Trying to make preamble for d8.

sdk/lib/_internal/lib/preambles/d8.js

Index: sdk/lib/_internal/lib/preambles/d8.js
diff --git a/sdk/lib/_internal/lib/preambles/d8.js b/sdk/lib/_internal/lib/preambles/d8.js
index 2b20e498350596c49ba89a8227e4eef465dfeb83..b26e6fddb9ecde7313019b9c00ad0bffcdf224e3 100644
--- a/sdk/lib/_internal/lib/preambles/d8.js
+++ b/sdk/lib/_internal/lib/preambles/d8.js
@@ -3,3 +3,253 @@
 // BSD-style license that can be found in the LICENSE file.
 
 // Javascript preamble, that lets the output of dart2js run on V8's d8 shell.
+
+var setTimeout;
+var clearTimeout;
+var setInterval;
+var clearInterval;
+var dartMainRunner;
+var scheduleImmediate;
+
+(function() {
+  // Event loop.
+
+  // Task queue as cyclic list queue.
+  var taskQueue = new Array(8);  // Length is power of 2.
+  var head = 0;
+  var tail = 0;
+  var mask = taskQueue.length - 1;
+  function addTask(elem) {
+    taskQueue[head] = elem;
+    head = (head + 1) & mask;
+    if (head == tail) _growTaskQueue();
+  }
+  function removeTask() {
+    if (head == tail) return;
+    var result = taskQueue[tail];
+    taskQueue[tail] = undefined;
+    tail = (tail + 1) & mask;
+    return result;
+  }
+  function _growTaskQueue() {
+    // head == tail.
+    var length = mask + 1;
+    var split = head;
+    taskQueue.length = length * 2;
+    if (split * 2 < length) {  // split < length / 2
+      for (var i = 0; i < split; i++) {
+        taskQueue[length + i] = taskQueue[i];
+        taskQueue[i] = undefined;
+      }
+      tail += length;
+    } else {
+      for (var i = split; i < length; i++) {
+        taskQueue[length + i] = taskQueue[i];
+        taskQueue[i] = undefined;
+      }
+      head += length;
+    }
+    mask = taskQueue.length - 1;
+  }
+
+  // Mapping from timer id to timer function.
+  // The timer id is written on the function as .$timerId.
+  // That field is cleared when the timer is cancelled, but it is not returned
+  // from the queue until its time comes.
+  var timerIds = {};
+  var timerIdCounter = 1;  // Counter used to assing ids.
+
+  // Zero-timer queue as simple array queue using push/shift.
+  var zeroTimerQueue = [];
+
+  function addTimer(f, ms) {
+    var id = timerIdCounter++;
+    f.$timerId = id;
+    timerIds[id] = f;
+    if (ms == 0) {
+      zeroTimerQueue.push(f);
+    } else {
+      addDelayedTimer(f, ms);
+    }
+    return id;
+  }
+
+  function nextZeroTimer() {
+    while (zeroTimerQueue.length > 0) {
+      var action = zeroTimerQueue.shift();
+      if (action.$timerId !== undefined) return action;
+    }
+  }
+
+  function nextEvent() {
+    var action = removeTask();
+    if (action) {
+      return action;
+    }
+    do {
+      action = nextZeroTimer();
+      if (action) break;
+      var nextList = nextDelayedTimerQueue();
+      if (!nextList) {
+        return;
+      }
+      var newTime = nextList.shift();
+      advanceTimeTo(newTime);
+      zeroTimerQueue = nextList;
+    } while (true)
+    var id = action.$timerId;
+    clearTimerId(action, id);
+    return action;
+  }
+
+  // Mocking time.
+  var timeOffset = 0;
+  var now = function() {
+    installMockDate();
+    now = Date.now;

[floitsch, 2014/03/19 14:08:31]

I don't understand this.

[Lasse Reichstein Nielsen, 2014/04/11 10:28:43]

Comment added.

