Bump to v4.12.0.

README.md

@@ -1,4 +1,4 @@
-# lodash-es v4.8.0
+# lodash-es v4.12.0
 
 The [Lodash](https://lodash.com/) library exported as [ES](http://www.ecma-international.org/ecma-262/6.0/) modules.
 
@@ -7,4 +7,4 @@ Generated using [lodash-cli](https://www.npmjs.com/package/lodash-cli):
 $ lodash modularize exports=es -o ./
 ```
 
-See the [package source](https://github.com/lodash/lodash/tree/4.8.0-es) for more details.
+See the [package source](https://github.com/lodash/lodash/tree/4.12.0-es) for more details.

_Hash.js

@@ -1,18 +1,32 @@
-import nativeCreate from './_nativeCreate';
-
-/** Used for built-in method references. */
-var objectProto = Object.prototype;
+import hashClear from './_hashClear';
+import hashDelete from './_hashDelete';
+import hashGet from './_hashGet';
+import hashHas from './_hashHas';
+import hashSet from './_hashSet';
 
 /**
- * Creates an hash object.
+ * Creates a hash object.
  *
  * @private
  * @constructor
- * @returns {Object} Returns the new hash object.
+ * @param {Array} [entries] The key-value pairs to cache.
  */
-function Hash() {}
+function Hash(entries) {
+  var index = -1,
+      length = entries ? entries.length : 0;
 
-// Avoid inheriting from `Object.prototype` when possible.
-Hash.prototype = nativeCreate ? nativeCreate(null) : objectProto;
+  this.clear();
+  while (++index < length) {
+    var entry = entries[index];
+    this.set(entry[0], entry[1]);
+  }
+}
+
+// Add methods to `Hash`.
+Hash.prototype.clear = hashClear;
+Hash.prototype['delete'] = hashDelete;
+Hash.prototype.get = hashGet;
+Hash.prototype.has = hashHas;
+Hash.prototype.set = hashSet;
 
 export default Hash;

_ListCache.js

@@ -0,0 +1,32 @@
+import listCacheClear from './_listCacheClear';
+import listCacheDelete from './_listCacheDelete';
+import listCacheGet from './_listCacheGet';
+import listCacheHas from './_listCacheHas';
+import listCacheSet from './_listCacheSet';
+
+/**
+ * Creates an list cache object.
+ *
+ * @private
+ * @constructor
+ * @param {Array} [entries] The key-value pairs to cache.
+ */
+function ListCache(entries) {
+  var index = -1,
+      length = entries ? entries.length : 0;
+
+  this.clear();
+  while (++index < length) {
+    var entry = entries[index];
+    this.set(entry[0], entry[1]);
+  }
+}
+
+// Add methods to `ListCache`.
+ListCache.prototype.clear = listCacheClear;
+ListCache.prototype['delete'] = listCacheDelete;
+ListCache.prototype.get = listCacheGet;
+ListCache.prototype.has = listCacheHas;
+ListCache.prototype.set = listCacheSet;
+
+export default ListCache;

_MapCache.js

@@ -1,32 +1,32 @@
-import mapClear from './_mapClear';
-import mapDelete from './_mapDelete';
-import mapGet from './_mapGet';
-import mapHas from './_mapHas';
-import mapSet from './_mapSet';
+import mapCacheClear from './_mapCacheClear';
+import mapCacheDelete from './_mapCacheDelete';
+import mapCacheGet from './_mapCacheGet';
+import mapCacheHas from './_mapCacheHas';
+import mapCacheSet from './_mapCacheSet';
 
 /**
  * Creates a map cache object to store key-value pairs.
  *
  * @private
  * @constructor
- * @param {Array} [values] The values to cache.
+ * @param {Array} [entries] The key-value pairs to cache.
  */
-function MapCache(values) {
+function MapCache(entries) {
   var index = -1,
-      length = values ? values.length : 0;
+      length = entries ? entries.length : 0;
 
   this.clear();
   while (++index < length) {
-    var entry = values[index];
+    var entry = entries[index];
     this.set(entry[0], entry[1]);
   }
 }
 
 // Add methods to `MapCache`.
-MapCache.prototype.clear = mapClear;
-MapCache.prototype['delete'] = mapDelete;
-MapCache.prototype.get = mapGet;
-MapCache.prototype.has = mapHas;
-MapCache.prototype.set = mapSet;
+MapCache.prototype.clear = mapCacheClear;
+MapCache.prototype['delete'] = mapCacheDelete;
+MapCache.prototype.get = mapCacheGet;
+MapCache.prototype.has = mapCacheHas;
+MapCache.prototype.set = mapCacheSet;
 
 export default MapCache;

_SetCache.js

@@ -1,9 +1,10 @@
 import MapCache from './_MapCache';
-import cachePush from './_cachePush';
+import setCacheAdd from './_setCacheAdd';
+import setCacheHas from './_setCacheHas';
 
 /**
  *
- * Creates a set cache object to store unique values.
+ * Creates an array cache object to store unique values.
  *
  * @private
  * @constructor
@@ -15,11 +16,12 @@ function SetCache(values) {
 
   this.__data__ = new MapCache;
   while (++index < length) {
-    this.push(values[index]);
+    this.add(values[index]);
   }
 }
 
 // Add methods to `SetCache`.
-SetCache.prototype.push = cachePush;
+SetCache.prototype.add = SetCache.prototype.push = setCacheAdd;
+SetCache.prototype.has = setCacheHas;
 
 export default SetCache;

_Stack.js

@@ -1,3 +1,4 @@
+import ListCache from './_ListCache';
 import stackClear from './_stackClear';
 import stackDelete from './_stackDelete';
 import stackGet from './_stackGet';
@@ -9,17 +10,10 @@ import stackSet from './_stackSet';
  *
  * @private
  * @constructor
- * @param {Array} [values] The values to cache.
+ * @param {Array} [entries] The key-value pairs to cache.
  */
-function Stack(values) {
-  var index = -1,
-      length = values ? values.length : 0;
-
-  this.clear();
-  while (++index < length) {
-    var entry = values[index];
-    this.set(entry[0], entry[1]);
-  }
+function Stack(entries) {
+  this.__data__ = new ListCache(entries);
 }
 
 // Add methods to `Stack`.

_arrayConcat.js

@@ -1,25 +0,0 @@
-/**
- * Creates a new array concatenating `array` with `other`.
- *
- * @private
- * @param {Array} array The first array to concatenate.
- * @param {Array} other The second array to concatenate.
- * @returns {Array} Returns the new concatenated array.
- */
-function arrayConcat(array, other) {
-  var index = -1,
-      length = array.length,
-      othIndex = -1,
-      othLength = other.length,
-      result = Array(length + othLength);
-
-  while (++index < length) {
-    result[index] = array[index];
-  }
-  while (++othIndex < othLength) {
-    result[index++] = other[othIndex];
-  }
-  return result;
-}
-
-export default arrayConcat;

_assocGet.js

@@ -1,16 +0,0 @@
-import assocIndexOf from './_assocIndexOf';
-
-/**
- * Gets the associative array value for `key`.
- *
- * @private
- * @param {Array} array The array to query.
- * @param {string} key The key of the value to get.
- * @returns {*} Returns the entry value.
- */
-function assocGet(array, key) {
-  var index = assocIndexOf(array, key);
-  return index < 0 ? undefined : array[index][1];
-}
-
-export default assocGet;

_assocSet.js

@@ -1,20 +0,0 @@
-import assocIndexOf from './_assocIndexOf';
-
-/**
- * Sets the associative array `key` to `value`.
- *
- * @private
- * @param {Array} array The array to modify.
- * @param {string} key The key of the value to set.
- * @param {*} value The value to set.
- */
-function assocSet(array, key, value) {
-  var index = assocIndexOf(array, key);
-  if (index < 0) {
-    array.push([key, value]);
-  } else {
-    array[index][1] = value;
-  }
-}
-
-export default assocSet;

_baseAt.js

@@ -6,7 +6,7 @@ import get from './get';
  * @private
  * @param {Object} object The object to iterate over.
  * @param {string[]} paths The property paths of elements to pick.
- * @returns {Array} Returns the new array of picked elements.
+ * @returns {Array} Returns the picked elements.
  */
 function baseAt(object, paths) {
   var index = -1,

_baseCastKey.js

@@ -1,14 +0,0 @@
-import isSymbol from './isSymbol';
-
-/**
- * Casts `value` to a string if it's not a string or symbol.
- *
- * @private
- * @param {*} value The value to inspect.
- * @returns {string|symbol} Returns the cast key.
- */
-function baseCastKey(key) {
-  return (typeof key == 'string' || isSymbol(key)) ? key : (key + '');
-}
-
-export default baseCastKey;

_baseConforms.js

@@ -5,7 +5,7 @@ import keys from './keys';
  *
  * @private
  * @param {Object} source The object of property predicates to conform to.
- * @returns {Function} Returns the new function.
+ * @returns {Function} Returns the new spec function.
