Implement external strings.

runtime/vm/raw_object.h

 // 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.
 
 #ifndef VM_RAW_OBJECT_H_
 #define VM_RAW_OBJECT_H_
 
 #include "vm/assert.h"
 #include "vm/globals.h"
 #include "vm/snapshot.h"
@@ skipping 31 matching lines @@
     V(Number)                                                                  \
       V(Integer)                                                               \
         V(Smi)                                                                 \
         V(Mint)                                                                \
         V(Bigint)                                                              \
       V(Double)                                                                \
     V(String)                                                                  \
       V(OneByteString)                                                         \
       V(TwoByteString)                                                         \
       V(FourByteString)                                                        \
+      V(ExternalOneByteString)                                                 \
+      V(ExternalTwoByteString)                                                 \
+      V(ExternalFourByteString)                                                \
     V(Bool)                                                                    \
     V(Array)                                                                   \
       V(ImmutableArray)                                                        \
     V(Closure)                                                                 \
     V(Stacktrace)                                                              \
     V(JSRegExp)                                                                \
 
 #define CLASS_LIST(V)                                                          \
   V(Object)                                                                    \
   CLASS_LIST_NO_OBJECT(V)
@@ skipping 618 matching lines @@
 
 
 class RawFourByteString : public RawString {
   RAW_HEAP_OBJECT_IMPLEMENTATION(FourByteString);
 
   // Variable length data follows here.
   uint32_t data_[0];
 };
 
 
+class RawExternalOneByteString : public RawString {
+  RAW_HEAP_OBJECT_IMPLEMENTATION(ExternalOneByteString);
+
+  uint8_t* data_;

[turnidge, 2011/10/25 18:07:20]

Out of curiosity, can we rely on external strings being null terminated?

[cshapiro, 2011/10/25 20:42:47]

Certainly not.  We inherit a length field from the String class which makes that
kind of length encoding unnecessary.

[turnidge, 2011/10/25 20:45:15]

Ah, thanks.

+};
+
+
+class RawExternalTwoByteString : public RawString {
+  RAW_HEAP_OBJECT_IMPLEMENTATION(ExternalTwoByteString);
+
+  uint16_t* data_;
+};
+
+
+class RawExternalFourByteString : public RawString {
+  RAW_HEAP_OBJECT_IMPLEMENTATION(ExternalFourByteString);
+
+  uint32_t* data_;
+};
+
+
 class RawBool : public RawInstance {
   RAW_HEAP_OBJECT_IMPLEMENTATION(Bool);
 
   bool value_;
 };
 
 
 class RawArray : public RawInstance {
   RAW_HEAP_OBJECT_IMPLEMENTATION(Array);
 
@@ skipping 71 matching lines @@
   intptr_t type_;  // Uninitialized, simple or complex.
   intptr_t flags_;  // Represents global/local, case insensitive, multiline.
 
   // Variable length data follows here.
   uint8_t data_[0];
 };
 
 }  // namespace dart
 
 #endif  // VM_RAW_OBJECT_H_