Pull new version of protobuf sources.

third_party/protobuf/src/google/protobuf/util/internal/protostream_objectwriter.cc

Index: third_party/protobuf/src/google/protobuf/util/internal/protostream_objectwriter.cc
diff --git a/third_party/protobuf/src/google/protobuf/util/internal/protostream_objectwriter.cc b/third_party/protobuf/src/google/protobuf/util/internal/protostream_objectwriter.cc
new file mode 100644
index 0000000000000000000000000000000000000000..f9ddbf326d4c58b7b84c82dac2d24e2b9c0ef203
--- /dev/null
+++ b/third_party/protobuf/src/google/protobuf/util/internal/protostream_objectwriter.cc
@@ -0,0 +1,1557 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#include <google/protobuf/util/internal/protostream_objectwriter.h>
+
+#include <functional>
+#include <stack>
+
+#include <google/protobuf/stubs/time.h>
+#include <google/protobuf/wire_format_lite.h>
+#include <google/protobuf/util/internal/field_mask_utility.h>
+#include <google/protobuf/util/internal/object_location_tracker.h>
+#include <google/protobuf/util/internal/constants.h>
+#include <google/protobuf/util/internal/utility.h>
+#include <google/protobuf/stubs/strutil.h>
+#include <google/protobuf/stubs/map_util.h>
+#include <google/protobuf/stubs/statusor.h>
+
+
+namespace google {
+namespace protobuf {
+namespace util {
+namespace converter {
+
+using google::protobuf::internal::WireFormatLite;
+using google::protobuf::io::CodedOutputStream;
+using util::error::INVALID_ARGUMENT;
+using util::Status;
+using util::StatusOr;
+
+
+ProtoStreamObjectWriter::ProtoStreamObjectWriter(
+    TypeResolver* type_resolver, const google::protobuf::Type& type,
+    strings::ByteSink* output, ErrorListener* listener)
+    : master_type_(type),
+      typeinfo_(TypeInfo::NewTypeInfo(type_resolver)),
+      own_typeinfo_(true),
+      done_(false),
+      element_(NULL),
+      size_insert_(),
+      output_(output),
+      buffer_(),
+      adapter_(&buffer_),
+      stream_(new CodedOutputStream(&adapter_)),
+      listener_(listener),
+      invalid_depth_(0),
+      tracker_(new ObjectLocationTracker()) {}
+
+ProtoStreamObjectWriter::ProtoStreamObjectWriter(
+    TypeInfo* typeinfo, const google::protobuf::Type& type,
+    strings::ByteSink* output, ErrorListener* listener)
+    : master_type_(type),
+      typeinfo_(typeinfo),
+      own_typeinfo_(false),
+      done_(false),
+      element_(NULL),
+      size_insert_(),
+      output_(output),
+      buffer_(),
+      adapter_(&buffer_),
+      stream_(new CodedOutputStream(&adapter_)),
+      listener_(listener),
+      invalid_depth_(0),
+      tracker_(new ObjectLocationTracker()) {}
+
+ProtoStreamObjectWriter::~ProtoStreamObjectWriter() {
+  // Cleanup explicitly in order to avoid destructor stack overflow when input
+  // is deeply nested.
+  while (element_ != NULL) {
+    element_.reset(element_->pop());
+  }
+  if (own_typeinfo_) {
+    delete typeinfo_;
+  }
+}
+
+namespace {
+
+// Writes an INT32 field, including tag to the stream.
+inline Status WriteInt32(int field_number, const DataPiece& data,
+                         CodedOutputStream* stream) {
+  StatusOr<int32> i32 = data.ToInt32();
+  if (i32.ok()) {
+    WireFormatLite::WriteInt32(field_number, i32.ValueOrDie(), stream);
+  }
+  return i32.status();
+}
+
+// writes an SFIXED32 field, including tag, to the stream.
+inline Status WriteSFixed32(int field_number, const DataPiece& data,
+                            CodedOutputStream* stream) {
+  StatusOr<int32> i32 = data.ToInt32();
+  if (i32.ok()) {
+    WireFormatLite::WriteSFixed32(field_number, i32.ValueOrDie(), stream);
+  }
+  return i32.status();
+}
+
+// Writes an SINT32 field, including tag, to the stream.
+inline Status WriteSInt32(int field_number, const DataPiece& data,
+                          CodedOutputStream* stream) {
+  StatusOr<int32> i32 = data.ToInt32();
+  if (i32.ok()) {
+    WireFormatLite::WriteSInt32(field_number, i32.ValueOrDie(), stream);
+  }
+  return i32.status();
+}
+
+// Writes a FIXED32 field, including tag, to the stream.
+inline Status WriteFixed32(int field_number, const DataPiece& data,
+                           CodedOutputStream* stream) {
+  StatusOr<uint32> u32 = data.ToUint32();
+  if (u32.ok()) {
+    WireFormatLite::WriteFixed32(field_number, u32.ValueOrDie(), stream);
+  }
+  return u32.status();
+}
+
+// Writes a UINT32 field, including tag, to the stream.
+inline Status WriteUInt32(int field_number, const DataPiece& data,
+                          CodedOutputStream* stream) {
+  StatusOr<uint32> u32 = data.ToUint32();
+  if (u32.ok()) {
+    WireFormatLite::WriteUInt32(field_number, u32.ValueOrDie(), stream);
+  }
+  return u32.status();
+}
+
+// Writes an INT64 field, including tag, to the stream.
+inline Status WriteInt64(int field_number, const DataPiece& data,
+                         CodedOutputStream* stream) {
+  StatusOr<int64> i64 = data.ToInt64();
+  if (i64.ok()) {
+    WireFormatLite::WriteInt64(field_number, i64.ValueOrDie(), stream);
+  }
+  return i64.status();
+}
+
+// Writes an SFIXED64 field, including tag, to the stream.
+inline Status WriteSFixed64(int field_number, const DataPiece& data,
+                            CodedOutputStream* stream) {
+  StatusOr<int64> i64 = data.ToInt64();
+  if (i64.ok()) {
+    WireFormatLite::WriteSFixed64(field_number, i64.ValueOrDie(), stream);
+  }
+  return i64.status();
+}
+
+// Writes an SINT64 field, including tag, to the stream.
+inline Status WriteSInt64(int field_number, const DataPiece& data,
+                          CodedOutputStream* stream) {
+  StatusOr<int64> i64 = data.ToInt64();
+  if (i64.ok()) {
+    WireFormatLite::WriteSInt64(field_number, i64.ValueOrDie(), stream);
+  }
+  return i64.status();
+}
+
+// Writes a FIXED64 field, including tag, to the stream.
+inline Status WriteFixed64(int field_number, const DataPiece& data,
+                           CodedOutputStream* stream) {
+  StatusOr<uint64> u64 = data.ToUint64();
+  if (u64.ok()) {
+    WireFormatLite::WriteFixed64(field_number, u64.ValueOrDie(), stream);
+  }
+  return u64.status();
+}
+
+// Writes a UINT64 field, including tag, to the stream.
+inline Status WriteUInt64(int field_number, const DataPiece& data,
+                          CodedOutputStream* stream) {
+  StatusOr<uint64> u64 = data.ToUint64();
+  if (u64.ok()) {
+    WireFormatLite::WriteUInt64(field_number, u64.ValueOrDie(), stream);
+  }
+  return u64.status();
+}
+
+// Writes a DOUBLE field, including tag, to the stream.
+inline Status WriteDouble(int field_number, const DataPiece& data,
+                          CodedOutputStream* stream) {
+  StatusOr<double> d = data.ToDouble();
+  if (d.ok()) {
+    WireFormatLite::WriteDouble(field_number, d.ValueOrDie(), stream);
+  }
+  return d.status();
+}
+
+// Writes a FLOAT field, including tag, to the stream.
