From 0a158ee830581a188b40e60f1e43104d2369a405 Mon Sep 17 00:00:00 2001
From: pf <peter.f.j.featherstone@bath.edu>
Date: Sun, 19 Jul 2020 17:32:16 +0100
Subject: [PATCH] [JSON] rough and ready code for generating (de)serialisation
 macros. Current upper bound on number of member variables is set to 64

---
 third_party/macro_builder/main.cpp | 43 ++++++++++++++++++++++++++++++
 1 file changed, 43 insertions(+)
 create mode 100644 third_party/macro_builder/main.cpp

diff --git a/third_party/macro_builder/main.cpp b/third_party/macro_builder/main.cpp
new file mode 100644
index 000000000..e676daacc
--- /dev/null
+++ b/third_party/macro_builder/main.cpp
@@ -0,0 +1,43 @@
+#include <cstdlib>
+#include <iostream>
+#include <sstream>
+
+using namespace std;
+
+void build_code(int max_args)
+{
+    stringstream ss;
+    ss << "#define NLOHMANN_JSON_EXPAND( x ) x" << endl;
+    ss << "#define NLOHMANN_JSON_GET_MACRO(";
+    for (int i = 0 ; i < max_args ; i++)
+        ss << "_" << i + 1 << ", ";
+    ss << "NAME,...) NAME" << endl;
+    
+    ss << "#define NLOHMANN_JSON_PASTE(...) NLOHMANN_JSON_EXPAND(NLOHMANN_JSON_GET_MACRO(__VA_ARGS__, \\" << endl;
+    for (int i = max_args ; i > 1 ; i--)
+        ss << "NLOHMANN_JSON_PASTE" << i << ", \\" << endl;
+    ss << "NLOHMANN_JSON_PASTE1)(__VA_ARGS__))" << endl;
+    
+    ss << "#define NLOHMANN_JSON_PASTE2(func, v1) func(v1)" << endl;
+    for (int i = 3 ; i <= max_args ; i++)
+    {
+        ss << "#define NLOHMANN_JSON_PASTE" << i << "(func, "; 
+        for (int j = 1 ; j < i -1 ; j++)
+            ss << "v" << j << ", "; 
+        ss << "v" << i-1 << ") NLOHMANN_JSON_PASTE2(func, v1) NLOHMANN_JSON_PASTE" << i-1 << "(func, ";
+        for (int j = 2 ; j < i-1 ; j++)
+            ss << "v" << j << ", ";
+        ss << "v" << i-1 << ")" << endl;
+    }
+    
+    cout << ss.str() << endl;
+}
+
+int main(int argc, char** argv) 
+{
+    int max_args = 64;
+    build_code(max_args);
+       
+    return 0;
+}
+