  */
 function baseConforms(source) {
   var props = keys(source),

_baseDifference.js

@@ -47,6 +47,7 @@ function baseDifference(array, values, iteratee, comparator) {
     var value = array[index],
         computed = iteratee ? iteratee(value) : value;
 
+    value = (comparator || value !== 0) ? value : 0;
     if (isCommon && computed === computed) {
       var valuesIndex = valuesLength;
       while (valuesIndex--) {

_baseExtremum.js

@@ -1,3 +1,5 @@
+import isSymbol from './isSymbol';
+
 /**
  * The base implementation of methods like `_.max` and `_.min` which accepts a
  * `comparator` to determine the extremum value.
@@ -17,7 +19,7 @@ function baseExtremum(array, iteratee, comparator) {
         current = iteratee(value);
 
     if (current != null && (computed === undefined
-          ? current === current
+          ? (current === current && !isSymbol(current))
           : comparator(current, computed)
         )) {
       var computed = current,

_baseFlatten.js

@@ -1,7 +1,5 @@
 import arrayPush from './_arrayPush';
-import isArguments from './isArguments';
-import isArray from './isArray';
-import isArrayLikeObject from './isArrayLikeObject';
+import isFlattenable from './_isFlattenable';
 
 /**
  * The base implementation of `_.flatten` with support for restricting flattening.
@@ -9,23 +7,24 @@ import isArrayLikeObject from './isArrayLikeObject';
  * @private
  * @param {Array} array The array to flatten.
  * @param {number} depth The maximum recursion depth.
- * @param {boolean} [isStrict] Restrict flattening to arrays-like objects.
+ * @param {boolean} [predicate=isFlattenable] The function invoked per iteration.
+ * @param {boolean} [isStrict] Restrict to values that pass `predicate` checks.
  * @param {Array} [result=[]] The initial result value.
  * @returns {Array} Returns the new flattened array.
  */
-function baseFlatten(array, depth, isStrict, result) {
-  result || (result = []);
-
+function baseFlatten(array, depth, predicate, isStrict, result) {
   var index = -1,
       length = array.length;
 
+  predicate || (predicate = isFlattenable);
+  result || (result = []);
+
   while (++index < length) {
     var value = array[index];
-    if (depth > 0 && isArrayLikeObject(value) &&
-        (isStrict || isArray(value) || isArguments(value))) {
+    if (depth > 0 && predicate(value)) {
       if (depth > 1) {
         // Recursively flatten arrays (susceptible to call stack limits).
-        baseFlatten(value, depth - 1, isStrict, result);
+        baseFlatten(value, depth - 1, predicate, isStrict, result);
       } else {
         arrayPush(result, value);
       }

_baseFor.js

@@ -2,7 +2,7 @@ import createBaseFor from './_createBaseFor';
 
 /**
  * The base implementation of `baseForOwn` which iterates over `object`
- * properties returned by `keysFunc` invoking `iteratee` for each property.
+ * properties returned by `keysFunc` and invokes `iteratee` for each property.
  * Iteratee functions may exit iteration early by explicitly returning `false`.
  *
  * @private

_baseFunctions.js

@@ -8,7 +8,7 @@ import isFunction from './isFunction';
  * @private
  * @param {Object} object The object to inspect.
  * @param {Array} props The property names to filter.
- * @returns {Array} Returns the new array of filtered property names.
+ * @returns {Array} Returns the function names.
  */
 function baseFunctions(object, props) {
   return arrayFilter(props, function(key) {

_baseGet.js

@@ -1,5 +1,6 @@
-import baseCastPath from './_baseCastPath';
+import castPath from './_castPath';
 import isKey from './_isKey';
+import toKey from './_toKey';
 
 /**
  * The base implementation of `_.get` without support for default values.
@@ -10,13 +11,13 @@ import isKey from './_isKey';
  * @returns {*} Returns the resolved value.
  */
 function baseGet(object, path) {
-  path = isKey(path, object) ? [path] : baseCastPath(path);
+  path = isKey(path, object) ? [path] : castPath(path);
 
   var index = 0,
       length = path.length;
 
   while (object != null && index < length) {
-    object = object[path[index++]];
+    object = object[toKey(path[index++])];
   }
   return (index && index == length) ? object : undefined;
 }

_baseGetAllKeys.js

@@ -14,9 +14,7 @@ import isArray from './isArray';
  */
 function baseGetAllKeys(object, keysFunc, symbolsFunc) {
   var result = keysFunc(object);
-  return isArray(object)
-    ? result
-    : arrayPush(result, symbolsFunc(object));
+  return isArray(object) ? result : arrayPush(result, symbolsFunc(object));
 }
 
 export default baseGetAllKeys;

_baseGt.js

@@ -0,0 +1,14 @@
+/**
+ * The base implementation of `_.gt` which doesn't coerce arguments to numbers.
+ *
+ * @private
+ * @param {*} value The value to compare.
+ * @param {*} other The other value to compare.
+ * @returns {boolean} Returns `true` if `value` is greater than `other`,
+ *  else `false`.
+ */
+function baseGt(value, other) {
+  return value > other;
+}
+
+export default baseGt;

_baseIntersection.js

@@ -47,6 +47,7 @@ function baseIntersection(arrays, iteratee, comparator) {
     var value = array[index],
         computed = iteratee ? iteratee(value) : value;
 
+    value = (comparator || value !== 0) ? value : 0;
     if (!(seen
           ? cacheHas(seen, computed)
           : includes(result, computed, comparator)

_baseInvoke.js

@@ -1,8 +1,9 @@
 import apply from './_apply';
-import baseCastPath from './_baseCastPath';
+import castPath from './_castPath';
 import isKey from './_isKey';
 import last from './last';
 import parent from './_parent';
+import toKey from './_toKey';
 
 /**
  * The base implementation of `_.invoke` without support for individual
@@ -16,11 +17,11 @@ import parent from './_parent';
  */
 function baseInvoke(object, path, args) {
   if (!isKey(path, object)) {
-    path = baseCastPath(path);
+    path = castPath(path);
     object = parent(object, path);
     path = last(path);
   }
-  var func = object == null ? object : object[path];
+  var func = object == null ? object : object[toKey(path)];
   return func == null ? undefined : apply(func, object, args);
 }
 

_baseLt.js

@@ -0,0 +1,14 @@
+/**
+ * The base implementation of `_.lt` which doesn't coerce arguments to numbers.
+ *
+ * @private
+ * @param {*} value The value to compare.
+ * @param {*} other The other value to compare.
+ * @returns {boolean} Returns `true` if `value` is less than `other`,
+ *  else `false`.
+ */
+function baseLt(value, other) {
+  return value < other;
+}
+
+export default baseLt;

_baseMatches.js

@@ -7,7 +7,7 @@ import matchesStrictComparable from './_matchesStrictComparable';
  *
  * @private
  * @param {Object} source The object of property values to match.
- * @returns {Function} Returns the new function.
+ * @returns {Function} Returns the new spec function.
  */
 function baseMatches(source) {
   var matchData = getMatchData(source);

_baseMatchesProperty.js

@@ -4,6 +4,7 @@ import hasIn from './hasIn';
 import isKey from './_isKey';
 import isStrictComparable from './_isStrictComparable';
 import matchesStrictComparable from './_matchesStrictComparable';
+import toKey from './_toKey';
 
 /** Used to compose bitmasks for comparison styles. */
 var UNORDERED_COMPARE_FLAG = 1,
@@ -15,11 +16,11 @@ var UNORDERED_COMPARE_FLAG = 1,
  * @private
  * @param {string} path The path of the property to get.
  * @param {*} srcValue The value to match.
- * @returns {Function} Returns the new function.
+ * @returns {Function} Returns the new spec function.
  */
 function baseMatchesProperty(path, srcValue) {
   if (isKey(path) && isStrictComparable(srcValue)) {
-    return matchesStrictComparable(path, srcValue);
+    return matchesStrictComparable(toKey(path), srcValue);
   }
   return function(object) {
     var objValue = get(object, path);

_baseNth.js

@@ -0,0 +1,20 @@
+import isIndex from './_isIndex';
+
+/**
+ * The base implementation of `_.nth` which doesn't coerce `n` to an integer.
+ *
+ * @private
+ * @param {Array} array The array to query.
+ * @param {number} n The index of the element to return.
+ * @returns {*} Returns the nth element of `array`.
+ */
+function baseNth(array, n) {
+  var length = array.length;
+  if (!length) {
+    return;
+  }
+  n += n < 0 ? length : 0;
+  return isIndex(n, length) ? array[n] : undefined;
+}
+
+export default baseNth;

_baseOrderBy.js

@@ -2,6 +2,7 @@ import arrayMap from './_arrayMap';
 import baseIteratee from './_baseIteratee';
 import baseMap from './_baseMap';
 import baseSortBy from './_baseSortBy';
+import baseUnary from './_baseUnary';
 import compareMultiple from './_compareMultiple';
 import identity from './identity';
 
@@ -16,7 +17,7 @@ import identity from './identity';
  */
 function baseOrderBy(collection, iteratees, orders) {
   var index = -1;
-  iteratees = arrayMap(iteratees.length ? iteratees : [identity], baseIteratee);
+  iteratees = arrayMap(iteratees.length ? iteratees : [identity], baseUnary(baseIteratee));
 
   var result = baseMap(collection, function(value, key, collection) {
     var criteria = arrayMap(iteratees, function(iteratee) {

_baseProperty.js

@@ -3,7 +3,7 @@
  *
  * @private
  * @param {string} key The key of the property to get.
