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					635 lines
				
				17 KiB
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											3 years ago
										 | /** | ||
|  |  * @license React | ||
|  |  * scheduler.development.js | ||
|  |  * | ||
|  |  * Copyright (c) Facebook, Inc. and its affiliates. | ||
|  |  * | ||
|  |  * This source code is licensed under the MIT license found in the | ||
|  |  * LICENSE file in the root directory of this source tree. | ||
|  |  */ | ||
|  | 
 | ||
|  | 'use strict'; | ||
|  | 
 | ||
|  | if (process.env.NODE_ENV !== "production") { | ||
|  |   (function() { | ||
|  | 
 | ||
|  |           'use strict'; | ||
|  | 
 | ||
|  | /* global __REACT_DEVTOOLS_GLOBAL_HOOK__ */ | ||
|  | if ( | ||
|  |   typeof __REACT_DEVTOOLS_GLOBAL_HOOK__ !== 'undefined' && | ||
|  |   typeof __REACT_DEVTOOLS_GLOBAL_HOOK__.registerInternalModuleStart === | ||
|  |     'function' | ||
|  | ) { | ||
|  |   __REACT_DEVTOOLS_GLOBAL_HOOK__.registerInternalModuleStart(new Error()); | ||
|  | } | ||
|  |           var enableSchedulerDebugging = false; | ||
|  | var enableProfiling = false; | ||
|  | var frameYieldMs = 5; | ||
|  | 
 | ||
|  | function push(heap, node) { | ||
|  |   var index = heap.length; | ||
|  |   heap.push(node); | ||
|  |   siftUp(heap, node, index); | ||
|  | } | ||
|  | function peek(heap) { | ||
|  |   return heap.length === 0 ? null : heap[0]; | ||
|  | } | ||
|  | function pop(heap) { | ||
|  |   if (heap.length === 0) { | ||
|  |     return null; | ||
|  |   } | ||
|  | 
 | ||
|  |   var first = heap[0]; | ||
|  |   var last = heap.pop(); | ||
|  | 
 | ||
|  |   if (last !== first) { | ||
|  |     heap[0] = last; | ||
|  |     siftDown(heap, last, 0); | ||
|  |   } | ||
|  | 
 | ||
|  |   return first; | ||
|  | } | ||
|  | 
 | ||
|  | function siftUp(heap, node, i) { | ||
|  |   var index = i; | ||
|  | 
 | ||
|  |   while (index > 0) { | ||
|  |     var parentIndex = index - 1 >>> 1; | ||
|  |     var parent = heap[parentIndex]; | ||
|  | 
 | ||
|  |     if (compare(parent, node) > 0) { | ||
|  |       // The parent is larger. Swap positions.
 | ||
|  |       heap[parentIndex] = node; | ||
|  |       heap[index] = parent; | ||
|  |       index = parentIndex; | ||
|  |     } else { | ||
|  |       // The parent is smaller. Exit.
 | ||
|  |       return; | ||
|  |     } | ||
|  |   } | ||
|  | } | ||
|  | 
 | ||
|  | function siftDown(heap, node, i) { | ||
|  |   var index = i; | ||
|  |   var length = heap.length; | ||
|  |   var halfLength = length >>> 1; | ||
|  | 
 | ||
|  |   while (index < halfLength) { | ||
|  |     var leftIndex = (index + 1) * 2 - 1; | ||
|  |     var left = heap[leftIndex]; | ||
|  |     var rightIndex = leftIndex + 1; | ||
|  |     var right = heap[rightIndex]; // If the left or right node is smaller, swap with the smaller of those.
 | ||
|  | 
 | ||
|  |     if (compare(left, node) < 0) { | ||
|  |       if (rightIndex < length && compare(right, left) < 0) { | ||
|  |         heap[index] = right; | ||
|  |         heap[rightIndex] = node; | ||
|  |         index = rightIndex; | ||
|  |       } else { | ||
|  |         heap[index] = left; | ||
|  |         heap[leftIndex] = node; | ||
|  |         index = leftIndex; | ||
|  |       } | ||
|  |     } else if (rightIndex < length && compare(right, node) < 0) { | ||
|  |       heap[index] = right; | ||
|  |       heap[rightIndex] = node; | ||
|  |       index = rightIndex; | ||
|  |     } else { | ||
|  |       // Neither child is smaller. Exit.
