Move internal modules to “internal” folder.

.internal/equalByTag.js

@@ -0,0 +1,110 @@
+import eq from './eq.js';
+import equalArrays from './.internal/equalArrays.js';
+import mapToArray from './.internal/mapToArray.js';
+import setToArray from './.internal/setToArray.js';
+
+/** Used to compose bitmasks for value comparisons. */
+const COMPARE_PARTIAL_FLAG = 1;
+const COMPARE_UNORDERED_FLAG = 2;
+
+/** `Object#toString` result references. */
+const boolTag = '[object Boolean]';
+const dateTag = '[object Date]';
+const errorTag = '[object Error]';
+const mapTag = '[object Map]';
+const numberTag = '[object Number]';
+const regexpTag = '[object RegExp]';
+const setTag = '[object Set]';
+const stringTag = '[object String]';
+const symbolTag = '[object Symbol]';
+
+const arrayBufferTag = '[object ArrayBuffer]';
+const dataViewTag = '[object DataView]';
+
+/** Used to convert symbols to primitives and strings. */
+const symbolProto = Symbol ? Symbol.prototype : undefined;
+const symbolValueOf = symbolProto ? symbolProto.valueOf : undefined;
+
+/**
+ * A specialized version of `baseIsEqualDeep` for comparing objects of
+ * the same `toStringTag`.
+ *
+ * **Note:** This function only supports comparing values with tags of
+ * `Boolean`, `Date`, `Error`, `Number`, `RegExp`, or `String`.
+ *
+ * @private
+ * @param {Object} object The object to compare.
+ * @param {Object} other The other object to compare.
+ * @param {string} tag The `toStringTag` of the objects to compare.
+ * @param {number} bitmask The bitmask flags. See `baseIsEqual` for more details.
+ * @param {Function} customizer The function to customize comparisons.
+ * @param {Function} equalFunc The function to determine equivalents of values.
+ * @param {Object} stack Tracks traversed `object` and `other` objects.
+ * @returns {boolean} Returns `true` if the objects are equivalent, else `false`.
+ */
+function equalByTag(object, other, tag, bitmask, customizer, equalFunc, stack) {
+  switch (tag) {
+    case dataViewTag:
+      if ((object.byteLength != other.byteLength) ||
+          (object.byteOffset != other.byteOffset)) {
+        return false;
+      }
+      object = object.buffer;
+      other = other.buffer;
+
+    case arrayBufferTag:
+      if ((object.byteLength != other.byteLength) ||
+          !equalFunc(new Uint8Array(object), new Uint8Array(other))) {
+        return false;
+      }
+      return true;
+
+    case boolTag:
+    case dateTag:
+    case numberTag:
+      // Coerce booleans to `1` or `0` and dates to milliseconds.
+      // Invalid dates are coerced to `NaN`.
+      return eq(+object, +other);
+
+    case errorTag:
+      return object.name == other.name && object.message == other.message;
+
+    case regexpTag:
+    case stringTag:
+      // Coerce regexes to strings and treat strings, primitives and objects,
+      // as equal. See http://www.ecma-international.org/ecma-262/7.0/#sec-regexp.prototype.tostring
+      // for more details.
+      return object == `${ other }`;
+
+    case mapTag:
+      let convert = mapToArray;
+
+    case setTag:
+      const isPartial = bitmask & COMPARE_PARTIAL_FLAG;
+      convert || (convert = setToArray);
+
+      if (object.size != other.size && !isPartial) {
+        return false;
+      }
+      // Assume cyclic values are equal.
+      const stacked = stack.get(object);
+      if (stacked) {
+        return stacked == other;
+      }
+      bitmask |= COMPARE_UNORDERED_FLAG;
+
+      // Recursively compare objects (susceptible to call stack limits).
+      stack.set(object, other);
+      const result = equalArrays(convert(object), convert(other), bitmask, customizer, equalFunc, stack);
+      stack['delete'](object);
+      return result;
+
+    case symbolTag:
+      if (symbolValueOf) {
+        return symbolValueOf.call(object) == symbolValueOf.call(other);
+      }
+  }
+  return false;
+}
+
+export default equalByTag;