/**

* lodash (Custom Build) <https://lodash.com/>
* Build: `lodash modularize exports="npm" -o ./`
* Copyright jQuery Foundation and other contributors <https://jquery.org/>
* Released under MIT license <https://lodash.com/license>
* Based on Underscore.js 1.8.3 <http://underscorejs.org/LICENSE>
* Copyright Jeremy Ashkenas, DocumentCloud and Investigative Reporters & Editors
*/

/** Used as references for various `Number` constants. */ var MAX_SAFE_INTEGER = 9007199254740991;

/** `Object#toString` result references. */ var argsTag = '[object Arguments]',

funcTag = '[object Function]',
genTag = '[object GeneratorFunction]';

/** Used to detect unsigned integer values. */ var reIsUint = /^(?:0|d*)$/;

/**

* A faster alternative to `Function#apply`, this function invokes `func`
* with the `this` binding of `thisArg` and the arguments of `args`.
*
* @private
* @param {Function} func The function to invoke.
* @param {*} thisArg The `this` binding of `func`.
* @param {Array} args The arguments to invoke `func` with.
* @returns {*} Returns the result of `func`.
*/

function apply(func, thisArg, args) {

switch (args.length) {
  case 0: return func.call(thisArg);
  case 1: return func.call(thisArg, args[0]);
  case 2: return func.call(thisArg, args[0], args[1]);
  case 3: return func.call(thisArg, args[0], args[1], args[2]);
}
return func.apply(thisArg, args);

}

/**

* The base implementation of `_.times` without support for iteratee shorthands
* or max array length checks.
*
* @private
* @param {number} n The number of times to invoke `iteratee`.
* @param {Function} iteratee The function invoked per iteration.
* @returns {Array} Returns the array of results.
*/

function baseTimes(n, iteratee) {

var index = -1,
    result = Array(n);

while (++index < n) {
  result[index] = iteratee(index);
}
return result;

}

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

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

/**

* Used to resolve the
* [`toStringTag`](http://ecma-international.org/ecma-262/7.0/#sec-object.prototype.tostring)
* of values.
*/

var objectToString = objectProto.toString;

/** Built-in value references. */ var propertyIsEnumerable = objectProto.propertyIsEnumerable;

/* Built-in method references for those with the same name as other `lodash` methods. */ var nativeMax = Math.max;

/**

* Creates an array of the enumerable property names of the array-like `value`.
*
* @private
* @param {*} value The value to query.
* @param {boolean} inherited Specify returning inherited property names.
* @returns {Array} Returns the array of property names.
*/

function arrayLikeKeys(value, inherited) {

// Safari 8.1 makes `arguments.callee` enumerable in strict mode.
// Safari 9 makes `arguments.length` enumerable in strict mode.
var result = (isArray(value) || isArguments(value))
  ? baseTimes(value.length, String)
  : [];

var length = result.length,
    skipIndexes = !!length;

for (var key in value) {
  if ((inherited || hasOwnProperty.call(value, key)) &&
      !(skipIndexes && (key == 'length' || isIndex(key, length)))) {
    result.push(key);
  }
}
return result;

}

/**

* Assigns `value` to `key` of `object` if the existing value is not equivalent
* using [`SameValueZero`](http://ecma-international.org/ecma-262/7.0/#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 (!(hasOwnProperty.call(object, key) && eq(objValue, value)) ||
    (value === undefined && !(key in object))) {
  object[key] = value;
}

}

/**

* The base implementation of `_.keysIn` which doesn't treat sparse arrays as dense.
*
* @private
* @param {Object} object The object to query.
* @returns {Array} Returns the array of property names.
*/

function baseKeysIn(object) {

if (!isObject(object)) {
  return nativeKeysIn(object);
}
var isProto = isPrototype(object),
    result = [];

for (var key in object) {
  if (!(key == 'constructor' && (isProto || !hasOwnProperty.call(object, key)))) {
    result.push(key);
  }
}
return result;

}

/**

* The base implementation of `_.rest` which doesn't validate or coerce arguments.
*
* @private
* @param {Function} func The function to apply a rest parameter to.
* @param {number} [start=func.length-1] The start position of the rest parameter.
* @returns {Function} Returns the new function.
*/

function baseRest(func, start) {

start = nativeMax(start === undefined ? (func.length - 1) : start, 0);
return function() {
  var args = arguments,
      index = -1,
      length = nativeMax(args.length - start, 0),
      array = Array(length);

  while (++index < length) {
    array[index] = args[start + index];
  }
  index = -1;
  var otherArgs = Array(start + 1);
  while (++index < start) {
    otherArgs[index] = args[index];
  }
  otherArgs[start] = array;
  return apply(func, this, otherArgs);
};