 | ||
|  |       return; | ||
|  |     } | ||
|  |   } | ||
|  | } | ||
|  | 
 | ||
|  | function compare(a, b) { | ||
|  |   // Compare sort index first, then task id.
 | ||
|  |   var diff = a.sortIndex - b.sortIndex; | ||
|  |   return diff !== 0 ? diff : a.id - b.id; | ||
|  | } | ||
|  | 
 | ||
|  | // TODO: Use symbols?
 | ||
|  | var ImmediatePriority = 1; | ||
|  | var UserBlockingPriority = 2; | ||
|  | var NormalPriority = 3; | ||
|  | var LowPriority = 4; | ||
|  | var IdlePriority = 5; | ||
|  | 
 | ||
|  | function markTaskErrored(task, ms) { | ||
|  | } | ||
|  | 
 | ||
|  | /* eslint-disable no-var */ | ||
|  | 
 | ||
|  | var hasPerformanceNow = typeof performance === 'object' && typeof performance.now === 'function'; | ||
|  | 
 | ||
|  | if (hasPerformanceNow) { | ||
|  |   var localPerformance = performance; | ||
|  | 
 | ||
|  |   exports.unstable_now = function () { | ||
|  |     return localPerformance.now(); | ||
|  |   }; | ||
|  | } else { | ||
|  |   var localDate = Date; | ||
|  |   var initialTime = localDate.now(); | ||
|  | 
 | ||
|  |   exports.unstable_now = function () { | ||
|  |     return localDate.now() - initialTime; | ||
|  |   }; | ||
|  | } // Max 31 bit integer. The max integer size in V8 for 32-bit systems.
 | ||
|  | // Math.pow(2, 30) - 1
 | ||
|  | // 0b111111111111111111111111111111
 | ||
|  | 
 | ||
|  | 
 | ||
|  | var maxSigned31BitInt = 1073741823; // Times out immediately
 | ||
|  | 
 | ||
|  | var IMMEDIATE_PRIORITY_TIMEOUT = -1; // Eventually times out
 | ||
|  | 
 | ||
|  | var USER_BLOCKING_PRIORITY_TIMEOUT = 250; | ||
|  | var NORMAL_PRIORITY_TIMEOUT = 5000; | ||
|  | var LOW_PRIORITY_TIMEOUT = 10000; // Never times out
 | ||
|  | 
 | ||
|  | var IDLE_PRIORITY_TIMEOUT = maxSigned31BitInt; // Tasks are stored on a min heap
 | ||
|  | 
 | ||
|  | var taskQueue = []; | ||
|  | var timerQueue = []; // Incrementing id counter. Used to maintain insertion order.
 | ||
|  | 
 | ||
|  | var taskIdCounter = 1; // Pausing the scheduler is useful for debugging.
 | ||
|  | var currentTask = null; | ||
|  | var currentPriorityLevel = NormalPriority; // This is set while performing work, to prevent re-entrance.
 | ||
|  | 
 | ||
|  | var isPerformingWork = false; | ||
|  | var isHostCallbackScheduled = false; | ||
|  | var isHostTimeoutScheduled = false; // Capture local references to native APIs, in case a polyfill overrides them.
 | ||
|  | 
 | ||
|  | var localSetTimeout = typeof setTimeout === 'function' ? setTimeout : null; | ||
|  | var localClearTimeout = typeof clearTimeout === 'function' ? clearTimeout : null; | ||
|  | var localSetImmediate = typeof setImmediate !== 'undefined' ? setImmediate : null; // IE and Node.js + jsdom
 | ||
|  | 
 | ||
|  | var isInputPending = typeof navigator !== 'undefined' && navigator.scheduling !== undefined && navigator.scheduling.isInputPending !== undefined ? navigator.scheduling.isInputPending.bind(navigator.scheduling) : null; | ||
|  | 
 | ||
|  | function advanceTimers(currentTime) { | ||
|  |   // Check for tasks that are no longer delayed and add them to the queue.
 | ||
|  |   var timer = peek(timerQueue); | ||
|  | 
 | ||
|  |   while (timer !== null) { | ||
|  |     if (timer.callback === null) { | ||
|  |       // Timer was cancelled.
