feat(change_detection): ensure that expression do not change after they have been checked

modules/change_detection/src/change_detector.js

@@ -6,14 +6,37 @@ import {ListWrapper, List} from 'facade/collection';
 export * from './record';
 export * from './record_range'
 
+class ExpressionChangedAfterItHasBeenChecked extends Error {
+  message:string;
+
+  constructor(record:Record) {
+    this.message = `Expression '${record.expressionAsString()}' has changed after it was checked. ` +
+      `Previous value: '${record.previousValue}'. Current value: '${record.currentValue}'`;
+  }
+
+  toString():string {
+    return this.message;
+  }
+}
+
 export class ChangeDetector {
   _rootRecordRange:RecordRange;
+  _enforceNoNewChanges:boolean;
 
-  constructor(recordRange:RecordRange) {
+  constructor(recordRange:RecordRange, enforceNoNewChanges:boolean = false) {
     this._rootRecordRange = recordRange;
+    this._enforceNoNewChanges = enforceNoNewChanges;
   }
 
   detectChanges():int {
+    var count = this._detectChanges(false);
+    if (this._enforceNoNewChanges) {
+      this._detectChanges(true)
+    }
+    return count;
+  }
+
+  _detectChanges(throwOnChange:boolean):int {
     var count = 0;
     var updatedRecords = null;
     var record = this._rootRecordRange.findFirstEnabledRecord();
@@ -23,6 +46,7 @@ export class ChangeDetector {
       if (record.check()) {
         count++;
         if (record.terminatesExpression()) {
+          if (throwOnChange) throw new ExpressionChangedAfterItHasBeenChecked(record);
           currentRange = record.recordRange;
           currentGroup = record.groupMemento();
           updatedRecords = this._addRecord(updatedRecords, record);

modules/change_detection/src/parser/ast.js

@@ -17,6 +17,10 @@ export class AST {
 
   visit(visitor, args) {
   }
+
+  toString():string {
+    return "AST";
+  }
 }
 
 export class EmptyExpr extends AST {
@@ -378,13 +382,33 @@ export class FunctionCall extends AST {
   }
 }
 
-export class ASTWithSource {
+export class ASTWithSource extends AST {
   ast:AST;
   source:string;
   constructor(ast:AST, source:string) {
     this.source = source;
     this.ast = ast;
   }
+
+  eval(context) {
+    return this.ast.eval(context);
+  }
+
+  get isAssignable() {
+    return this.ast.isAssignable;
+  }
+
+  assign(context, value) {
+    return this.ast.assign(context, value);
+  }
+
+  visit(visitor, args) {
+    return this.ast.visit(visitor, args);
+  }
+
+  toString():string {
+    return this.source;
+  }
 }
 
 export class TemplateBinding {

modules/change_detection/src/record.js

@@ -35,6 +35,7 @@ export class ProtoRecord {
   name:string;
   dest:any;
   groupMemento:any;
+  expressionAsString:string;
 
   next:ProtoRecord;
 
@@ -46,7 +47,8 @@ export class ProtoRecord {
               arity:int,
               name:string,
               dest,
-              groupMemento) {
+              groupMemento,
+              expressionAsString:string) {
 
     this.recordRange = recordRange;
     this._mode = mode;
@@ -55,6 +57,7 @@ export class ProtoRecord {
     this.name = name;
     this.dest = dest;
     this.groupMemento = groupMemento;
+    this.expressionAsString = expressionAsString;
 
     this.next = null;
     // The concrete Record instantiated from this ProtoRecord
@@ -341,6 +344,10 @@ export class Record {
     return this.protoRecord.dest;
   }
 
+  expressionAsString() {
+    return this.protoRecord.expressionAsString;
+  }
+
   groupMemento() {
     return isPresent(this.protoRecord) ? this.protoRecord.groupMemento : null;
   }

modules/change_detection/src/record_range.js

@@ -44,7 +44,7 @@ export class ProtoRecordRange {
   /**
    * Parses [ast] into [ProtoRecord]s and adds them to [ProtoRecordRange].
    *
-   * @param ast The expression to watch
+   * @param astWithSource The expression to watch
    * @param expressionMemento an opaque object which will be passed to ChangeDispatcher on
    *        detecting a change.
    * @param groupMemento
@@ -62,7 +62,6 @@ export class ProtoRecordRange {
     if (content) {
       ast = new Collection(ast);
     }
-
     this.recordCreator.createRecordsFromAST(ast, expressionMemento, groupMemento);
   }
 
@@ -318,11 +317,13 @@ class ProtoRecordCreator {
   headRecord:ProtoRecord;
   tailRecord:ProtoRecord;
   groupMemento:any;
+  expressionAsString:string;
 
   constructor(protoRecordRange) {
     this.protoRecordRange = protoRecordRange;
     this.headRecord = null;
     this.tailRecord = null;
+    this.expressionAsString = null;
   }
 
   visitImplicitReceiver(ast:ImplicitReceiver, args) {
@@ -434,11 +435,13 @@ class ProtoRecordCreator {
 
   createRecordsFromAST(ast:AST, expressionMemento:any, groupMemento:any){
     this.groupMemento = groupMemento;
+    this.expressionAsString = ast.toString();
     ast.visit(this, expressionMemento);
   }
 
   construct(recordType, funcOrValue, arity, name, dest) {
-    return new ProtoRecord(this.protoRecordRange, recordType, funcOrValue, arity, name, dest, this.groupMemento);
+    return new ProtoRecord(this.protoRecordRange, recordType, funcOrValue, arity,
+        name, dest, this.groupMemento, this.expressionAsString);
   }
 
   add(protoRecord:ProtoRecord) {