+inline Status WriteFloat(int field_number, const DataPiece& data,
+                         CodedOutputStream* stream) {
+  StatusOr<float> f = data.ToFloat();
+  if (f.ok()) {
+    WireFormatLite::WriteFloat(field_number, f.ValueOrDie(), stream);
+  }
+  return f.status();
+}
+
+// Writes a BOOL field, including tag, to the stream.
+inline Status WriteBool(int field_number, const DataPiece& data,
+                        CodedOutputStream* stream) {
+  StatusOr<bool> b = data.ToBool();
+  if (b.ok()) {
+    WireFormatLite::WriteBool(field_number, b.ValueOrDie(), stream);
+  }
+  return b.status();
+}
+
+// Writes a BYTES field, including tag, to the stream.
+inline Status WriteBytes(int field_number, const DataPiece& data,
+                         CodedOutputStream* stream) {
+  StatusOr<string> c = data.ToBytes();
+  if (c.ok()) {
+    WireFormatLite::WriteBytes(field_number, c.ValueOrDie(), stream);
+  }
+  return c.status();
+}
+
+// Writes a STRING field, including tag, to the stream.
+inline Status WriteString(int field_number, const DataPiece& data,
+                          CodedOutputStream* stream) {
+  StatusOr<string> s = data.ToString();
+  if (s.ok()) {
+    WireFormatLite::WriteString(field_number, s.ValueOrDie(), stream);
+  }
+  return s.status();
+}
+
+// Writes an ENUM field, including tag, to the stream.
+inline Status WriteEnum(int field_number, const DataPiece& data,
+                        const google::protobuf::Enum* enum_type,
+                        CodedOutputStream* stream) {
+  StatusOr<int> e = data.ToEnum(enum_type);
+  if (e.ok()) {
+    WireFormatLite::WriteEnum(field_number, e.ValueOrDie(), stream);
+  }
+  return e.status();
+}
+
+// Given a google::protobuf::Type, returns the set of all required fields.
+std::set<const google::protobuf::Field*> GetRequiredFields(
+    const google::protobuf::Type& type) {
+  std::set<const google::protobuf::Field*> required;
+  for (int i = 0; i < type.fields_size(); i++) {
+    const google::protobuf::Field& field = type.fields(i);
+    if (field.cardinality() ==
+        google::protobuf::Field_Cardinality_CARDINALITY_REQUIRED) {
+      required.insert(&field);
+    }
+  }
+  return required;
+}
+
+// Utility method to split a string representation of Timestamp or Duration and
+// return the parts.
+void SplitSecondsAndNanos(StringPiece input, StringPiece* seconds,
+                          StringPiece* nanos) {
+  size_t idx = input.rfind('.');
+  if (idx != string::npos) {
+    *seconds = input.substr(0, idx);
+    *nanos = input.substr(idx + 1);
+  } else {
+    *seconds = input;
+    *nanos = StringPiece();
+  }
+}
+
+}  // namespace
+
+ProtoStreamObjectWriter::AnyWriter::AnyWriter(ProtoStreamObjectWriter* parent)
+    : parent_(parent),
+      ow_(),
+      invalid_(false),
+      data_(),
+      output_(&data_),
+      depth_(0),
+      has_injected_value_message_(false) {}
+
+ProtoStreamObjectWriter::AnyWriter::~AnyWriter() {}
+
+void ProtoStreamObjectWriter::AnyWriter::StartObject(StringPiece name) {
+  ++depth_;
+  // If an object writer is absent, that means we have not called StartAny()
+  // before reaching here. This is an invalid state. StartAny() gets called
+  // whenever we see an "@type" being rendered (see AnyWriter::RenderDataPiece).
+  if (ow_ == NULL) {
+    // Make sure we are not already in an invalid state. This avoids making
+    // multiple unnecessary InvalidValue calls.
+    if (!invalid_) {
+      parent_->InvalidValue("Any",
+                            StrCat("Missing or invalid @type for any field in ",
+                                   parent_->master_type_.name()));
+      invalid_ = true;
+    }
+  } else if (!has_injected_value_message_ || depth_ != 1 || name != "value") {
+    // We don't propagate to ow_ StartObject("value") calls for nested Anys or
+    // Struct at depth 1 as they are nested one level deep with an injected
+    // "value" field.
+    ow_->StartObject(name);
+  }
+}
+
+bool ProtoStreamObjectWriter::AnyWriter::EndObject() {
+  --depth_;
+  // As long as depth_ >= 0, we know we haven't reached the end of Any.
+  // Propagate these EndObject() calls to the contained ow_.  If we are in a
+  // nested Any or Struct type, ignore the second to last EndObject call (depth_
+  // == -1)
+  if (ow_ != NULL && (!has_injected_value_message_ || depth_ >= 0)) {
+    ow_->EndObject();
+  }
+  // A negative depth_ implies that we have reached the end of Any
+  // object. Now we write out its contents.
+  if (depth_ < 0) {
+    WriteAny();
+    return false;
+  }
+  return true;
+}
+
+void ProtoStreamObjectWriter::AnyWriter::StartList(StringPiece name) {
+  ++depth_;
+  // We expect ow_ to be present as this call only makes sense inside an Any.
+  if (ow_ == NULL) {
+    if (!invalid_) {
+      parent_->InvalidValue("Any",
+                            StrCat("Missing or invalid @type for any field in ",
+                                   parent_->master_type_.name()));
+      invalid_ = true;
+    }
+  } else {
+    ow_->StartList(name);
+  }
+}
+
+void ProtoStreamObjectWriter::AnyWriter::EndList() {
+  --depth_;
+  if (depth_ < 0) {
+    GOOGLE_LOG(DFATAL) << "Mismatched EndList found, should not be possible";
+    depth_ = 0;
+  }
+  // We don't write an error on the close, only on the open
+  if (ow_ != NULL) {
+    ow_->EndList();
+  }
+}
+
+void ProtoStreamObjectWriter::AnyWriter::RenderDataPiece(
+    StringPiece name, const DataPiece& value) {
+  // Start an Any only at depth_ 0. Other RenderDataPiece calls with "@type"
+  // should go to the contained ow_ as they indicate nested Anys.
+  if (depth_ == 0 && ow_ == NULL && name == "@type") {
+    StartAny(value);
+  } else if (ow_ == NULL) {
+    if (!invalid_) {
+      parent_->InvalidValue("Any",
+                            StrCat("Missing or invalid @type for any field in ",
+                                   parent_->master_type_.name()));
+      invalid_ = true;
+    }
+  } else {
+    // Check to see if the data needs to be rendered with well-known-type
+    // renderer.
+    const TypeRenderer* type_renderer =
+        FindTypeRenderer(GetFullTypeWithUrl(ow_->master_type_.name()));
+    if (type_renderer) {
+      // TODO(rikka): Don't just ignore the util::Status object!
+      (*type_renderer)(ow_.get(), value);
+    } else {
+      ow_->RenderDataPiece(name, value);
+    }
+  }
+}
+
+void ProtoStreamObjectWriter::AnyWriter::StartAny(const DataPiece& value) {
+  // Figure out the type url. This is a copy-paste from WriteString but we also
+  // need the value, so we can't just call through to that.
+  if (value.type() == DataPiece::TYPE_STRING) {
+    type_url_ = value.str().ToString();
+  } else {
+    StatusOr<string> s = value.ToString();
+    if (!s.ok()) {
+      parent_->InvalidValue("String", s.status().error_message());
+      invalid_ = true;
+      return;
+    }
+    type_url_ = s.ValueOrDie();
+  }
+  // Resolve the type url, and report an error if we failed to resolve it.
