es.promise.js

'use strict';
var $ = require('../internals/export');
var IS_PURE = require('../internals/is-pure');
var global = require('../internals/global');
var getBuiltIn = require('../internals/get-built-in');
var NativePromise = require('../internals/native-promise-constructor');
var redefine = require('../internals/redefine');
var redefineAll = require('../internals/redefine-all');
var setToStringTag = require('../internals/set-to-string-tag');
var setSpecies = require('../internals/set-species');
var isObject = require('../internals/is-object');
var aFunction = require('../internals/a-function');
var anInstance = require('../internals/an-instance');
var classof = require('../internals/classof-raw');
var inspectSource = require('../internals/inspect-source');
var iterate = require('../internals/iterate');
var checkCorrectnessOfIteration = require('../internals/check-correctness-of-iteration');
var speciesConstructor = require('../internals/species-constructor');
var task = require('../internals/task').set;
var microtask = require('../internals/microtask');
var promiseResolve = require('../internals/promise-resolve');
var hostReportErrors = require('../internals/host-report-errors');
var newPromiseCapabilityModule = require('../internals/new-promise-capability');
var perform = require('../internals/perform');
var InternalStateModule = require('../internals/internal-state');
var isForced = require('../internals/is-forced');
var wellKnownSymbol = require('../internals/well-known-symbol');
var V8_VERSION = require('../internals/engine-v8-version');

var SPECIES = wellKnownSymbol('species');
var PROMISE = 'Promise';
var getInternalState = InternalStateModule.get;
var setInternalState = InternalStateModule.set;
var getInternalPromiseState = InternalStateModule.getterFor(PROMISE);
var PromiseConstructor = NativePromise;
var TypeError = global.TypeError;
var document = global.document;
var process = global.process;
var $fetch = getBuiltIn('fetch');
var newPromiseCapability = newPromiseCapabilityModule.f;
var newGenericPromiseCapability = newPromiseCapability;
var IS_NODE = classof(process) == 'process';
var DISPATCH_EVENT = !!(document && document.createEvent && global.dispatchEvent);
var UNHANDLED_REJECTION = 'unhandledrejection';
var REJECTION_HANDLED = 'rejectionhandled';
var PENDING = 0;
var FULFILLED = 1;
var REJECTED = 2;
var HANDLED = 1;
var UNHANDLED = 2;
var Internal, OwnPromiseCapability, PromiseWrapper, nativeThen;

var FORCED = isForced(PROMISE, function () {
  var GLOBAL_CORE_JS_PROMISE = inspectSource(PromiseConstructor) !== String(PromiseConstructor);
  if (!GLOBAL_CORE_JS_PROMISE) {
    // V8 6.6 (Node 10 and Chrome 66) have a bug with resolving custom thenables
    // https://bugs.chromium.org/p/chromium/issues/detail?id=830565
    // We can't detect it synchronously, so just check versions
    if (V8_VERSION === 66) return true;
    // Unhandled rejections tracking support, NodeJS Promise without it fails @@species test
    if (!IS_NODE && typeof PromiseRejectionEvent != 'function') return true;
  }
  // We need Promise#finally in the pure version for preventing prototype pollution
  if (IS_PURE && !PromiseConstructor.prototype['finally']) return true;
  // We can't use @@species feature detection in V8 since it causes
  // deoptimization and performance degradation
  // https://github.com/zloirock/core-js/issues/679
  if (V8_VERSION >= 51 && /native code/.test(PromiseConstructor)) return false;
  // Detect correctness of subclassing with @@species support
  var promise = PromiseConstructor.resolve(1);
  var FakePromise = function (exec) {
    exec(function () { /* empty */ }, function () { /* empty */ });
  };
  var constructor = promise.constructor = {};
  constructor[SPECIES] = FakePromise;
  return !(promise.then(function () { /* empty */ }) instanceof FakePromise);
});

var INCORRECT_ITERATION = FORCED || !checkCorrectnessOfIteration(function (iterable) {
  PromiseConstructor.all(iterable)['catch'](function () { /* empty */ });
});

