Use a common subroutine for the snapshot reading and writing of strings.

runtime/vm/raw_object_snapshot.cc

Index: runtime/vm/raw_object_snapshot.cc
diff --git a/runtime/vm/raw_object_snapshot.cc b/runtime/vm/raw_object_snapshot.cc
index 9a1be618eab884ab160b2025a087f5029beea9a7..562131242bdb0dd7d840c67c63a427c4ca725ae5 100644
--- a/runtime/vm/raw_object_snapshot.cc
+++ b/runtime/vm/raw_object_snapshot.cc
@@ -990,147 +990,137 @@ void RawString::WriteTo(SnapshotWriter* writer,
 }
 
 
-RawOneByteString* OneByteString::ReadFrom(SnapshotReader* reader,
-                                          intptr_t object_id,
-                                          bool classes_serialized) {
+template<typename CharType,
+         typename StringType,
+         typename RawStringType,
+         typename CharAddrType,
+         typename SetHashType>
+static RawStringType* ReadStringFrom(SnapshotReader* reader,
+                                     intptr_t object_id,
+                                     bool classes_serialized,
+                                     CharAddrType char_addr,
+                                     SetHashType set_hash) {
   ASSERT(reader != NULL);
   // Read the length so that we can determine instance size to allocate.
   RawSmi* smi_len = GetSmi(reader->Read<intptr_t>());
   intptr_t len = Smi::Value(smi_len);
   RawSmi* smi_hash = GetSmi(reader->Read<intptr_t>());
 
-  // Set up the one byte string object.
-  OneByteString& str_obj = OneByteString::ZoneHandle(
-      OneByteString::New(len, classes_serialized ? Heap::kOld : Heap::kNew));
+  // Set up the string object.
+  StringType& str_obj = StringType::ZoneHandle(
+      StringType::New(len, classes_serialized ? Heap::kOld : Heap::kNew));
   for (intptr_t i = 0; i < len; i++) {
-    *str_obj.CharAddr(i) = reader->Read<uint8_t>();
+    *((str_obj).*(char_addr))(i) = reader->Read<CharType>();
   }
 
   reader->AddBackwardReference(object_id, &str_obj);
-  RawOneByteString* raw_str = str_obj.raw();
-  raw_str->ptr()->hash_ = smi_hash;
+  ((str_obj).*(set_hash))(Smi::Value(smi_hash));

[turnidge, 2011/10/27 17:28:35]

Thinking out loud...  Optional...

If you wanted to get rid of the set_hash parameter and make this line a bit more
readable, you could do:

(str_obj).SetHash(Smi::Value(smi_hash));

To make that work, you would need to declare that ReadStringFrom is a friend of
class String.  In some sense, it is, as it messes with all sorts of funny string
internals.  Another option is that ReadStringFrom could become a protected
static method on String itself.

I tried to see a way to get rid of the char_addr parameter as well, but I was
foiled by the differing return types.  So given that that needs to stay, keeping
the set_hash parameter as well is no big deal.

So feel free to ignore this...

   return str_obj.raw();
 }
 
 
-void RawOneByteString::WriteTo(SnapshotWriter* writer,
-                               intptr_t object_id,
-                               bool serialize_classes) {
-  ASSERT(writer != NULL);
-  intptr_t len = Smi::Value(ptr()->length_);
-
-  // Write out the serialization header value for this object.
-  writer->WriteObjectHeader(kInlined, object_id);
-
-  // Write out the class information.
-  writer->WriteObjectHeader(kObjectId, ObjectStore::kOneByteStringClass);
-
-  // Write out the length field.
-  writer->Write<RawObject*>(ptr()->length_);
-
-  // Write out the hash field.
-  writer->Write<RawObject*>(ptr()->hash_);
-
-  // Write out the string.
-  for (intptr_t i = 0; i < len; i++) {
-    writer->Write<uint8_t>(ptr()->data_[i]);
-  }
+RawOneByteString* OneByteString::ReadFrom(SnapshotReader* reader,
+                                          intptr_t object_id,
+                                          bool classes_serialized) {
+  return ReadStringFrom<uint8_t, OneByteString, RawOneByteString>(
+      reader,
+      object_id,
+      classes_serialized,
+      &OneByteString::CharAddr,
+      &OneByteString::SetHash);
 }
 
 
 RawTwoByteString* TwoByteString::ReadFrom(SnapshotReader* reader,
                                           intptr_t object_id,
                                           bool classes_serialized) {
-  ASSERT(reader != NULL);
-  // Read the length so that we can determine instance size to allocate.
-  RawSmi* smi_len = GetSmi(reader->Read<intptr_t>());
-  intptr_t len = Smi::Value(smi_len);
-  RawSmi* smi_hash = GetSmi(reader->Read<intptr_t>());
+  return ReadStringFrom<uint16_t, TwoByteString, RawTwoByteString>(
+      reader,
+      object_id,
+      classes_serialized,
+      &TwoByteString::CharAddr,
+      &TwoByteString::SetHash);
+}
 