+  StatusOr<const google::protobuf::Type*> resolved_type =
+      parent_->typeinfo_->ResolveTypeUrl(type_url_);
+  if (!resolved_type.ok()) {
+    parent_->InvalidValue("Any", resolved_type.status().error_message());
+    invalid_ = true;
+    return;
+  }
+  // At this point, type is never null.
+  const google::protobuf::Type* type = resolved_type.ValueOrDie();
+
+  // If this is the case of an Any in an Any or Struct in an Any, we need to
+  // expect a StartObject call with "value" while we're at depth_ 0, which we
+  // should ignore (not propagate to our nested object writer). We also need to
+  // ignore the second-to-last EndObject call, and not propagate that either.
+  if (type->name() == kAnyType || type->name() == kStructType) {
+    has_injected_value_message_ = true;
+  }
+
+  // Create our object writer and initialize it with the first StartObject
+  // call.
+  ow_.reset(new ProtoStreamObjectWriter(parent_->typeinfo_, *type, &output_,
+                                        parent_->listener_));
+  ow_->StartObject("");
+}
+
+void ProtoStreamObjectWriter::AnyWriter::WriteAny() {
+  if (ow_ == NULL) {
+    // If we had no object writer, we never got any content, so just return
+    // immediately, which is equivalent to writing an empty Any.
+    return;
+  }
+  // Render the type_url and value fields directly to the stream.
+  // type_url has tag 1 and value has tag 2.
+  WireFormatLite::WriteString(1, type_url_, parent_->stream_.get());
+  if (!data_.empty()) {
+    WireFormatLite::WriteBytes(2, data_, parent_->stream_.get());
+  }
+}
+
+ProtoStreamObjectWriter::ProtoElement::ProtoElement(
+    TypeInfo* typeinfo, const google::protobuf::Type& type,
+    ProtoStreamObjectWriter* enclosing)
+    : BaseElement(NULL),
+      ow_(enclosing),
+      any_(),
+      field_(NULL),
+      typeinfo_(typeinfo),
+      type_(type),
+      required_fields_(GetRequiredFields(type)),
+      is_repeated_type_(false),
+      size_index_(-1),
+      array_index_(-1),
+      element_type_(GetElementType(type_)) {
+  if (element_type_ == ANY) {
+    any_.reset(new AnyWriter(ow_));
+  }
+}
+
+ProtoStreamObjectWriter::ProtoElement::ProtoElement(
+    ProtoStreamObjectWriter::ProtoElement* parent,
+    const google::protobuf::Field* field, const google::protobuf::Type& type,
+    ElementType element_type)
+    : BaseElement(parent),
+      ow_(this->parent()->ow_),
+      any_(),
+      field_(field),
+      typeinfo_(this->parent()->typeinfo_),
+      type_(type),
+      is_repeated_type_(element_type == ProtoElement::LIST ||
+                        element_type == ProtoElement::STRUCT_LIST ||
+                        element_type == ProtoElement::MAP ||
+                        element_type == ProtoElement::STRUCT_MAP),
+      size_index_(!is_repeated_type_ &&
+                          field->kind() ==
+                              google::protobuf::Field_Kind_TYPE_MESSAGE
+                      ? ow_->size_insert_.size()
+                      : -1),
+      array_index_(is_repeated_type_ ? 0 : -1),
+      element_type_(element_type) {
+  if (!is_repeated_type_) {
+    if (field->cardinality() ==
+        google::protobuf::Field_Cardinality_CARDINALITY_REPEATED) {
+      // Update array_index_ if it is an explicit list.
+      if (this->parent()->array_index_ >= 0) this->parent()->array_index_++;
+    } else {
+      this->parent()->RegisterField(field);
+    }
+    if (field->kind() == google::protobuf::Field_Kind_TYPE_MESSAGE) {
+      required_fields_ = GetRequiredFields(type_);
+      int start_pos = ow_->stream_->ByteCount();
+      // length of serialized message is the final buffer position minus
+      // starting buffer position, plus length adjustments for size fields
+      // of any nested messages. We start with -start_pos here, so we only
+      // need to add the final buffer position to it at the end.
+      SizeInfo info = {start_pos, -start_pos};
+      ow_->size_insert_.push_back(info);
+    }
+  }
+  if (element_type == ANY) {
+    any_.reset(new AnyWriter(ow_));
+  }
+}
+
+ProtoStreamObjectWriter::ProtoElement*
+ProtoStreamObjectWriter::ProtoElement::pop() {
+  // Calls the registered error listener for any required field(s) not yet
+  // seen.
+  for (set<const google::protobuf::Field*>::iterator it =
+           required_fields_.begin();
+       it != required_fields_.end(); ++it) {
+    ow_->MissingField((*it)->name());
+  }
+  // Computes the total number of proto bytes used by a message, also adjusts
+  // the size of all parent messages by the length of this size field.
+  // If size_index_ < 0, this is not a message, so no size field is added.
+  if (size_index_ >= 0) {
+    // Add the final buffer position to compute the total length of this
+    // serialized message. The stored value (before this addition) already
+    // contains the total length of the size fields of all nested messages
+    // minus the initial buffer position.
+    ow_->size_insert_[size_index_].size += ow_->stream_->ByteCount();
+    // Calculate the length required to serialize the size field of the
+    // message, and propagate this additional size information upward to
+    // all enclosing messages.
+    int size = ow_->size_insert_[size_index_].size;
+    int length = CodedOutputStream::VarintSize32(size);
+    for (ProtoElement* e = parent(); e != NULL; e = e->parent()) {
+      // Only nested messages have size field, lists do not have size field.
+      if (e->size_index_ >= 0) {
+        ow_->size_insert_[e->size_index_].size += length;
+      }
+    }
+  }
+  return BaseElement::pop<ProtoElement>();
+}
+
+void ProtoStreamObjectWriter::ProtoElement::RegisterField(
+    const google::protobuf::Field* field) {
+  if (!required_fields_.empty() &&
+      field->cardinality() ==
+          google::protobuf::Field_Cardinality_CARDINALITY_REQUIRED) {
+    required_fields_.erase(field);
+  }
+}
+
+string ProtoStreamObjectWriter::ProtoElement::ToString() const {
+  if (parent() == NULL) return "";
+  string loc = parent()->ToString();
+  if (field_->cardinality() !=
+          google::protobuf::Field_Cardinality_CARDINALITY_REPEATED ||
+      parent()->field_ != field_) {
+    string name = field_->name();
+    int i = 0;
+    while (i < name.size() && (ascii_isalnum(name[i]) || name[i] == '_')) ++i;
+    if (i > 0 && i == name.size()) {  // safe field name
+      if (loc.empty()) {
+        loc = name;
+      } else {
+        StrAppend(&loc, ".", name);
+      }
+    } else {
+      StrAppend(&loc, "[\"", CEscape(name), "\"]");
+    }
+  }
+  if (field_->cardinality() ==
+          google::protobuf::Field_Cardinality_CARDINALITY_REPEATED &&
+      array_index_ > 0) {
+    StrAppend(&loc, "[", array_index_ - 1, "]");
+  }
+  return loc.empty() ? "." : loc;
+}
+
+inline void ProtoStreamObjectWriter::InvalidName(StringPiece unknown_name,
+                                                 StringPiece message) {
+  listener_->InvalidName(location(), ToSnakeCase(unknown_name), message);
+}
+
+inline void ProtoStreamObjectWriter::InvalidValue(StringPiece type_name,
+                                                  StringPiece value) {
+  listener_->InvalidValue(location(), type_name, value);
+}
+
+inline void ProtoStreamObjectWriter::MissingField(StringPiece missing_name) {
+  listener_->MissingField(location(), missing_name);
+}
+
+ProtoStreamObjectWriter* ProtoStreamObjectWriter::StartObject(
+    StringPiece name) {
+  // Starting the root message. Create the root ProtoElement and return.