- * @returns {Function} Returns the new function.
+ * @returns {Function} Returns the new accessor function.
  */
 function baseProperty(key) {
   return function(object) {

_basePropertyDeep.js

@@ -5,7 +5,7 @@ import baseGet from './_baseGet';
  *
  * @private
  * @param {Array|string} path The path of the property to get.
- * @returns {Function} Returns the new function.
+ * @returns {Function} Returns the new accessor function.
  */
 function basePropertyDeep(path) {
   return function(object) {

_basePullAt.js

@@ -1,8 +1,9 @@
-import baseCastPath from './_baseCastPath';
+import castPath from './_castPath';
 import isIndex from './_isIndex';
 import isKey from './_isKey';
 import last from './last';
 import parent from './_parent';
+import toKey from './_toKey';
 
 /** Used for built-in method references. */
 var arrayProto = Array.prototype;
@@ -25,21 +26,21 @@ function basePullAt(array, indexes) {
 
   while (length--) {
     var index = indexes[length];
-    if (lastIndex == length || index != previous) {
+    if (length == lastIndex || index !== previous) {
       var previous = index;
       if (isIndex(index)) {
         splice.call(array, index, 1);
       }
       else if (!isKey(index, array)) {
-        var path = baseCastPath(index),
+        var path = castPath(index),
             object = parent(array, path);
 
         if (object != null) {
-          delete object[last(path)];
+          delete object[toKey(last(path))];
         }
       }
       else {
-        delete array[index];
+        delete array[toKey(index)];
       }
     }
   }

_baseRange.js

@@ -11,7 +11,7 @@ var nativeCeil = Math.ceil,
  * @param {number} end The end of the range.
  * @param {number} step The value to increment or decrement by.
  * @param {boolean} [fromRight] Specify iterating from right to left.
- * @returns {Array} Returns the new array of numbers.
+ * @returns {Array} Returns the range of numbers.
  */
 function baseRange(start, end, step, fromRight) {
   var index = -1,

_baseSet.js

@@ -1,8 +1,9 @@
 import assignValue from './_assignValue';
-import baseCastPath from './_baseCastPath';
+import castPath from './_castPath';
 import isIndex from './_isIndex';
 import isKey from './_isKey';
 import isObject from './isObject';
+import toKey from './_toKey';
 
 /**
  * The base implementation of `_.set`.
@@ -15,7 +16,7 @@ import isObject from './isObject';
  * @returns {Object} Returns `object`.
  */
 function baseSet(object, path, value, customizer) {
-  path = isKey(path, object) ? [path] : baseCastPath(path);
+  path = isKey(path, object) ? [path] : castPath(path);
 
   var index = -1,
       length = path.length,
@@ -23,7 +24,7 @@ function baseSet(object, path, value, customizer) {
       nested = object;
 
   while (nested != null && ++index < length) {
-    var key = path[index];
+    var key = toKey(path[index]);
     if (isObject(nested)) {
       var newValue = value;
       if (index != lastIndex) {

_baseSortedIndex.js

@@ -1,5 +1,6 @@
 import baseSortedIndexBy from './_baseSortedIndexBy';
 import identity from './identity';
+import isSymbol from './isSymbol';
 
 /** Used as references for the maximum length and index of an array. */
 var MAX_ARRAY_LENGTH = 4294967295,
@@ -26,7 +27,8 @@ function baseSortedIndex(array, value, retHighest) {
       var mid = (low + high) >>> 1,
           computed = array[mid];
 
-      if ((retHighest ? (computed <= value) : (computed < value)) && computed !== null) {
+      if (computed !== null && !isSymbol(computed) &&
+          (retHighest ? (computed <= value) : (computed < value))) {
         low = mid + 1;
       } else {
         high = mid;

_baseSortedIndexBy.js

@@ -1,3 +1,5 @@
+import isSymbol from './isSymbol';
+
 /** Used as references for the maximum length and index of an array. */
 var MAX_ARRAY_LENGTH = 4294967295,
     MAX_ARRAY_INDEX = MAX_ARRAY_LENGTH - 1;
@@ -26,21 +28,26 @@ function baseSortedIndexBy(array, value, iteratee, retHighest) {
       high = array ? array.length : 0,
       valIsNaN = value !== value,
       valIsNull = value === null,
-      valIsUndef = value === undefined;
+      valIsSymbol = isSymbol(value),
+      valIsUndefined = value === undefined;
 
   while (low < high) {
     var mid = nativeFloor((low + high) / 2),
         computed = iteratee(array[mid]),
-        isDef = computed !== undefined,
-        isReflexive = computed === computed;
+        othIsDefined = computed !== undefined,
+        othIsNull = computed === null,
+        othIsReflexive = computed === computed,
+        othIsSymbol = isSymbol(computed);
 
     if (valIsNaN) {
-      var setLow = isReflexive || retHighest;
+      var setLow = retHighest || othIsReflexive;
+    } else if (valIsUndefined) {
+      setLow = othIsReflexive && (retHighest || othIsDefined);
     } else if (valIsNull) {
-      setLow = isReflexive && isDef && (retHighest || computed != null);
-    } else if (valIsUndef) {
-      setLow = isReflexive && (retHighest || isDef);
-    } else if (computed == null) {
+      setLow = othIsReflexive && othIsDefined && (retHighest || !othIsNull);
+    } else if (valIsSymbol) {
+      setLow = othIsReflexive && othIsDefined && !othIsNull && (retHighest || !othIsSymbol);
+    } else if (othIsNull || othIsSymbol) {
       setLow = false;
     } else {
       setLow = retHighest ? (computed <= value) : (computed < value);

_baseSortedUniq.js

@@ -1,14 +1,30 @@
-import baseSortedUniqBy from './_baseSortedUniqBy';
+import eq from './eq';
 
 /**
- * The base implementation of `_.sortedUniq`.
+ * The base implementation of `_.sortedUniq` and `_.sortedUniqBy` without
+ * support for iteratee shorthands.
  *
  * @private
  * @param {Array} array The array to inspect.
+ * @param {Function} [iteratee] The iteratee invoked per element.
  * @returns {Array} Returns the new duplicate free array.
  */
-function baseSortedUniq(array) {
-  return baseSortedUniqBy(array);
+function baseSortedUniq(array, iteratee) {
+  var index = -1,
+      length = array.length,
+      resIndex = 0,
+      result = [];
+
+  while (++index < length) {
+    var value = array[index],
+        computed = iteratee ? iteratee(value) : value;
+
+    if (!index || !eq(computed, seen)) {
+      var seen = computed;
+      result[resIndex++] = value === 0 ? 0 : value;
+    }
+  }
+  return result;
 }
 
 export default baseSortedUniq;

_baseSortedUniqBy.js

@@ -1,33 +0,0 @@
-import eq from './eq';
-
-/**
- * The base implementation of `_.sortedUniqBy` without support for iteratee
- * shorthands.
- *
- * @private
- * @param {Array} array The array to inspect.
- * @param {Function} [iteratee] The iteratee invoked per element.
- * @returns {Array} Returns the new duplicate free array.
- */
-function baseSortedUniqBy(array, iteratee) {
-  var index = 0,
-      length = array.length,
-      value = array[0],
-      computed = iteratee ? iteratee(value) : value,
-      seen = computed,
-      resIndex = 1,
-      result = [value];
-
-  while (++index < length) {
-    value = array[index],
-    computed = iteratee ? iteratee(value) : value;
-
-    if (!eq(computed, seen)) {
-      seen = computed;
-      result[resIndex++] = value;
-    }
-  }
-  return result;
-}
-
-export default baseSortedUniqBy;

_baseToNumber.js

@@ -0,0 +1,24 @@
+import isSymbol from './isSymbol';
+
+/** Used as references for various `Number` constants. */
+var NAN = 0 / 0;
+
+/**
+ * The base implementation of `_.toNumber` which doesn't ensure correct
+ * conversions of binary, hexadecimal, or octal string values.
+ *
+ * @private
+ * @param {*} value The value to process.
+ * @returns {number} Returns the number.
+ */
+function baseToNumber(value) {
+  if (typeof value == 'number') {
+    return value;
+  }
+  if (isSymbol(value)) {
+    return NAN;
+  }
+  return +value;
+}
+
+export default baseToNumber;

_baseToPairs.js

@@ -7,7 +7,7 @@ import arrayMap from './_arrayMap';
  * @private
  * @param {Object} object The object to query.
  * @param {Array} props The property names to get values for.
- * @returns {Object} Returns the new array of key-value pairs.
+ * @returns {Object} Returns the key-value pairs.
