[Android] Add GinJavaBridgeValue for Gin Java Bridge

content/common/android/gin_java_bridge_value.cc

+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "content/common/android/gin_java_bridge_value.h"
+
+namespace content {
+
+namespace {
+
+// The magic value is only used to prevent accidental attempts of reading
+// GinJavaBridgeValue from a random BinaryValue.  GinJavaBridgeValue is not
+// intended for scenarios where with BinaryValues are being used for anything
+// else than holding GinJavaBridgeValues.  If a need for such scenario ever
+// emerges, the best solution would be to extend GinJavaBridgeValue to be able
+// to wrap raw BinaryValues.
+const uint32 kHeaderMagic = 0xBEEFCAFE;
+
+#pragma pack(push, 4)
+struct Header : public Pickle::Header {
+  uint32 magic;
+  int32 type;
+};
+#pragma pack(pop)
+
+}
+
+// static
+scoped_ptr<base::BinaryValue> GinJavaBridgeValue::CreateUndefinedValue() {
+  GinJavaBridgeValue gin_value(TYPE_UNDEFINED);
+  return make_scoped_ptr(gin_value.SerializeToBinaryValue());
+}
+
+// static
+scoped_ptr<base::BinaryValue> GinJavaBridgeValue::CreateNonFiniteValue(
+    float in_value) {
+  GinJavaBridgeValue gin_value(TYPE_NONFINITE);
+  gin_value.pickle_.WriteFloat(in_value);
+  return make_scoped_ptr(gin_value.SerializeToBinaryValue());
+}
+
+// static
+scoped_ptr<base::BinaryValue> GinJavaBridgeValue::CreateNonFiniteValue(
+    double in_value) {
+  return CreateNonFiniteValue(static_cast<float>(in_value)).Pass();
+}
+
+// static
+scoped_ptr<base::BinaryValue> GinJavaBridgeValue::CreateObjectIDValue(
+    int32 in_value) {
+  GinJavaBridgeValue gin_value(TYPE_OBJECT_ID);
+  gin_value.pickle_.WriteInt(in_value);
+  return make_scoped_ptr(gin_value.SerializeToBinaryValue());
+}
+
+// static
+bool GinJavaBridgeValue::ContainsGinJavaBridgeValue(const base::Value* value) {
+  if (!value->IsType(base::Value::TYPE_BINARY))
+    return false;
+  const base::BinaryValue* binary_value =
+      reinterpret_cast<const base::BinaryValue*>(value);
+  if (binary_value->GetSize() < sizeof(Header))
+    return false;
+  Pickle pickle(binary_value->GetBuffer(), binary_value->GetSize());
+  // Broken binary value: payload or header size is wrong
+  if (!pickle.data() || pickle.size() - pickle.payload_size() != sizeof(Header))
+    return false;
+  Header* header = pickle.headerT<Header>();
+  return (header->magic == kHeaderMagic &&
+          header->type >= TYPE_FIRST_VALUE && header->type < TYPE_LAST_VALUE);
+}
+
+// static
+scoped_ptr<const GinJavaBridgeValue> GinJavaBridgeValue::FromValue(
+    const base::Value* value) {
+  return scoped_ptr<const GinJavaBridgeValue>(
+      value->IsType(base::Value::TYPE_BINARY)
+          ? new GinJavaBridgeValue(
+                reinterpret_cast<const base::BinaryValue*>(value))
+          : NULL);
+}
+
+GinJavaBridgeValue::Type GinJavaBridgeValue::GetType() const {
+  const Header* header = pickle_.headerT<Header>();
+  DCHECK(header->type >= TYPE_FIRST_VALUE && header->type < TYPE_LAST_VALUE);
+  return static_cast<Type>(header->type);
+}
+
+bool GinJavaBridgeValue::IsType(Type type) const {
+  return GetType() == type;
+}
+
+bool GinJavaBridgeValue::GetAsNonFinite(float* out_value) const {
+  if (GetType() == TYPE_NONFINITE) {
+    PickleIterator iter(pickle_);
+    return iter.ReadFloat(out_value);
+  } else {
+    return false;
+  }
+}
+
+bool GinJavaBridgeValue::GetAsObjectID(int32* out_object_id) const {
+  if (GetType() == TYPE_OBJECT_ID) {
+    PickleIterator iter(pickle_);
+    return iter.ReadInt(out_object_id);
+  } else {
+    return false;
+  }
+}
+
+GinJavaBridgeValue::GinJavaBridgeValue(Type type) :
+    pickle_(sizeof(Header)) {
+  Header* header = pickle_.headerT<Header>();
+  header->magic = kHeaderMagic;
+  header->type = type;
+}
+
+GinJavaBridgeValue::GinJavaBridgeValue(const base::BinaryValue* value)
+    : pickle_(value->GetBuffer(), value->GetSize()) {
+  DCHECK(ContainsGinJavaBridgeValue(value));
+}
+
+base::BinaryValue* GinJavaBridgeValue::SerializeToBinaryValue() {
+  return base::BinaryValue::CreateWithCopiedBuffer(
+      reinterpret_cast<const char*>(pickle_.data()), pickle_.size());
+}
+
+}  // namespace content