lodash/lodash.iteratee/index.js

/**
 * lodash 4.1.1 (Custom Build) <https://lodash.com/>
 * Build: `lodash modularize exports="npm" -o ./`
 * Copyright 2012-2016 The Dojo Foundation <http://dojofoundation.org/>
 * Based on Underscore.js 1.8.3 <http://underscorejs.org/LICENSE>
 * Copyright 2009-2016 Jeremy Ashkenas, DocumentCloud and Investigative Reporters & Editors
 * Available under MIT license <https://lodash.com/license>
 */
var Stack = require('lodash._stack'),
    arrayEach = require('lodash._arrayeach'),
    baseFor = require('lodash._basefor'),
    baseIsEqual = require('lodash._baseisequal'),
    baseIsMatch = require('lodash._baseismatch'),
    get = require('lodash.get'),
    hasIn = require('lodash.hasin'),
    isBuffer = require('lodash.isbuffer'),
    keys = require('lodash.keys'),
    root = require('lodash._root'),
    toPairs = require('lodash.topairs'),
    toString = require('lodash.tostring');

/** Used to compose bitmasks for comparison styles. */
var UNORDERED_COMPARE_FLAG = 1,
    PARTIAL_COMPARE_FLAG = 2;

/** `Object#toString` result references. */
var argsTag = '[object Arguments]',
    arrayTag = '[object Array]',
    boolTag = '[object Boolean]',
    dateTag = '[object Date]',
    errorTag = '[object Error]',
    funcTag = '[object Function]',
    genTag = '[object GeneratorFunction]',
    mapTag = '[object Map]',
    numberTag = '[object Number]',
    objectTag = '[object Object]',
    regexpTag = '[object RegExp]',
    setTag = '[object Set]',
    stringTag = '[object String]',
    symbolTag = '[object Symbol]',
    weakMapTag = '[object WeakMap]';

var arrayBufferTag = '[object ArrayBuffer]',
    float32Tag = '[object Float32Array]',
    float64Tag = '[object Float64Array]',
    int8Tag = '[object Int8Array]',
    int16Tag = '[object Int16Array]',
    int32Tag = '[object Int32Array]',
    uint8Tag = '[object Uint8Array]',
    uint8ClampedTag = '[object Uint8ClampedArray]',
    uint16Tag = '[object Uint16Array]',
    uint32Tag = '[object Uint32Array]';

/** Used to match property names within property paths. */
var reIsDeepProp = /\.|\[(?:[^[\]]*|(["'])(?:(?!\1)[^\\]|\\.)*?\1)\]/,
    reIsPlainProp = /^\w*$/,
    rePropName = /[^.[\]]+|\[(?:(-?\d+(?:\.\d+)?)|(["'])((?:(?!\2)[^\\]|\\.)*?)\2)\]/g;

/** Used to match `RegExp` [syntax characters](http://ecma-international.org/ecma-262/6.0/#sec-patterns). */
var reRegExpChar = /[\\^$.*+?()[\]{}|]/g;

/** Used to match backslashes in property paths. */
var reEscapeChar = /\\(\\)?/g;

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

/** Used to detect host constructors (Safari > 5). */
var reIsHostCtor = /^\[object .+?Constructor\]$/;

/** Used to identify `toStringTag` values supported by `_.clone`. */
var cloneableTags = {};
cloneableTags[argsTag] = cloneableTags[arrayTag] =
cloneableTags[arrayBufferTag] = cloneableTags[boolTag] =
cloneableTags[dateTag] = cloneableTags[float32Tag] =
cloneableTags[float64Tag] = cloneableTags[int8Tag] =
cloneableTags[int16Tag] = cloneableTags[int32Tag] =
cloneableTags[mapTag] = cloneableTags[numberTag] =
cloneableTags[objectTag] = cloneableTags[regexpTag] =
cloneableTags[setTag] = cloneableTags[stringTag] =
cloneableTags[symbolTag] = cloneableTags[uint8Tag] =
cloneableTags[uint8ClampedTag] = cloneableTags[uint16Tag] =
cloneableTags[uint32Tag] = true;
cloneableTags[errorTag] = cloneableTags[funcTag] =
cloneableTags[weakMapTag] = false;