  */
 function baseToPairs(object, props) {
   return arrayMap(props, function(key) {

_baseToString.js

@@ -0,0 +1,31 @@
+import Symbol from './_Symbol';
+import isSymbol from './isSymbol';
+
+/** Used as references for various `Number` constants. */
+var INFINITY = 1 / 0;
+
+/** Used to convert symbols to primitives and strings. */
+var symbolProto = Symbol ? Symbol.prototype : undefined,
+    symbolToString = symbolProto ? symbolProto.toString : undefined;
+
+/**
+ * The base implementation of `_.toString` which doesn't convert nullish
+ * values to empty strings.
+ *
+ * @private
+ * @param {*} value The value to process.
+ * @returns {string} Returns the string.
+ */
+function baseToString(value) {
+  // Exit early for strings to avoid a performance hit in some environments.
+  if (typeof value == 'string') {
+    return value;
+  }
+  if (isSymbol(value)) {
+    return symbolToString ? symbolToString.call(value) : '';
+  }
+  var result = (value + '');
+  return (result == '0' && (1 / value) == -INFINITY) ? '-0' : result;
+}
+
+export default baseToString;

_baseUnary.js

@@ -3,7 +3,7 @@
  *
  * @private
  * @param {Function} func The function to cap arguments for.
- * @returns {Function} Returns the new function.
+ * @returns {Function} Returns the new capped function.
  */
 function baseUnary(func) {
   return function(value) {

_baseUniq.js

@@ -46,6 +46,7 @@ function baseUniq(array, iteratee, comparator) {
     var value = array[index],
         computed = iteratee ? iteratee(value) : value;
 
+    value = (comparator || value !== 0) ? value : 0;
     if (isCommon && computed === computed) {
       var seenIndex = seen.length;
       while (seenIndex--) {

_baseUnset.js

@@ -1,8 +1,9 @@
-import baseCastPath from './_baseCastPath';
-import has from './has';
+import baseHas from './_baseHas';
+import castPath from './_castPath';
 import isKey from './_isKey';
 import last from './last';
 import parent from './_parent';
+import toKey from './_toKey';
 
 /**
  * The base implementation of `_.unset`.
@@ -13,10 +14,11 @@ import parent from './_parent';
  * @returns {boolean} Returns `true` if the property is deleted, else `false`.
  */
 function baseUnset(object, path) {
-  path = isKey(path, object) ? [path] : baseCastPath(path);
+  path = isKey(path, object) ? [path] : castPath(path);
   object = parent(object, path);
-  var key = last(path);
-  return (object != null && has(object, key)) ? delete object[key] : true;
+
+  var key = toKey(last(path));
+  return !(object != null && baseHas(object, key)) || delete object[key];
 }
 
 export default baseUnset;

_cacheHas.js

@@ -1,25 +1,13 @@
-import isKeyable from './_isKeyable';
-
-/** Used to stand-in for `undefined` hash values. */
-var HASH_UNDEFINED = '__lodash_hash_undefined__';
-
 /**
- * Checks if `value` is in `cache`.
+ * Checks if a cache value for `key` exists.
  *
  * @private
- * @param {Object} cache The set cache to search.
- * @param {*} value The value to search for.
- * @returns {number} Returns `true` if `value` is found, else `false`.
+ * @param {Object} cache The cache to query.
+ * @param {string} key The key of the entry to check.
+ * @returns {boolean} Returns `true` if an entry for `key` exists, else `false`.
  */
-function cacheHas(cache, value) {
-  var map = cache.__data__;
-  if (isKeyable(value)) {
-    var data = map.__data__,
-        hash = typeof value == 'string' ? data.string : data.hash;
-
-    return hash[value] === HASH_UNDEFINED;
-  }
-  return map.has(value);
+function cacheHas(cache, key) {
+  return cache.has(key);
 }
 
 export default cacheHas;

_cachePush.js

@@ -1,27 +0,0 @@
-import isKeyable from './_isKeyable';
-
-/** Used to stand-in for `undefined` hash values. */
-var HASH_UNDEFINED = '__lodash_hash_undefined__';
-
-/**
- * Adds `value` to the set cache.
- *
- * @private
- * @name push
- * @memberOf SetCache
- * @param {*} value The value to cache.
- */
-function cachePush(value) {
-  var map = this.__data__;
-  if (isKeyable(value)) {
-    var data = map.__data__,
-        hash = typeof value == 'string' ? data.string : data.hash;
-
-    hash[value] = HASH_UNDEFINED;
-  }
-  else {
-    map.set(value, HASH_UNDEFINED);
-  }
-}
-
-export default cachePush;

_castArrayLikeObject.js

@@ -7,8 +7,8 @@ import isArrayLikeObject from './isArrayLikeObject';
  * @param {*} value The value to inspect.
  * @returns {Array|Object} Returns the cast array-like object.
  */
-function baseCastArrayLikeObject(value) {
+function castArrayLikeObject(value) {
   return isArrayLikeObject(value) ? value : [];
 }
 
-export default baseCastArrayLikeObject;
+export default castArrayLikeObject;

_castFunction.js

@@ -7,8 +7,8 @@ import identity from './identity';
  * @param {*} value The value to inspect.
  * @returns {Function} Returns cast function.
  */
-function baseCastFunction(value) {
+function castFunction(value) {
   return typeof value == 'function' ? value : identity;
 }
 
-export default baseCastFunction;
+export default castFunction;

_castPath.js

@@ -8,8 +8,8 @@ import stringToPath from './_stringToPath';
  * @param {*} value The value to inspect.
  * @returns {Array} Returns the cast property path array.
  */
-function baseCastPath(value) {
+function castPath(value) {
   return isArray(value) ? value : stringToPath(value);
 }
 
-export default baseCastPath;
+export default castPath;

_castSlice.js

@@ -0,0 +1,18 @@
+import baseSlice from './_baseSlice';
+
+/**
+ * Casts `array` to a slice if it's needed.
+ *
+ * @private
+ * @param {Array} array The array to inspect.
+ * @param {number} start The start position.
+ * @param {number} [end=array.length] The end position.
+ * @returns {Array} Returns the cast slice.
+ */
+function castSlice(array, start, end) {
+  var length = array.length;
+  end = end === undefined ? length : end;
+  return (!start && end >= length) ? array : baseSlice(array, start, end);
+}
+
+export default castSlice;

_compareAscending.js

@@ -1,3 +1,5 @@
+import isSymbol from './isSymbol';
+
 /**
  * Compares values to sort them in ascending order.
  *
@@ -8,22 +10,28 @@
  */
 function compareAscending(value, other) {
   if (value !== other) {
-    var valIsNull = value === null,
-        valIsUndef = value === undefined,
-        valIsReflexive = value === value;
+    var valIsDefined = value !== undefined,
+        valIsNull = value === null,
+        valIsReflexive = value === value,
+        valIsSymbol = isSymbol(value);
 
-    var othIsNull = other === null,
-        othIsUndef = other === undefined,
-        othIsReflexive = other === other;
+    var othIsDefined = other !== undefined,
+        othIsNull = other === null,
+        othIsReflexive = other === other,
+        othIsSymbol = isSymbol(other);
 
-    if ((value > other && !othIsNull) || !valIsReflexive ||
-        (valIsNull && !othIsUndef && othIsReflexive) ||
-        (valIsUndef && othIsReflexive)) {
+    if ((!othIsNull && !othIsSymbol && !valIsSymbol && value > other) ||
+        (valIsSymbol && othIsDefined && othIsReflexive && !othIsNull && !othIsSymbol) ||
+        (valIsNull && othIsDefined && othIsReflexive) ||
+        (!valIsDefined && othIsReflexive) ||
+        !valIsReflexive) {
       return 1;
     }
-    if ((value < other && !valIsNull) || !othIsReflexive ||
-        (othIsNull && !valIsUndef && valIsReflexive) ||
-        (othIsUndef && valIsReflexive)) {
+    if ((!valIsNull && !valIsSymbol && !othIsSymbol && value < other) ||
+        (othIsSymbol && valIsDefined && valIsReflexive && !valIsNull && !valIsSymbol) ||
+        (othIsNull && valIsDefined && valIsReflexive) ||
+        (!othIsDefined && valIsReflexive) ||
+        !othIsReflexive) {
       return -1;
     }
   }

_composeArgs.js

@@ -6,7 +6,7 @@ var nativeMax = Math.max;
  * placeholders, and provided arguments into a single array of arguments.
  *
  * @private
- * @param {Array|Object} args The provided arguments.
+ * @param {Array} args The provided arguments.
  * @param {Array} partials The arguments to prepend to those provided.
  * @param {Array} holders The `partials` placeholder indexes.
  * @params {boolean} [isCurried] Specify composing for a curried function.

_composeArgsRight.js

@@ -6,7 +6,7 @@ var nativeMax = Math.max;
  * is tailored for `_.partialRight`.
  *
  * @private
- * @param {Array|Object} args The provided arguments.
+ * @param {Array} args The provided arguments.
  * @param {Array} partials The arguments to append to those provided.
  * @param {Array} holders The `partials` placeholder indexes.