 | ||
|  |       pop(timerQueue); | ||
|  |     } else if (timer.startTime <= currentTime) { | ||
|  |       // Timer fired. Transfer to the task queue.
 | ||
|  |       pop(timerQueue); | ||
|  |       timer.sortIndex = timer.expirationTime; | ||
|  |       push(taskQueue, timer); | ||
|  |     } else { | ||
|  |       // Remaining timers are pending.
 | ||
|  |       return; | ||
|  |     } | ||
|  | 
 | ||
|  |     timer = peek(timerQueue); | ||
|  |   } | ||
|  | } | ||
|  | 
 | ||
|  | function handleTimeout(currentTime) { | ||
|  |   isHostTimeoutScheduled = false; | ||
|  |   advanceTimers(currentTime); | ||
|  | 
 | ||
|  |   if (!isHostCallbackScheduled) { | ||
|  |     if (peek(taskQueue) !== null) { | ||
|  |       isHostCallbackScheduled = true; | ||
|  |       requestHostCallback(flushWork); | ||
|  |     } else { | ||
|  |       var firstTimer = peek(timerQueue); | ||
|  | 
 | ||
|  |       if (firstTimer !== null) { | ||
|  |         requestHostTimeout(handleTimeout, firstTimer.startTime - currentTime); | ||
|  |       } | ||
|  |     } | ||
|  |   } | ||
|  | } | ||
|  | 
 | ||
|  | function flushWork(hasTimeRemaining, initialTime) { | ||
|  | 
 | ||
|  | 
 | ||
|  |   isHostCallbackScheduled = false; | ||
|  | 
 | ||
|  |   if (isHostTimeoutScheduled) { | ||
|  |     // We scheduled a timeout but it's no longer needed. Cancel it.
 | ||
|  |     isHostTimeoutScheduled = false; | ||
|  |     cancelHostTimeout(); | ||
|  |   } | ||
|  | 
 | ||
|  |   isPerformingWork = true; | ||
|  |   var previousPriorityLevel = currentPriorityLevel; | ||
|  | 
 | ||
|  |   try { | ||
|  |     if (enableProfiling) { | ||
|  |       try { | ||
|  |         return workLoop(hasTimeRemaining, initialTime); | ||
|  |       } catch (error) { | ||
|  |         if (currentTask !== null) { | ||
|  |           var currentTime = exports.unstable_now(); | ||
|  |           markTaskErrored(currentTask, currentTime); | ||
|  |           currentTask.isQueued = false; | ||
|  |         } | ||
|  | 
 | ||
|  |         throw error; | ||
|  |       } | ||
|  |     } else { | ||
|  |       // No catch in prod code path.
 | ||
|  |       return workLoop(hasTimeRemaining, initialTime); | ||
|  |     } | ||
|  |   } finally { | ||
|  |     currentTask = null; | ||
|  |     currentPriorityLevel = previousPriorityLevel; | ||
|  |     isPerformingWork = false; | ||
|  |   } | ||
|  | } | ||
|  | 
 | ||
|  | function workLoop(hasTimeRemaining, initialTime) { | ||
|  |   var currentTime = initialTime; | ||
|  |   advanceTimers(currentTime); | ||
|  |   currentTask = peek(taskQueue); | ||
|  | 
 | ||
|  |   while (currentTask !== null && !(enableSchedulerDebugging )) { | ||
|  |     if (currentTask.expirationTime > currentTime && (!hasTimeRemaining || shouldYieldToHost())) { | ||
|  |       // This currentTask hasn't expired, and we've reached the deadline.