/**
 * Adds the key-value `pair` to `map`.
 *
 * @private
 * @param {Object} map The map to modify.
 * @param {Array} pair The key-value pair to add.
 * @returns {Object} Returns `map`.
 */
function addMapEntry(map, pair) {
  map.set(pair[0], pair[1]);
  return map;
}

/**
 * Adds `value` to `set`.
 *
 * @private
 * @param {Object} set The set to modify.
 * @param {*} value The value to add.
 * @returns {Object} Returns `set`.
 */
function addSetEntry(set, value) {
  set.add(value);
  return set;
}

/**
 * A specialized version of `_.reduce` for arrays without support for
 * iteratee shorthands.
 *
 * @private
 * @param {Array} array The array to iterate over.
 * @param {Function} iteratee The function invoked per iteration.
 * @param {*} [accumulator] The initial value.
 * @param {boolean} [initAccum] Specify using the first element of `array` as the initial value.
 * @returns {*} Returns the accumulated value.
 */
function arrayReduce(array, iteratee, accumulator, initAccum) {
  var index = -1,
      length = array.length;

  if (initAccum && length) {
    accumulator = array[++index];
  }
  while (++index < length) {
    accumulator = iteratee(accumulator, array[index], index, array);
  }
  return accumulator;
}

/**
 * Checks if `value` is a host object in IE < 9.
 *
 * @private
 * @param {*} value The value to check.
 * @returns {boolean} Returns `true` if `value` is a host object, else `false`.
 */
function isHostObject(value) {
  // Many host objects are `Object` objects that can coerce to strings
  // despite having improperly defined `toString` methods.
  var result = false;
  if (value != null && typeof value.toString != 'function') {
    try {
      result = !!(value + '');
    } catch (e) {}
  }
  return result;
}

/**
 * Converts `map` to an array.
 *
 * @private
 * @param {Object} map The map to convert.
 * @returns {Array} Returns the converted array.
 */
function mapToArray(map) {
  var index = -1,
      result = Array(map.size);

  map.forEach(function(value, key) {
    result[++index] = [key, value];
  });
  return result;
}

/**
 * Converts `set` to an array.
 *
 * @private
 * @param {Object} set The set to convert.
 * @returns {Array} Returns the converted array.
 */
function setToArray(set) {
  var index = -1,
      result = Array(set.size);

  set.forEach(function(value) {
    result[++index] = value;
  });
  return result;
}

/** Used for built-in method references. */
var objectProto = Object.prototype;

/** Used to resolve the decompiled source of functions. */
var funcToString = Function.prototype.toString;

/** Used to check objects for own properties. */
var hasOwnProperty = objectProto.hasOwnProperty;

/**
 * Used to resolve the [`toStringTag`](http://ecma-international.org/ecma-262/6.0/#sec-object.prototype.tostring)
 * of values.
 */
var objectToString = objectProto.toString;

/** Used to detect if a method is native. */
var reIsNative = RegExp('^' +
  funcToString.call(hasOwnProperty).replace(reRegExpChar, '\\$&')
  .replace(/hasOwnProperty|(function).*?(?=\\\()| for .+?(?=\\\])/g, '$1.*?') + '$'
);

/** Built-in value references. */
var Symbol = root.Symbol,
    Uint8Array = root.Uint8Array,
    getOwnPropertySymbols = Object.getOwnPropertySymbols;

/* Built-in method references that are verified to be native. */
var Map = getNative(root, 'Map'),
    Set = getNative(root, 'Set'),
    WeakMap = getNative(root, 'WeakMap');

/** Used to detect maps, sets, and weakmaps. */
var mapCtorString = Map ? funcToString.call(Map) : '',
    setCtorString = Set ? funcToString.call(Set) : '',
    weakMapCtorString = WeakMap ? funcToString.call(WeakMap) : '';