  * @params {boolean} [isCurried] Specify composing for a curried function.

_copyObject.js

@@ -1,4 +1,4 @@
-import copyObjectWith from './_copyObjectWith';
+import assignValue from './_assignValue';
 
 /**
  * Copies properties of `source` to `object`.
@@ -7,10 +7,25 @@ import copyObjectWith from './_copyObjectWith';
  * @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) {
-  return copyObjectWith(source, props, 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)
+      : source[key];
+
+    assignValue(object, key, newValue);
+  }
+  return object;
 }
 
 export default copyObject;

_copyObjectWith.js

@@ -1,32 +0,0 @@
-import assignValue from './_assignValue';
-
-/**
- * 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 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 copyObjectWith(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)
-      : source[key];
-
-    assignValue(object, key, newValue);
-  }
-  return object;
-}
-
-export default copyObjectWith;

_createAssigner.js

@@ -15,7 +15,7 @@ function createAssigner(assigner) {
         customizer = length > 1 ? sources[length - 1] : undefined,
         guard = length > 2 ? sources[2] : undefined;
 
-    customizer = typeof customizer == 'function'
+    customizer = (assigner.length > 3 && typeof customizer == 'function')
       ? (length--, customizer)
       : undefined;
 

_createCaseFirst.js

@@ -1,24 +1,14 @@
+import castSlice from './_castSlice';
+import reHasComplexSymbol from './_reHasComplexSymbol';
 import stringToArray from './_stringToArray';
 import toString from './toString';
 
-/** Used to compose unicode character classes. */
-var rsAstralRange = '\\ud800-\\udfff',
-    rsComboMarksRange = '\\u0300-\\u036f\\ufe20-\\ufe23',
-    rsComboSymbolsRange = '\\u20d0-\\u20f0',
-    rsVarRange = '\\ufe0e\\ufe0f';
-
-/** Used to compose unicode capture groups. */
-var rsZWJ = '\\u200d';
-
-/** Used to detect strings with [zero-width joiners or code points from the astral planes](http://eev.ee/blog/2015/09/12/dark-corners-of-unicode/). */
-var reHasComplexSymbol = RegExp('[' + rsZWJ + rsAstralRange  + rsComboMarksRange + rsComboSymbolsRange + rsVarRange + ']');
-
 /**
  * Creates a function like `_.lowerFirst`.
  *
  * @private
  * @param {string} methodName The name of the `String` case method to use.
- * @returns {Function} Returns the new function.
+ * @returns {Function} Returns the new case function.
  */
 function createCaseFirst(methodName) {
   return function(string) {
@@ -28,8 +18,13 @@ function createCaseFirst(methodName) {
       ? stringToArray(string)
       : undefined;
 
-    var chr = strSymbols ? strSymbols[0] : string.charAt(0),
-        trailing = strSymbols ? strSymbols.slice(1).join('') : string.slice(1);
+    var chr = strSymbols
+      ? strSymbols[0]
+      : string.charAt(0);
+
+    var trailing = strSymbols
+      ? castSlice(strSymbols, 1).join('')
+      : string.slice(1);
 
     return chr[methodName]() + trailing;
   };

_createCompounder.js

@@ -2,6 +2,12 @@ import arrayReduce from './_arrayReduce';
 import deburr from './deburr';
 import words from './words';
 
+/** Used to compose unicode capture groups. */
+var rsApos = "['\u2019]";
+
+/** Used to match apostrophes. */
+var reApos = RegExp(rsApos, 'g');
+
 /**
  * Creates a function like `_.camelCase`.
  *
@@ -11,7 +17,7 @@ import words from './words';
  */
 function createCompounder(callback) {
   return function(string) {
-    return arrayReduce(words(deburr(string)), callback, '');
+    return arrayReduce(words(deburr(string).replace(reApos, '')), callback, '');
   };
 }
 

_createCurryWrapper.js

@@ -2,7 +2,7 @@ import apply from './_apply';
 import createCtorWrapper from './_createCtorWrapper';
 import createHybridWrapper from './_createHybridWrapper';
 import createRecurryWrapper from './_createRecurryWrapper';
-import getPlaceholder from './_getPlaceholder';
+import getHolder from './_getHolder';
 import replaceHolders from './_replaceHolders';
 import root from './_root';
 
@@ -23,7 +23,7 @@ function createCurryWrapper(func, bitmask, arity) {
     var length = arguments.length,
         args = Array(length),
         index = length,
-        placeholder = getPlaceholder(wrapper);
+        placeholder = getHolder(wrapper);
 
     while (index--) {
       args[index] = arguments[index];

_createHybridWrapper.js

@@ -3,7 +3,7 @@ import composeArgsRight from './_composeArgsRight';
 import countHolders from './_countHolders';
 import createCtorWrapper from './_createCtorWrapper';
 import createRecurryWrapper from './_createRecurryWrapper';
-import getPlaceholder from './_getPlaceholder';
+import getHolder from './_getHolder';
 import reorder from './_reorder';
 import replaceHolders from './_replaceHolders';
 import root from './_root';
@@ -46,14 +46,14 @@ function createHybridWrapper(func, bitmask, thisArg, partials, holders, partials
 
   function wrapper() {
     var length = arguments.length,
-        index = length,
-        args = Array(length);
+        args = Array(length),
+        index = length;
 
     while (index--) {
       args[index] = arguments[index];
     }
     if (isCurried) {
-      var placeholder = getPlaceholder(wrapper),
+      var placeholder = getHolder(wrapper),
           holdersCount = countHolders(args, placeholder);
     }
     if (partials) {

_createMathOperation.js

@@ -1,3 +1,6 @@
+import baseToNumber from './_baseToNumber';
+import baseToString from './_baseToString';
+
 /**
  * Creates a function that performs a mathematical operation on two values.
  *
@@ -15,7 +18,17 @@ function createMathOperation(operator) {
       result = value;
     }
     if (other !== undefined) {
-      result = result === undefined ? other : operator(result, other);
+      if (result === undefined) {
+        return other;
+      }
+      if (typeof value == 'string' || typeof other == 'string') {
+        value = baseToString(value);
+        other = baseToString(other);
+      } else {
+        value = baseToNumber(value);
+        other = baseToNumber(other);
+      }
+      result = operator(value, other);
     }
     return result;
   };

_createOver.js

@@ -1,6 +1,10 @@
 import apply from './_apply';
 import arrayMap from './_arrayMap';
+import baseFlatten from './_baseFlatten';
 import baseIteratee from './_baseIteratee';
+import baseUnary from './_baseUnary';
+import isArray from './isArray';
+import isFlattenableIteratee from './_isFlattenableIteratee';
 import rest from './rest';
 
 /**
@@ -8,11 +12,14 @@ import rest from './rest';
  *
  * @private
  * @param {Function} arrayFunc The function to iterate over iteratees.
- * @returns {Function} Returns the new invoker function.
+ * @returns {Function} Returns the new over function.
  */
 function createOver(arrayFunc) {
   return rest(function(iteratees) {
-    iteratees = arrayMap(iteratees, baseIteratee);
+    iteratees = (iteratees.length == 1 && isArray(iteratees[0]))
+      ? arrayMap(iteratees[0], baseUnary(baseIteratee))
+      : arrayMap(baseFlatten(iteratees, 1, isFlattenableIteratee), baseUnary(baseIteratee));
+
     return rest(function(args) {
       var thisArg = this;
       return arrayFunc(iteratees, function(iteratee) {

_createPadding.js

@@ -1,19 +1,10 @@
 import baseRepeat from './_baseRepeat';
+import baseToString from './_baseToString';
+import castSlice from './_castSlice';
+import reHasComplexSymbol from './_reHasComplexSymbol';
 import stringSize from './_stringSize';
 import stringToArray from './_stringToArray';
 
-/** Used to compose unicode character classes. */
-var rsAstralRange = '\\ud800-\\udfff',
-    rsComboMarksRange = '\\u0300-\\u036f\\ufe20-\\ufe23',
-    rsComboSymbolsRange = '\\u20d0-\\u20f0',
-    rsVarRange = '\\ufe0e\\ufe0f';
-
-/** Used to compose unicode capture groups. */
-var rsZWJ = '\\u200d';
-
-/** Used to detect strings with [zero-width joiners or code points from the astral planes](http://eev.ee/blog/2015/09/12/dark-corners-of-unicode/). */
-var reHasComplexSymbol = RegExp('[' + rsZWJ + rsAstralRange  + rsComboMarksRange + rsComboSymbolsRange + rsVarRange + ']');
-
 /* Built-in method references for those with the same name as other `lodash` methods. */
 var nativeCeil = Math.ceil;
 
@@ -27,7 +18,7 @@ var nativeCeil = Math.ceil;
  * @returns {string} Returns the padding for `string`.