 | ||
|  |       break; | ||
|  |     } | ||
|  | 
 | ||
|  |     var callback = currentTask.callback; | ||
|  | 
 | ||
|  |     if (typeof callback === 'function') { | ||
|  |       currentTask.callback = null; | ||
|  |       currentPriorityLevel = currentTask.priorityLevel; | ||
|  |       var didUserCallbackTimeout = currentTask.expirationTime <= currentTime; | ||
|  | 
 | ||
|  |       var continuationCallback = callback(didUserCallbackTimeout); | ||
|  |       currentTime = exports.unstable_now(); | ||
|  | 
 | ||
|  |       if (typeof continuationCallback === 'function') { | ||
|  |         currentTask.callback = continuationCallback; | ||
|  |       } else { | ||
|  | 
 | ||
|  |         if (currentTask === peek(taskQueue)) { | ||
|  |           pop(taskQueue); | ||
|  |         } | ||
|  |       } | ||
|  | 
 | ||
|  |       advanceTimers(currentTime); | ||
|  |     } else { | ||
|  |       pop(taskQueue); | ||
|  |     } | ||
|  | 
 | ||
|  |     currentTask = peek(taskQueue); | ||
|  |   } // Return whether there's additional work
 | ||
|  | 
 | ||
|  | 
 | ||
|  |   if (currentTask !== null) { | ||
|  |     return true; | ||
|  |   } else { | ||
|  |     var firstTimer = peek(timerQueue); | ||
|  | 
 | ||
|  |     if (firstTimer !== null) { | ||
|  |       requestHostTimeout(handleTimeout, firstTimer.startTime - currentTime); | ||
|  |     } | ||
|  | 
 | ||
|  |     return false; | ||
|  |   } | ||
|  | } | ||
|  | 
 | ||
|  | function unstable_runWithPriority(priorityLevel, eventHandler) { | ||
|  |   switch (priorityLevel) { | ||
|  |     case ImmediatePriority: | ||
|  |     case UserBlockingPriority: | ||
|  |     case NormalPriority: | ||
|  |     case LowPriority: | ||
|  |     case IdlePriority: | ||
|  |       break; | ||
|  | 
 | ||
|  |     default: | ||
|  |       priorityLevel = NormalPriority; | ||
|  |   } | ||
|  | 
 | ||
|  |   var previousPriorityLevel = currentPriorityLevel; | ||
|  |   currentPriorityLevel = priorityLevel; | ||
|  | 
 | ||
|  |   try { | ||
|  |     return eventHandler(); | ||
|  |   } finally { | ||
|  |     currentPriorityLevel = previousPriorityLevel; | ||
|  |   } | ||
|  | } | ||
|  | 
 | ||
|  | function unstable_next(eventHandler) { | ||
|  |   var priorityLevel; | ||
|  | 
 | ||
|  |   switch (currentPriorityLevel) { | ||
|  |     case ImmediatePriority: | ||
|  |     case UserBlockingPriority: | ||
|  |     case NormalPriority: | ||
|  |       // Shift down to normal priority
 | ||
|  |       priorityLevel = NormalPriority; | ||
|  |       break; | ||
|  | 
 | ||
|  |     default: | ||
|  |       // Anything lower than normal priority should remain at the current level.
 | ||
|  |       priorityLevel = currentPriorityLevel; | ||
|  |       break; | ||
|  |   } | ||
|  | 
 | ||
|  |   var previousPriorityLevel = currentPriorityLevel; | ||
|  |   currentPriorityLevel = priorityLevel; | ||
|  | 
 | ||
|  |   try { | ||
|  |     return eventHandler(); | ||
|  |   } finally { | ||
|  |     currentPriorityLevel = previousPriorityLevel; | ||
|  |   } | ||
|  | } | ||
|  | 
 | ||
|  | function unstable_wrapCallback(callback) { | ||
|  |   var parentPriorityLevel = currentPriorityLevel; | ||
|  |   return function () { | ||
|  |     // This is a fork of runWithPriority, inlined for performance.
