;
  lodash.foldl = reduce;
  lodash.foldr = reduceRight;
  lodash.head = first;
  lodash.include = contains;
  lodash.inject = reduce;
  lodash.methods = functions;
  lodash.select = filter;
  lodash.tail = rest;
  lodash.take = first;
  lodash.unique = uniq;

  // add pseudo private properties used and removed during the build process
  lodash._iteratorTemplate = iteratorTemplate;
  lodash._shimKeys = shimKeys;

  /*--------------------------------------------------------------------------*/

  // assign private `LoDash` constructor's prototype
  LoDash.prototype = lodash.prototype;

  // add all static functions to `LoDash.prototype`
  mixin(lodash);

  // add `LoDash.prototype.chain` after calling `mixin()` to avoid overwriting
  // it with the wrapped `lodash.chain`
  LoDash.prototype.chain = wrapperChain;
  LoDash.prototype.value = wrapperValue;

  // add all mutator Array functions to the wrapper.
  forEach(['pop', 'push', 'reverse', 'shift', 'sort', 'splice', 'unshift'], function(methodName) {
    var func = ArrayProto[methodName];

    LoDash.prototype[methodName] = function() {
      var value = this._wrapped;
      func.apply(value, arguments);

      // Firefox < 10, IE compatibility mode, and IE < 9 have buggy Array
      // `shift()` and `splice()` functions that fail to remove the last element,
      // `value[0]`, of array-like objects even though the `length` property is
      // set to `0`. The `shift()` method is buggy in IE 8 compatibility mode,
      // while `splice()` is buggy regardless of mode in IE < 9 and buggy in
      // compatibility mode in IE 9.
      if (value.length === 0) {
        delete value[0];
      }
      if (this._chain) {
        value = new LoDash(value);
        value._chain = true;
      }
      return value;
    };
  });

  // add all accessor Array functions to the wrapper.
  forEach(['concat', 'join', 'slice'], function(methodName) {
    var func = ArrayProto[methodName];

    LoDash.prototype[methodName] = function() {
      var value = this._wrapped,
          result = func.apply(value, arguments);

      if (this._chain) {
        result = new LoDash(result);
        result._chain = true;
      }
      return result;
    };
  });

  /*--------------------------------------------------------------------------*/

  // expose Lo-Dash
  // some AMD build optimizers, like r.js, check for specific condition patterns like the following:
  if (typeof define == 'function' && typeof define.amd == 'object' && define.amd) {
    // Expose Lo-Dash to the global object even when an AMD loader is present in
    // case Lo-Dash was injected by a third-party script and not intended to be
    // loaded as a module. The global assignment can be reverted in the Lo-Dash
    // module via its `noConflict()` method.
    window._ = lodash;

    // define as an anonymous module so, through path mapping, it can be
    // referenced as the "underscore" module
    define(function() {
      return lodash;
    });
  }
  // check for `exports` after `define` in case a build optimizer adds an `exports` object
  else if (freeExports) {
    // in Node.js or RingoJS v0.8.0+
    if (typeof module == 'object' && module && module.exports == freeExports) {
      (module.exports = lodash)._ = lodash;
    }
    // in Narwhal or RingoJS v0.7.0-
    else {
      freeExports._ = lodash;
    }
  }
  else {
    // in a browser or Rhino
    window._ = lodash;
  }
}(this));