  */
 function createPadding(length, chars) {
-  chars = chars === undefined ? ' ' : (chars + '');
+  chars = chars === undefined ? ' ' : baseToString(chars);
 
   var charsLength = chars.length;
   if (charsLength < 2) {
@@ -35,7 +26,7 @@ function createPadding(length, chars) {
   }
   var result = baseRepeat(chars, nativeCeil(length / stringSize(chars)));
   return reHasComplexSymbol.test(chars)
-    ? stringToArray(result).slice(0, length).join('')
+    ? castSlice(stringToArray(result), 0, length).join('')
     : result.slice(0, length);
 }
 

_createRecurryWrapper.js

@@ -1,4 +1,3 @@
-import copyArray from './_copyArray';
 import isLaziable from './_isLaziable';
 import setData from './_setData';
 
@@ -30,7 +29,6 @@ var BIND_FLAG = 1,
  */
 function createRecurryWrapper(func, bitmask, wrapFunc, placeholder, thisArg, partials, holders, argPos, ary, arity) {
   var isCurry = bitmask & CURRY_FLAG,
-      newArgPos = argPos ? copyArray(argPos) : undefined,
       newHolders = isCurry ? holders : undefined,
       newHoldersRight = isCurry ? undefined : holders,
       newPartials = isCurry ? partials : undefined,
@@ -44,7 +42,7 @@ function createRecurryWrapper(func, bitmask, wrapFunc, placeholder, thisArg, par
   }
   var newData = [
     func, bitmask, thisArg, newPartials, newHolders, newPartialsRight,
-    newHoldersRight, newArgPos, ary, arity
+    newHoldersRight, argPos, ary, arity
   ];
 
   var result = wrapFunc.apply(undefined, newData);

_createRelationalOperation.js

@@ -0,0 +1,20 @@
+import toNumber from './toNumber';
+
+/**
+ * Creates a function that performs a relational operation on two values.
+ *
+ * @private
+ * @param {Function} operator The function to perform the operation.
+ * @returns {Function} Returns the new relational operation function.
+ */
+function createRelationalOperation(operator) {
+  return function(value, other) {
+    if (!(typeof value == 'string' && typeof other == 'string')) {
+      value = toNumber(value);
+      other = toNumber(other);
+    }
+    return operator(value, other);
+  };
+}
+
+export default createRelationalOperation;

_createSet.js

@@ -1,5 +1,9 @@
 import Set from './_Set';
 import noop from './noop';
+import setToArray from './_setToArray';
+
+/** Used as references for various `Number` constants. */
+var INFINITY = 1 / 0;
 
 /**
  * Creates a set of `values`.
@@ -8,7 +12,7 @@ import noop from './noop';
  * @param {Array} values The values to add to the set.
  * @returns {Object} Returns the new set.
  */
-var createSet = !(Set && new Set([1, 2]).size === 2) ? noop : function(values) {
+var createSet = !(Set && (1 / setToArray(new Set([,-0]))[1]) == INFINITY) ? noop : function(values) {
   return new Set(values);
 };
 

_createToPairs.js

@@ -0,0 +1,30 @@
+import baseToPairs from './_baseToPairs';
+import getTag from './_getTag';
+import mapToArray from './_mapToArray';
+import setToPairs from './_setToPairs';
+
+/** `Object#toString` result references. */
+var mapTag = '[object Map]',
+    setTag = '[object Set]';
+
+/**
+ * Creates a `_.toPairs` or `_.toPairsIn` function.
+ *
+ * @private
+ * @param {Function} keysFunc The function to get the keys of a given object.
+ * @returns {Function} Returns the new pairs function.
+ */
+function createToPairs(keysFunc) {
+  return function(object) {
+    var tag = getTag(object);
+    if (tag == mapTag) {
+      return mapToArray(object);
+    }
+    if (tag == setTag) {
+      return setToPairs(object);
+    }
+    return baseToPairs(object, keysFunc(object));
+  };
+}
+
+export default createToPairs;

_createWrapper.js

@@ -39,6 +39,7 @@ var nativeMax = Math.max;
  *    64 - `_.partialRight`
  *   128 - `_.rearg`
  *   256 - `_.ary`
+ *   512 - `_.flip`
  * @param {*} [thisArg] The `this` binding of `func`.
  * @param {Array} [partials] The arguments to be partially applied.
  * @param {Array} [holders] The `partials` placeholder indexes.

_equalArrays.js

@@ -1,3 +1,4 @@
+import SetCache from './_SetCache';
 import arraySome from './_arraySome';
 
 /** Used to compose bitmasks for comparison styles. */
@@ -19,9 +20,7 @@ var UNORDERED_COMPARE_FLAG = 1,
  * @returns {boolean} Returns `true` if the arrays are equivalent, else `false`.
  */
 function equalArrays(array, other, equalFunc, customizer, bitmask, stack) {
-  var index = -1,
-      isPartial = bitmask & PARTIAL_COMPARE_FLAG,
-      isUnordered = bitmask & UNORDERED_COMPARE_FLAG,
+  var isPartial = bitmask & PARTIAL_COMPARE_FLAG,
       arrLength = array.length,
       othLength = other.length;
 
@@ -33,7 +32,10 @@ function equalArrays(array, other, equalFunc, customizer, bitmask, stack) {
   if (stacked) {
     return stacked == other;
   }
-  var result = true;
+  var index = -1,
+      result = true,
+      seen = (bitmask & UNORDERED_COMPARE_FLAG) ? new SetCache : undefined;
+
   stack.set(array, other);
 
   // Ignore non-index properties.
@@ -54,10 +56,12 @@ function equalArrays(array, other, equalFunc, customizer, bitmask, stack) {
       break;
     }
     // Recursively compare arrays (susceptible to call stack limits).
-    if (isUnordered) {
-      if (!arraySome(other, function(othValue) {
-            return arrValue === othValue ||
-              equalFunc(arrValue, othValue, customizer, bitmask, stack);
+    if (seen) {
+      if (!arraySome(other, function(othValue, othIndex) {
+            if (!seen.has(othIndex) &&
+                (arrValue === othValue || equalFunc(arrValue, othValue, customizer, bitmask, stack))) {
+              return seen.add(othIndex);
+            }
           })) {
         result = false;
         break;

_getHolder.js

@@ -5,9 +5,9 @@
  * @param {Function} func The function to inspect.
  * @returns {*} Returns the placeholder value.
  */
-function getPlaceholder(func) {
+function getHolder(func) {
   var object = func;
   return object.placeholder;
 }
 
-export default getPlaceholder;
+export default getHolder;

_getMapData.js

@@ -0,0 +1,18 @@
+import isKeyable from './_isKeyable';
+
+/**
+ * Gets the data for `map`.
+ *
+ * @private
+ * @param {Object} map The map to query.
+ * @param {string} key The reference key.
+ * @returns {*} Returns the map data.
+ */
+function getMapData(map, key) {
+  var data = map.__data__;
+  return isKeyable(key)
+    ? data[typeof key == 'string' ? 'string' : 'hash']
+    : data.map;
+}
+
+export default getMapData;

_getTag.js

@@ -51,8 +51,8 @@ if ((DataView && getTag(new DataView(new ArrayBuffer(1))) != dataViewTag) ||
     (WeakMap && getTag(new WeakMap) != weakMapTag)) {
   getTag = function(value) {
     var result = objectToString.call(value),
-        Ctor = result == objectTag ? value.constructor : null,
-        ctorString = toSource(Ctor);
+        Ctor = result == objectTag ? value.constructor : undefined,
+        ctorString = Ctor ? toSource(Ctor) : undefined;
 
     if (ctorString) {
       switch (ctorString) {

_hasPath.js

@@ -1,10 +1,11 @@
-import baseCastPath from './_baseCastPath';
+import castPath from './_castPath';
 import isArguments from './isArguments';
 import isArray from './isArray';
 import isIndex from './_isIndex';
 import isKey from './_isKey';
 import isLength from './isLength';
 import isString from './isString';
+import toKey from './_toKey';
 
 /**
  * Checks if `path` exists on `object`.
@@ -16,14 +17,14 @@ import isString from './isString';
  * @returns {boolean} Returns `true` if `path` exists, else `false`.
  */
 function hasPath(object, path, hasFunc) {
-  path = isKey(path, object) ? [path] : baseCastPath(path);
+  path = isKey(path, object) ? [path] : castPath(path);
 
   var result,
       index = -1,
       length = path.length;
 
   while (++index < length) {
-    var key = path[index];
+    var key = toKey(path[index]);
     if (!(result = object != null && hasFunc(object, key))) {
       break;
     }

_hashClear.js

@@ -0,0 +1,14 @@
+import nativeCreate from './_nativeCreate';
+
+/**
+ * Removes all key-value entries from the hash.
+ *
+ * @private
+ * @name clear
+ * @memberOf Hash
+ */
+function hashClear() {
+  this.__data__ = nativeCreate ? nativeCreate(null) : {};
+}
+
+export default hashClear;

_hashDelete.js

@@ -1,15 +1,15 @@
-import hashHas from './_hashHas';
-
 /**
  * Removes `key` and its value from the hash.
  *
  * @private
+ * @name delete
+ * @memberOf Hash
  * @param {Object} hash The hash to modify.
  * @param {string} key The key of the value to remove.
  * @returns {boolean} Returns `true` if the entry was removed, else `false`.