/** Used to convert symbols to primitives and strings. */
var symbolProto = Symbol ? Symbol.prototype : undefined,
    symbolValueOf = Symbol ? symbolProto.valueOf : undefined;

/**
 * Assigns `value` to `key` of `object` if the existing value is not equivalent
 * using [`SameValueZero`](http://ecma-international.org/ecma-262/6.0/#sec-samevaluezero)
 * for equality comparisons.
 *
 * @private
 * @param {Object} object The object to modify.
 * @param {string} key The key of the property to assign.
 * @param {*} value The value to assign.
 */
function assignValue(object, key, value) {
  var objValue = object[key];
  if ((!eq(objValue, value) ||
        (eq(objValue, objectProto[key]) && !hasOwnProperty.call(object, key))) ||
      (value === undefined && !(key in object))) {
    object[key] = value;
  }
}

/**
 * The base implementation of `_.assign` without support for multiple sources
 * or `customizer` functions.
 *
 * @private
 * @param {Object} object The destination object.
 * @param {Object} source The source object.
 * @returns {Object} Returns `object`.
 */
function baseAssign(object, source) {
  return object && copyObject(source, keys(source), object);
}

/**
 * The base implementation of `_.clone` and `_.cloneDeep` which tracks
 * traversed objects.
 *
 * @private
 * @param {*} value The value to clone.
 * @param {boolean} [isDeep] Specify a deep clone.
 * @param {Function} [customizer] The function to customize cloning.
 * @param {string} [key] The key of `value`.
 * @param {Object} [object] The parent object of `value`.
 * @param {Object} [stack] Tracks traversed objects and their clone counterparts.
 * @returns {*} Returns the cloned value.
 */
function baseClone(value, isDeep, customizer, key, object, stack) {
  var result;
  if (customizer) {
    result = object ? customizer(value, key, object, stack) : customizer(value);
  }
  if (result !== undefined) {
    return result;
  }
  if (!isObject(value)) {
    return value;
  }
  var isArr = isArray(value);
  if (isArr) {
    result = initCloneArray(value);
    if (!isDeep) {
      return copyArray(value, result);
    }
  } else {
    var tag = getTag(value),
        isFunc = tag == funcTag || tag == genTag;

    if (isBuffer(value)) {
      return cloneBuffer(value, isDeep);
    }
    if (tag == objectTag || tag == argsTag || (isFunc && !object)) {
      if (isHostObject(value)) {
        return object ? value : {};
      }
      result = initCloneObject(isFunc ? {} : value);
      if (!isDeep) {
        return copySymbols(value, baseAssign(result, value));
      }
    } else {
      return cloneableTags[tag]
        ? initCloneByTag(value, tag, isDeep)
        : (object ? value : {});
    }
  }
  // Check for circular references and return its corresponding clone.
  stack || (stack = new Stack);
  var stacked = stack.get(value);
  if (stacked) {
    return stacked;
  }
  stack.set(value, result);

  // Recursively populate clone (susceptible to call stack limits).
  (isArr ? arrayEach : baseForOwn)(value, function(subValue, key) {
    assignValue(result, key, baseClone(subValue, isDeep, customizer, key, value, stack));
  });
  return isArr ? result : copySymbols(value, result);
}

/**
 * The base implementation of `_.create` without support for assigning
 * properties to the created object.
 *
 * @private
 * @param {Object} prototype The object to inherit from.
 * @returns {Object} Returns the new object.
 */
var baseCreate = (function() {
  function object() {}
  return function(prototype) {
    if (isObject(prototype)) {
      object.prototype = prototype;
      var result = new object;
      object.prototype = undefined;
    }
    return result || {};
  };
}());

/**
 * The base implementation of `_.forOwn` without support for iteratee shorthands.
 *
 * @private
 * @param {Object} object The object to iterate over.
 * @param {Function} iteratee The function invoked per iteration.
 * @returns {Object} Returns `object`.
 */
function baseForOwn(object, iteratee) {
  return object && baseFor(object, iteratee, keys);
}