+  if (element_ == NULL) {
+    if (!name.empty()) {
+      InvalidName(name, "Root element should not be named.");
+    }
+    element_.reset(new ProtoElement(typeinfo_, master_type_, this));
+
+    // If master type is a special type that needs extra values to be written to
+    // stream, we write those values.
+    if (master_type_.name() == kStructType) {
+      StartStruct(NULL);
+    } else if (master_type_.name() == kStructValueType) {
+      // We got a StartObject call with google.protobuf.Value field. This means
+      // we are starting an object within google.protobuf.Value type. The only
+      // object within that type is a struct type. So start a struct.
+      const google::protobuf::Field* field = StartStructValueInStruct(NULL);
+      StartStruct(field);
+    }
+    return this;
+  }
+
+  const google::protobuf::Field* field = NULL;
+  if (element_ != NULL && element_->IsAny()) {
+    element_->any()->StartObject(name);
+    return this;
+  } else if (element_ != NULL &&
+             (element_->IsMap() || element_->IsStructMap())) {
+    field = StartMapEntry(name);
+    if (element_->IsStructMapEntry()) {
+      // If the top element is a map entry, this means we are starting another
+      // struct within a struct.
+      field = StartStructValueInStruct(field);
+    }
+  } else if (element_ != NULL && element_->IsStructList()) {
+    // If the top element is a list, then we are starting a list field within a
+    // struct.
+    field = Lookup(name);
+    field = StartStructValueInStruct(field);
+  } else {
+    field = BeginNamed(name, false);
+  }
+  if (field == NULL) {
+    return this;
+  }
+
+  const google::protobuf::Type* type = LookupType(field);
+  if (type == NULL) {
+    ++invalid_depth_;
+    InvalidName(name,
+                StrCat("Missing descriptor for field: ", field->type_url()));
+    return this;
+  }
+
+  if (field->type_url() == GetFullTypeWithUrl(kStructType)) {
+    // Start a struct object.
+    StartStruct(field);
+  } else if (field->type_url() == GetFullTypeWithUrl(kStructValueType)) {
+    // We got a StartObject call with google.protobuf.Value field. This means we
+    // are starting an object within google.protobuf.Value type. The only object
+    // within that type is a struct type. So start a struct.
+    field = StartStructValueInStruct(field);
+    StartStruct(field);
+  } else if (field->type_url() == GetFullTypeWithUrl(kAnyType)) {
+    // Begin an Any. We can't do the real work till we get the @type field.
+    WriteTag(*field);
+    element_.reset(
+        new ProtoElement(element_.release(), field, *type, ProtoElement::ANY));
+  } else if (IsMap(*field)) {
+    // Begin a map.
+    // A map is triggered by a StartObject() call if the current field has a map
+    // type. Map values are written to proto in a manner detailed in comments
+    // above StartMapEntry() function.
+    element_.reset(
+        new ProtoElement(element_.release(), field, *type, ProtoElement::MAP));
+  } else {
+    WriteTag(*field);
+    element_.reset(new ProtoElement(element_.release(), field, *type,
+                                    ProtoElement::MESSAGE));
+  }
+  return this;
+}
+
+// Proto3 maps are represented on the wire as a message with
+// "key" and a "value".
+//
+// For example, the syntax:
+// map<key_type, value_type> map_field = N;
+//
+// is represented as:
+// message MapFieldEntry {
+//   option map_entry = true;   // marks the map construct in the descriptor
+//
+//   key_type key = 1;
+//   value_type value = 2;
+// }
+// repeated MapFieldEntry map_field = N;
+//
+// See go/proto3-maps for more information.
+const google::protobuf::Field* ProtoStreamObjectWriter::StartMapEntry(
+    StringPiece name) {
+  // top of stack is already a map field
+  const google::protobuf::Field* field = element_->field();
+  const google::protobuf::Type& type = element_->type();
+  // If we come from a regular map, use MAP_ENTRY or if we come from a struct,
+  // use STRUCT_MAP_ENTRY. These values are used later in StartObject/StartList
+  // or RenderDataPiece for making appropriate decisions.
+  ProtoElement::ElementType element_type = element_->IsStructMap()
+                                               ? ProtoElement::STRUCT_MAP_ENTRY
+                                               : ProtoElement::MAP_ENTRY;
+  WriteTag(*field);
+  element_.reset(
+      new ProtoElement(element_.release(), field, type, element_type));
+  RenderDataPiece("key", DataPiece(name));
+  return BeginNamed("value", false);
+}
+
+// Starts a google.protobuf.Struct.
+// 'field' represents a field in a message of type google.protobuf.Struct.  A
+// struct contains a map with name 'fields'. This function starts this map as
+// well.
+// When 'field' is NULL, it means that the top level message is of struct
+// type.
+void ProtoStreamObjectWriter::StartStruct(
+    const google::protobuf::Field* field) {
+  const google::protobuf::Type* type = NULL;
+  if (field) {
+    type = LookupType(field);
+    WriteTag(*field);
+    element_.reset(new ProtoElement(element_.release(), field, *type,
+                                    ProtoElement::STRUCT));
+  }
+  const google::protobuf::Field* struct_field = BeginNamed("fields", false);
+
+  if (!struct_field) {
+    // It is a programmatic error if this happens. Log an error.
+    GOOGLE_LOG(ERROR) << "Invalid internal state. Cannot find 'fields' within "
+               << (field ? field->type_url() : "google.protobuf.Struct");
+    return;
+  }
+
+  type = LookupType(struct_field);
+  element_.reset(new ProtoElement(element_.release(), struct_field, *type,
+                                  ProtoElement::STRUCT_MAP));
+}
+
+// Starts a "struct_value" within struct.proto's google.protobuf.Value type.
+// 'field' should be of the type google.protobuf.Value.
+// Returns the field identifying "struct_value" within the given field.
+//
+// If field is NULL, then we are starting struct_value at the top-level, in
+// this case skip writing any tag information for the passed field.
+const google::protobuf::Field*
+ProtoStreamObjectWriter::StartStructValueInStruct(
+    const google::protobuf::Field* field) {
+  if (field) {
+    const google::protobuf::Type* type = LookupType(field);
+    WriteTag(*field);
+    element_.reset(new ProtoElement(element_.release(), field, *type,
+                                    ProtoElement::STRUCT_VALUE));
+  }
+  return BeginNamed("struct_value", false);
+}
+
+// Starts a "list_value" within struct.proto's google.protobuf.Value type.
+// 'field' should be of the type google.protobuf.Value.
+// Returns the field identifying "list_value" within the given field.
+//
+// If field is NULL, then we are starting list_value at the top-level, in
+// this case skip writing any tag information for the passed field.
+const google::protobuf::Field* ProtoStreamObjectWriter::StartListValueInStruct(
+    const google::protobuf::Field* field) {
+  if (field) {
+    const google::protobuf::Type* type = LookupType(field);
+    WriteTag(*field);
+    element_.reset(new ProtoElement(element_.release(), field, *type,
+                                    ProtoElement::STRUCT_VALUE));
+  }
+  const google::protobuf::Field* list_value = BeginNamed("list_value", false);
+
+  if (!list_value) {
+    // It is a programmatic error if this happens. Log an error.
+    GOOGLE_LOG(ERROR) << "Invalid internal state. Cannot find 'list_value' within "
+               << (field ? field->type_url() : "google.protobuf.Value");
+    return field;
+  }
+
+  return StartRepeatedValuesInListValue(list_value);
+}
+
+// Starts the repeated "values" field in struct.proto's
+// google.protobuf.ListValue type. 'field' should be of type
+// google.protobuf.ListValue.
