Make string juxtaposition combine properly with string interpolations.

frog/leg/ssa/nodes.dart

Index: frog/leg/ssa/nodes.dart
diff --git a/frog/leg/ssa/nodes.dart b/frog/leg/ssa/nodes.dart
index 9657192e0ab9f538fa21b398e125f20d321abe67..80dfedbe90cca3e83d014502b5b40efc6c163994 100644
--- a/frog/leg/ssa/nodes.dart
+++ b/frog/leg/ssa/nodes.dart
@@ -1387,6 +1387,28 @@ class HAdd extends HBinaryArithmetic {
   }
 
   AddOperation get operation() => const AddOperation();
+
+  HInstruction fold(HGraph graph) {

[ngeoffray, 2012/03/14 12:29:58]

Is that dead code? There is no fold method in the instructions anymore, and line
1409 would fail.

[Lasse Reichstein Nielsen, 2012/03/14 13:04:49]

It's probably dead, just leftover of a merge that didn't recognize it as gone.
I'll remove it and check.

+    // TODO(floitsch): move this code to the compile-time-constant handler.
+    if (left.isConstantString() && right is HConstant) {
+      HConstant op1 = left;
+      HConstant op2 = right;
+      DartString leftString = op1.constant.value;
+      DartString otherString = null;
+      if (right.isConstantString()) {
+        otherString = op2.constant.value;
+      } else {
+        assert(op2.isConstantNumber() ||
+               op2.isConstantBoolean() ||
+               op2.isConstantNull());
+        otherString = new DartString.literal(op2.constant.value.toString());
+      }
+      DartString cons = new DartString.concat(leftString, otherString);
+      return graph.addConstantString(cons);
+    }
+    return super.fold(graph);
+  }
+
   int typeCode() => 5;
   bool typeEquals(other) => other is HAdd;
   bool dataEquals(HInstruction other) => true;