Type-safe OSC message sending

src/CMakeLists.txt

@@ -219,6 +219,7 @@ target_link_libraries (sfizz_parser PUBLIC absl::strings PRIVATE absl::flat_hash
 # OSC messaging library
 set (SFIZZ_MESSAGING_HEADERS
     sfizz/Messaging.h
+    sfizz/Messaging.hpp
     sfizz_message.h)
 
 set (SFIZZ_MESSAGING_SOURCES

src/sfizz/Messaging.h

@@ -6,9 +6,14 @@
 
 #pragma once
 #include "sfizz_message.h"
+#include <type_traits>
 
 namespace sfz {
 
+template <char Tag> struct OscDataTraits;
+template <char Tag> using OscType = typename OscDataTraits<Tag>::type;
+template <char Tag> using OscDecayedType = typename std::decay<OscType<Tag>>::type;
+
 class Client {
 public:
     explicit Client(void* data) : data_(data) {}
@@ -17,15 +22,18 @@ public:
     bool canReceive() const { return receive_ != nullptr; }
     void receive(int delay, const char* path, const char* sig, const sfizz_arg_t* args);
 
+    template <char... Sig>
+    void receive(int delay, const char* path, OscDecayedType<Sig>... values);
+
+private:
+    template <char Tag>
+    sfizz_arg_t make_arg(OscDecayedType<Tag> value);
+
 private:
     void* data_ = nullptr;
     sfizz_receive_t* receive_ = nullptr;
 };
 
-inline void Client::receive(int delay, const char* path, const char* sig, const sfizz_arg_t* args)
-{
-    if (receive_)
-        receive_(data_, delay, path, sig, args);
-}
-
 } // namespace sfz
+
+#include "Messaging.hpp"

src/sfizz/Messaging.hpp

@@ -0,0 +1,76 @@
+// SPDX-License-Identifier: BSD-2-Clause
+
+// This code is part of the sfizz library and is licensed under a BSD 2-clause
+// license. You should have receive a LICENSE.md file along with the code.
+// If not, contact the sfizz maintainers at https://github.com/sfztools/sfizz
+
+#pragma once
+#include "Messaging.h"
+#include <cstddef>
+#include <cstring>
+
+namespace sfz {
+
+///
+inline void Client::receive(int delay, const char* path, const char* sig, const sfizz_arg_t* args)
+{
+    if (receive_)
+        receive_(data_, delay, path, sig, args);
+}
+
+template <char... Sig>
+inline void Client::receive(int delay, const char* path, OscDecayedType<Sig>... values)
+{
+    constexpr size_t size = sizeof...(Sig);
+    char sig[size + 1] { Sig..., '\0' };
+    sfizz_arg_t args[size] { OscDataTraits<Sig>::make_arg(values)... };
+    receive(delay, path, sig, args);
+}
+
+///
+#define OSC_SCALAR_TRAITS(tag, member)                  \
+    template <> struct OscDataTraits<tag> {             \
+        typedef decltype(sfizz_arg_t::member) type;     \
+        static_assert(std::is_scalar<type>::value, ""); \
+        static inline sfizz_arg_t make_arg(type v) {    \
+            sfizz_arg_t a; a.member = v; return a;      \
+        }                                               \
+    }
+#define OSC_BYTEARRAY_TRAITS(tag, member)               \
+    template <> struct OscDataTraits<tag> {             \
+        typedef decltype(sfizz_arg_t::member) type;     \
+        static_assert(std::is_array<type>::value, ""); \
+        static inline sfizz_arg_t make_arg(type v) {    \
+            sfizz_arg_t a;                              \
+            std::memcpy(a.member, v, sizeof(a.member)); \
+            return a;                                   \
+        }                                               \
+    }
+#define OSC_VOID_TRAITS(tag)                            \
+    template <> struct OscDataTraits<tag> {             \
+        typedef struct Nothing {} type;                 \
+        static inline sfizz_arg_t make_arg(type v) {    \
+            sfizz_arg_t a; (void)v; return a;           \
+        }                                               \
+    }
+
+OSC_SCALAR_TRAITS('i', i);
+OSC_SCALAR_TRAITS('c', i);
+OSC_SCALAR_TRAITS('r', i);
+OSC_BYTEARRAY_TRAITS('m', m);
+OSC_SCALAR_TRAITS('h', h);
+OSC_SCALAR_TRAITS('f', f);
+OSC_SCALAR_TRAITS('d', d);
+OSC_SCALAR_TRAITS('s', s);
+OSC_SCALAR_TRAITS('S', s);
+OSC_SCALAR_TRAITS('b', b);
+OSC_VOID_TRAITS('T');
+OSC_VOID_TRAITS('F');
+OSC_VOID_TRAITS('N');
+OSC_VOID_TRAITS('I');
+
+#undef OSC_SCALAR_TRAITS
+#undef OSC_BYTEARRAY_TRAITS
+#undef OSC_VOID_TRAITS
+
+} // namespace sfz