+//
+// If field is NULL, then we are starting ListValue at the top-level, in
+// this case skip writing any tag information for the passed field.
+const google::protobuf::Field*
+ProtoStreamObjectWriter::StartRepeatedValuesInListValue(
+    const google::protobuf::Field* field) {
+  if (field) {
+    const google::protobuf::Type* type = LookupType(field);
+    WriteTag(*field);
+    element_.reset(new ProtoElement(element_.release(), field, *type,
+                                    ProtoElement::STRUCT_LIST_VALUE));
+  }
+  return BeginNamed("values", true);
+}
+
+void ProtoStreamObjectWriter::SkipElements() {
+  if (element_ == NULL) return;
+
+  ProtoElement::ElementType element_type = element_->element_type();
+  while (element_type == ProtoElement::STRUCT ||
+         element_type == ProtoElement::STRUCT_LIST_VALUE ||
+         element_type == ProtoElement::STRUCT_VALUE ||
+         element_type == ProtoElement::STRUCT_MAP_ENTRY ||
+         element_type == ProtoElement::MAP_ENTRY) {
+    element_.reset(element_->pop());
+    element_type =
+        element_ != NULL ? element_->element_type() : ProtoElement::MESSAGE;
+  }
+}
+
+ProtoStreamObjectWriter* ProtoStreamObjectWriter::EndObject() {
+  if (invalid_depth_ > 0) {
+    --invalid_depth_;
+    return this;
+  }
+  if (element_ != NULL && element_->IsAny()) {
+    if (element_->any()->EndObject()) {
+      return this;
+    }
+  }
+  if (element_ != NULL) {
+    element_.reset(element_->pop());
+  }
+
+  // Skip sentinel elements added to keep track of new proto3 types - map,
+  // struct.
+  SkipElements();
+
+  // If ending the root element,
+  // then serialize the full message with calculated sizes.
+  if (element_ == NULL) {
+    WriteRootMessage();
+  }
+  return this;
+}
+
+ProtoStreamObjectWriter* ProtoStreamObjectWriter::StartList(StringPiece name) {
+  const google::protobuf::Field* field = NULL;
+  // Since we cannot have a top-level repeated item in protobuf, the only way
+  // element_ can be null when here is when we start a top-level list
+  // google.protobuf.ListValue.
+  if (element_ == NULL) {
+    if (!name.empty()) {
+      InvalidName(name, "Root element should not be named.");
+    }
+    element_.reset(new ProtoElement(typeinfo_, master_type_, this));
+
+    // If master type is a special type that needs extra values to be written to
+    // stream, we write those values.
+    if (master_type_.name() == kStructValueType) {
+      // We got a StartList with google.protobuf.Value master type. This means
+      // we have to start the "list_value" within google.protobuf.Value.
+      field = StartListValueInStruct(NULL);
+    } else if (master_type_.name() == kStructListValueType) {
+      // We got a StartList with google.protobuf.ListValue master type. This
+      // means we have to start the "values" within google.protobuf.ListValue.
+      field = StartRepeatedValuesInListValue(NULL);
+    }
+
+    // field is NULL when master_type_ is anything other than
+    // google.protobuf.Value or google.protobuf.ListValue.
+    if (field) {
+      const google::protobuf::Type* type = LookupType(field);
+      element_.reset(new ProtoElement(element_.release(), field, *type,
+                                      ProtoElement::STRUCT_LIST));
+    }
+    return this;
+  }
+
+  if (element_->IsAny()) {
+    element_->any()->StartList(name);
+    return this;
+  }
+  // The type of element we push to stack.
+  ProtoElement::ElementType element_type = ProtoElement::LIST;
+
+  // Check if we need to start a map. This can heppen when there is either a map
+  // or a struct type within a list.
+  if (element_->IsMap() || element_->IsStructMap()) {
+    field = StartMapEntry(name);
+    if (field == NULL) return this;
+
+    if (element_->IsStructMapEntry()) {
+      // If the top element is a map entry, this means we are starting a list
+      // within a struct or a map.
+      // An example sequence of calls would be
+      //    StartObject -> StartList
+      field = StartListValueInStruct(field);
+      if (field == NULL) return this;
+    }
+
+    element_type = ProtoElement::STRUCT_LIST;
+  } else if (element_->IsStructList()) {
+    // If the top element is a STRUCT_LIST, this means we are starting a list
+    // within the current list (inside a struct).
+    // An example call sequence would be
+    //    StartObject -> StartList -> StartList
+    // with StartObject starting a struct.
+
+    // Lookup the last list type in element stack as we are adding an element of
+    // the same type.
+    field = Lookup(name);
+    if (field == NULL) return this;
+
+    field = StartListValueInStruct(field);
+    if (field == NULL) return this;
+
+    element_type = ProtoElement::STRUCT_LIST;
+  } else {
+    // Lookup field corresponding to 'name'. If it is a google.protobuf.Value
+    // or google.protobuf.ListValue type, then StartList is a valid call, start
+    // this list.
+    // We cannot use Lookup() here as it will produce InvalidName() error if the
+    // field is not found. We do not want to error here as it would cause us to
+    // report errors twice, once here and again later in BeginNamed() call.
+    // Also we ignore if the field is not found here as it is caught later.
+    field = typeinfo_->FindField(&element_->type(), name);
+
+    // It is an error to try to bind to map, which behind the scenes is a list.
+    if (field && IsMap(*field)) {
+      // Push field to stack for error location tracking & reporting.
+      element_.reset(new ProtoElement(element_.release(), field,
+                                      *LookupType(field),
+                                      ProtoElement::MESSAGE));
+      InvalidValue("Map", "Cannot bind a list to map.");
+      ++invalid_depth_;
+      element_->pop();
+      return this;
+    }
+
+    if (field && field->type_url() == GetFullTypeWithUrl(kStructValueType)) {
+      // There are 2 cases possible:
+      //   a. g.p.Value is repeated
+      //   b. g.p.Value is not repeated
+      //
+      // For case (a), the StartList should bind to the repeated g.p.Value.
+      // For case (b), the StartList should bind to g.p.ListValue within the
+      // g.p.Value.
+      //
+      // This means, for case (a), we treat it just like any other repeated
+      // message, except we would apply an appropriate element_type so future
+      // Start or Render calls are routed appropriately.
+      if (field->cardinality() !=
+          google::protobuf::Field_Cardinality_CARDINALITY_REPEATED) {
+        field = StartListValueInStruct(field);
+      }
+      element_type = ProtoElement::STRUCT_LIST;
+    } else if (field &&
+               field->type_url() == GetFullTypeWithUrl(kStructListValueType)) {
+      // We got a StartList with google.protobuf.ListValue master type. This
+      // means we have to start the "values" within google.protobuf.ListValue.
+      field = StartRepeatedValuesInListValue(field);
+    } else {
+      // If no special types are to be bound, fall back to normal processing of
+      // StartList.
+      field = BeginNamed(name, true);
+    }
+    if (field == NULL) return this;
+  }
+
+  const google::protobuf::Type* type = LookupType(field);
+  if (type == NULL) {
+    ++invalid_depth_;
+    InvalidName(name,
+                StrCat("Missing descriptor for field: ", field->type_url()));
+    return this;
+  }
+
+  element_.reset(
+      new ProtoElement(element_.release(), field, *type, element_type));
+  return this;
+}
+
+ProtoStreamObjectWriter* ProtoStreamObjectWriter::EndList() {
+  if (invalid_depth_ > 0) {
+    --invalid_depth_;
+  } else if (element_ != NULL) {
+    if (element_->IsAny()) {
+      element_->any()->EndList();
+    } else {
+      element_.reset(element_->pop());
+      // Skip sentinel elements added to keep track of new proto3 types - map,
+      // struct.
