Implementation of message reader for converting a message snapshot into a C structure

runtime/vm/snapshot.h

Index: runtime/vm/snapshot.h
diff --git a/runtime/vm/snapshot.h b/runtime/vm/snapshot.h
index 42bff45915c1c5c240608e9edeb42795bcc824ad..fee634782352cdd141c95599dafd6e135b22200b 100644
--- a/runtime/vm/snapshot.h
+++ b/runtime/vm/snapshot.h
@@ -37,6 +37,7 @@ class RawMint;
 class RawObject;
 class RawOneByteString;
 class RawScript;
+class RawSmi;
 class RawTokenStream;
 class RawType;
 class RawTypeParameter;
@@ -193,6 +194,7 @@ class ReadStream : public ValueObject {
 
   // SnapshotReader needs access to the private Raw classes.
   friend class SnapshotReader;
+  friend class CMessageReader;
   DISALLOW_COPY_AND_ASSIGN(ReadStream);
 };
 
@@ -298,12 +300,9 @@ class WriteStream : public ValueObject {
 };
 
 
-// Reads a snapshot into objects.
-class SnapshotReader {
+class BaseReader {
  public:
-  SnapshotReader(const Snapshot* snapshot, Isolate* isolate);
-  ~SnapshotReader() { }
-
+  BaseReader(const uint8_t* buffer, intptr_t size) : stream_(buffer, size) {}
   // Reads raw data (for basic types).
   // sizeof(T) must be in {1,2,4,8}.
   template <typename T>
@@ -318,6 +317,20 @@ class SnapshotReader {
     return value;
   }
 
+  RawSmi* ReadAsSmi();
+  intptr_t ReadSmiValue();
+
+ private:
+  ReadStream stream_;  // input stream.
+};
+
+
+// Reads a snapshot into objects.
+class SnapshotReader : public BaseReader {
+ public:
+  SnapshotReader(const Snapshot* snapshot, Isolate* isolate);
+  ~SnapshotReader() { }
+
   Isolate* isolate() const { return isolate_; }
   Heap* heap() const { return isolate_->heap(); }
   ObjectStore* object_store() const { return isolate_->object_store(); }
@@ -377,7 +390,6 @@ class SnapshotReader {
   // Based on header field check to see if it is an internal VM class.
   RawClass* LookupInternalClass(intptr_t class_header);
 
-  ReadStream stream_;  // input stream.
   Snapshot::Kind kind_;  // Indicates type of snapshot(full, script, message).
   Isolate* isolate_;  // Current isolate.
   Class& cls_;  // Temporary Class handle.
@@ -392,6 +404,41 @@ class SnapshotReader {
 };
 
 
+// Reads a message snapshot into C structure.
+class CMessageReader : public BaseReader {
+ public:
+  CMessageReader(const uint8_t* buffer, intptr_t length, ReAlloc alloc);
+  ~CMessageReader() { }
+
+  Dart_CObject* ReadObject();
+
+ private:
+  // Allocates a Dart_CObject object on the C heap.
+  Dart_CObject* AllocateDartValue();
+  // Allocates a Dart_CObject object with the specified type on the C heap.
+  Dart_CObject* AllocateDartValue(Dart_CObject::Type type);
+  // Allocates a Dart_CObject object for the null object on the C heap.
+  Dart_CObject* AllocateDartValueNull();
+  // Allocates a Dart_CObject object for a boolean object on the C heap.
+  Dart_CObject* AllocateDartValueBool(bool value);
+  // Allocates a Dart_CObject object for for a 32-bit integer on the C heap.
+  Dart_CObject* AllocateDartValueInt32(int32_t value);
+  // Allocates a Dart_CObject object for a double on the C heap.
+  Dart_CObject* AllocateDartValueDouble(double value);
+  // Allocates a Dart_CObject object for string data on the C heap.
+  Dart_CObject* AllocateDartValueString(intptr_t length);
+  // Allocates a C array of Dart_CObject objects on the C heap.
+  Dart_CObject* AllocateDartValueArray(intptr_t length);
+
+  intptr_t LookupInternalClass(intptr_t class_header);
+  Dart_CObject* ReadInlinedObject(intptr_t object_id);
+  Dart_CObject* ReadObjectImpl(intptr_t header);
+  Dart_CObject* ReadIndexedObject(intptr_t object_id);
+
+  ReAlloc alloc_;
+};
+
+
 class BaseWriter {
  public:
   // Size of the snapshot.