// helpers
var isThenable = function (it) {
  var then;
  return isObject(it) && typeof (then = it.then) == 'function' ? then : false;
};

var notify = function (promise, state, isReject) {
  if (state.notified) return;
  state.notified = true;
  var chain = state.reactions;
  microtask(function () {
    var value = state.value;
    var ok = state.state == FULFILLED;
    var index = 0;
    // variable length - can't use forEach
    while (chain.length > index) {
      var reaction = chain[index++];
      var handler = ok ? reaction.ok : reaction.fail;
      var resolve = reaction.resolve;
      var reject = reaction.reject;
      var domain = reaction.domain;
      var result, then, exited;
      try {
        if (handler) {
          if (!ok) {
            if (state.rejection === UNHANDLED) onHandleUnhandled(promise, state);
            state.rejection = HANDLED;
          }
          if (handler === true) result = value;
          else {
            if (domain) domain.enter();
            result = handler(value); // can throw
            if (domain) {
              domain.exit();
              exited = true;
            }
          }
          if (result === reaction.promise) {
            reject(TypeError('Promise-chain cycle'));
          } else if (then = isThenable(result)) {
            then.call(result, resolve, reject);
          } else resolve(result);
        } else reject(value);
      } catch (error) {
        if (domain && !exited) domain.exit();
        reject(error);
      }
    }
    state.reactions = [];
    state.notified = false;
    if (isReject && !state.rejection) onUnhandled(promise, state);
  });
};

var dispatchEvent = function (name, promise, reason) {
  var event, handler;
  if (DISPATCH_EVENT) {
    event = document.createEvent('Event');
    event.promise = promise;
    event.reason = reason;
    event.initEvent(name, false, true);
    global.dispatchEvent(event);
  } else event = { promise: promise, reason: reason };
  if (handler = global['on' + name]) handler(event);
  else if (name === UNHANDLED_REJECTION) hostReportErrors('Unhandled promise rejection', reason);
};

var onUnhandled = function (promise, state) {
  task.call(global, function () {
    var value = state.value;
    var IS_UNHANDLED = isUnhandled(state);
    var result;
    if (IS_UNHANDLED) {
      result = perform(function () {
        if (IS_NODE) {
          process.emit('unhandledRejection', value, promise);
        } else dispatchEvent(UNHANDLED_REJECTION, promise, value);
      });
      // Browsers should not trigger `rejectionHandled` event if it was handled here, NodeJS - should
      state.rejection = IS_NODE || isUnhandled(state) ? UNHANDLED : HANDLED;
      if (result.error) throw result.value;
    }
  });
};

var isUnhandled = function (state) {
  return state.rejection !== HANDLED && !state.parent;
};

var onHandleUnhandled = function (promise, state) {
  task.call(global, function () {
    if (IS_NODE) {
      process.emit('rejectionHandled', promise);
    } else dispatchEvent(REJECTION_HANDLED, promise, state.value);
  });
};

var bind = function (fn, promise, state, unwrap) {
  return function (value) {
    fn(promise, state, value, unwrap);
  };
};

var internalReject = function (promise, state, value, unwrap) {
  if (state.done) return;
  state.done = true;
  if (unwrap) state = unwrap;
  state.value = value;
  state.state = REJECTED;
  notify(promise, state, true);
};

var internalResolve = function (promise, state, value, unwrap) {
  if (state.done) return;
  state.done = true;
  if (unwrap) state = unwrap;
  try {
    if (promise === value) throw TypeError("Promise can't be resolved itself");
    var then = isThenable(value);
    if (then) {
      microtask(function () {
        var wrapper = { done: false };
        try {
          then.call(value,
            bind(internalResolve, promise, wrapper, state),
            bind(internalReject, promise, wrapper, state)
          );
        } catch (error) {
          internalReject(promise, wrapper, error, state);
        }
      });
    } else {
      state.value = value;
      state.state = FULFILLED;
      notify(promise, state, false);
    }
  } catch (error) {
    internalReject(promise, { done: false }, error, state);
  }
};

