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..73cf8c36bcd6280ce82298533db710b1f28eac84 100644
--- a/sdk/lib/_internal/lib/preambles/d8.js
+++ b/sdk/lib/_internal/lib/preambles/d8.js
@@ -3,3 +3,131 @@
 // 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 hasTask() {
+    return head != tail;
+  }
+  function removeTask() {
+    if (head == tail) return;

[floitsch, 2014/03/18 13:18:23]

if (!hasTask()) return;
?

[Lasse Reichstein Nielsen, 2014/03/19 10:24:41]

I removed hasTask, and use return of undefined to represent emptyness.

+    var result = taskQueue[tail];
+    taskQueue[tail] = undefined;
+    tail = (tail + 1) & mask;
+    return result;
+  }
+  function _growTaskQueue() {
+    // head == tail.
+    var length = taskQueue.length;
+    var split = head;
+    taskQueue.length = length * 2;
+    if (split * 2 < length) {  // split < length / 2

[floitsch, 2014/03/18 13:18:23]

I wouldn't do the optimization of copying the smaller section.
This should be rare, and small. No need to complicate the code.

[Lasse Reichstein Nielsen, 2014/03/19 10:24:41]

But now it's there, so why remove it? :)

+      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;
+  }
+
+  // Timer queue as simple array queue using push/shift.
+  var timerIds = {};
+  var timerQueue = [];  // TODO: make this a sort of priority queue.
+  var timerIdCounter = 1;
+  var timerLiveCount = 0;
+  function addTimer(f, ms) {
+    if (ms != 0) throw "Unsupported error: non-zero timer: " + ms + " ms";
+    var id = timerIdCounter++;
+    f.$timerId = id;
+    timerIds[id] = f;
+    timerQueue.push(f);
+    timerLiveCount++;
+    return id;
+  }
+
+  function cancelTimer(id) {
+    var f = timerIds[id];
+    if (f == null) return;
+    f.$timerId = undefined;
+    delete timerIds[id];
+    timerLiveCount--;
+  }
+
+  function removeTimer() {
+    do {
+      var f = timerQueue.shift();
+      var id = f.$timerId;
+    } while (id == undefined);
+    delete timerIds[id];

[floitsch, 2014/03/18 13:18:23]

Use cancelTimer here.

[Lasse Reichstein Nielsen, 2014/03/19 10:24:41]

Good idea.

+    f.$timerId = undefined;
+    timerLiveCount--;
+    if (timerLiveCount == 0) {
+      timerQueue.length = 0;  // only cancelled timers left, drop them quickly.
+    }
+    return f;
+  }
+
+  function hasTimer() { return timerLiveCount > 0; }
+
+  function eventLoop(action) {
+    for(;;) {
+      try {
+        action();
+      } catch (e) {
+        if (typeof onerror == "function") {

[floitsch, 2014/03/18 13:18:23]

Not sure we want to introduce this already in this CL.
But ok with it.

[Lasse Reichstein Nielsen, 2014/03/19 10:24:41]

Let's keep it as tentative for now. It's not being used.

+          onerror(e, null, -1);
+        } else {
+          throw e;
+        }
+      }
+      // Handle task queue.
+      if (hasTask()) {
+        action = removeTask();
+        continue;
+      }
+      if (hasTimer()) {
+        action = removeTimer();
+        continue;
+      }
+      break;
+    }
+  }
+
+  dartMainRunner = function(main, args) {
+    // Initialize.
+    var action = function() { main(args); }
+    eventLoop(action);
+  };
+  setTimeout = addTimer;
+  clearTimeout = cancelTimer;
+  setInterval = clearInterval = function () {
+    throw "Unsupported error: interval timer";
+  }
+  scheduleImmediate = addTask;
+})();
+