From 1565dec0f4a86e4bda7095dd7415234f7c7a84e9 Mon Sep 17 00:00:00 2001
From: Mikko Rasa <tdb@tdb.fi>
Date: Sun, 11 Dec 2022 01:21:11 +0200
Subject: [PATCH] Refactor the API for defining packets in Protocol

A variadic template function provides a nicer interface than chained call
operators.  Required C++ standard version is now C++14 due to deduced
automatic return types.
---
 Build                       |  2 +-
 source/net/communicator.cpp |  2 +-
 source/net/protocol.cpp     |  2 +-
 source/net/protocol.h       | 15 ++++++++++++---
 tests/protocol.cpp          |  8 ++++----
 5 files changed, 19 insertions(+), 10 deletions(-)

diff --git a/Build b/Build
index 286ea39..44bf9c0 100644
--- a/Build
+++ b/Build
@@ -14,7 +14,7 @@ package "mspnet"
 
 	build_info
 	{
-		standard CXX "c++11";
+		standard CXX "c++14";
 	};
 
 	library "mspnet"
diff --git a/source/net/communicator.cpp b/source/net/communicator.cpp
index f77ada2..3ac62d7 100644
--- a/source/net/communicator.cpp
+++ b/source/net/communicator.cpp
@@ -23,7 +23,7 @@ public:
 HandshakeProtocol::HandshakeProtocol():
 	Protocol(0x7F00)
 {
-	add<Handshake>()(&Handshake::hash);
+	add<Handshake>(&Handshake::hash);
 }
 
 
diff --git a/source/net/protocol.cpp b/source/net/protocol.cpp
index 95ba175..ce200a2 100644
--- a/source/net/protocol.cpp
+++ b/source/net/protocol.cpp
@@ -15,7 +15,7 @@ Protocol::Protocol(unsigned npi):
 	next_packet_id(npi)
 {
 	PacketDefBuilder<PacketHeader, Serializer<PacketHeader>>(*this, header_def, Serializer<PacketHeader>())
-		(&PacketHeader::type)(&PacketHeader::length);
+		.fields(&PacketHeader::type, &PacketHeader::length);
 }
 
 Protocol::~Protocol()
diff --git a/source/net/protocol.h b/source/net/protocol.h
index ae1c3c0..35d3cb2 100644
--- a/source/net/protocol.h
+++ b/source/net/protocol.h
@@ -171,9 +171,12 @@ private:
 
 	public:
 		PacketDefBuilder(const Protocol &, PacketTypeDef<P> &, const S &);
-		
+
 		template<typename T>
-		PacketDefBuilder<P, typename S::template Next<T>> operator()(T P::*);
+		PacketDefBuilder<P, typename S::template Next<T>> fields(T P::*);
+
+		template<typename T1, typename T2, typename... Rest>
+		auto fields(T1 P::*first, T2 P::*second, Rest P::*...rest) { return fields(first).fields(second, rest...); }
 	};
 
 	struct PacketHeader
@@ -209,9 +212,15 @@ protected:
 	template<typename P>
 	PacketDefBuilder<P, Serializer<P>> add(unsigned);
 
+	template<typename P, typename T, typename... Rest>
+	auto add(unsigned id, T P::*field, Rest P::*...rest) { return add<P>(id).fields(field, rest...); }
+
 	template<typename P>
 	PacketDefBuilder<P, Serializer<P>> add();
 
+	template<typename P, typename T, typename... Rest>
+	auto add(T P::*field, Rest P::*...rest) { return add<P>().fields(field, rest...); }
+
 	const PacketDefBase &get_packet_by_class_id(unsigned) const;
 	const PacketDefBase &get_packet_by_id(unsigned) const;
 
@@ -455,7 +464,7 @@ Protocol::PacketDefBuilder<P, S>::PacketDefBuilder(const Protocol &p, PacketType
 
 template<typename P, typename S>
 template<typename T>
-Protocol::PacketDefBuilder<P, typename S::template Next<T>> Protocol::PacketDefBuilder<P, S>::operator()(T P::*ptr)
+Protocol::PacketDefBuilder<P, typename S::template Next<T>> Protocol::PacketDefBuilder<P, S>::fields(T P::*ptr)
 {
 	typename S::template Next<T> next_ser(serializer, ptr, protocol);
 	pktdef.set_serializer(next_ser);
diff --git a/tests/protocol.cpp b/tests/protocol.cpp
index 0f4b7d2..bca1161 100644
--- a/tests/protocol.cpp
+++ b/tests/protocol.cpp
@@ -56,10 +56,10 @@ struct Packet4
 
 Protocol::Protocol()
 {
-	add<Packet1>()(&Packet1::value);
-	add<Packet2>()(&Packet2::value);
-	add<Packet3>()(&Packet3::values);
-	add<Packet4>()(&Packet4::sub1)(&Packet4::sub2);
+	add<Packet1>(&Packet1::value);
+	add<Packet2>(&Packet2::value);
+	add<Packet3>(&Packet3::values);
+	add<Packet4>(&Packet4::sub1, &Packet4::sub2);
 }
 
 template<typename T>
-- 
2.45.2