}

/**

* Copies properties of `source` to `object`.
*
* @private
* @param {Object} source The object to copy properties from.
* @param {Array} props The property identifiers 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 copyObject(source, props, object, customizer) {

object || (object = {});

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

while (++index < length) {
  var key = props[index];

  var newValue = customizer
    ? customizer(object[key], source[key], key, object, source)
    : undefined;

  assignValue(object, key, newValue === undefined ? source[key] : newValue);
}
return object;

}

/**

* Creates a function like `_.assign`.
*
* @private
* @param {Function} assigner The function to assign values.
* @returns {Function} Returns the new assigner function.
*/

function createAssigner(assigner) {

return baseRest(function(object, sources) {
  var index = -1,
      length = sources.length,
      customizer = length > 1 ? sources[length - 1] : undefined,
      guard = length > 2 ? sources[2] : undefined;

  customizer = (assigner.length > 3 && typeof customizer == 'function')
    ? (length--, customizer)
    : undefined;

  if (guard && isIterateeCall(sources[0], sources[1], guard)) {
    customizer = length < 3 ? undefined : customizer;
    length = 1;
  }
  object = Object(object);
  while (++index < length) {
    var source = sources[index];
    if (source) {
      assigner(object, source, index, customizer);
    }
  }
  return object;
});

}

/**

* Checks if `value` is a valid array-like index.
*
* @private
* @param {*} value The value to check.
* @param {number} [length=MAX_SAFE_INTEGER] The upper bounds of a valid index.
* @returns {boolean} Returns `true` if `value` is a valid index, else `false`.
*/

function isIndex(value, length) {

length = length == null ? MAX_SAFE_INTEGER : length;
return !!length &&
  (typeof value == 'number' || reIsUint.test(value)) &&
  (value > -1 && value % 1 == 0 && value < length);

}

/**

* Checks if the given arguments are from an iteratee call.
*
* @private
* @param {*} value The potential iteratee value argument.
* @param {*} index The potential iteratee index or key argument.
* @param {*} object The potential iteratee object argument.
* @returns {boolean} Returns `true` if the arguments are from an iteratee call,
*  else `false`.
*/

function isIterateeCall(value, index, object) {

if (!isObject(object)) {
  return false;
}
var type = typeof index;
if (type == 'number'
      ? (isArrayLike(object) && isIndex(index, object.length))
      : (type == 'string' && index in object)
    ) {
  return eq(object[index], value);
}
return false;

}

/**

* 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;

}

/**

* This function is like
* [`Object.keys`](http://ecma-international.org/ecma-262/7.0/#sec-object.keys)
* except that it includes inherited enumerable properties.
*
* @private
* @param {Object} object The object to query.
* @returns {Array} Returns the array of property names.
*/

function nativeKeysIn(object) {

var result = [];
if (object != null) {
  for (var key in Object(object)) {
    result.push(key);
  }
}
return result;

}

/**

* Performs a
* [`SameValueZero`](http://ecma-international.org/ecma-262/7.0/#sec-samevaluezero)
* comparison between two values to determine if they are equivalent.
*
* @static
* @memberOf _
* @since 4.0.0
* @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 = { 'a': 1 };
* var other = { 'a': 1 };
*
* _.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 likely an `arguments` object.
*
* @static
* @memberOf _
* @since 0.1.0
* @category Lang
* @param {*} value The value to check.
* @returns {boolean} Returns `true` if `value` is an `arguments` object,
*  else `false`.
* @example
*
* _.isArguments(function() { return arguments; }());
* // => true
*
* _.isArguments([1, 2, 3]);
* // => false
*/

function isArguments(value) {

// Safari 8.1 makes `arguments.callee` enumerable in strict mode.
return isArrayLikeObject(value) && hasOwnProperty.call(value, 'callee') &&
  (!propertyIsEnumerable.call(value, 'callee') || objectToString.call(value) == argsTag);