+      SkipElements();
+    }
+  }
+
+  // When element_ is NULL, we have reached the root message type. Write out
+  // the bytes.
+  if (element_ == NULL) {
+    WriteRootMessage();
+  }
+  return this;
+}
+
+Status ProtoStreamObjectWriter::RenderStructValue(ProtoStreamObjectWriter* ow,
+                                                  const DataPiece& data) {
+  string struct_field_name;
+  switch (data.type()) {
+    // Our JSON parser parses numbers as either int64, uint64, or double.
+    case DataPiece::TYPE_INT64:
+    case DataPiece::TYPE_UINT64:
+    case DataPiece::TYPE_DOUBLE: {
+      struct_field_name = "number_value";
+      break;
+    }
+    case DataPiece::TYPE_STRING: {
+      struct_field_name = "string_value";
+      break;
+    }
+    case DataPiece::TYPE_BOOL: {
+      struct_field_name = "bool_value";
+      break;
+    }
+    case DataPiece::TYPE_NULL: {
+      struct_field_name = "null_value";
+      break;
+    }
+    default: {
+      return Status(INVALID_ARGUMENT,
+                    "Invalid struct data type. Only number, string, boolean or "
+                    "null values are supported.");
+    }
+  }
+  ow->RenderDataPiece(struct_field_name, data);
+  return Status::OK;
+}
+
+Status ProtoStreamObjectWriter::RenderTimestamp(ProtoStreamObjectWriter* ow,
+                                                const DataPiece& data) {
+  if (data.type() != DataPiece::TYPE_STRING) {
+    return Status(INVALID_ARGUMENT,
+                  StrCat("Invalid data type for timestamp, value is ",
+                         data.ValueAsStringOrDefault("")));
+  }
+
+  StringPiece value(data.str());
+
+  int64 seconds;
+  int32 nanos;
+  if (!::google::protobuf::internal::ParseTime(value.ToString(), &seconds,
+                                               &nanos)) {
+    return Status(INVALID_ARGUMENT, StrCat("Invalid time format: ", value));
+  }
+
+
+  ow->RenderDataPiece("seconds", DataPiece(seconds));
+  ow->RenderDataPiece("nanos", DataPiece(nanos));
+  return Status::OK;
+}
+
+static inline util::Status RenderOneFieldPath(ProtoStreamObjectWriter* ow,
+                                                StringPiece path) {
+  ow->RenderDataPiece("paths",
+                      DataPiece(ConvertFieldMaskPath(path, &ToSnakeCase)));
+  return Status::OK;
+}
+
+Status ProtoStreamObjectWriter::RenderFieldMask(ProtoStreamObjectWriter* ow,
+                                                const DataPiece& data) {
+  if (data.type() != DataPiece::TYPE_STRING) {
+    return Status(INVALID_ARGUMENT,
+                  StrCat("Invalid data type for field mask, value is ",
+                         data.ValueAsStringOrDefault("")));
+  }
+
+  // TODO(tsun): figure out how to do proto descriptor based snake case
+  // conversions as much as possible. Because ToSnakeCase sometimes returns the
+  // wrong value.
+  google::protobuf::scoped_ptr<ResultCallback1<util::Status, StringPiece> > callback(
+      NewPermanentCallback(&RenderOneFieldPath, ow));
+  return DecodeCompactFieldMaskPaths(data.str(), callback.get());
+}
+
+Status ProtoStreamObjectWriter::RenderDuration(ProtoStreamObjectWriter* ow,
+                                               const DataPiece& data) {
+  if (data.type() != DataPiece::TYPE_STRING) {
+    return Status(INVALID_ARGUMENT,
+                  StrCat("Invalid data type for duration, value is ",
+                         data.ValueAsStringOrDefault("")));
+  }
+
+  StringPiece value(data.str());
+
+  if (!value.ends_with("s")) {
+    return Status(INVALID_ARGUMENT,
+                  "Illegal duration format; duration must end with 's'");
+  }
+  value = value.substr(0, value.size() - 1);
+  int sign = 1;
+  if (value.starts_with("-")) {
+    sign = -1;
+    value = value.substr(1);
+  }
+
+  StringPiece s_secs, s_nanos;
+  SplitSecondsAndNanos(value, &s_secs, &s_nanos);
+  uint64 unsigned_seconds;
+  if (!safe_strtou64(s_secs, &unsigned_seconds)) {
+    return Status(INVALID_ARGUMENT,
+                  "Invalid duration format, failed to parse seconds");
+  }
+
+  double d_nanos = 0;
+  if (!safe_strtod("0." + s_nanos.ToString(), &d_nanos)) {
+    return Status(INVALID_ARGUMENT,
+                  "Invalid duration format, failed to parse nanos seconds");
+  }
+
+  int32 nanos = sign * static_cast<int32>(d_nanos * kNanosPerSecond);
+  int64 seconds = sign * unsigned_seconds;
+
+  if (seconds > kMaxSeconds || seconds < kMinSeconds ||
+      nanos <= -kNanosPerSecond || nanos >= kNanosPerSecond) {
+    return Status(INVALID_ARGUMENT, "Duration value exceeds limits");
+  }
+
+  ow->RenderDataPiece("seconds", DataPiece(seconds));
+  ow->RenderDataPiece("nanos", DataPiece(nanos));
+  return Status::OK;
+}
+
+Status ProtoStreamObjectWriter::RenderWrapperType(ProtoStreamObjectWriter* ow,
+                                                  const DataPiece& data) {
+  ow->RenderDataPiece("value", data);
+  return Status::OK;
+}
+
+ProtoStreamObjectWriter* ProtoStreamObjectWriter::RenderDataPiece(
+    StringPiece name, const DataPiece& data) {
+  Status status;
+  if (invalid_depth_ > 0) return this;
+  if (element_ != NULL && element_->IsAny()) {
+    element_->any()->RenderDataPiece(name, data);
+    return this;
+  }
+
+  const google::protobuf::Field* field = NULL;
+  string type_url;
+  bool is_map_entry = false;
+  if (element_ == NULL) {
+    type_url = GetFullTypeWithUrl(master_type_.name());
+  } else {
+    if (element_->IsMap() || element_->IsStructMap()) {
+      is_map_entry = true;
+      field = StartMapEntry(name);
+    } else {
+      field = Lookup(name);
+    }
+    if (field == NULL) {
+      return this;
+    }
+    type_url = field->type_url();
+  }
+
+  // Check if there are any well known type renderers available for type_url.
+  const TypeRenderer* type_renderer = FindTypeRenderer(type_url);
+  if (type_renderer != NULL) {
+    // Push the current element to stack so lookups in type_renderer will
+    // find the fields. We do an EndObject soon after, which pops this. This is
+    // safe because all well-known types are messages.
+    if (element_ == NULL) {
+      element_.reset(new ProtoElement(typeinfo_, master_type_, this));
+    } else {
+      if (field) {
+        WriteTag(*field);
+        const google::protobuf::Type* type = LookupType(field);
+        element_.reset(new ProtoElement(element_.release(), field, *type,
+                                        ProtoElement::MESSAGE));
+      }
+    }
+    status = (*type_renderer)(this, data);
+    if (!status.ok()) {
+      InvalidValue(type_url,
+                   StrCat("Field '", name, "', ", status.error_message()));
+    }
+    EndObject();
+    return this;
+  } else if (element_ == NULL) {  // no message type found at root
+    element_.reset(new ProtoElement(typeinfo_, master_type_, this));
+    InvalidName(name, "Root element must be a message.");
+    return this;
+  }
+
+  if (field == NULL) {
+    return this;
+  }
+  const google::protobuf::Type* type = LookupType(field);
+  if (type == NULL) {
+    InvalidName(name,
+                StrCat("Missing descriptor for field: ", field->type_url()));
+    return this;
+  }
+
+  // Whether we should pop at the end. Set to true if the data field is a
+  // message type, which can happen in case of struct values.
