Add support for catch statements.

BUG=
[email protected], [email protected]

Review-Url: https://codereview.chromium.org/3002003002 .

Author: zhivkag

pkg/kernel/lib/interpreter/interpreter.dart

@@ -18,13 +18,13 @@ class NotImplemented {
 }
 
 class Interpreter {
-  Program program;
-  StatementExecuter visitor = new StatementExecuter();
-
   // The execution of the program starts with empty main environment.
   static MainEnvironment mainEnvironment =
       new MainEnvironment(<Member, Location>{});
 
+  final Program program;
+  final StatementExecuter visitor = new StatementExecuter();
+
   Interpreter(this.program);
 
   void run() {
@@ -1577,9 +1577,36 @@ class CatchHandler extends ExceptionHandler {
   CatchHandler(this.catches, this.environment, this.state);
 
   Configuration call(Value exception, StackTrace stackTrace) {
+    if (catches.isEmpty) {
+      return new ThrowConfiguration(
+          state.exceptionComponents.handler, exception, stackTrace);
+    }
+
     // TODO(zhivkag): Check if there is a matching catch clause instead.
-    return new ThrowConfiguration(
-        state.exceptionComponents.handler, exception, stackTrace);
+    var currentCatch = catches.first;
+    if (currentCatch.guard is DynamicType) {
+      // Exception is caught, execute the body.
+
+      var env = environment;
+      if (currentCatch.exception != null) {
+        env = env.extend(currentCatch.exception, exception);
+      }
+      if (currentCatch.stackTrace != null) {
+        env = env.extend(
+            currentCatch.stackTrace, new StringValue(stackTrace.toString()));
+      }
+      var ecs = new ExceptionComponents(state.exceptionComponents.handler,
+          state.exceptionComponents.stackTrace, stackTrace, exception);
+      var newState = new State.initial()
+          .withContinuation(state.continuation)
+          .withReturnContinuation(state.returnContinuation)
+          .withException(ecs);
+      return new ExecConfiguration(currentCatch.body, env, newState);
+    }
+
+    var catchHandler =
+        new CatchHandler(catches.skip(1).toList(), environment, state);
+    return new ThrowConfiguration(catchHandler, exception, stackTrace);
   }
 }
 
@@ -1661,7 +1688,7 @@ class StackTrace {
 /// - It throws, in which case the handler is returned and applied accordingly.
 class StatementExecuter
     extends StatementVisitor1<Configuration, ExecConfiguration> {
-  Evaluator evaluator = new Evaluator();
+  final Evaluator evaluator = new Evaluator();
 
   void trampolinedExecution(Configuration configuration) {
     while (configuration != null) {

pkg/kernel/testcases/interpreter/try_catch_finally_test.dart

@@ -9,11 +9,13 @@ main() {
     print('hello2');
   }
   print('hello3');
-  print(foo());
-  print(bar());
+  print(fReturns());
+  print(fFinalizes());
+  print(fThrows());
 }
 
-int foo() {
+/// Tests that the return in finally is executed.
+int fReturns() {
   try {
     print('foo 1');
     return 1;
@@ -23,7 +25,8 @@ int foo() {
   }
 }
 
-int bar() {
+/// Tests that finally is executed before returning.
+int fFinalizes() {
   try {
     print('bar 1');
     return 1;
@@ -32,3 +35,16 @@ int bar() {
   }
   return 0;
 }
+
+/// Tests that the exception is caught.
+int fThrows() {
+  try {
+    print(37);
+    throw 'Error';
+  } catch (e, _) {
+    print('Caught $e');
+  } finally {
+    print("Finalizer");
+  }
+  return 34;
+}

pkg/kernel/testcases/interpreter/try_catch_finally_test.dart.expect

@@ -1,14 +1,20 @@
 print(String: hello1)
 print(String: hello2)
 print(String: hello3)
-static-invocation-foo
+static-invocation-fReturns
 print(String: foo 1)
 return
 print(String: foo 2)
 return
 print(int: 2)
-static-invocation-bar
+static-invocation-fFinalizes
 print(String: bar 1)
 return
 print(String: bar 2)
 print(int: 1)
+static-invocation-fThrows
+print(int: 37)
+print(String: Caught Error)
+print(String: Finalizer)
+return
+print(int: 34)