 | ||
|  |     var previousPriorityLevel = currentPriorityLevel; | ||
|  |     currentPriorityLevel = parentPriorityLevel; | ||
|  | 
 | ||
|  |     try { | ||
|  |       return callback.apply(this, arguments); | ||
|  |     } finally { | ||
|  |       currentPriorityLevel = previousPriorityLevel; | ||
|  |     } | ||
|  |   }; | ||
|  | } | ||
|  | 
 | ||
|  | function unstable_scheduleCallback(priorityLevel, callback, options) { | ||
|  |   var currentTime = exports.unstable_now(); | ||
|  |   var startTime; | ||
|  | 
 | ||
|  |   if (typeof options === 'object' && options !== null) { | ||
|  |     var delay = options.delay; | ||
|  | 
 | ||
|  |     if (typeof delay === 'number' && delay > 0) { | ||
|  |       startTime = currentTime + delay; | ||
|  |     } else { | ||
|  |       startTime = currentTime; | ||
|  |     } | ||
|  |   } else { | ||
|  |     startTime = currentTime; | ||
|  |   } | ||
|  | 
 | ||
|  |   var timeout; | ||
|  | 
 | ||
|  |   switch (priorityLevel) { | ||
|  |     case ImmediatePriority: | ||
|  |       timeout = IMMEDIATE_PRIORITY_TIMEOUT; | ||
|  |       break; | ||
|  | 
 | ||
|  |     case UserBlockingPriority: | ||
|  |       timeout = USER_BLOCKING_PRIORITY_TIMEOUT; | ||
|  |       break; | ||
|  | 
 | ||
|  |     case IdlePriority: | ||
|  |       timeout = IDLE_PRIORITY_TIMEOUT; | ||
|  |       break; | ||
|  | 
 | ||
|  |     case LowPriority: | ||
|  |       timeout = LOW_PRIORITY_TIMEOUT; | ||
|  |       break; | ||
|  | 
 | ||
|  |     case NormalPriority: | ||
|  |     default: | ||
|  |       timeout = NORMAL_PRIORITY_TIMEOUT; | ||
|  |       break; | ||
|  |   } | ||
|  | 
 | ||
|  |   var expirationTime = startTime + timeout; | ||
|  |   var newTask = { | ||
|  |     id: taskIdCounter++, | ||
|  |     callback: callback, | ||
|  |     priorityLevel: priorityLevel, | ||
|  |     startTime: startTime, | ||
|  |     expirationTime: expirationTime, | ||
|  |     sortIndex: -1 | ||
|  |   }; | ||
|  | 
 | ||
|  |   if (startTime > currentTime) { | ||
|  |     // This is a delayed task.
 | ||
|  |     newTask.sortIndex = startTime; | ||
|  |     push(timerQueue, newTask); | ||
|  | 
 | ||
|  |     if (peek(taskQueue) === null && newTask === peek(timerQueue)) { | ||
|  |       // All tasks are delayed, and this is the task with the earliest delay.
 | ||
|  |       if (isHostTimeoutScheduled) { | ||
|  |         // Cancel an existing timeout.
 | ||
|  |         cancelHostTimeout(); | ||
|  |       } else { | ||
|  |         isHostTimeoutScheduled = true; | ||
|  |       } // Schedule a timeout.
 | ||
|  | 
 | ||
|  | 
 | ||
|  |       requestHostTimeout(handleTimeout, startTime - currentTime); | ||
|  |     } | ||
|  |   } else { | ||
|  |     newTask.sortIndex = expirationTime; | ||
|  |     push(taskQueue, newTask); | ||
|  |     // wait until the next time we yield.
 | ||
|  | 
 | ||
|  | 
 | ||
|  |     if (!isHostCallbackScheduled && !isPerformingWork) { | ||
|  |       isHostCallbackScheduled = true; | ||
|  |       requestHostCallback(flushWork); | ||
|  |     } | ||
|  |   } | ||
|  | 
 | ||
|  |   return newTask; | ||
|  | } | ||
|  | 
 | ||
|  | function unstable_pauseExecution() { | ||
|  | } | ||
|  | 
 | ||
|  | function unstable_continueExecution() { | ||
|  | 
 | ||
|  |   if (!isHostCallbackScheduled && !isPerformingWork) { | ||
|  |     isHostCallbackScheduled = true; | ||
|  |     requestHostCallback(flushWork); | ||
|  |   } | ||
|  | } | ||
|  | 
 | ||
|  | function unstable_getFirstCallbackNode() { | ||
|  |   return peek(taskQueue); | ||
|  | } | ||
|  | 
 | ||
|  | function unstable_cancelCallback(task) { | ||
|  |   // remove from the queue because you can't remove arbitrary nodes from an
 | ||
|  |   // array based heap, only the first one.)
 | ||
|  | 
 | ||
|  | 
 | ||
|  |   task.callback = null; | ||
|  | } | ||
|  | 
 | ||
|  | function unstable_getCurrentPriorityLevel() { | ||
|  |   return currentPriorityLevel; | ||
|  | } | ||
|  | 
 | ||
|  | var isMessageLoopRunning = false; | ||
|  | var scheduledHostCallback = null; | ||
|  | var taskTimeoutID = -1; // Scheduler periodically yields in case there is other work on the main
 | ||
|  | // thread, like user events. By default, it yields multiple times per frame.