+  bool should_pop = false;
+
+  RenderSimpleDataPiece(*field, *type, data);
+
+  if (should_pop && element_ != NULL) {
+    element_.reset(element_->pop());
+  }
+
+  if (is_map_entry) {
+    // Ending map is the same as ending an object.
+    EndObject();
+  }
+  return this;
+}
+
+void ProtoStreamObjectWriter::RenderSimpleDataPiece(
+    const google::protobuf::Field& field, const google::protobuf::Type& type,
+    const DataPiece& data) {
+  // If we are rendering explicit null values and the backend proto field is not
+  // of the google.protobuf.NullType type, we do nothing.
+  if (data.type() == DataPiece::TYPE_NULL &&
+      field.type_url() != kStructNullValueTypeUrl) {
+    return;
+  }
+
+  // Pushing a ProtoElement and then pop it off at the end for 2 purposes:
+  // error location reporting and required field accounting.
+  element_.reset(new ProtoElement(element_.release(), &field, type,
+                                  ProtoElement::MESSAGE));
+
+  // Make sure that field represents a simple data type.
+  if (field.kind() == google::protobuf::Field_Kind_TYPE_UNKNOWN ||
+      field.kind() == google::protobuf::Field_Kind_TYPE_MESSAGE) {
+    InvalidValue(field.type_url().empty()
+                     ? google::protobuf::Field_Kind_Name(field.kind())
+                     : field.type_url(),
+                 data.ValueAsStringOrDefault(""));
+    return;
+  }
+
+  Status status;
+  switch (field.kind()) {
+    case google::protobuf::Field_Kind_TYPE_INT32: {
+      status = WriteInt32(field.number(), data, stream_.get());
+      break;
+    }
+    case google::protobuf::Field_Kind_TYPE_SFIXED32: {
+      status = WriteSFixed32(field.number(), data, stream_.get());
+      break;
+    }
+    case google::protobuf::Field_Kind_TYPE_SINT32: {
+      status = WriteSInt32(field.number(), data, stream_.get());
+      break;
+    }
+    case google::protobuf::Field_Kind_TYPE_FIXED32: {
+      status = WriteFixed32(field.number(), data, stream_.get());
+      break;
+    }
+    case google::protobuf::Field_Kind_TYPE_UINT32: {
+      status = WriteUInt32(field.number(), data, stream_.get());
+      break;
+    }
+    case google::protobuf::Field_Kind_TYPE_INT64: {
+      status = WriteInt64(field.number(), data, stream_.get());
+      break;
+    }
+    case google::protobuf::Field_Kind_TYPE_SFIXED64: {
+      status = WriteSFixed64(field.number(), data, stream_.get());
+      break;
+    }
+    case google::protobuf::Field_Kind_TYPE_SINT64: {
+      status = WriteSInt64(field.number(), data, stream_.get());
+      break;
+    }
+    case google::protobuf::Field_Kind_TYPE_FIXED64: {
+      status = WriteFixed64(field.number(), data, stream_.get());
+      break;
+    }
+    case google::protobuf::Field_Kind_TYPE_UINT64: {
+      status = WriteUInt64(field.number(), data, stream_.get());
+      break;
+    }
+    case google::protobuf::Field_Kind_TYPE_DOUBLE: {
+      status = WriteDouble(field.number(), data, stream_.get());
+      break;
+    }
+    case google::protobuf::Field_Kind_TYPE_FLOAT: {
+      status = WriteFloat(field.number(), data, stream_.get());
+      break;
+    }
+    case google::protobuf::Field_Kind_TYPE_BOOL: {
+      status = WriteBool(field.number(), data, stream_.get());
+      break;
+    }
+    case google::protobuf::Field_Kind_TYPE_BYTES: {
+      status = WriteBytes(field.number(), data, stream_.get());
+      break;
+    }
+    case google::protobuf::Field_Kind_TYPE_STRING: {
+      status = WriteString(field.number(), data, stream_.get());
+      break;
+    }
+    case google::protobuf::Field_Kind_TYPE_ENUM: {
+      status = WriteEnum(field.number(), data,
+                         typeinfo_->GetEnum(field.type_url()), stream_.get());
+      break;
+    }
+    default:  // TYPE_GROUP or TYPE_MESSAGE
+      status = Status(INVALID_ARGUMENT, data.ToString().ValueOrDie());
+  }
+  if (!status.ok()) {
+    InvalidValue(google::protobuf::Field_Kind_Name(field.kind()),
+                 status.error_message());
+  }
+  element_.reset(element_->pop());
+}
+
+// Map of functions that are responsible for rendering well known type
+// represented by the key.
+hash_map<string, ProtoStreamObjectWriter::TypeRenderer>*
+ProtoStreamObjectWriter::CreateRendererMap() {
+  google::protobuf::scoped_ptr<hash_map<string, ProtoStreamObjectWriter::TypeRenderer> >
+      result(new hash_map<string, ProtoStreamObjectWriter::TypeRenderer>());
+  (*result)["type.googleapis.com/google.protobuf.Timestamp"] =
+      &ProtoStreamObjectWriter::RenderTimestamp;
+  (*result)["type.googleapis.com/google.protobuf.Duration"] =
+      &ProtoStreamObjectWriter::RenderDuration;
+  (*result)["type.googleapis.com/google.protobuf.FieldMask"] =
+      &ProtoStreamObjectWriter::RenderFieldMask;
+  (*result)["type.googleapis.com/google.protobuf.Double"] =
+      &ProtoStreamObjectWriter::RenderWrapperType;
+  (*result)["type.googleapis.com/google.protobuf.Float"] =
+      &ProtoStreamObjectWriter::RenderWrapperType;
+  (*result)["type.googleapis.com/google.protobuf.Int64"] =
+      &ProtoStreamObjectWriter::RenderWrapperType;
+  (*result)["type.googleapis.com/google.protobuf.UInt64"] =
+      &ProtoStreamObjectWriter::RenderWrapperType;
+  (*result)["type.googleapis.com/google.protobuf.Int32"] =
+      &ProtoStreamObjectWriter::RenderWrapperType;
+  (*result)["type.googleapis.com/google.protobuf.UInt32"] =
+      &ProtoStreamObjectWriter::RenderWrapperType;
+  (*result)["type.googleapis.com/google.protobuf.Bool"] =
+      &ProtoStreamObjectWriter::RenderWrapperType;
+  (*result)["type.googleapis.com/google.protobuf.String"] =
+      &ProtoStreamObjectWriter::RenderWrapperType;
+  (*result)["type.googleapis.com/google.protobuf.Bytes"] =
+      &ProtoStreamObjectWriter::RenderWrapperType;
+  (*result)["type.googleapis.com/google.protobuf.DoubleValue"] =
+      &ProtoStreamObjectWriter::RenderWrapperType;
+  (*result)["type.googleapis.com/google.protobuf.FloatValue"] =
+      &ProtoStreamObjectWriter::RenderWrapperType;
+  (*result)["type.googleapis.com/google.protobuf.Int64Value"] =
+      &ProtoStreamObjectWriter::RenderWrapperType;
+  (*result)["type.googleapis.com/google.protobuf.UInt64Value"] =
+      &ProtoStreamObjectWriter::RenderWrapperType;
+  (*result)["type.googleapis.com/google.protobuf.Int32Value"] =
+      &ProtoStreamObjectWriter::RenderWrapperType;
+  (*result)["type.googleapis.com/google.protobuf.UInt32Value"] =
+      &ProtoStreamObjectWriter::RenderWrapperType;
+  (*result)["type.googleapis.com/google.protobuf.BoolValue"] =
+      &ProtoStreamObjectWriter::RenderWrapperType;
+  (*result)["type.googleapis.com/google.protobuf.StringValue"] =
+      &ProtoStreamObjectWriter::RenderWrapperType;
+  (*result)["type.googleapis.com/google.protobuf.BytesValue"] =
+      &ProtoStreamObjectWriter::RenderWrapperType;
+  (*result)["type.googleapis.com/google.protobuf.Value"] =
+      &ProtoStreamObjectWriter::RenderStructValue;
+  return result.release();
+}
+
+ProtoStreamObjectWriter::TypeRenderer*
+ProtoStreamObjectWriter::FindTypeRenderer(const string& type_url) {
+  static hash_map<string, TypeRenderer>* renderers = CreateRendererMap();
+  return FindOrNull(*renderers, type_url);
+}
+
+ProtoStreamObjectWriter::ProtoElement::ElementType
+ProtoStreamObjectWriter::GetElementType(const google::protobuf::Type& type) {
+  if (type.name() == kAnyType) {
+    return ProtoElement::ANY;
+  } else if (type.name() == kStructType) {
+    return ProtoElement::STRUCT;
+  } else if (type.name() == kStructValueType) {
+    return ProtoElement::STRUCT_VALUE;
+  } else if (type.name() == kStructListValueType) {
+    return ProtoElement::STRUCT_LIST_VALUE;
+  } else {
+    return ProtoElement::MESSAGE;
+  }
+}
+
+const google::protobuf::Field* ProtoStreamObjectWriter::BeginNamed(
+    StringPiece name, bool is_list) {
+  if (invalid_depth_ > 0) {
+    ++invalid_depth_;
+    return NULL;
+  }
+  const google::protobuf::Field* field = Lookup(name);
+  if (field == NULL) {
+    ++invalid_depth_;
+    // InvalidName() already called in Lookup().