+    return Date.now();
+  };
+  var originalDate = Date;
+  var originalNow = originalDate.now;
+  function advanceTimeTo(time) {
+    timeOffset = time - originalNow();
+  }
+  function installMockDate() {
+    var NewDate = function Date(Y, M, D, h, m, s, ms) {
+      if (this instanceof Date) {
+        // Assume a construct call.
+        switch (arguments.length) {
+          case 0:  return new originalDate(originalNow() + timeOffset);
+          case 1:  return new originalDate(Y);
+          case 2:  return new originalDate(Y, M);
+          case 3:  return new originalDate(Y, M, D);
+          case 4:  return new originalDate(Y, M, D, h);
+          case 5:  return new originalDate(Y, M, D, h, m);
+          case 6:  return new originalDate(Y, M, D, h, m, s);
+          default: return new originalDate(Y, M, D, h, m, s, ms);
+        }
+      }
+      return new originalDate(originalNow() + timeOffset).toString();
+    };
+    NewDate.now = function now() { return originalNow() + timeOffset; };
+    NewDate.prototype = originalDate.prototype;
+    originalDate.prototype.constructor = NewDate;
+    Date = NewDate;
+  }
+
+  // Heap priority queue with key index.
+  // Each entry is list of [timeout, callback1 ... callbackn].
+  var timerHeap = [];
+  var timerIndex = {};
+  function addDelayedTimer(f, ms) {
+    var timeout = now() + ms;
+    var timerList = timerIndex[timeout];
+    if (timerList == null) {
+      timerList = [timeout, f];
+      timerIndex[timeout] = timerList;
+      var index = timerHeap.length;
+      timerHeap.length += 1;
+      bubbleUp(index, timeout, timerList);
+    } else {
+      timerList.push(f);
+    }
+  }
+
+  function nextDelayedTimerQueue() {
+    if (timerHeap.length == 0) return null;
+    var result = timerHeap[0];
+    var last = timerHeap.pop();
+    if (timerHeap.length > 0) {
+      bubbleDown(0, last[0], last);
+    }
+    return result;
+  }
+
+  function bubbleUp(index, key, value) {
+    while (index != 0) {
+      var parentIndex = (index - 1) >> 1;
+      var parent = timerHeap[parentIndex];
+      var parentKey = parent[0];
+      if (key > parentKey) break;
+      timerHeap[index] = parent;
+      index = parentIndex;
+    }
+    timerHeap[index] = value;
+  }
+
+  function bubbleDown(index, key, value) {
+    while (true) {
+      var rightChildIndex = index * 2 + 2;
+      if (rightChildIndex > timerHeap.length) break;

[floitsch, 2014/03/19 14:08:31]

Nit.
It's hard to see that this test checks for the leftChildIndex.

I would prefer to compute the leftChildIndex first. Then check if it's in bound.
Then +1 for the rightChild and check again.
Now we have two different checks to see if the index is in bound.

The extreme version even keeps the check for the indices the same:

var minChild, minChildIndex;
var minChildKey = key + 1;  // Aborts if no child is found.
var leftChildIndex = index * 2 + 1;
if (leftChildIndex < length) {
  minChild = ...
  ...
  var rightChildIndex = leftChildIndex + 1;
  if (rightChildIndex < length) {
}
if (minChildKey > key) break;
...

+      var leftChildIndex = rightChildIndex - 1;
+      var minChildIndex = leftChildIndex;
+      var minChild = timerHeap[leftChildIndex];
+      var minChildKey = minChild[0];
+      if (rightChildIndex < timerHeap.length) {
+        var rightChild = timerHeap[rightChildIndex];
+        var rightKey = rightChild[0];
+        if (rightKey < minChildKey) {
+          minChildIndex = rightChildIndex;
+          minChild = rightChild;
+          minChildKey = rightKey;
+        }
+      }
+      if (minChildKey > key) break;
+      timerHeap[index] = minChild;
+      index = minChildIndex;
+    }
+    timerHeap[index] = value;
+  }
+
+  function addInterval(f, ms) {
+    var id = timerIdCounter++;
+    function repeat() {
+      // Reactivate with the same id.
+      repeat.$timerId = id;
+      timerIds[id] = repeat;
+      addDelayedTimer(repeat, ms);
+      f();
+    }
+    repeat.$timerId = id;
+    timerIds[id] = repeat;
+    addDelayedTimer(repeat, ms);
+    return id;
+  }
+
+  function cancelTimer(id) {
+    var f = timerIds[id];
+    if (f == null) return;
+    clearTimerId(f, id);
+  }
+
+  function clearTimerId(f, id) {
+    f.$timerId = undefined;
+    delete timerIds[id];
+  }
+
+  function eventLoop(action) {
+    while (action) {
+      try {
+        action();
+      } catch (e) {
+        if (typeof onerror == "function") {
+          onerror(e, null, -1);
+        } else {
+          throw e;
+        }
+      }
+      action = nextEvent();
+    }
+  }
+
+  dartMainRunner = function(main, args) {
+    // Initialize.
+    var action = function() { main(args); }
+    eventLoop(action);
+  };
+  setTimeout = addTimer;
+  clearTimeout = cancelTimer;
+  setInterval = addInterval;
+  clearInterval = cancelTimer;
+  scheduleImmediate = addTask;
+})();