-  // Set up the two byte string object.
-  TwoByteString& str_obj = TwoByteString::ZoneHandle(
-      TwoByteString::New(len, classes_serialized ? Heap::kOld : Heap::kNew));
-  for (intptr_t i = 0; i < len; i++) {
-    *str_obj.CharAddr(i) = reader->Read<uint16_t>();
-  }
 
-  reader->AddBackwardReference(object_id, &str_obj);
-  RawTwoByteString* raw_str = str_obj.raw();
-  raw_str->ptr()->hash_ = smi_hash;
-  return str_obj.raw();
+RawFourByteString* FourByteString::ReadFrom(SnapshotReader* reader,
+                                            intptr_t object_id,
+                                            bool classes_serialized) {
+  return ReadStringFrom<uint32_t, FourByteString, RawFourByteString>(
+      reader,
+      object_id,
+      classes_serialized,
+      &FourByteString::CharAddr,
+      &FourByteString::SetHash);
 }
 
 
-void RawTwoByteString::WriteTo(SnapshotWriter* writer,
-                               intptr_t object_id,
-                               bool serialize_classes) {
+template<typename CharType>
+static void StringWriteTo(SnapshotWriter* writer,
+                          intptr_t object_id,
+                          intptr_t class_id,
+                          bool serialize_classes,
+                          RawSmi* length,
+                          RawSmi* hash,
+                          CharType* data) {
   ASSERT(writer != NULL);
-  intptr_t len = Smi::Value(ptr()->length_);
+  intptr_t len = Smi::Value(length);
 
   // Write out the serialization header value for this object.
   writer->WriteObjectHeader(kInlined, object_id);
 
   // Write out the class information.
-  writer->WriteObjectHeader(kObjectId, ObjectStore::kTwoByteStringClass);
+  writer->WriteObjectHeader(kObjectId, class_id);
 
   // Write out the length field.
-  writer->Write<RawObject*>(ptr()->length_);
+  writer->Write<RawObject*>(length);
 
   // Write out the hash field.
-  writer->Write<RawObject*>(ptr()->hash_);
+  writer->Write<RawObject*>(hash);
 
   // Write out the string.
   for (intptr_t i = 0; i < len; i++) {
-    writer->Write<uint16_t>(ptr()->data_[i]);
+    writer->Write<CharType>(data[i]);
   }
 }
 
 
-RawFourByteString* FourByteString::ReadFrom(SnapshotReader* reader,
-                                            intptr_t object_id,
-                                            bool classes_serialized) {
-  ASSERT(reader != NULL);
-  // Read the length so that we can determine instance size to allocate.
-  RawSmi* smi_len = GetSmi(reader->Read<intptr_t>());
-  intptr_t len = Smi::Value(smi_len);
-  RawSmi* smi_hash = GetSmi(reader->Read<intptr_t>());
+void RawOneByteString::WriteTo(SnapshotWriter* writer,
+                               intptr_t object_id,
+                               bool serialize_classes) {
+  StringWriteTo<uint8_t>(writer,
+                         object_id,
+                         ObjectStore::kOneByteStringClass,
+                         serialize_classes,
+                         ptr()->length_,
+                         ptr()->hash_,
+                         ptr()->data_);
+}
 
-  // Set up the four byte string object.
-  FourByteString& str_obj = FourByteString::ZoneHandle(
-      FourByteString::New(len, classes_serialized ? Heap::kOld : Heap::kNew));
-  for (intptr_t i = 0; i < len; i++) {
-    *str_obj.CharAddr(i) = reader->Read<uint32_t>();
-  }
 
-  reader->AddBackwardReference(object_id, &str_obj);
-  RawFourByteString* raw_str = str_obj.raw();
-  raw_str->ptr()->hash_ = smi_hash;
-  return str_obj.raw();
+void RawTwoByteString::WriteTo(SnapshotWriter* writer,
+                               intptr_t object_id,
+                               bool serialize_classes) {
+  StringWriteTo<uint16_t>(writer,
+                          object_id,
+                          ObjectStore::kTwoByteStringClass,
+                          serialize_classes,
+                          ptr()->length_,
+                          ptr()->hash_,
+                          ptr()->data_);
 }
 
 
 void RawFourByteString::WriteTo(SnapshotWriter* writer,
                                 intptr_t object_id,
                                 bool serialize_classes) {
-  ASSERT(writer != NULL);
-  intptr_t len = Smi::Value(ptr()->length_);
-
-  // Write out the serialization header value for this object.
-  writer->WriteObjectHeader(kInlined, object_id);
-
-  // Write out the class information.
-  writer->WriteObjectHeader(kObjectId, ObjectStore::kFourByteStringClass);
-
-  // Write out the length field.
-  writer->Write<RawObject*>(ptr()->length_);
-
-  // Write out the hash field.
-  writer->Write<RawObject*>(ptr()->hash_);
-
-  // Write out the string.
-  for (intptr_t i = 0; i < len; i++) {
-    writer->Write<uint32_t>(ptr()->data_[i]);
-  }
+  StringWriteTo<uint32_t>(writer,
+                          object_id,
+                          ObjectStore::kFourByteStringClass,
+                          serialize_classes,
+                          ptr()->length_,
+                          ptr()->hash_,
+                          ptr()->data_);
 }