 | ||
|  | // It does not attempt to align with frame boundaries, since most tasks don't
 | ||
|  | // need to be frame aligned; for those that do, use requestAnimationFrame.
 | ||
|  | 
 | ||
|  | var frameInterval = frameYieldMs; | ||
|  | var startTime = -1; | ||
|  | 
 | ||
|  | function shouldYieldToHost() { | ||
|  |   var timeElapsed = exports.unstable_now() - startTime; | ||
|  | 
 | ||
|  |   if (timeElapsed < frameInterval) { | ||
|  |     // The main thread has only been blocked for a really short amount of time;
 | ||
|  |     // smaller than a single frame. Don't yield yet.
 | ||
|  |     return false; | ||
|  |   } // The main thread has been blocked for a non-negligible amount of time. We
 | ||
|  | 
 | ||
|  | 
 | ||
|  |   return true; | ||
|  | } | ||
|  | 
 | ||
|  | function requestPaint() { | ||
|  | 
 | ||
|  | } | ||
|  | 
 | ||
|  | function forceFrameRate(fps) { | ||
|  |   if (fps < 0 || fps > 125) { | ||
|  |     // Using console['error'] to evade Babel and ESLint
 | ||
|  |     console['error']('forceFrameRate takes a positive int between 0 and 125, ' + 'forcing frame rates higher than 125 fps is not supported'); | ||
|  |     return; | ||
|  |   } | ||
|  | 
 | ||
|  |   if (fps > 0) { | ||
|  |     frameInterval = Math.floor(1000 / fps); | ||
|  |   } else { | ||
|  |     // reset the framerate
 | ||
|  |     frameInterval = frameYieldMs; | ||
|  |   } | ||
|  | } | ||
|  | 
 | ||
|  | var performWorkUntilDeadline = function () { | ||
|  |   if (scheduledHostCallback !== null) { | ||
|  |     var currentTime = exports.unstable_now(); // Keep track of the start time so we can measure how long the main thread
 | ||
|  |     // has been blocked.
 | ||
|  | 
 | ||
|  |     startTime = currentTime; | ||
|  |     var hasTimeRemaining = true; // If a scheduler task throws, exit the current browser task so the
 | ||
|  |     // error can be observed.
 | ||
|  |     //
 | ||
|  |     // Intentionally not using a try-catch, since that makes some debugging
 | ||
|  |     // techniques harder. Instead, if `scheduledHostCallback` errors, then
 | ||
|  |     // `hasMoreWork` will remain true, and we'll continue the work loop.
 | ||
|  | 
 | ||
|  |     var hasMoreWork = true; | ||
|  | 
 | ||
|  |     try { | ||
|  |       hasMoreWork = scheduledHostCallback(hasTimeRemaining, currentTime); | ||
|  |     } finally { | ||
|  |       if (hasMoreWork) { | ||
|  |         // If there's more work, schedule the next message event at the end
 | ||
|  |         // of the preceding one.
 | ||
|  |         schedulePerformWorkUntilDeadline(); | ||
|  |       } else { | ||
|  |         isMessageLoopRunning = false; | ||
|  |         scheduledHostCallback = null; | ||
|  |       } | ||
|  |     } | ||
|  |   } else { | ||
|  |     isMessageLoopRunning = false; | ||
|  |   } // Yielding to the browser will give it a chance to paint, so we can
 | ||
|  | }; | ||
|  | 
 | ||
|  | var schedulePerformWorkUntilDeadline; | ||
|  | 
 | ||
|  | if (typeof localSetImmediate === 'function') { | ||
|  |   // Node.js and old IE.
 | ||
|  |   // There's a few reasons for why we prefer setImmediate.
 | ||
|  |   //
 | ||
|  |   // Unlike MessageChannel, it doesn't prevent a Node.js process from exiting.
 | ||
|  |   // (Even though this is a DOM fork of the Scheduler, you could get here
 | ||
|  |   // with a mix of Node.js 15+, which has a MessageChannel, and jsdom.)
 | ||
|  |   // https://github.com/facebook/react/issues/20756
 | ||
|  |   //
 | ||
|  |   // But also, it runs earlier which is the semantic we want.