/**
 * The base implementation of `_.get` without support for default values.
 *
 * @private
 * @param {Object} object The object to query.
 * @param {Array|string} path The path of the property to get.
 * @returns {*} Returns the resolved value.
 */
function baseGet(object, path) {
  path = isKey(path, object) ? [path + ''] : baseToPath(path);

  var index = 0,
      length = path.length;

  while (object != null && index < length) {
    object = object[path[index++]];
  }
  return (index && index == length) ? object : undefined;
}

/**
 * The base implementation of `_.iteratee`.
 *
 * @private
 * @param {*} [value=_.identity] The value to convert to an iteratee.
 * @returns {Function} Returns the iteratee.
 */
function baseIteratee(value) {
  var type = typeof value;
  if (type == 'function') {
    return value;
  }
  if (value == null) {
    return identity;
  }
  if (type == 'object') {
    return isArray(value)
      ? baseMatchesProperty(value[0], value[1])
      : baseMatches(value);
  }
  return property(value);
}

/**
 * The base implementation of `_.matches` which doesn't clone `source`.
 *
 * @private
 * @param {Object} source The object of property values to match.
 * @returns {Function} Returns the new function.
 */
function baseMatches(source) {
  var matchData = getMatchData(source);
  if (matchData.length == 1 && matchData[0][2]) {
    var key = matchData[0][0],
        value = matchData[0][1];

    return function(object) {
      if (object == null) {
        return false;
      }
      return object[key] === value &&
        (value !== undefined || (key in Object(object)));
    };
  }
  return function(object) {
    return object === source || baseIsMatch(object, source, matchData);
  };
}

/**
 * The base implementation of `_.matchesProperty` which doesn't clone `srcValue`.
 *
 * @private
 * @param {string} path The path of the property to get.
 * @param {*} srcValue The value to match.
 * @returns {Function} Returns the new function.
 */
function baseMatchesProperty(path, srcValue) {
  return function(object) {
    var objValue = get(object, path);
    return (objValue === undefined && objValue === srcValue)
      ? hasIn(object, path)
      : baseIsEqual(srcValue, objValue, undefined, UNORDERED_COMPARE_FLAG | PARTIAL_COMPARE_FLAG);
  };
}

/**
 * The base implementation of `_.property` without support for deep paths.
 *
 * @private
 * @param {string} key The key of the property to get.
 * @returns {Function} Returns the new function.
 */
function baseProperty(key) {
  return function(object) {
    return object == null ? undefined : object[key];
  };
}

/**
 * A specialized version of `baseProperty` which supports deep paths.
 *
 * @private
 * @param {Array|string} path The path of the property to get.
 * @returns {Function} Returns the new function.
 */
function basePropertyDeep(path) {
  return function(object) {
    return baseGet(object, path);
  };
}

/**
 * The base implementation of `_.toPath` which only converts `value` to a
 * path if it's not one.
 *
 * @private
 * @param {*} value The value to process.
 * @returns {Array} Returns the property path array.
 */
function baseToPath(value) {
  return isArray(value) ? value : stringToPath(value);
}

/**
 * Creates a clone of  `buffer`.
 *
 * @private
 * @param {Buffer} buffer The buffer to clone.
 * @param {boolean} [isDeep] Specify a deep clone.
 * @returns {Buffer} Returns the cloned buffer.
 */
function cloneBuffer(buffer, isDeep) {
  if (isDeep) {
    return buffer.slice();
  }
  var Ctor = buffer.constructor,
      result = new Ctor(buffer.length);

  buffer.copy(result);
  return result;
}

/**
 * Creates a clone of `arrayBuffer`.
 *
 * @private
 * @param {ArrayBuffer} arrayBuffer The array buffer to clone.
 * @returns {ArrayBuffer} Returns the cloned array buffer.
 */
function cloneArrayBuffer(arrayBuffer) {
  var Ctor = arrayBuffer.constructor,
      result = new Ctor(arrayBuffer.byteLength),
      view = new Uint8Array(result);

  view.set(new Uint8Array(arrayBuffer));
  return result;
}

/**
 * Creates a clone of `map`.
 *
 * @private
 * @param {Object} map The map to clone.
 * @returns {Object} Returns the cloned map.
 */
function cloneMap(map) {
  var Ctor = map.constructor;
  return arrayReduce(mapToArray(map), addMapEntry, new Ctor);
}