// constructor polyfill
if (FORCED) {
  // 25.4.3.1 Promise(executor)
  PromiseConstructor = function Promise(executor) {
    anInstance(this, PromiseConstructor, PROMISE);
    aFunction(executor);
    Internal.call(this);
    var state = getInternalState(this);
    try {
      executor(bind(internalResolve, this, state), bind(internalReject, this, state));
    } catch (error) {
      internalReject(this, state, error);
    }
  };
  // eslint-disable-next-line no-unused-vars
  Internal = function Promise(executor) {
    setInternalState(this, {
      type: PROMISE,
      done: false,
      notified: false,
      parent: false,
      reactions: [],
      rejection: false,
      state: PENDING,
      value: undefined
    });
  };
  Internal.prototype = redefineAll(PromiseConstructor.prototype, {
    // `Promise.prototype.then` method
    // https://tc39.github.io/ecma262/#sec-promise.prototype.then
    then: function then(onFulfilled, onRejected) {
      var state = getInternalPromiseState(this);
      var reaction = newPromiseCapability(speciesConstructor(this, PromiseConstructor));
      reaction.ok = typeof onFulfilled == 'function' ? onFulfilled : true;
      reaction.fail = typeof onRejected == 'function' && onRejected;
      reaction.domain = IS_NODE ? process.domain : undefined;
      state.parent = true;
      state.reactions.push(reaction);
      if (state.state != PENDING) notify(this, state, false);
      return reaction.promise;
    },
    // `Promise.prototype.catch` method
    // https://tc39.github.io/ecma262/#sec-promise.prototype.catch
    'catch': function (onRejected) {
      return this.then(undefined, onRejected);
    }
  });
  OwnPromiseCapability = function () {
    var promise = new Internal();
    var state = getInternalState(promise);
    this.promise = promise;
    this.resolve = bind(internalResolve, promise, state);
    this.reject = bind(internalReject, promise, state);
  };
  newPromiseCapabilityModule.f = newPromiseCapability = function (C) {
    return C === PromiseConstructor || C === PromiseWrapper
      ? new OwnPromiseCapability(C)
      : newGenericPromiseCapability(C);
  };

  if (!IS_PURE && typeof NativePromise == 'function') {
    nativeThen = NativePromise.prototype.then;

    // wrap native Promise#then for native async functions
    redefine(NativePromise.prototype, 'then', function then(onFulfilled, onRejected) {
      var that = this;
      return new PromiseConstructor(function (resolve, reject) {
        nativeThen.call(that, resolve, reject);
      }).then(onFulfilled, onRejected);
    // https://github.com/zloirock/core-js/issues/640
    }, { unsafe: true });

    // wrap fetch result
    if (typeof $fetch == 'function') $({ global: true, enumerable: true, forced: true }, {
      // eslint-disable-next-line no-unused-vars
      fetch: function fetch(input /* , init */) {
        return promiseResolve(PromiseConstructor, $fetch.apply(global, arguments));
      }
    });
  }
}

$({ global: true, wrap: true, forced: FORCED }, {
  Promise: PromiseConstructor
});

setToStringTag(PromiseConstructor, PROMISE, false, true);
setSpecies(PROMISE);

PromiseWrapper = getBuiltIn(PROMISE);

// statics
$({ target: PROMISE, stat: true, forced: FORCED }, {
  // `Promise.reject` method
  // https://tc39.github.io/ecma262/#sec-promise.reject
  reject: function reject(r) {
    var capability = newPromiseCapability(this);
    capability.reject.call(undefined, r);
    return capability.promise;
  }
});

$({ target: PROMISE, stat: true, forced: IS_PURE || FORCED }, {
  // `Promise.resolve` method
  // https://tc39.github.io/ecma262/#sec-promise.resolve
  resolve: function resolve(x) {
    return promiseResolve(IS_PURE && this === PromiseWrapper ? PromiseConstructor : this, x);
  }
});

$({ target: PROMISE, stat: true, forced: INCORRECT_ITERATION }, {
  // `Promise.all` method
  // https://tc39.github.io/ecma262/#sec-promise.all
  all: function all(iterable) {
    var C = this;
    var capability = newPromiseCapability(C);
    var resolve = capability.resolve;
    var reject = capability.reject;
    var result = perform(function () {
      var $promiseResolve = aFunction(C.resolve);
      var values = [];
      var counter = 0;
      var remaining = 1;
      iterate(iterable, function (promise) {
        var index = counter++;
        var alreadyCalled = false;
        values.push(undefined);
        remaining++;
        $promiseResolve.call(C, promise).then(function (value) {
          if (alreadyCalled) return;
          alreadyCalled = true;
          values[index] = value;
          --remaining || resolve(values);
        }, reject);
      });
      --remaining || resolve(values);
    });
    if (result.error) reject(result.value);
    return capability.promise;
  },
  // `Promise.race` method
  // https://tc39.github.io/ecma262/#sec-promise.race
  race: function race(iterable) {
    var C = this;
    var capability = newPromiseCapability(C);
    var reject = capability.reject;
    var result = perform(function () {
      var $promiseResolve = aFunction(C.resolve);
      iterate(iterable, function (promise) {
        $promiseResolve.call(C, promise).then(capability.resolve, reject);
      });
    });
    if (result.error) reject(result.value);
    return capability.promise;
  }
});