Move various top-level Unicode definitions into classes and methods.

runtime/lib/string.cc

Index: runtime/lib/string.cc
diff --git a/runtime/lib/string.cc b/runtime/lib/string.cc
index ed1528ed18d5a175e1088820d7c93b8f898675bd..b51bc60d314df9d77a5a2910015516acad6546ac 100644
--- a/runtime/lib/string.cc
+++ b/runtime/lib/string.cc
@@ -8,6 +8,7 @@
 #include "vm/native_entry.h"
 #include "vm/object.h"
 #include "vm/symbols.h"
+#include "vm/unicode.h"
 
 namespace dart {
 
@@ -34,10 +35,10 @@ DEFINE_NATIVE_ENTRY(StringBase_createFromCodePoints, 1) {
       GrowableArray<const Object*> args;
       Exceptions::ThrowByType(Exceptions::kArgument, args);
     } else {
-      if (value > 0xFF) {
+      if (!Utf::IsLatin1(value)) {
         is_one_byte_string = false;
       }
-      if (value > 0xFFFF) {
+      if (!Utf::IsBmp(value)) {

[siva, 2012/11/30 02:42:53]

if (Utf::IsSupplementary(value)) {
   ...
}
might make this more readable.

Actually a slightly more efficient way might be:

if (!Utf::IsLatin1(value)) {
  is_one_byte_string = false;
  if (Utf::IsSupplementary(value)) {
    utf16_len += 1;
  }
}

[cshapiro, 2012/11/30 03:21:24]

A great idea.  Done!

         utf16_len += 1;
       }
     }