/**
 * Creates a clone of `regexp`.
 *
 * @private
 * @param {Object} regexp The regexp to clone.
 * @returns {Object} Returns the cloned regexp.
 */
function cloneRegExp(regexp) {
  var Ctor = regexp.constructor,
      result = new Ctor(regexp.source, reFlags.exec(regexp));

  result.lastIndex = regexp.lastIndex;
  return result;
}

/**
 * Creates a clone of `set`.
 *
 * @private
 * @param {Object} set The set to clone.
 * @returns {Object} Returns the cloned set.
 */
function cloneSet(set) {
  var Ctor = set.constructor;
  return arrayReduce(setToArray(set), addSetEntry, new Ctor);
}

/**
 * Creates a clone of the `symbol` object.
 *
 * @private
 * @param {Object} symbol The symbol object to clone.
 * @returns {Object} Returns the cloned symbol object.
 */
function cloneSymbol(symbol) {
  return Symbol ? Object(symbolValueOf.call(symbol)) : {};
}

/**
 * Creates a clone of `typedArray`.
 *
 * @private
 * @param {Object} typedArray The typed array to clone.
 * @param {boolean} [isDeep] Specify a deep clone.
 * @returns {Object} Returns the cloned typed array.
 */
function cloneTypedArray(typedArray, isDeep) {
  var buffer = typedArray.buffer,
      Ctor = typedArray.constructor;

  return new Ctor(isDeep ? cloneArrayBuffer(buffer) : buffer, typedArray.byteOffset, typedArray.length);
}

/**
 * Copies the values of `source` to `array`.
 *
 * @private
 * @param {Array} source The array to copy values from.
 * @param {Array} [array=[]] The array to copy values to.
 * @returns {Array} Returns `array`.
 */
function copyArray(source, array) {
  var index = -1,
      length = source.length;

  array || (array = Array(length));
  while (++index < length) {
    array[index] = source[index];
  }
  return array;
}

/**
 * Copies properties of `source` to `object`.
 *
 * @private
 * @param {Object} source The object to copy properties from.
 * @param {Array} props The property names to copy.
 * @param {Object} [object={}] The object to copy properties to.
 * @returns {Object} Returns `object`.
 */
function copyObject(source, props, object) {
  return copyObjectWith(source, props, object);
}

/**
 * This function is like `copyObject` except that it accepts a function to
 * customize copied values.
 *
 * @private
 * @param {Object} source The object to copy properties from.
 * @param {Array} props The property names to copy.
 * @param {Object} [object={}] The object to copy properties to.
 * @param {Function} [customizer] The function to customize copied values.
 * @returns {Object} Returns `object`.
 */
function copyObjectWith(source, props, object, customizer) {
  object || (object = {});

  var index = -1,
      length = props.length;

  while (++index < length) {
    var key = props[index],
        newValue = customizer ? customizer(object[key], source[key], key, object, source) : source[key];

    assignValue(object, key, newValue);
  }
  return object;
}

/**
 * Copies own symbol properties of `source` to `object`.
 *
 * @private
 * @param {Object} source The object to copy symbols from.
 * @param {Object} [object={}] The object to copy symbols to.
 * @returns {Object} Returns `object`.
 */
function copySymbols(source, object) {
  return copyObject(source, getSymbols(source), object);
}