  */
-function hashDelete(hash, key) {
-  return hashHas(hash, key) && delete hash[key];
+function hashDelete(key) {
+  return this.has(key) && delete this.__data__[key];
 }
 
 export default hashDelete;

_hashGet.js

@@ -13,16 +13,18 @@ var hasOwnProperty = objectProto.hasOwnProperty;
  * Gets the hash value for `key`.
  *
  * @private
- * @param {Object} hash The hash to query.
+ * @name get
+ * @memberOf Hash
  * @param {string} key The key of the value to get.
  * @returns {*} Returns the entry value.
  */
-function hashGet(hash, key) {
+function hashGet(key) {
+  var data = this.__data__;
   if (nativeCreate) {
-    var result = hash[key];
+    var result = data[key];
     return result === HASH_UNDEFINED ? undefined : result;
   }
-  return hasOwnProperty.call(hash, key) ? hash[key] : undefined;
+  return hasOwnProperty.call(data, key) ? data[key] : undefined;
 }
 
 export default hashGet;

_hashHas.js

@@ -10,12 +10,14 @@ var hasOwnProperty = objectProto.hasOwnProperty;
  * Checks if a hash value for `key` exists.
  *
  * @private
- * @param {Object} hash The hash to query.
+ * @name has
+ * @memberOf Hash
  * @param {string} key The key of the entry to check.
  * @returns {boolean} Returns `true` if an entry for `key` exists, else `false`.
  */
-function hashHas(hash, key) {
-  return nativeCreate ? hash[key] !== undefined : hasOwnProperty.call(hash, key);
+function hashHas(key) {
+  var data = this.__data__;
+  return nativeCreate ? data[key] !== undefined : hasOwnProperty.call(data, key);
 }
 
 export default hashHas;

_hashSet.js

@@ -7,12 +7,16 @@ var HASH_UNDEFINED = '__lodash_hash_undefined__';
  * Sets the hash `key` to `value`.
  *
  * @private
- * @param {Object} hash The hash to modify.
+ * @name set
+ * @memberOf Hash
  * @param {string} key The key of the value to set.
  * @param {*} value The value to set.
+ * @returns {Object} Returns the hash instance.
  */
-function hashSet(hash, key, value) {
-  hash[key] = (nativeCreate && value === undefined) ? HASH_UNDEFINED : value;
+function hashSet(key, value) {
+  var data = this.__data__;
+  data[key] = (nativeCreate && value === undefined) ? HASH_UNDEFINED : value;
+  return this;
 }
 
 export default hashSet;

_isFlattenable.js

@@ -0,0 +1,15 @@
+import isArguments from './isArguments';
+import isArray from './isArray';
+
+/**
+ * Checks if `value` is a flattenable `arguments` object or array.
+ *
+ * @private
+ * @param {*} value The value to check.
+ * @returns {boolean} Returns `true` if `value` is flattenable, else `false`.
+ */
+function isFlattenable(value) {
+  return isArray(value) || isArguments(value);
+}
+
+export default isFlattenable;

_isFlattenableIteratee.js

@@ -0,0 +1,16 @@
+import isArray from './isArray';
+import isFunction from './isFunction';
+
+/**
+ * Checks if `value` is a flattenable array and not a `_.matchesProperty`
+ * iteratee shorthand.
+ *
+ * @private
+ * @param {*} value The value to check.
+ * @returns {boolean} Returns `true` if `value` is flattenable, else `false`.
+ */
+function isFlattenableIteratee(value) {
+  return isArray(value) && !(value.length == 2 && !isFunction(value[0]));
+}
+
+export default isFlattenableIteratee;

_isIndex.js

@@ -13,9 +13,10 @@ var reIsUint = /^(?:0|[1-9]\d*)$/;
  * @returns {boolean} Returns `true` if `value` is a valid index, else `false`.
  */
 function isIndex(value, length) {
-  value = (typeof value == 'number' || reIsUint.test(value)) ? +value : -1;
   length = length == null ? MAX_SAFE_INTEGER : length;
-  return value > -1 && value % 1 == 0 && value < length;
+  return !!length &&
+    (typeof value == 'number' || reIsUint.test(value)) &&
+    (value > -1 && value % 1 == 0 && value < length);
 }
 
 export default isIndex;

_isKey.js

@@ -14,13 +14,16 @@ var reIsDeepProp = /\.|\[(?:[^[\]]*|(["'])(?:(?!\1)[^\\]|\\.)*?\1)\]/,
  * @returns {boolean} Returns `true` if `value` is a property name, else `false`.
  */
 function isKey(value, object) {
+  if (isArray(value)) {
+    return false;
+  }
   var type = typeof value;
-  if (type == 'number' || type == 'symbol') {
+  if (type == 'number' || type == 'symbol' || type == 'boolean' ||
+      value == null || isSymbol(value)) {
     return true;
   }
-  return !isArray(value) &&
-    (isSymbol(value) || reIsPlainProp.test(value) || !reIsDeepProp.test(value) ||
-      (object != null && value in Object(object)));
+  return reIsPlainProp.test(value) || !reIsDeepProp.test(value) ||
+    (object != null && value in Object(object));
 }
 
 export default isKey;

_isKeyable.js

@@ -7,8 +7,9 @@
  */
 function isKeyable(value) {
   var type = typeof value;
-  return type == 'number' || type == 'boolean' ||
-    (type == 'string' && value != '__proto__') || value == null;
+  return (type == 'string' || type == 'number' || type == 'symbol' || type == 'boolean')
+    ? (value !== '__proto__')
+    : (value === null);
 }
 
 export default isKeyable;

_listCacheClear.js

@@ -0,0 +1,12 @@
+/**
+ * Removes all key-value entries from the list cache.
+ *
+ * @private
+ * @name clear
+ * @memberOf ListCache
+ */
+function listCacheClear() {
+  this.__data__ = [];
+}
+
+export default listCacheClear;

_listCacheDelete.js

@@ -7,25 +7,28 @@ var arrayProto = Array.prototype;
 var splice = arrayProto.splice;
 
 /**
- * Removes `key` and its value from the associative array.
+ * Removes `key` and its value from the list cache.
  *
  * @private
- * @param {Array} array The array to modify.
+ * @name delete
+ * @memberOf ListCache
  * @param {string} key The key of the value to remove.
  * @returns {boolean} Returns `true` if the entry was removed, else `false`.
  */
-function assocDelete(array, key) {
-  var index = assocIndexOf(array, key);
+function listCacheDelete(key) {
+  var data = this.__data__,
+      index = assocIndexOf(data, key);
+
   if (index < 0) {
     return false;
   }
-  var lastIndex = array.length - 1;
+  var lastIndex = data.length - 1;
   if (index == lastIndex) {
-    array.pop();
+    data.pop();
   } else {
-    splice.call(array, index, 1);
+    splice.call(data, index, 1);
   }
   return true;
 }
 
-export default assocDelete;
+export default listCacheDelete;

_listCacheGet.js

@@ -0,0 +1,19 @@
+import assocIndexOf from './_assocIndexOf';
+
+/**
+ * Gets the list cache value for `key`.
+ *
+ * @private
+ * @name get
+ * @memberOf ListCache
+ * @param {string} key The key of the value to get.
+ * @returns {*} Returns the entry value.
+ */
+function listCacheGet(key) {
+  var data = this.__data__,
+      index = assocIndexOf(data, key);
+
+  return index < 0 ? undefined : data[index][1];
+}
+
+export default listCacheGet;

_listCacheHas.js

@@ -1,15 +1,16 @@
 import assocIndexOf from './_assocIndexOf';
 
 /**
- * Checks if an associative array value for `key` exists.
+ * Checks if a list cache value for `key` exists.
  *
  * @private
- * @param {Array} array The array to query.
+ * @name has
+ * @memberOf ListCache
  * @param {string} key The key of the entry to check.
  * @returns {boolean} Returns `true` if an entry for `key` exists, else `false`.
  */
-function assocHas(array, key) {
-  return assocIndexOf(array, key) > -1;
+function listCacheHas(key) {
+  return assocIndexOf(this.__data__, key) > -1;
 }
 
-export default assocHas;
+export default listCacheHas;

_listCacheSet.js

@@ -0,0 +1,25 @@
+import assocIndexOf from './_assocIndexOf';
+
+/**
+ * Sets the list cache `key` to `value`.
+ *
+ * @private
+ * @name set
+ * @memberOf ListCache
+ * @param {string} key The key of the value to set.
+ * @param {*} value The value to set.
+ * @returns {Object} Returns the list cache instance.
