Add IPC serialization support for base::Optional

ipc/ipc_message_utils.h

 // Copyright (c) 2012 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.
 
 #ifndef IPC_IPC_MESSAGE_UTILS_H_
 #define IPC_IPC_MESSAGE_UTILS_H_
 
 #include <limits.h>
 #include <stddef.h>
 #include <stdint.h>
 
 #include <algorithm>
 #include <map>
 #include <memory>
 #include <set>
 #include <string>
 #include <tuple>
 #include <vector>
 
 #include "base/containers/small_map.h"
 #include "base/containers/stack_container.h"
 #include "base/files/file.h"
 #include "base/format_macros.h"
 #include "base/memory/scoped_vector.h"
+#include "base/optional.h"
 #include "base/strings/string16.h"
 #include "base/strings/string_util.h"
 #include "base/strings/stringprintf.h"
 #include "build/build_config.h"
 #include "ipc/brokerable_attachment.h"
 #include "ipc/ipc_message_start.h"
 #include "ipc/ipc_param_traits.h"
 #include "ipc/ipc_sync_message.h"
 
 namespace base {
@@ skipping 332 matching lines @@
   typedef std::vector<bool> param_type;
   static void GetSize(base::PickleSizer* sizer, const param_type& p);
   static void Write(base::Pickle* m, const param_type& p);
   static bool Read(const base::Pickle* m,
                    base::PickleIterator* iter,
                    param_type* r);
   static void Log(const param_type& p, std::string* l);
 };
 
 template <class P>
-struct ParamTraits<std::vector<P> > {
+struct ParamTraits<std::vector<P>> {
   typedef std::vector<P> param_type;
   static void GetSize(base::PickleSizer* sizer, const param_type& p) {
     GetParamSize(sizer, static_cast<int>(p.size()));
     for (size_t i = 0; i < p.size(); i++)
       GetParamSize(sizer, p[i]);
   }
   static void Write(base::Pickle* m, const param_type& p) {
     WriteParam(m, static_cast<int>(p.size()));
     for (size_t i = 0; i < p.size(); i++)
       WriteParam(m, p[i]);
@@ skipping 589 matching lines @@
     return true;
   }
   static void Log(const param_type& p, std::string* l) {
     if (p)
       LogParam(*p, l);
     else
       l->append("NULL");
   }
 };
 
+template <class P>
+struct ParamTraits<base::Optional<P>> {
+  typedef base::Optional<P> param_type;
+  static void GetSize(base::PickleSizer* sizer, const param_type& p) {
+    const bool is_set = static_cast<bool>(p);
+    GetParamSize(sizer, is_set);
+    if (is_set)
+      GetParamSize(sizer, p.value());
+  }
+  static void Write(base::Pickle* m, const param_type& p) {
+    const bool is_set = static_cast<bool>(p);
+    WriteParam(m, is_set);
+    if (is_set)
+      WriteParam(m, p.value());
+  }
+  static bool Read(const base::Pickle* m,
+                   base::PickleIterator* iter,
+                   param_type* r) {
+    bool is_set = false;
+    if (!iter->ReadBool(&is_set))
+      return false;
+    if (is_set) {
+      P value;
+      if (!ReadParam(m, iter, &value))
+        return false;
+      *r = std::move(value);
+    }
+    return true;
+  }
+  static void Log(const param_type& p, std::string* l) {
+    if (p)
+      LogParam(p.value(), l);
+    else
+      l->append("(unset)");
+  }
+};
+
 // IPC types ParamTraits -------------------------------------------------------
 
 // A ChannelHandle is basically a platform-inspecific wrapper around the
 // fact that IPC endpoints are handled specially on POSIX.  See above comments
 // on FileDescriptor for more background.
 template<>
 struct IPC_EXPORT ParamTraits<IPC::ChannelHandle> {
   typedef ChannelHandle param_type;
   static void GetSize(base::PickleSizer* sizer, const param_type& p);
   static void Write(base::Pickle* m, const param_type& p);
@@ skipping 105 matching lines @@
 template <class ReplyParamType>
 inline void LogReplyParamsToMessage(const ReplyParamType& reply_params,
                                     const Message* msg) {}
 
 inline void ConnectMessageAndReply(const Message* msg, Message* reply) {}
 #endif
 
 }  // namespace IPC
 
 #endif  // IPC_IPC_MESSAGE_UTILS_H_