Mojo C++ bindings: expose serialization public API for mojo structs.

mojo/public/cpp/bindings/lib/serialization.h

Index: mojo/public/cpp/bindings/lib/serialization.h
diff --git a/mojo/public/cpp/bindings/lib/serialization.h b/mojo/public/cpp/bindings/lib/serialization.h
index 1cda65235c7107b0733c272e1f1dff6e07891a5f..b079c18da031aa55dd09bab6706379b95d0d1629 100644
--- a/mojo/public/cpp/bindings/lib/serialization.h
+++ b/mojo/public/cpp/bindings/lib/serialization.h
@@ -5,14 +5,18 @@
 #ifndef MOJO_PUBLIC_CPP_BINDINGS_LIB_SERIALIZATION_H_
 #define MOJO_PUBLIC_CPP_BINDINGS_LIB_SERIALIZATION_H_
 
+#include <string.h>
+
 #include "mojo/public/cpp/bindings/array_traits_carray.h"
 #include "mojo/public/cpp/bindings/array_traits_standard.h"
 #include "mojo/public/cpp/bindings/array_traits_stl.h"
 #include "mojo/public/cpp/bindings/lib/array_serialization.h"
+#include "mojo/public/cpp/bindings/lib/fixed_buffer.h"
 #include "mojo/public/cpp/bindings/lib/map_serialization.h"
 #include "mojo/public/cpp/bindings/lib/native_enum_serialization.h"
 #include "mojo/public/cpp/bindings/lib/native_struct_serialization.h"
 #include "mojo/public/cpp/bindings/lib/string_serialization.h"
+#include "mojo/public/cpp/bindings/lib/template_util.h"
 #include "mojo/public/cpp/bindings/map_traits_standard.h"
 #include "mojo/public/cpp/bindings/map_traits_stl.h"
 #include "mojo/public/cpp/bindings/string_traits_standard.h"
@@ -20,4 +24,89 @@
 #include "mojo/public/cpp/bindings/string_traits_string16.h"
 #include "mojo/public/cpp/bindings/string_traits_string_piece.h"
 
+namespace mojo {
+namespace internal {
+
+template <typename MojomType, typename DataArrayType, typename UserType>
+DataArrayType StructSerializeImpl(UserType* input) {
+  static_assert(IsSpecializationOf<StructPtr, MojomType>::value ||
+                    IsSpecializationOf<InlinedStructPtr, MojomType>::value,
+                "Unexpected type.");
+
+  SerializationContext context;
+  size_t size = PrepareToSerialize<MojomType>(*input, &context);
+  DCHECK_EQ(size, Align(size));
+
+  DataArrayType result(size);
+  if (size == 0)
+    return result;
+
+  void* result_buffer = &result.front();
+  // The serialization logic requires that the buffer is 8-byte aligned. If the
+  // result buffer is not properly aligned, we have to do an extra copy. In
+  // practice, this should never happen for mojo::Array (backed by std::vector).
+  bool need_copy = !IsAligned(result_buffer);
+
+  if (need_copy) {
+    // calloc sets the memory to all zero.
+    result_buffer = calloc(size, 1);
+    DCHECK(IsAligned(result_buffer));
+  }
+
+  FixedBuffer buffer;
+  buffer.Initialize(result_buffer, size);
+  typename MojomType::Struct::Data_* data = nullptr;
+  Serialize<MojomType>(*input, &buffer, &data, &context);
+
+  data->EncodePointers();
+
+  if (need_copy) {
+    memcpy(&result.front(), result_buffer, size);
+    free(result_buffer);
+  }
+
+  return result;
+}
+
+template <typename MojomType, typename DataArrayType, typename UserType>
+bool StructDeserializeImpl(DataArrayType input, UserType* output) {
+  static_assert(IsSpecializationOf<StructPtr, MojomType>::value ||
+                    IsSpecializationOf<InlinedStructPtr, MojomType>::value,
+                "Unexpected type.");
+  using DataType = typename MojomType::Struct::Data_;
+
+  if (input.is_null())
+    return false;
+
+  void* input_buffer = input.empty() ? nullptr : &input.front();
+
+  // Please see comments in StructSerializeImpl.
+  bool need_copy = !IsAligned(input_buffer);
+
+  if (need_copy) {
+    input_buffer = malloc(input.size());
+    DCHECK(IsAligned(input_buffer));
+    memcpy(input_buffer, &input.front(), input.size());
+  }
+
+  ValidationContext validation_context(input_buffer, input.size(), 0);
+  bool result = false;
+  if (DataType::Validate(input_buffer, &validation_context)) {
+    auto data = reinterpret_cast<DataType*>(input_buffer);
+    if (data)
+      data->DecodePointers();
+
+    SerializationContext context;
+    result = Deserialize<MojomType>(data, output, &context);
+  }
+
+  if (need_copy)
+    free(input_buffer);
+
+  return result;
+}
+
+}  // namespace internal
+}  // namespace mojo
+
 #endif  // MOJO_PUBLIC_CPP_BINDINGS_LIB_SERIALIZATION_H_