Add some support for the code-point code-unit distinction.

runtime/vm/object.h

Index: runtime/vm/object.h
diff --git a/runtime/vm/object.h b/runtime/vm/object.h
index 031a8541598da68e52d7e4eba1aefbd5114350b9..810fedf7044df9a58ca0e96e8ba74e7d20d305af 100644
--- a/runtime/vm/object.h
+++ b/runtime/vm/object.h
@@ -17,6 +17,7 @@
 #include "vm/os.h"
 #include "vm/raw_object.h"
 #include "vm/scanner.h"
+#include "vm/unicode.h"
 
 namespace dart {
 
@@ -3716,8 +3717,13 @@ class String : public Instance {
   static intptr_t Hash(const String& str, intptr_t begin_index, intptr_t len);
   static intptr_t Hash(const uint8_t* characters, intptr_t len);
   static intptr_t Hash(const uint16_t* characters, intptr_t len);
-  static intptr_t Hash(const uint32_t* characters, intptr_t len);
+  static intptr_t Hash(const int32_t* characters, intptr_t len);
 
+  // Despite the name, this does not return the character.  It returns the
+  // UTF-16 code unit at an index.  UTF-16 is a superset of ASCII so you can
+  // always use this if you are looking for ASCII.  If you need to support

[siva, 2012/11/16 22:32:04]

Should we say ASCII or Latin1 here?

[erikcorry, 2012/11/19 12:40:41]

Now says both.

+  // arbitrary Unicode characters then you should perhaps be using
+  // Utf16::CharCodeAt(string, index), which returns the full 21 bit code point.
   int32_t CharAt(intptr_t index) const;
 
   intptr_t CharSize() const;
@@ -3729,7 +3735,7 @@ class String : public Instance {
   bool Equals(const char* str) const;
   bool Equals(const uint8_t* characters, intptr_t len) const;
   bool Equals(const uint16_t* characters, intptr_t len) const;
-  bool Equals(const uint32_t* characters, intptr_t len) const;
+  bool Equals(const int32_t* characters, intptr_t len) const;
 
   virtual bool Equals(const Instance& other) const;
 
@@ -3780,7 +3786,7 @@ class String : public Instance {
                         Heap::Space space = Heap::kNew);
 
   // Creates a new String object from an array of UTF-32 encoded characters.
-  static RawString* New(const uint32_t* utf32_array,
+  static RawString* New(const int32_t* utf32_array,
                         intptr_t array_len,
                         Heap::Space space = Heap::kNew);
 
@@ -3926,7 +3932,7 @@ class OneByteString : public AllStatic {
   static RawOneByteString* New(const uint16_t* characters,
                                intptr_t len,
                                Heap::Space space);
-  static RawOneByteString* New(const uint32_t* characters,
+  static RawOneByteString* New(const int32_t* characters,
                                intptr_t len,
                                Heap::Space space);
   static RawOneByteString* New(const String& str,
@@ -3941,6 +3947,7 @@ class OneByteString : public AllStatic {
 
   static RawOneByteString* Transform(int32_t (*mapping)(int32_t ch),
                                      const String& str,
+                                     int out_length,

[siva, 2012/11/16 22:32:04]

we always use intptr_t for length values in the VM

[erikcorry, 2012/11/19 12:40:41]

Done.

                                      Heap::Space space);
 
   static const ClassId kClassId = kOneByteStringCid;
@@ -4009,7 +4016,7 @@ class TwoByteString : public AllStatic {
                                intptr_t len,
                                Heap::Space space);
   static RawTwoByteString* New(intptr_t utf16_len,
-                               const uint32_t* characters,
+                               const int32_t* characters,
                                intptr_t len,
                                Heap::Space space);
   static RawTwoByteString* New(const String& str,
@@ -4024,6 +4031,7 @@ class TwoByteString : public AllStatic {
 
   static RawTwoByteString* Transform(int32_t (*mapping)(int32_t ch),
                                      const String& str,
+                                     int out_length,

[siva, 2012/11/16 22:32:04]

Ditto.

[erikcorry, 2012/11/19 12:40:41]

Done.

                                      Heap::Space space);
 
   static RawTwoByteString* null() {