Support for "a is Function".

frog/leg/ssa/codegen.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 class SsaCodeGeneratorTask extends CompilerTask {
   SsaCodeGeneratorTask(Compiler compiler) : super(compiler);
   String get name() => 'SSA code generator';
 
   String generate(WorkItem work, HGraph graph) {
     return measure(() {
@@ skipping 924 matching lines @@
     endExpression(JSPrecedence.EQUALITY_PRECEDENCE);
   }
 
   void checkNull(HInstruction input) {
     beginExpression(JSPrecedence.EQUALITY_PRECEDENCE);
     use(input, JSPrecedence.EQUALITY_PRECEDENCE);
     buffer.add(" === (void 0)");
     endExpression(JSPrecedence.EQUALITY_PRECEDENCE);
   }
 
+  void checkFunction(HInstruction input, Element element) {
+    beginExpression(JSPrecedence.LOGICAL_OR_PRECEDENCE);
+    beginExpression(JSPrecedence.EQUALITY_PRECEDENCE);
+    buffer.add('typeof ');
+    use(input, JSPrecedence.PREFIX_PRECEDENCE);
+    buffer.add(" === 'function'");
+    endExpression(JSPrecedence.EQUALITY_PRECEDENCE);
+    buffer.add(" || ");
+    beginExpression(JSPrecedence.LOGICAL_AND_PRECEDENCE);
+    checkObject(input, '===');
+    buffer.add(" && ");
+    checkType(input, element);
+    endExpression(JSPrecedence.LOGICAL_AND_PRECEDENCE);
+    endExpression(JSPrecedence.LOGICAL_OR_PRECEDENCE);
+  }
+
+  void checkType(HInstruction input, Element element) {
+    buffer.add('!!');
+    use(input, JSPrecedence.MEMBER_PRECEDENCE);
+    buffer.add('.');
+    buffer.add(compiler.namer.operatorIs(element));
+  }
+
   void visitIs(HIs node) {
     Element element = node.typeExpression;
     compiler.registerIsCheck(element);
     LibraryElement coreLibrary = compiler.coreLibrary;
     ClassElement objectClass = coreLibrary.find(const SourceString('Object'));
     HInstruction input = node.expression;
     if (node.nullOk) {
       beginExpression(JSPrecedence.LOGICAL_OR_PRECEDENCE);
       checkNull(input);
       buffer.add(' || ');
     }
     if (element == objectClass) {
       // TODO(ahe): This probably belongs in the constant folder.
       buffer.add('true');
     } else if (element == coreLibrary.find(const SourceString('String'))) {
       checkString(input, '===');
     } else if (element == coreLibrary.find(const SourceString('double'))) {
       checkDouble(input, '===');
     } else if (element == coreLibrary.find(const SourceString('num'))) {
       checkNum(input, '===');
     } else if (element == coreLibrary.find(const SourceString('bool'))) {
       checkBool(input, '===');
+    } else if (element == coreLibrary.find(const SourceString('Function'))) {
+      checkFunction(input, element);
     } else if (element == coreLibrary.find(const SourceString('int'))) {
       beginExpression(JSPrecedence.LOGICAL_AND_PRECEDENCE);
       checkNum(input, '===');
       buffer.add(' && ');
       checkInt(input, '===');
       endExpression(JSPrecedence.LOGICAL_AND_PRECEDENCE);
     } else {
       beginExpression(JSPrecedence.LOGICAL_AND_PRECEDENCE);
       if (isStringSupertype(element)) {
         checkString(input, '===');
@@ skipping 10 matching lines @@
         checkArray(input, '===');
         buffer.add(' || ');
         precedence = JSPrecedence.LOGICAL_OR_PRECEDENCE;
       } else if (element.isClass() && (element.dynamic.isNative()
                                        || isSupertypeOfNativeClass(element))) {
         buffer.add("(");
         endParen = true;
       } else {
         beginExpression(precedence);
       }
-      buffer.add('!!');
-      use(input, JSPrecedence.MEMBER_PRECEDENCE);
-      buffer.add('.');
-      buffer.add(compiler.namer.operatorIs(node.typeExpression));
+      checkType(input, node.typeExpression);
       if (element.isClass() && (element.dynamic.isNative()
                                 || isSupertypeOfNativeClass(element))) {
         buffer.add(' || ');
         beginExpression(JSPrecedence.LOGICAL_AND_PRECEDENCE);
         // First check if the object is not a Dart object. If the
         // object is a Dart object, we know the property check was
         // sufficient.
         compiler.registerIsCheck(objectClass);
         buffer.add('!');
         use(input, JSPrecedence.MEMBER_PRECEDENCE);
@@ skipping 394 matching lines @@
       startBailoutSwitch();
     }
   }
 
   void endElse(HIf node) {
     if (node.elseBlock.hasBailouts()) {
       endBailoutSwitch();
     }
   }
 }