Add support for 'throw' expression

pkg/kernel/lib/interpreter/interpreter.dart

Index: pkg/kernel/lib/interpreter/interpreter.dart
diff --git a/pkg/kernel/lib/interpreter/interpreter.dart b/pkg/kernel/lib/interpreter/interpreter.dart
index 710d106bac7bbac513fbc35d0ba67d3c8cb610a9..e85045273c3f3b5bca3a90088d0da94fd2157f56 100644
--- a/pkg/kernel/lib/interpreter/interpreter.dart
+++ b/pkg/kernel/lib/interpreter/interpreter.dart
@@ -252,6 +252,13 @@ class Evaluator extends ExpressionVisitor1<Configuration, EvalConfiguration> {
         config.continuation, config.environment.thisInstance);
   }
 
+  Configuration visitThrow(Throw node, EvalConfiguration config) {
+    var cont = new ThrowEK(config.handlers);
+
+    return new EvalConfiguration(
+        node.expression, config.environment, config.handlers, cont);
+  }
+
   // Evaluation of BasicLiterals.
   Configuration visitStringLiteral(
       StringLiteral node, EvalConfiguration config) {
@@ -1201,6 +1208,16 @@ class InitializerListEK extends ExpressionContinuation {
   }
 }
 
+class ThrowEK extends ExpressionContinuation {
+  final Handlers handlers;
+
+  ThrowEK(this.handlers);
+
+  Configuration call(Value value) {
+    return new ThrowConfiguration(handlers.handler, value, handlers.stackTrace);
+  }
+}
+
 // ------------------------------------------------------------------------
 //                        Exceptions Handlers
 // ------------------------------------------------------------------------
@@ -1211,6 +1228,22 @@ abstract class ExceptionHandler extends Continuation {
   Configuration call(Value exception, StackTrace stacktrace);
 }
 
+/// Handler for showing an exception to the user and returning a halting the
+/// execution of the program when an exception is not handled.
+class MainHandler extends ExceptionHandler {
+  ExceptionHandler get nextHandler =>
+      throw 'The current handler is the main exception handler';
+
+  Configuration call(Value exception, StackTrace stacktrace) {
+    var errorMessage = 'Uncaught exception '
+        '"${exception.value.runtimeType} : ${exception.value}"\n'
+        '${stacktrace.toString()}';
+    log.info(errorMessage);
+    print(errorMessage);
+    return null;
+  }
+}
+
 // ------------------------------------------------------------------------
 //                        Exceptions
 // ------------------------------------------------------------------------
@@ -1232,10 +1265,9 @@ class Handlers {
   Handlers(this.handler, this.stackTrace, this.currentStackTrace,
       this.currentException);
 
-  // TODO(zhivkag): Add a top level handler for initial exception state.
   Handlers.initial()
-      : handler = null,
-        stackTrace = null,
+      : handler = new MainHandler(),
+        stackTrace = new StackTrace(null, null),
         currentStackTrace = null,
         currentException = null;
 }
@@ -1245,6 +1277,16 @@ class StackTrace {
   final StackTrace stackTrace;
 
   StackTrace(this.expression, this.stackTrace);
+
+  String toString() {
+    var buffer = new StringBuffer('in main()');
+    var current = this;
+    while (current.expression != null) {
+      buffer.write('at ${current.expression.toString()}');

[Dmitry Stefantsov, 2017/08/03 09:01:36]

I think we need a newline at the end of this string literal.

[zhivkag, 2017/08/03 10:35:50]

Done.

+      current = current.stackTrace;
+    }
+    return buffer.toString();
+  }
 }
 
 /// Executes statements.