/**
 * Gets the property names, values, and compare flags of `object`.
 *
 * @private
 * @param {Object} object The object to query.
 * @returns {Array} Returns the match data of `object`.
 */
function getMatchData(object) {
  var result = toPairs(object),
      length = result.length;

  while (length--) {
    result[length][2] = isStrictComparable(result[length][1]);
  }
  return result;
}

/**
 * Gets the native function at `key` of `object`.
 *
 * @private
 * @param {Object} object The object to query.
 * @param {string} key The key of the method to get.
 * @returns {*} Returns the function if it's native, else `undefined`.
 */
function getNative(object, key) {
  var value = object == null ? undefined : object[key];
  return isNative(value) ? value : undefined;
}

/**
 * Creates an array of the own symbol properties of `object`.
 *
 * @private
 * @param {Object} object The object to query.
 * @returns {Array} Returns the array of symbols.
 */
var getSymbols = getOwnPropertySymbols || function() {
  return [];
};

/**
 * Gets the `toStringTag` of `value`.
 *
 * @private
 * @param {*} value The value to query.
 * @returns {string} Returns the `toStringTag`.
 */
function getTag(value) {
  return objectToString.call(value);
}

// Fallback for IE 11 providing `toStringTag` values for maps, sets, and weakmaps.
if ((Map && getTag(new Map) != mapTag) ||
    (Set && getTag(new Set) != setTag) ||
    (WeakMap && getTag(new WeakMap) != weakMapTag)) {
  getTag = function(value) {
    var result = objectToString.call(value),
        Ctor = result == objectTag ? value.constructor : null,
        ctorString = typeof Ctor == 'function' ? funcToString.call(Ctor) : '';

    if (ctorString) {
      switch (ctorString) {
        case mapCtorString: return mapTag;
        case setCtorString: return setTag;
        case weakMapCtorString: return weakMapTag;
      }
    }
    return result;
  };
}

/**
 * Initializes an array clone.
 *
 * @private
 * @param {Array} array The array to clone.
 * @returns {Array} Returns the initialized clone.
 */
function initCloneArray(array) {
  var length = array.length,
      result = array.constructor(length);

  // Add properties assigned by `RegExp#exec`.
  if (length && typeof array[0] == 'string' && hasOwnProperty.call(array, 'index')) {
    result.index = array.index;
    result.input = array.input;
  }
  return result;
}

/**
 * Initializes an object clone.
 *
 * @private
 * @param {Object} object The object to clone.
 * @returns {Object} Returns the initialized clone.
 */
function initCloneObject(object) {
  if (isPrototype(object)) {
    return {};
  }
  var Ctor = object.constructor;
  return baseCreate(isFunction(Ctor) ? Ctor.prototype : undefined);
}

/**
 * Initializes an object clone based on its `toStringTag`.
 *
 * **Note:** This function only supports cloning values with tags of
 * `Boolean`, `Date`, `Error`, `Number`, `RegExp`, or `String`.
 *
 * @private
 * @param {Object} object The object to clone.
 * @param {string} tag The `toStringTag` of the object to clone.
 * @param {boolean} [isDeep] Specify a deep clone.
 * @returns {Object} Returns the initialized clone.
 */
function initCloneByTag(object, tag, isDeep) {
  var Ctor = object.constructor;
  switch (tag) {
    case arrayBufferTag:
      return cloneArrayBuffer(object);

    case boolTag:
    case dateTag:
      return new Ctor(+object);

    case float32Tag: case float64Tag:
    case int8Tag: case int16Tag: case int32Tag:
    case uint8Tag: case uint8ClampedTag: case uint16Tag: case uint32Tag:
      return cloneTypedArray(object, isDeep);

    case mapTag:
      return cloneMap(object);

    case numberTag:
    case stringTag:
      return new Ctor(object);

    case regexpTag:
      return cloneRegExp(object);

    case setTag:
      return cloneSet(object);

    case symbolTag:
      return cloneSymbol(object);
  }
}

/**
 * Checks if `value` is a property name and not a property path.
 *
 * @private
 * @param {*} value The value to check.
 * @param {Object} [object] The object to query keys on.
 * @returns {boolean} Returns `true` if `value` is a property name, else `false`.
 */
function isKey(value, object) {
  if (typeof value == 'number') {
    return true;
  }
  return !isArray(value) &&
    (reIsPlainProp.test(value) || !reIsDeepProp.test(value) ||
      (object != null && value in Object(object)));
}