}

/**

* Checks if `value` is classified as an `Array` object.
*
* @static
* @memberOf _
* @since 0.1.0
* @category Lang
* @param {*} value The value to check.
* @returns {boolean} Returns `true` if `value` is an array, 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 array-like. A value is considered array-like if it's
* not a function and has a `value.length` that's an integer greater than or
* equal to `0` and less than or equal to `Number.MAX_SAFE_INTEGER`.
*
* @static
* @memberOf _
* @since 4.0.0
* @category Lang
* @param {*} value The value to check.
* @returns {boolean} Returns `true` if `value` is array-like, else `false`.
* @example
*
* _.isArrayLike([1, 2, 3]);
* // => true
*
* _.isArrayLike(document.body.children);
* // => true
*
* _.isArrayLike('abc');
* // => true
*
* _.isArrayLike(_.noop);
* // => false
*/

function isArrayLike(value) {

return value != null && isLength(value.length) && !isFunction(value);

}

/**

* This method is like `_.isArrayLike` except that it also checks if `value`
* is an object.
*
* @static
* @memberOf _
* @since 4.0.0
* @category Lang
* @param {*} value The value to check.
* @returns {boolean} Returns `true` if `value` is an array-like object,
*  else `false`.
* @example
*
* _.isArrayLikeObject([1, 2, 3]);
* // => true
*
* _.isArrayLikeObject(document.body.children);
* // => true
*
* _.isArrayLikeObject('abc');
* // => false
*
* _.isArrayLikeObject(_.noop);
* // => false
*/

function isArrayLikeObject(value) {

return isObjectLike(value) && isArrayLike(value);

}

/**

* Checks if `value` is classified as a `Function` object.
*
* @static
* @memberOf _
* @since 0.1.0
* @category Lang
* @param {*} value The value to check.
* @returns {boolean} Returns `true` if `value` is a function, else `false`.
* @example
*
* _.isFunction(_);
* // => true
*
* _.isFunction(/abc/);
* // => false
*/

function isFunction(value) {

// The use of `Object#toString` avoids issues with the `typeof` operator
// in Safari 8-9 which returns 'object' for typed array and other constructors.
var tag = isObject(value) ? objectToString.call(value) : '';
return tag == funcTag || tag == genTag;

}

/**

* Checks if `value` is a valid array-like length.
*
* **Note:** This method is loosely based on
* [`ToLength`](http://ecma-international.org/ecma-262/7.0/#sec-tolength).
*
* @static
* @memberOf _
* @since 4.0.0
* @category Lang
* @param {*} value The value to check.
* @returns {boolean} Returns `true` if `value` is a valid length, else `false`.
* @example
*
* _.isLength(3);
* // => true
*
* _.isLength(Number.MIN_VALUE);
* // => false
*
* _.isLength(Infinity);
* // => false
*
* _.isLength('3');
* // => false
*/

function isLength(value) {

return typeof value == 'number' &&
  value > -1 && value % 1 == 0 && value <= MAX_SAFE_INTEGER;

}

/**

* Checks if `value` is the
* [language type](http://www.ecma-international.org/ecma-262/7.0/#sec-ecmascript-language-types)
* of `Object`. (e.g. arrays, functions, objects, regexes, `new Number(0)`, and `new String('')`)
*
* @static
* @memberOf _
* @since 0.1.0
* @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 _
* @since 4.0.0
* @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';

}

/**

* This method is like `_.assign` except that it iterates over own and
* inherited source properties.
*
* **Note:** This method mutates `object`.
*
* @static
* @memberOf _
* @since 4.0.0
* @alias extend
* @category Object
* @param {Object} object The destination object.
* @param {...Object} [sources] The source objects.
* @returns {Object} Returns `object`.
* @see _.assign
* @example
*
* function Foo() {
*   this.a = 1;
* }
*
* function Bar() {
*   this.c = 3;
* }
*
* Foo.prototype.b = 2;
* Bar.prototype.d = 4;
*
* _.assignIn({ 'a': 0 }, new Foo, new Bar);
* // => { 'a': 1, 'b': 2, 'c': 3, 'd': 4 }
*/

var assignIn = createAssigner(function(object, source) {

copyObject(source, keysIn(source), object);

});

/**

* Creates an array of the own and inherited enumerable property names of `object`.
*
* **Note:** Non-object values are coerced to objects.
*
* @static
* @memberOf _
* @since 3.0.0
* @category Object
* @param {Object} object The object to query.
* @returns {Array} Returns the array of property names.
* @example
*
* function Foo() {
*   this.a = 1;
*   this.b = 2;
* }
*
* Foo.prototype.c = 3;
*
* _.keysIn(new Foo);
* // => ['a', 'b', 'c'] (iteration order is not guaranteed)
*/

function keysIn(object) {

return isArrayLike(object) ? arrayLikeKeys(object, true) : baseKeysIn(object);

}

module.exports = assignIn;