+    return NULL;
+  }
+  if (is_list &&
+      field->cardinality() !=
+          google::protobuf::Field_Cardinality_CARDINALITY_REPEATED) {
+    ++invalid_depth_;
+    InvalidName(name, "Proto field is not repeating, cannot start list.");
+    return NULL;
+  }
+  return field;
+}
+
+const google::protobuf::Field* ProtoStreamObjectWriter::Lookup(
+    StringPiece unnormalized_name) {
+  ProtoElement* e = element();
+  if (e == NULL) {
+    InvalidName(unnormalized_name, "Root element must be a message.");
+    return NULL;
+  }
+  if (unnormalized_name.empty()) {
+    // Objects in repeated field inherit the same field descriptor.
+    if (e->field() == NULL) {
+      InvalidName(unnormalized_name, "Proto fields must have a name.");
+    } else if (e->field()->cardinality() !=
+               google::protobuf::Field_Cardinality_CARDINALITY_REPEATED) {
+      InvalidName(unnormalized_name, "Proto fields must have a name.");
+      return NULL;
+    }
+    return e->field();
+  }
+  const google::protobuf::Field* field =
+      typeinfo_->FindField(&e->type(), unnormalized_name);
+  if (field == NULL) InvalidName(unnormalized_name, "Cannot find field.");
+  return field;
+}
+
+const google::protobuf::Type* ProtoStreamObjectWriter::LookupType(
+    const google::protobuf::Field* field) {
+  return (field->kind() == google::protobuf::Field_Kind_TYPE_MESSAGE
+              ? typeinfo_->GetType(field->type_url())
+              : &element_->type());
+}
+
+// Looks up the oneof struct field based on the data type.
+StatusOr<const google::protobuf::Field*>
+ProtoStreamObjectWriter::LookupStructField(DataPiece::Type type) {
+  const google::protobuf::Field* field = NULL;
+  switch (type) {
+    // Our JSON parser parses numbers as either int64, uint64, or double.
+    case DataPiece::TYPE_INT64:
+    case DataPiece::TYPE_UINT64:
+    case DataPiece::TYPE_DOUBLE: {
+      field = Lookup("number_value");
+      break;
+    }
+    case DataPiece::TYPE_STRING: {
+      field = Lookup("string_value");
+      break;
+    }
+    case DataPiece::TYPE_BOOL: {
+      field = Lookup("bool_value");
+      break;
+    }
+    case DataPiece::TYPE_NULL: {
+      field = Lookup("null_value");
+      break;
+    }
+    default: { return Status(INVALID_ARGUMENT, "Invalid struct data type"); }
+  }
+  if (field == NULL) {
+    return Status(INVALID_ARGUMENT, "Could not lookup struct field");
+  }
+  return field;
+}
+
+void ProtoStreamObjectWriter::WriteRootMessage() {
+  GOOGLE_DCHECK(!done_);
+  int curr_pos = 0;
+  // Calls the destructor of CodedOutputStream to remove any uninitialized
+  // memory from the Cord before we read it.
+  stream_.reset(NULL);
+  const void* data;
+  int length;
+  google::protobuf::io::ArrayInputStream input_stream(buffer_.data(), buffer_.size());
+  while (input_stream.Next(&data, &length)) {
+    if (length == 0) continue;
+    int num_bytes = length;
+    // Write up to where we need to insert the size field.
+    // The number of bytes we may write is the smaller of:
+    //   - the current fragment size
+    //   - the distance to the next position where a size field needs to be
+    //     inserted.
+    if (!size_insert_.empty() &&
+        size_insert_.front().pos - curr_pos < num_bytes) {
+      num_bytes = size_insert_.front().pos - curr_pos;
+    }
+    output_->Append(static_cast<const char*>(data), num_bytes);
+    if (num_bytes < length) {
+      input_stream.BackUp(length - num_bytes);
+    }
+    curr_pos += num_bytes;
+    // Insert the size field.
+    //   size_insert_.front():      the next <index, size> pair to be written.
+    //   size_insert_.front().pos:  position of the size field.
+    //   size_insert_.front().size: the size (integer) to be inserted.
+    if (!size_insert_.empty() && curr_pos == size_insert_.front().pos) {
+      // Varint32 occupies at most 10 bytes.
+      uint8 insert_buffer[10];
+      uint8* insert_buffer_pos = CodedOutputStream::WriteVarint32ToArray(
+          size_insert_.front().size, insert_buffer);
+      output_->Append(reinterpret_cast<const char*>(insert_buffer),
+                      insert_buffer_pos - insert_buffer);
+      size_insert_.pop_front();
+    }
+  }
+  output_->Flush();
+  stream_.reset(new CodedOutputStream(&adapter_));
+  done_ = true;
+}
+
+bool ProtoStreamObjectWriter::IsMap(const google::protobuf::Field& field) {
+  if (field.type_url().empty() ||
+      field.kind() != google::protobuf::Field_Kind_TYPE_MESSAGE ||
+      field.cardinality() !=
+          google::protobuf::Field_Cardinality_CARDINALITY_REPEATED) {
+    return false;
+  }
+  const google::protobuf::Type* field_type =
+      typeinfo_->GetType(field.type_url());
+
+  return GetBoolOptionOrDefault(field_type->options(),
+                                "google.protobuf.MessageOptions.map_entry", false);
+}
+
+void ProtoStreamObjectWriter::WriteTag(const google::protobuf::Field& field) {
+  WireFormatLite::WireType wire_type = WireFormatLite::WireTypeForFieldType(
+      static_cast<WireFormatLite::FieldType>(field.kind()));
+  stream_->WriteTag(WireFormatLite::MakeTag(field.number(), wire_type));
+}
+
+}  // namespace converter
+}  // namespace util
+}  // namespace protobuf
+}  // namespace google