/**
 * Checks if `value` is likely a prototype object.
 *
 * @private
 * @param {*} value The value to check.
 * @returns {boolean} Returns `true` if `value` is a prototype, else `false`.
 */
function isPrototype(value) {
  var Ctor = value && value.constructor,
      proto = (typeof Ctor == 'function' && Ctor.prototype) || objectProto;

  return value === proto;
}

/**
 * Checks if `value` is suitable for strict equality comparisons, i.e. `===`.
 *
 * @private
 * @param {*} value The value to check.
 * @returns {boolean} Returns `true` if `value` if suitable for strict
 *  equality comparisons, else `false`.
 */
function isStrictComparable(value) {
  return value === value && !isObject(value);
}

/**
 * Converts `string` to a property path array.
 *
 * @private
 * @param {string} string The string to convert.
 * @returns {Array} Returns the property path array.
 */
function stringToPath(string) {
  var result = [];
  toString(string).replace(rePropName, function(match, number, quote, string) {
    result.push(quote ? string.replace(reEscapeChar, '$1') : (number || match));
  });
  return result;
}

/**
 * Performs a [`SameValueZero`](http://ecma-international.org/ecma-262/6.0/#sec-samevaluezero)
 * comparison between two values to determine if they are equivalent.
 *
 * @static
 * @memberOf _
 * @category Lang
 * @param {*} value The value to compare.
 * @param {*} other The other value to compare.
 * @returns {boolean} Returns `true` if the values are equivalent, else `false`.
 * @example
 *
 * var object = { 'user': 'fred' };
 * var other = { 'user': 'fred' };
 *
 * _.eq(object, object);
 * // => true
 *
 * _.eq(object, other);
 * // => false
 *
 * _.eq('a', 'a');
 * // => true
 *
 * _.eq('a', Object('a'));
 * // => false
 *
 * _.eq(NaN, NaN);
 * // => true
 */
function eq(value, other) {
  return value === other || (value !== value && other !== other);
}

/**
 * Checks if `value` is classified as an `Array` object.
 *
 * @static
 * @memberOf _
 * @type Function
 * @category Lang
 * @param {*} value The value to check.
 * @returns {boolean} Returns `true` if `value` is correctly classified, else `false`.
 * @example
 *
 * _.isArray([1, 2, 3]);
 * // => true
 *
 * _.isArray(document.body.children);
 * // => false
 *
 * _.isArray('abc');
 * // => false
 *
 * _.isArray(_.noop);
 * // => false
 */
var isArray = Array.isArray;

/**
 * Checks if `value` is classified as a `Function` object.
 *
 * @static
 * @memberOf _
 * @category Lang
 * @param {*} value The value to check.
 * @returns {boolean} Returns `true` if `value` is correctly classified, else `false`.
 * @example
 *
 * _.isFunction(_);
 * // => true
 *
 * _.isFunction(/abc/);
 * // => false
 */
function isFunction(value) {
  // The use of `Object#toString` avoids issues with the `typeof` operator
  // in Safari 8 which returns 'object' for typed array constructors, and
  // PhantomJS 1.9 which returns 'function' for `NodeList` instances.
  var tag = isObject(value) ? objectToString.call(value) : '';
  return tag == funcTag || tag == genTag;
}

