Lua cpp expose

Exposition to Lua runtime mechanism proposition.

The user has to create an object that is LuaScriptAbleObject, make it inherit the CRTPLuaScriptObject class and voila.

For example, a simple FooBar examples might be:

// Default sample exposer for lua scripts
script_class (SampleObject) {
    LUA_SCRIPTABLE_CLASS(SampleObject)

    SampleObject()  noexcept { fprintf(stderr, "CREATE SampleObject\n"); }
    ~SampleObject() noexcept { fprintf(stderr, "DESTROY SampleObject\n"); }

    static int foo(lua_State *L) noexcept
    {
        SampleObject *obj = CHECK(L, 1);
        double bar        = luaL_checknumber(L, 2);
        return 0;
    }

    static constexpr inline auto metaMethods = { luaRegDefaultGC, LUA_DECL_CREATE(SampleObject) };
    static constexpr inline auto methods     = { LUA_DECL_METHOD(SampleObject, foo) };
};

A sample file for a script can be found at utils/lua/sample-spec.lua, this is just a proposition.

src/Lib/Script/LuaScript.cc

+#include "LuaScript.hh"
+#include "lua.hpp"
+
+using namespace Vivy::Script;
+
+/// LuaContext implementation
+
+LuaContext::LuaContext() noexcept
+    : L(luaL_newstate())
+{
+    luaL_openlibs(L);
+}
+
+LuaContext::~LuaContext() noexcept
+{
+}
+
+lua_State *
+LuaContext::getState() const noexcept
+{
+    return L;
+}
+
+int
+LuaContext::loadFile(const char *file) noexcept
+{
+    int rc = luaL_loadfile(L, file);
+    if (rc == LUA_OK)
+        return lua_pcall(L, 0, LUA_MULTRET, 0);
+    return rc;
+}
+
+/// SampleObject implementation
+
+SampleObject::SampleObject() noexcept
+{
+}
+
+int
+SampleObject::foo(lua_State *L) noexcept
+{
+    SampleObject *obj = CHECK(L, 1);
+    double bar        = luaL_checknumber(L, 2);
+    fprintf(stderr, "SampleObject(%p)::foo -> %f\n", static_cast<void *>(obj), bar);
+    return 0;
+}
+
+LuaMethodTable
+SampleObject::getMetaMethods() noexcept
+{
+    return { LUA_DECL_METHOD(SampleObject, foo) };
+}
+
+LuaMethodTable
+SampleObject::getMethods() noexcept
+{
+    return { luaRegDefaultGC };
+}