Fixing string compile-time constant evaluation

frog/member.dart

 // Copyright (c) 2011, 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 formal parameter to a [Method]. */
 class Parameter {
   FormalNode definition;
   Member method;
 
   String name;
@@ skipping 1159 matching lines @@
       }
     } else if (declaringType.isString) {
       if (name == '\$index') {
         // Note: this could technically propagate constness, but that's not
         // specified explicitly and the VM doesn't do that.
         return new Value(declaringType, '${target.code}[${argsCode[0]}]',
           node.span);
       } else if (name == '\$add') {
         if (allConst) {
           var val0 = target.dynamic.actualValue;
+          var quote0 = val0[0];
           val0 = val0.substring(1, val0.length - 1);
           var val1 = args.values[0].dynamic.actualValue;
+          var quote1 = null;
           if (args.values[0].type.isString) {
+            quote1 = val1[0];
             val1 = val1.substring(1, val1.length - 1);
           }
-          var value = '${val0}${val1}';
-          value = '"' + value.replaceAll('"', '\\"') + '"';
+          // ensure that both strings use the same quote char:

[Jennifer Messerly, 2011/11/29 18:55:48]

it'd be really nice if this was pulled out into its own function

[Siggi Cherem (dart-lang), 2011/11/29 19:09:26]

Done.

+          var value;
+          if (quote0 == quote1 || quote1 == null) {
+            // if both strings use the same quote, then merge them together
+            value = '$quote0${val0}${val1}$quote0';
+          } else if (quote0 == '"') {
+            // if they are different, escape the single-quote to be double-quote
+            // the choice of single vs double is arbitrary, but choosing one
+            // ensures that we only do this escaping once on a string portion.
+            assert(quote1 == "'");
+            value = '$quote0${val0}${toDoubleQuote(val1)}$quote0';
+          } else {
+            assert(quote1 == '"');
+            value = '$quote1${toDoubleQuote(val0)}${val1}$quote1';
+          }
           return new EvaluatedValue(world.stringType, value, value, node.span);
         }
 
         // Ensure we generate toString on the right side
         return new Value(declaringType, '${target.code} + ${argsCode[0]}',
           node.span);
       }
     } else if (declaringType.isNative) {
       if (name == '\$index') {
         // Note: this could technically propagate constness, but that's not
@@ skipping 461 matching lines @@
   }
 
   void forEach(void f(Member member)) {
     factories.forEach((_, Map constructors) {
       constructors.forEach((_, Member member) {
         f(member);
       });
     });
   }
 }