/**
 * Checks if `value` is the [language type](https://es5.github.io/#x8) of `Object`.
 * (e.g. arrays, functions, objects, regexes, `new Number(0)`, and `new String('')`)
 *
 * @static
 * @memberOf _
 * @category Lang
 * @param {*} value The value to check.
 * @returns {boolean} Returns `true` if `value` is an object, else `false`.
 * @example
 *
 * _.isObject({});
 * // => true
 *
 * _.isObject([1, 2, 3]);
 * // => true
 *
 * _.isObject(_.noop);
 * // => true
 *
 * _.isObject(null);
 * // => false
 */
function isObject(value) {
  var type = typeof value;
  return !!value && (type == 'object' || type == 'function');
}

/**
 * Checks if `value` is object-like. A value is object-like if it's not `null`
 * and has a `typeof` result of "object".
 *
 * @static
 * @memberOf _
 * @category Lang
 * @param {*} value The value to check.
 * @returns {boolean} Returns `true` if `value` is object-like, else `false`.
 * @example
 *
 * _.isObjectLike({});
 * // => true
 *
 * _.isObjectLike([1, 2, 3]);
 * // => true
 *
 * _.isObjectLike(_.noop);
 * // => false
 *
 * _.isObjectLike(null);
 * // => false
 */
function isObjectLike(value) {
  return !!value && typeof value == 'object';
}

/**
 * Checks if `value` is a native function.
 *
 * @static
 * @memberOf _
 * @category Lang
 * @param {*} value The value to check.
 * @returns {boolean} Returns `true` if `value` is a native function, else `false`.
 * @example
 *
 * _.isNative(Array.prototype.push);
 * // => true
 *
 * _.isNative(_);
 * // => false
 */
function isNative(value) {
  if (value == null) {
    return false;
  }
  if (isFunction(value)) {
    return reIsNative.test(funcToString.call(value));
  }
  return isObjectLike(value) &&
    (isHostObject(value) ? reIsNative : reIsHostCtor).test(value);
}

/**
 * This method returns the first argument given to it.
 *
 * @static
 * @memberOf _
 * @category Util
 * @param {*} value Any value.
 * @returns {*} Returns `value`.
 * @example
 *
 * var object = { 'user': 'fred' };
 *
 * _.identity(object) === object;
 * // => true
 */
function identity(value) {
  return value;
}

/**
 * Creates a function that invokes `func` with the arguments of the created
 * function. If `func` is a property name the created callback returns the
 * property value for a given element. If `func` is an object the created
 * callback returns `true` for elements that contain the equivalent object properties, otherwise it returns `false`.
 *
 * @static
 * @memberOf _
 * @category Util
 * @param {*} [func=_.identity] The value to convert to a callback.
 * @returns {Function} Returns the callback.
 * @example
 *
 * var users = [
 *   { 'user': 'barney', 'age': 36 },
 *   { 'user': 'fred',   'age': 40 }
 * ];
 *
 * // Create custom iteratee shorthands.
 * _.iteratee = _.wrap(_.iteratee, function(callback, func) {
 *   var p = /^(\S+)\s*([<>])\s*(\S+)$/.exec(func);
 *   return !p ? callback(func) : function(object) {
 *     return (p[2] == '>' ? object[p[1]] > p[3] : object[p[1]] < p[3]);
 *   };
 * });
 *
 * _.filter(users, 'age > 36');
 * // => [{ 'user': 'fred', 'age': 40 }]
 */
function iteratee(func) {
  return baseIteratee(typeof func == 'function' ? func : baseClone(func, true));
}

/**
 * Creates a function that returns the value at `path` of a given object.
 *
 * @static
 * @memberOf _
 * @category Util
 * @param {Array|string} path The path of the property to get.
 * @returns {Function} Returns the new function.
 * @example
 *
 * var objects = [
 *   { 'a': { 'b': { 'c': 2 } } },
 *   { 'a': { 'b': { 'c': 1 } } }
 * ];
 *
 * _.map(objects, _.property('a.b.c'));
 * // => [2, 1]
 *
 * _.map(_.sortBy(objects, _.property(['a', 'b', 'c'])), 'a.b.c');
 * // => [1, 2]
 */
function property(path) {
  return isKey(path) ? baseProperty(path) : basePropertyDeep(path);
}

module.exports = iteratee;