 | ||
|  |   // If other browsers ever implement it, it's better to use it.
 | ||
|  |   // Although both of these would be inferior to native scheduling.
 | ||
|  |   schedulePerformWorkUntilDeadline = function () { | ||
|  |     localSetImmediate(performWorkUntilDeadline); | ||
|  |   }; | ||
|  | } else if (typeof MessageChannel !== 'undefined') { | ||
|  |   // DOM and Worker environments.
 | ||
|  |   // We prefer MessageChannel because of the 4ms setTimeout clamping.
 | ||
|  |   var channel = new MessageChannel(); | ||
|  |   var port = channel.port2; | ||
|  |   channel.port1.onmessage = performWorkUntilDeadline; | ||
|  | 
 | ||
|  |   schedulePerformWorkUntilDeadline = function () { | ||
|  |     port.postMessage(null); | ||
|  |   }; | ||
|  | } else { | ||
|  |   // We should only fallback here in non-browser environments.
 | ||
|  |   schedulePerformWorkUntilDeadline = function () { | ||
|  |     localSetTimeout(performWorkUntilDeadline, 0); | ||
|  |   }; | ||
|  | } | ||
|  | 
 | ||
|  | function requestHostCallback(callback) { | ||
|  |   scheduledHostCallback = callback; | ||
|  | 
 | ||
|  |   if (!isMessageLoopRunning) { | ||
|  |     isMessageLoopRunning = true; | ||
|  |     schedulePerformWorkUntilDeadline(); | ||
|  |   } | ||
|  | } | ||
|  | 
 | ||
|  | function requestHostTimeout(callback, ms) { | ||
|  |   taskTimeoutID = localSetTimeout(function () { | ||
|  |     callback(exports.unstable_now()); | ||
|  |   }, ms); | ||
|  | } | ||
|  | 
 | ||
|  | function cancelHostTimeout() { | ||
|  |   localClearTimeout(taskTimeoutID); | ||
|  |   taskTimeoutID = -1; | ||
|  | } | ||
|  | 
 | ||
|  | var unstable_requestPaint = requestPaint; | ||
|  | var unstable_Profiling =  null; | ||
|  | 
 | ||
|  | exports.unstable_IdlePriority = IdlePriority; | ||
|  | exports.unstable_ImmediatePriority = ImmediatePriority; | ||
|  | exports.unstable_LowPriority = LowPriority; | ||
|  | exports.unstable_NormalPriority = NormalPriority; | ||
|  | exports.unstable_Profiling = unstable_Profiling; | ||
|  | exports.unstable_UserBlockingPriority = UserBlockingPriority; | ||
|  | exports.unstable_cancelCallback = unstable_cancelCallback; | ||
|  | exports.unstable_continueExecution = unstable_continueExecution; | ||
|  | exports.unstable_forceFrameRate = forceFrameRate; | ||
|  | exports.unstable_getCurrentPriorityLevel = unstable_getCurrentPriorityLevel; | ||
|  | exports.unstable_getFirstCallbackNode = unstable_getFirstCallbackNode; | ||
|  | exports.unstable_next = unstable_next; | ||
|  | exports.unstable_pauseExecution = unstable_pauseExecution; | ||
|  | exports.unstable_requestPaint = unstable_requestPaint; | ||
|  | exports.unstable_runWithPriority = unstable_runWithPriority; | ||
|  | exports.unstable_scheduleCallback = unstable_scheduleCallback; | ||
|  | exports.unstable_shouldYield = shouldYieldToHost; | ||
|  | exports.unstable_wrapCallback = unstable_wrapCallback; | ||
|  |           /* global __REACT_DEVTOOLS_GLOBAL_HOOK__ */ | ||
|  | if ( | ||
|  |   typeof __REACT_DEVTOOLS_GLOBAL_HOOK__ !== 'undefined' && | ||
|  |   typeof __REACT_DEVTOOLS_GLOBAL_HOOK__.registerInternalModuleStop === | ||
|  |     'function' | ||
|  | ) { | ||
|  |   __REACT_DEVTOOLS_GLOBAL_HOOK__.registerInternalModuleStop(new Error()); | ||
|  | } | ||
|  |          | ||
|  |   })(); | ||
|  | } |