+ */
+function listCacheSet(key, value) {
+  var data = this.__data__,
+      index = assocIndexOf(data, key);
+
+  if (index < 0) {
+    data.push([key, value]);
+  } else {
+    data[index][1] = value;
+  }
+  return this;
+}
+
+export default listCacheSet;

_mapCacheClear.js

@@ -1,4 +1,5 @@
 import Hash from './_Hash';
+import ListCache from './_ListCache';
 import Map from './_Map';
 
 /**
@@ -8,12 +9,12 @@ import Map from './_Map';
  * @name clear
  * @memberOf MapCache
  */
-function mapClear() {
+function mapCacheClear() {
   this.__data__ = {
     'hash': new Hash,
-    'map': Map ? new Map : [],
+    'map': new (Map || ListCache),
     'string': new Hash
   };
 }
 
-export default mapClear;
+export default mapCacheClear;

_mapCacheDelete.js

@@ -0,0 +1,16 @@
+import getMapData from './_getMapData';
+
+/**
+ * Removes `key` and its value from the map.
+ *
+ * @private
+ * @name delete
+ * @memberOf MapCache
+ * @param {string} key The key of the value to remove.
+ * @returns {boolean} Returns `true` if the entry was removed, else `false`.
+ */
+function mapCacheDelete(key) {
+  return getMapData(this, key)['delete'](key);
+}
+
+export default mapCacheDelete;

_mapCacheGet.js

@@ -0,0 +1,16 @@
+import getMapData from './_getMapData';
+
+/**
+ * Gets the map value for `key`.
+ *
+ * @private
+ * @name get
+ * @memberOf MapCache
+ * @param {string} key The key of the value to get.
+ * @returns {*} Returns the entry value.
+ */
+function mapCacheGet(key) {
+  return getMapData(this, key).get(key);
+}
+
+export default mapCacheGet;

_mapCacheHas.js

@@ -0,0 +1,16 @@
+import getMapData from './_getMapData';
+
+/**
+ * Checks if a map value for `key` exists.
+ *
+ * @private
+ * @name has
+ * @memberOf MapCache
+ * @param {string} key The key of the entry to check.
+ * @returns {boolean} Returns `true` if an entry for `key` exists, else `false`.
+ */
+function mapCacheHas(key) {
+  return getMapData(this, key).has(key);
+}
+
+export default mapCacheHas;

_mapCacheSet.js

@@ -0,0 +1,18 @@
+import getMapData from './_getMapData';
+
+/**
+ * Sets the map `key` to `value`.
+ *
+ * @private
+ * @name set
+ * @memberOf MapCache
+ * @param {string} key The key of the value to set.
+ * @param {*} value The value to set.
+ * @returns {Object} Returns the map cache instance.
+ */
+function mapCacheSet(key, value) {
+  getMapData(this, key).set(key, value);
+  return this;
+}
+
+export default mapCacheSet;

_mapDelete.js

@@ -1,23 +0,0 @@
-import Map from './_Map';
-import assocDelete from './_assocDelete';
-import hashDelete from './_hashDelete';
-import isKeyable from './_isKeyable';
-
-/**
- * Removes `key` and its value from the map.
- *
- * @private
- * @name delete
- * @memberOf MapCache
- * @param {string} key The key of the value to remove.
- * @returns {boolean} Returns `true` if the entry was removed, else `false`.
- */
-function mapDelete(key) {
-  var data = this.__data__;
-  if (isKeyable(key)) {
-    return hashDelete(typeof key == 'string' ? data.string : data.hash, key);
-  }
-  return Map ? data.map['delete'](key) : assocDelete(data.map, key);
-}
-
-export default mapDelete;

_mapGet.js

@@ -1,23 +0,0 @@
-import Map from './_Map';
-import assocGet from './_assocGet';
-import hashGet from './_hashGet';
-import isKeyable from './_isKeyable';
-
-/**
- * Gets the map value for `key`.
- *
- * @private
- * @name get
- * @memberOf MapCache
- * @param {string} key The key of the value to get.
- * @returns {*} Returns the entry value.
- */
-function mapGet(key) {
-  var data = this.__data__;
-  if (isKeyable(key)) {
-    return hashGet(typeof key == 'string' ? data.string : data.hash, key);
-  }
-  return Map ? data.map.get(key) : assocGet(data.map, key);
-}
-
-export default mapGet;

_mapHas.js

@@ -1,23 +0,0 @@
-import Map from './_Map';
-import assocHas from './_assocHas';
-import hashHas from './_hashHas';
-import isKeyable from './_isKeyable';
-
-/**
- * Checks if a map value for `key` exists.
- *
- * @private
- * @name has
- * @memberOf MapCache
- * @param {string} key The key of the entry to check.
- * @returns {boolean} Returns `true` if an entry for `key` exists, else `false`.
- */
-function mapHas(key) {
-  var data = this.__data__;
-  if (isKeyable(key)) {
-    return hashHas(typeof key == 'string' ? data.string : data.hash, key);
-  }
-  return Map ? data.map.has(key) : assocHas(data.map, key);
-}
-
-export default mapHas;

_mapSet.js

@@ -1,28 +0,0 @@
-import Map from './_Map';
-import assocSet from './_assocSet';
-import hashSet from './_hashSet';
-import isKeyable from './_isKeyable';
-
-/**
- * Sets the map `key` to `value`.
- *
- * @private
- * @name set
- * @memberOf MapCache
- * @param {string} key The key of the value to set.
- * @param {*} value The value to set.
- * @returns {Object} Returns the map cache instance.
- */
-function mapSet(key, value) {
-  var data = this.__data__;
-  if (isKeyable(key)) {
-    hashSet(typeof key == 'string' ? data.string : data.hash, key, value);
-  } else if (Map) {
-    data.map.set(key, value);
-  } else {
-    assocSet(data.map, key, value);
-  }
-  return this;
-}
-
-export default mapSet;

_mapToArray.js

@@ -1,9 +1,9 @@
 /**
- * Converts `map` to an array.
+ * Converts `map` to its key-value pairs.
  *
  * @private
  * @param {Object} map The map to convert.
- * @returns {Array} Returns the converted array.
+ * @returns {Array} Returns the key-value pairs.
  */
 function mapToArray(map) {
   var index = -1,

_matchesStrictComparable.js

@@ -5,7 +5,7 @@
  * @private
  * @param {string} key The key of the property to get.
  * @param {*} srcValue The value to match.
- * @returns {Function} Returns the new function.
+ * @returns {Function} Returns the new spec function.
  */
 function matchesStrictComparable(key, srcValue) {
   return function(object) {

_mergeData.js

@@ -1,6 +1,5 @@
 import composeArgs from './_composeArgs';
 import composeArgsRight from './_composeArgsRight';
-import copyArray from './_copyArray';
 import replaceHolders from './_replaceHolders';
 
 /** Used as the internal argument placeholder. */
@@ -58,20 +57,20 @@ function mergeData(data, source) {
   var value = source[3];
   if (value) {
     var partials = data[3];
-    data[3] = partials ? composeArgs(partials, value, source[4]) : copyArray(value);
-    data[4] = partials ? replaceHolders(data[3], PLACEHOLDER) : copyArray(source[4]);
+    data[3] = partials ? composeArgs(partials, value, source[4]) : value;
+    data[4] = partials ? replaceHolders(data[3], PLACEHOLDER) : source[4];
   }
   // Compose partial right arguments.
   value = source[5];
   if (value) {
     partials = data[5];
-    data[5] = partials ? composeArgsRight(partials, value, source[6]) : copyArray(value);
-    data[6] = partials ? replaceHolders(data[5], PLACEHOLDER) : copyArray(source[6]);
+    data[5] = partials ? composeArgsRight(partials, value, source[6]) : value;
+    data[6] = partials ? replaceHolders(data[5], PLACEHOLDER) : source[6];
   }
   // Use source `argPos` if available.
   value = source[7];
   if (value) {
-    data[7] = copyArray(value);
+    data[7] = value;
   }
   // Use source `ary` if it's smaller.
   if (srcBitmask & ARY_FLAG) {

_reHasComplexSymbol.js

@@ -0,0 +1,13 @@
+/** Used to compose unicode character classes. */
+var rsAstralRange = '\\ud800-\\udfff',
+    rsComboMarksRange = '\\u0300-\\u036f\\ufe20-\\ufe23',
+    rsComboSymbolsRange = '\\u20d0-\\u20f0',
+    rsVarRange = '\\ufe0e\\ufe0f';
+
+/** Used to compose unicode capture groups. */
+var rsZWJ = '\\u200d';
+
+/** Used to detect strings with [zero-width joiners or code points from the astral planes](http://eev.ee/blog/2015/09/12/dark-corners-of-unicode/). */
+var reHasComplexSymbol = RegExp('[' + rsZWJ + rsAstralRange  + rsComboMarksRange + rsComboSymbolsRange + rsVarRange + ']');
+
+export default reHasComplexSymbol;

_setCacheAdd.js

@@ -0,0 +1,19 @@
+/** Used to stand-in for `undefined` hash values. */
+var HASH_UNDEFINED = '__lodash_hash_undefined__';
+
+/**
+ * Adds `value` to the array cache.
+ *
+ * @private
+ * @name add
+ * @memberOf SetCache
+ * @alias push
+ * @param {*} value The value to cache.
+ * @returns {Object} Returns the cache instance.
+ */
+function setCacheAdd(value) {
+  this.__data__.set(value, HASH_UNDEFINED);
+  return this;
+}
+
+export default setCacheAdd;