feat(scope): move domWrite and domRead from RootScope to Scope

Closes #1161

Author: vsavkin

lib/core/scope.dart

@@ -127,6 +127,9 @@ class Scope {
 
   Scope _parentScope;
 
+  _FunctionChain _domReadHead, _domReadTail;
+  _FunctionChain _domWriteHead, _domWriteTail;
+
   Scope get parentScope => _parentScope;
 
   final ScopeStats _stats;
@@ -413,6 +416,72 @@ class Scope {
     }
     return counts;
   }
+
+  /**
+   * Internal. Use [View.domWrite] instead.
+   */
+  void domWrite(fn()) {
+    var chain = new _FunctionChain(fn);
+    if (_domWriteHead == null) {
+      _domWriteHead = _domWriteTail = chain;
+    } else {
+      _domWriteTail = _domWriteTail._next = chain;
+    }
+    rootScope._domWriteCounter ++;
+  }
+
+  /**
+   * Internal. Use [View.domRead] instead.
+   */
+  void domRead(fn()) {
+    var chain = new _FunctionChain(fn);
+    if (_domReadHead == null) {
+      _domReadHead = _domReadTail = chain;
+    } else {
+      _domReadTail = _domReadTail._next = chain;
+    }
+    rootScope._domReadCounter ++;
+  }
+
+  void _runDomWrites() {
+    Scope child = _childHead;
+    while (child != null) {
+      child._runDomWrites();
+      child = child._next;
+    }
+
+    while (_domWriteHead != null) {
+      try {
+        _domWriteHead.fn();
+      } catch (e, s) {
+        _exceptionHandler(e, s);
+      }
+      rootScope._domWriteCounter --;
+      _domWriteHead = _domWriteHead._next;
+    }
+    _domWriteTail = null;
+  }
+
+  void _runDomReads() {
+    Scope child = _childHead;
+    while (child != null) {
+      child._runDomReads();
+      child = child._next;
+    }
+
+    while (_domReadHead != null) {
+      try {
+        _domReadHead.fn();
+      } catch (e, s) {
+        _exceptionHandler(e, s);
+      }
+      rootScope._domReadCounter --;
+      _domReadHead = _domReadHead._next;
+    }
+  }
+
+
+  ExceptionHandler get _exceptionHandler => rootScope._exceptionHandler;
 }
 
 _mapEqual(Map a, Map b) => a.length == b.length &&
@@ -587,10 +656,10 @@ class RootScope extends Scope {
   final Map<String, AST> astCache = new HashMap<String, AST>();
 
   _FunctionChain _runAsyncHead, _runAsyncTail;
-  _FunctionChain _domWriteHead, _domWriteTail;
-  _FunctionChain _domReadHead, _domReadTail;
 
   final ScopeStats _scopeStats;
+  int _domWriteCounter = 0;
+  int _domReadCounter = 0;
 
   String _state;
 
@@ -734,37 +803,25 @@ class RootScope extends Scope {
     bool runObservers = true;
     try {
       do {
-        if (_domWriteHead != null) _stats.domWriteStart();
-        while (_domWriteHead != null) {
-          try {
-            _domWriteHead.fn();
-          } catch (e, s) {
-            _exceptionHandler(e, s);
-          }
-          _domWriteHead = _domWriteHead._next;
-          if (_domWriteHead == null) _stats.domWriteEnd();
+        if (_domWriteCounter > 0) {
+          _stats.domWriteStart();
+          _runDomWrites();
+          _stats.domWriteEnd();
         }
-        _domWriteTail = null;
         if (runObservers) {
           runObservers = false;
           readOnlyGroup.detectChanges(exceptionHandler:_exceptionHandler,
               fieldStopwatch: _scopeStats.fieldStopwatch,
               evalStopwatch: _scopeStats.evalStopwatch,
               processStopwatch: _scopeStats.processStopwatch);
         }
-        if (_domReadHead != null) _stats.domReadStart();
-        while (_domReadHead != null) {
-          try {
-            _domReadHead.fn();
-          } catch (e, s) {
-            _exceptionHandler(e, s);
-          }
-          _domReadHead = _domReadHead._next;
-          if (_domReadHead == null) _stats.domReadEnd();
+        if (_domReadCounter > 0) {
+          _stats.domReadStart();
+          _runDomReads();
+          _stats.domReadEnd();
         }
-        _domReadTail = null;
         _runAsyncFns();
-      } while (_domWriteHead != null || _domReadHead != null || _runAsyncHead != null);
+      } while (_domWriteCounter > 0 || _domReadCounter > 0 || _runAsyncHead != null);
       _stats.flushEnd();
       assert((() {
         _stats.flushAssertStart();
@@ -822,24 +879,6 @@ class RootScope extends Scope {
     return count;
   }
 
-  void domWrite(fn()) {
-    var chain = new _FunctionChain(fn);
-    if (_domWriteHead == null) {
-      _domWriteHead = _domWriteTail = chain;
-    } else {
-      _domWriteTail = _domWriteTail._next = chain;
-    }
-  }
-
-  void domRead(fn()) {
-    var chain = new _FunctionChain(fn);
-    if (_domReadHead == null) {
-      _domReadHead = _domReadTail = chain;
-    } else {
-      _domReadTail = _domReadTail._next = chain;
-    }
-  }
-
   void destroy() {}
 
   void _transitionState(String from, String to) {

lib/core_dom/view.dart

@@ -21,6 +21,14 @@ class View {
   void registerEvent(String eventName) {
     eventHandler.register(eventName);
   }
+
+  void domWrite(fn()) {
+    scope.domWrite(fn);
+  }
+
+  void domRead(fn()) {
+    scope.domRead(fn);
+  }
 }
 
 /**

test/core/scope_spec.dart

@@ -1558,7 +1558,7 @@ void main() {
         module.bind(ExceptionHandler, toImplementation: LoggingExceptionHandler);
       });
 
-      it(r'should run writes before reads', (RootScope rootScope, Logger logger, ExceptionHandler e) {
+      it('should run writes before reads', (RootScope rootScope, Logger logger, ExceptionHandler e) {
         LoggingExceptionHandler exceptionHandler = e as LoggingExceptionHandler;
         rootScope.domWrite(() {
           logger('write1');
@@ -1579,6 +1579,40 @@ void main() {
         expect(exceptionHandler.errors[0].error).toEqual('write1');
         expect(exceptionHandler.errors[1].error).toEqual('read1');
       });
+
+      it("should run writes of child scopes first", (RootScope rootScope, Logger logger) {
+        final childScope = rootScope.createChild({});
+        childScope.domWrite(() {
+          logger("child1");
+        });
+        rootScope.domWrite(() {
+          logger("root");
+        });
+        childScope.domWrite(() {
+          logger("child2");
+        });
+
+        rootScope.flush();
+
+        expect(logger).toEqual(['child1', 'child2', 'root']);
+      });
+
+      it("should run reads of child scopes first", (RootScope rootScope, Logger logger) {
+        final childScope = rootScope.createChild({});
+        childScope.domRead(() {
+          logger("child1");
+        });
+        rootScope.domRead(() {
+          logger("root");
+        });
+        childScope.domRead(() {
+          logger("child2");
+        });
+
+        rootScope.flush();
+
+        expect(logger).toEqual(['child1', 'child2', 'root']);
+      });
     });
 
     describe('exceptionHander', () {