New treatment of native methods.

lib/compiler/implementation/native_handler.dart

Index: lib/compiler/implementation/native_handler.dart
diff --git a/lib/compiler/implementation/native_handler.dart b/lib/compiler/implementation/native_handler.dart
index ef02e8f27ea96e8ba9a832ac8c2ec279eac06b0d..d86de223f94d6311f222d43a11e04018c2438b24 100644
--- a/lib/compiler/implementation/native_handler.dart
+++ b/lib/compiler/implementation/native_handler.dart
@@ -80,8 +80,6 @@ void maybeEnableNative(Compiler compiler,
       || libraryName == 'dart:dom_deprecated'
       || libraryName == 'dart:isolate'
       || libraryName == 'dart:html') {
-    library.define(new ForeignElement(
-        const SourceString('native'), library), compiler);
     library.canUseNative = true;
     if (compiler.jsIndexingBehaviorInterface !== null) {
       library.define(compiler.jsIndexingBehaviorInterface, compiler);
@@ -141,35 +139,24 @@ Token handleNativeClassBody(Listener listener, Token token) {
   return token;
 }
 
-RegExp nativeRedirectionRegExp = const RegExp(@'^[a-zA-Z][a-zA-Z_$0-9]*$');
-
 Token handleNativeFunctionBody(ElementListener listener, Token token) {
   checkAllowedLibrary(listener, token);
   Token begin = token;
-  listener.beginExpressionStatement(token);
-  listener.handleIdentifier(token);
+  listener.beginReturnStatement(token);
   token = token.next;
+  bool hasExpression = false;
   if (token.kind === STRING_TOKEN) {
+    hasExpression = true;
     listener.beginLiteralString(token);
     listener.endLiteralString(0);
-    LiteralString str = listener.popNode();
-    listener.pushNode(new NodeList.singleton(str));
-    listener.endSend(token);
     token = token.next;
-    // If this native method is just redirecting to another method,
-    // we add a return node to match the SSA builder expectations.
-    if (nativeRedirectionRegExp.hasMatch(str.dartString.slowToString())) {
-      listener.endReturnStatement(true, begin, token);
-    } else {
-      listener.endExpressionStatement(token);

[Anton Muhin, 2012/06/18 10:04:52]

now we treat all natives as returns, even though there are cases like native
'this.x = 42' which formally has no returns.  That leads to returning a bool if
we need to wrap HForeign into HReturn.

[sra1, 2012/06/20 18:29:05]

I'm not sure that makes sense; some of the native strings are statements, not
expressions.

[Anton Muhin, 2012/06/20 18:51:49]

Stephen, both Peter and me are well aware of this problem---see the discussion. 
Still we think it's the best approach.  But if you have any over proposals,
that'd be really great.

Plus there are plans to rework native system completely which will probably
render this CL fully obsolete, so I'd rather not spend too much time theorizing
about ideal approach but rather keep things as simple as possible.

That's my stance, Peter may very well have completely different view of the
story.

On 2012/06/20 18:29:05, sra1 wrote:

-    }
-  } else {
-    listener.pushNode(new NodeList.empty());
-    listener.endSend(token);
-    listener.endReturnStatement(true, begin, token);
   }
-  listener.endFunctionBody(1, begin, token);
-  // TODO(ngeoffray): expect a ';'.
+  listener.endReturnStatement(hasExpression, begin, token);
+  /* Fails thanks to lib/isolate/frog/isolateimpl.dart:143 --- native method w/ Dart body.

[Anton Muhin, 2012/06/18 10:04:52]

is it valid Dart?  I mean code in isolateimpl.dart.

[ahe, 2012/06/18 10:37:39]

No. Nothing about "native" is valid Dart.
Whatever is used to implement that stuff is needed. If you think it is easier,
convert the code to use the JS function instead. Let me know if you need to some
pointers.

[sra1, 2012/06/20 18:29:05]

Native methods with both a string JavaScript body and a Dart body was a trick
used by Frog to mark the dependencies of the native code.  For example, if the
native code throws a FooException, the Dart code would contain a call to the
constructor of FooException to ensure that the compiler knew it was used,
otherwise no code for FooException might be emitted.

We should rewrite all code using this trick as Dart code with embedded JS()
elements.

[Anton Muhin, 2012/06/20 18:51:49]

Thanks a lot for clarifications.  I wonder if it works now at all, but it might.

On 2012/06/20 18:29:05, sra1 wrote:

+  if (';' !== token.stringValue) {
+    return listener.expected(';', token);
+  }
+  */
   return token.next;
 }
 
@@ -196,7 +183,7 @@ bool isOverriddenMethod(FunctionElement element,
   return false;
 }
 
-void handleSsaNative(SsaBuilder builder, Send node) {
+void handleSsaNative(SsaBuilder builder, Expression nativeBody) {
   Compiler compiler = builder.compiler;
   FunctionElement element = builder.work.element;
   element.setNative();
@@ -215,7 +202,7 @@ void handleSsaNative(SsaBuilder builder, Send node) {
     builder.add(method);
     builder.push(new HInvokeStatic(Selector.INVOCATION_1,
         <HInstruction>[method, builder.localsHandler.readThis()]));
-    return;
+    return true;
   }
 
   HInstruction convertDartClosure(Element parameter, FunctionType type) {
@@ -230,19 +217,16 @@ void handleSsaNative(SsaBuilder builder, Send node) {
     return closure;
   }
 
-
   // Check which pattern this native method follows:
   // 1) foo() native; hasBody = false, isRedirecting = false
   // 2) foo() native "bar"; hasBody = false, isRedirecting = true
   // 3) foo() native "return 42"; hasBody = true, isRedirecting = false
+  RegExp nativeRedirectionRegExp = const RegExp(@'^[a-zA-Z][a-zA-Z_$0-9]*$');
   bool hasBody = false;
   bool isRedirecting = false;
   String nativeMethodName = element.name.slowToString();
-  if (!node.arguments.isEmpty()) {
-    if (!node.arguments.tail.isEmpty()) {
-      builder.compiler.cancel('More than one argument to native');
-    }
-    LiteralString jsCode = node.arguments.head;
+  if (nativeBody !== null) {
+    LiteralString jsCode = nativeBody.asLiteralString();
     String str = jsCode.dartString.slowToString();
     if (nativeRedirectionRegExp.hasMatch(str)) {
       nativeMethodName = str;
@@ -290,6 +274,7 @@ void handleSsaNative(SsaBuilder builder, Send node) {
     DartString jsCode = new DartString.literal(nativeMethodCall);
     builder.push(
         new HForeign(jsCode, const LiteralDartString('Object'), inputs));
+    return true;
   } else {
     // This is JS code written in a Dart file with the construct
     // native """ ... """;. It does not work well with mangling,
@@ -309,10 +294,11 @@ void handleSsaNative(SsaBuilder builder, Send node) {
             <HInstruction>[jsClosure]));
       }
     });
-    LiteralString jsCode = node.arguments.head;
+    LiteralString jsCode = nativeBody.asLiteralString();
     builder.push(new HForeign(jsCode.dartString,
                               const LiteralDartString('Object'),
                               <HInstruction>[]));
+    return false;
   }
 }