flow like the river

BACK_BACK/node_modules/graphql/jsutils/safeArrayFrom.js

@@ -0,0 +1,73 @@
+"use strict";
+
+Object.defineProperty(exports, "__esModule", {
+  value: true
+});
+exports.default = safeArrayFrom;
+
+var _symbols = require("../polyfills/symbols.js");
+
+function _typeof(obj) { "@babel/helpers - typeof"; if (typeof Symbol === "function" && typeof Symbol.iterator === "symbol") { _typeof = function _typeof(obj) { return typeof obj; }; } else { _typeof = function _typeof(obj) { return obj && typeof Symbol === "function" && obj.constructor === Symbol && obj !== Symbol.prototype ? "symbol" : typeof obj; }; } return _typeof(obj); }
+
+/**
+ * Safer version of `Array.from` that return `null` if value isn't convertible to array.
+ * Also protects against Array-like objects without items.
+ *
+ * @example
+ *
+ * safeArrayFrom([ 1, 2, 3 ]) // [1, 2, 3]
+ * safeArrayFrom('ABC') // null
+ * safeArrayFrom({ length: 1 }) // null
+ * safeArrayFrom({ length: 1, 0: 'Alpha' }) // ['Alpha']
+ * safeArrayFrom({ key: 'value' }) // null
+ * safeArrayFrom(new Map()) // []
+ *
+ */
+function safeArrayFrom(collection) {
+  var mapFn = arguments.length > 1 && arguments[1] !== undefined ? arguments[1] : function (item) {
+    return item;
+  };
+
+  if (collection == null || _typeof(collection) !== 'object') {
+    return null;
+  }
+
+  if (Array.isArray(collection)) {
+    return collection.map(mapFn);
+  } // Is Iterable?
+
+
+  var iteratorMethod = collection[_symbols.SYMBOL_ITERATOR];
+
+  if (typeof iteratorMethod === 'function') {
+    // $FlowFixMe[incompatible-use]
+    var iterator = iteratorMethod.call(collection);
+    var result = [];
+    var step;
+
+    for (var i = 0; !(step = iterator.next()).done; ++i) {
+      result.push(mapFn(step.value, i));
+    }
+
+    return result;
+  } // Is Array like?
+
+
+  var length = collection.length;
+
+  if (typeof length === 'number' && length >= 0 && length % 1 === 0) {
+    var _result = [];
+
+    for (var _i = 0; _i < length; ++_i) {
+      if (!Object.prototype.hasOwnProperty.call(collection, _i)) {
+        return null;
+      }
+
+      _result.push(mapFn(collection[String(_i)], _i));
+    }
+
+    return _result;
+  }
+
+  return null;
+}