flow like the river

VISUALIZACION/node_modules/graphql/subscription/mapAsyncIterator.js

@@ -0,0 +1,86 @@
+"use strict";
+
+Object.defineProperty(exports, "__esModule", {
+  value: true
+});
+exports.default = mapAsyncIterator;
+
+var _symbols = require("../polyfills/symbols.js");
+
+function _defineProperty(obj, key, value) { if (key in obj) { Object.defineProperty(obj, key, { value: value, enumerable: true, configurable: true, writable: true }); } else { obj[key] = value; } return obj; }
+
+/**
+ * Given an AsyncIterable and a callback function, return an AsyncIterator
+ * which produces values mapped via calling the callback function.
+ */
+function mapAsyncIterator(iterable, callback, rejectCallback) {
+  // $FlowFixMe[prop-missing]
+  var iteratorMethod = iterable[_symbols.SYMBOL_ASYNC_ITERATOR];
+  var iterator = iteratorMethod.call(iterable);
+  var $return;
+  var abruptClose;
+
+  if (typeof iterator.return === 'function') {
+    $return = iterator.return;
+
+    abruptClose = function abruptClose(error) {
+      var rethrow = function rethrow() {
+        return Promise.reject(error);
+      };
+
+      return $return.call(iterator).then(rethrow, rethrow);
+    };
+  }
+
+  function mapResult(result) {
+    return result.done ? result : asyncMapValue(result.value, callback).then(iteratorResult, abruptClose);
+  }
+
+  var mapReject;
+
+  if (rejectCallback) {
+    // Capture rejectCallback to ensure it cannot be null.
+    var reject = rejectCallback;
+
+    mapReject = function mapReject(error) {
+      return asyncMapValue(error, reject).then(iteratorResult, abruptClose);
+    };
+  }
+  /* TODO: Flow doesn't support symbols as keys:
+     https://github.com/facebook/flow/issues/3258 */
+
+
+  return _defineProperty({
+    next: function next() {
+      return iterator.next().then(mapResult, mapReject);
+    },
+    return: function _return() {
+      return $return ? $return.call(iterator).then(mapResult, mapReject) : Promise.resolve({
+        value: undefined,
+        done: true
+      });
+    },
+    throw: function _throw(error) {
+      if (typeof iterator.throw === 'function') {
+        return iterator.throw(error).then(mapResult, mapReject);
+      }
+
+      return Promise.reject(error).catch(abruptClose);
+    }
+  }, _symbols.SYMBOL_ASYNC_ITERATOR, function () {
+    return this;
+  });
+}
+
+function asyncMapValue(value, callback) {
+  return new Promise(function (resolve) {
+    return resolve(callback(value));
+  });
+}
+
+function iteratorResult(value) {
+  return {
+    value: value,
+    done: false
+  };
+}