Allow interpolated strings and adjacent strings to be compile-time constants.

frog/analyze.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.
 
 /**
  * A simple code analyzer for Dart.
  *
  * Currently used to ensure all concrete generic types are visited.
  * Also performs all static type checks - so these don't need to be
  * done in later phases.
@@ skipping 757 matching lines @@
 
   Value visitSuperExpression(SuperExpression node) {
     return _frame.makeSuperValue(node);
   }
 
   Value visitLiteralExpression(LiteralExpression node) {
     return new PureStaticValue(node.value.type, node.span, true);
   }
 
   Value visitStringConcatExpression(StringConcatExpression node) {
-    node.strings.forEach(visitValue);
-    return _frame._makeValue(world.stringType, node);
+    bool isConst = true;
+    node.strings.forEach((each) {
+      if (!visitValue(each).isConst) isConst = false;
+    });
+    return new PureStaticValue(world.stringType, node.span, isConst);
   }
 
   Value visitStringInterpExpression(StringInterpExpression node) {
-    node.pieces.forEach(visitValue);
-    return _frame._makeValue(world.stringType, node);
-
-    // TODO(jimhug): Do we need this more elaborate analysis?
-    /*
-    var ret = Value.fromString('', node.span);
-
-    for (var item in node.pieces) {
-      var val = visitValue(item);
-      var sval = val.invoke(_frame, 'toString', item, Arguments.EMPTY);
-      ret = ret.binop(TokenKind.ADD, sval, _frame, item);
-    }
-    return _frame._makeValue(world.stringType, node); //???ret;
-    */
+    bool isConst = true;
+    node.pieces.forEach((each) {
+      if (!visitValue(each).isConst) isConst = false;
+    });
+    return new PureStaticValue(world.stringType, node.span, isConst);
   }
 }