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

runtime/vm/raw_object_snapshot.cc

 // 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.
 
 #include "vm/bigint_operations.h"
 #include "vm/object.h"
 #include "vm/object_store.h"
 #include "vm/snapshot.h"
 #include "vm/visitor.h"
 
@@ skipping 972 matching lines @@
 }
 
 
 void RawString::WriteTo(SnapshotWriter* writer,
                         intptr_t object_id,
                         bool serialize_classes) {
   UNREACHABLE();  // String is an abstract class.
 }
 
 
+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 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).*(char_addr))(i) = reader->Read<CharType>();
+  }
+
+  reader->AddBackwardReference(object_id, &str_obj);
+  ((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();
+}
+
+
 RawOneByteString* OneByteString::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<uint8_t, OneByteString, RawOneByteString>(
+      reader,
+      object_id,
+      classes_serialized,
+      &OneByteString::CharAddr,
+      &OneByteString::SetHash);
+}
 
-  // Set up the one byte string object.
-  OneByteString& str_obj = OneByteString::ZoneHandle(
-      OneByteString::New(len, classes_serialized ? Heap::kOld : Heap::kNew));
+
+RawTwoByteString* TwoByteString::ReadFrom(SnapshotReader* reader,
+                                          intptr_t object_id,
+                                          bool classes_serialized) {
+  return ReadStringFrom<uint16_t, TwoByteString, RawTwoByteString>(
+      reader,
+      object_id,
+      classes_serialized,
+      &TwoByteString::CharAddr,
+      &TwoByteString::SetHash);
+}
+
+
+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);
+}
+
+
+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(length);
+
+  // Write out the serialization header value for this object.
+  writer->WriteObjectHeader(kInlined, object_id);
+
+  // Write out the class information.
+  writer->WriteObjectHeader(kObjectId, class_id);
+
+  // Write out the length field.
+  writer->Write<RawObject*>(length);
+
+  // Write out the hash field.
+  writer->Write<RawObject*>(hash);
+
+  // Write out the string.
   for (intptr_t i = 0; i < len; i++) {
-    *str_obj.CharAddr(i) = reader->Read<uint8_t>();
+    writer->Write<CharType>(data[i]);
   }
-
-  reader->AddBackwardReference(object_id, &str_obj);
-  RawOneByteString* raw_str = str_obj.raw();
-  raw_str->ptr()->hash_ = smi_hash;
-  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]);
-  }
-}
-
-
-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>());
-
-  // 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();
+  StringWriteTo<uint8_t>(writer,
+                         object_id,
+                         ObjectStore::kOneByteStringClass,
+                         serialize_classes,
+                         ptr()->length_,
+                         ptr()->hash_,
+                         ptr()->data_);
 }
 
 
 void RawTwoByteString::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::kTwoByteStringClass);
-
-  // 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<uint16_t>(ptr()->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>());
-
-  // 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();
+  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_);
 }
 
 
 RawBool* Bool::ReadFrom(SnapshotReader* reader,
                           intptr_t object_id,
                           bool classes_serialized) {
   UNREACHABLE();
   return Bool::null();
 }
 
@@ skipping 178 matching lines @@
   // Write out all the other fields.
   writer->Write<RawObject*>(ptr()->num_bracket_expressions_);
   writer->WriteObject(ptr()->pattern_);
   writer->Write<intptr_t>(ptr()->type_);
   writer->Write<intptr_t>(ptr()->flags_);
 
   // Do not write out the data part which is native.
 }
 
 }  // namespace dart