Merge pull request #29 from stephenberry/meta_macros

GLZ_META macros, addressing issue #27

.github/workflows/msvc.yml

@@ -36,7 +36,8 @@ jobs:
       run: conan install . -b missing
 
     - name: Configure CMake
-      run: cmake -B ${{github.workspace}}/build -DCMAKE_BUILD_TYPE=${{env.BUILD_TYPE}} -DCMAKE_TOOLCHAIN_FILE="./conan/conan_toolchain.cmake"
+      # using specific windows SDK to address this issue: https://stackoverflow.com/questions/65402366/c5105-and-other-compiler-warnings-when-building-with-github-actions-winsdk-10
+      run: cmake -B ${{github.workspace}}/build -DCMAKE_BUILD_TYPE=${{env.BUILD_TYPE}} -DCMAKE_TOOLCHAIN_FILE="./conan/conan_toolchain.cmake" -DCMAKE_SYSTEM_VERSION="10.0.22621.0"
 
     - name: Build
       run: cmake --build build --config ${{env.BUILD_TYPE}} -j 2

.github/workflows/msvc_cpm.yml

@@ -0,0 +1,34 @@
+name: msvc_cpm
+
+on:
+  push:
+    branches:
+    - main
+    - feature/*
+    paths-ignore:
+    - '**.md'
+  pull_request:
+    branches: [main]
+    paths-ignore:
+    - '**.md'
+
+env:
+  BUILD_TYPE: Release
+
+jobs:
+  build:
+    runs-on: windows-2019
+
+    steps:
+    - uses: actions/checkout@v3
+
+    # using specific windows SDK to address this issue: https://stackoverflow.com/questions/65402366/c5105-and-other-compiler-warnings-when-building-with-github-actions-winsdk-10
+    - name: Configure CMake
+      run: cmake -B ${{github.workspace}}/build -DCMAKE_BUILD_TYPE=${{env.BUILD_TYPE}} -DCMAKE_SYSTEM_VERSION="10.0.22621.0"
+
+    - name: Build
+      run: cmake --build build --config ${{env.BUILD_TYPE}} -j 2
+
+    - name: Test
+      working-directory: build
+      run: ctest -C ${{env.BUILD_TYPE}} -j 2 --output-on-failure

CMakeLists.txt

@@ -1,4 +1,4 @@
-cmake_minimum_required(VERSION 3.24)
+cmake_minimum_required(VERSION 3.18)
 
 include(cmake/prelude.cmake)
 
@@ -14,6 +14,11 @@ include(cmake/variables.cmake)
 add_library(glaze_glaze INTERFACE)
 add_library(glaze::glaze ALIAS glaze_glaze)
 
+if (MSVC)
+   # for a C++ standards compliant preprocessor:
+   target_compile_options(glaze_glaze INTERFACE "/Zc:preprocessor")
+endif()
+
 set_property(TARGET glaze_glaze PROPERTY EXPORT_NAME glaze)
 
 target_compile_features(glaze_glaze INTERFACE cxx_std_20)

README.md

@@ -192,6 +192,35 @@ struct my_struct
 
 > Template specialization of `glz::meta` is preferred when separating class definition from the serialization mapping. Local glaze metadata is helpful for working within the local namespace or when the class itself is templated.
 
+## Struct Registration Macros
+
+Glaze provides macros to more efficiently register your C++ structs.
+
+> In order to use these macros you must include the header: `glaze/core/macros.hpp`
+
+- GLZ_META is for external registration
+- GLZ_LOCAL_META is for internal registration
+
+```c++
+struct macro_t {
+   double x = 5.0;
+   std::string y = "yay!";
+   int z = 55;
+};
+
+GLZ_META(macro_t, x, y, z);
+
+struct local_macro_t {
+   double x = 5.0;
+   std::string y = "yay!";
+   int z = 55;
+
+   GLZ_LOCAL_META(local_macro_t, x, y, z);
+};
+```
+
+**Note: MSVC requires the compiler flag `/Zc:preprocessor` for a standards compliant preprocessor.**
+
 ## JSON Pointer Syntax
 
 [Here is a simple JSON pointer syntax explanation](https://github.com/stephenberry/JSON-Pointer)

include/glaze/core/macros.hpp

@@ -3,4 +3,33 @@
 
 #pragma once
 
+// utility macros
 
+// https://www.scs.stanford.edu/~dm/blog/va-opt.html
+
+#define PARENS ()
+
+#define EXPAND(...) EXPAND4(EXPAND4(EXPAND4(EXPAND4(__VA_ARGS__))))
+#define EXPAND4(...) EXPAND3(EXPAND3(EXPAND3(EXPAND3(__VA_ARGS__))))
+#define EXPAND3(...) EXPAND2(EXPAND2(EXPAND2(EXPAND2(__VA_ARGS__))))
+#define EXPAND2(...) EXPAND1(EXPAND1(EXPAND1(EXPAND1(__VA_ARGS__))))
+#define EXPAND1(...) __VA_ARGS__
+
+#define FOR_EACH(macro, ...) \
+  __VA_OPT__(EXPAND(FOR_EACH_HELPER(macro, __VA_ARGS__)))
+#define FOR_EACH_HELPER(macro, a, ...) \
+  macro(a)__VA_OPT__(,) \
+  __VA_OPT__(FOR_EACH_AGAIN PARENS (macro, __VA_ARGS__))
+#define FOR_EACH_AGAIN() FOR_EACH_HELPER
+
+// Glaze specific macros
+
+#define GLZ_X(a) #a, &T::a
+
+#define GLZ_META(C, ...) template <> struct glz::meta<C> { \
+using T = C; \
+static constexpr auto value = object(FOR_EACH(GLZ_X, __VA_ARGS__)); }
+
+#define GLZ_LOCAL_META(C, ...) struct glaze { \
+using T = C; \
+static constexpr auto value = glz::object(FOR_EACH(GLZ_X, __VA_ARGS__)); }

tests/json_test/json_test.cpp

@@ -11,6 +11,7 @@
 #include <list>
 #include <deque>
 
+#include "glaze/core/macros.hpp"
 #include "boost/ut.hpp"
 #include "glaze/json/json_ptr.hpp"
 #include "glaze/json/from_ptr.hpp"
@@ -1862,6 +1863,42 @@ suite nan_tests = [] {
    };
 };
 
+struct macro_t
+{
+   double x = 5.0;
+   std::string y = "yay!";
+   int z = 55;
+};
+
+GLZ_META(macro_t, x, y, z);
+
+struct local_macro_t
+{
+   double x = 5.0;
+   std::string y = "yay!";
+   int z = 55;
+
+   GLZ_LOCAL_META(local_macro_t, x, y, z);
+};
+
+suite macro_tests = [] {
+   "macro test"_test = [] {
+      macro_t obj{};
+      std::string b{};
+      glz::write_json(obj, b);
+
+      expect(b == R"({"x":5,"y":"yay!","z":55})");
+   };
+
+   "local macro test"_test = [] {
+      local_macro_t obj{};
+      std::string b{};
+      glz::write_json(obj, b);
+
+      expect(b == R"({"x":5,"y":"yay!","z":55})");
+   };
+};
+
 int main()
 {
    using namespace boost::ut;