SCRIPT: Add free functions and an example with a custom "print"

rsc/lua/lib.lua

@@ -24,6 +24,11 @@ function enum(tbl)
     return tbl
 end
 
+-- Check if a table contains a key
+function tableHasKey(tbl, key)
+    return tbl[key] ~= nil
+end
+
 -- Things used to iterate over with a job
 Iterable = enum {
     "LINE",
@@ -42,6 +47,7 @@ Vivy = {
     ["string"] = string,
     ["utf8"]   = utf8,
     ["table"]  = table,
+    ["print"]  = print,
 
     -- Custom things
     ["Iterable"] = Iterable,
@@ -73,18 +79,14 @@ Vivy = setmetatable(Vivy, {
     end
 })
 
--- Hide the io, os and debug libraries
-io    = nil
-os    = nil
-debug = nil
-
+-- Hide everything from the user, appart some specific things he can do.
 local _ENV = setmetatable(Vivy, {
     __newindex = function (t, k, v)
         -- Use the ReservedKeywords table here
-        if (k ~= "Vivy") then
-            rawset(t, k, v)
+        if (tableHasKey(ReservedKeywords, k)) then
+            error("The keyword " .. k .. " is protected!")
         else
-            error("Try to assign something to the protected global symbol 'Vivy'")
+            rawset(t, k, v)
         end
     end
 })

src/Lib/Script/CRTPLuaScriptObject.hh

@@ -76,7 +76,7 @@ public:
             lua_settable(L, metatable);
 
             for (const luaL_Reg &meta : Object::metaMethods) {
-                fprintf(stderr, "REGISTER %s\n", meta.name);
+                fprintf(stderr, "LUA: REGISTER %s\n", meta.name);
                 lua_pushstring(L, meta.name);
                 lua_pushcfunction(L, meta.func);
                 lua_settable(L, metatable);
@@ -87,7 +87,7 @@ public:
 
         // Fill the method table with specified methods
         for (const luaL_Reg &method : Object::methods) {
-            fprintf(stderr, "REGISTER %s\n", method.name);
+            fprintf(stderr, "LUA: REGISTER %s\n", method.name);
             lua_pushstring(L, method.name);
             lua_pushcfunction(L, method.func);
             lua_settable(L, methodtable);

src/Lib/Script/LuaContext.cc

 #include "CRTPLuaScriptObject.hh"
 #include "ScriptDocument.hh"
 #include "LuaContext.hh"
+#include "LuaFreeFunctions.hh"
 #include "lua.hpp"
 #include <cstdio>
 #include <QtGlobal>
@@ -18,8 +19,9 @@ LuaContext::LuaContext() noexcept
     if (!libVivy.open(QIODevice::ReadOnly | QIODevice::Text))
         qFatal("Failed to find packaged libVivy (:lia/lib.lua)");
 
-    loadString(libVivy.readAll().toStdString().c_str()); // Load the lib
+    FreeFunctions::registerFunctions(L);                 // Register the free functions
     SampleObject::Register(L);                           // Load the C++ objects
+    loadString(libVivy.readAll().toStdString().c_str()); // Load the lib
 }
 
 LuaContext::~LuaContext() noexcept { lua_close(L); }

src/Lib/Script/LuaFreeFunctions.cc

+#include "LuaFreeFunctions.hh"
+#include "LuaContext.hh"
+#include <initializer_list>
+#include <QtGlobal>
+
+using namespace Vivy::Script;
+
+static int
+vivyPrint(lua_State *L) noexcept
+{
+    luaL_checktype(L, 1, LUA_TSTRING);
+    qDebug() << "LUA - MSG:" << lua_tostring(L, 1);
+    return 0;
+}
+
+static inline constexpr std::initializer_list<std::tuple<const char *, int (*)(lua_State *)>>
+    functionsToRegister = {
+        { "print", vivyPrint },
+    };
+
+void
+FreeFunctions::registerFunctions(lua_State *L) noexcept
+{
+    for (const auto &[name, functionPtr] : functionsToRegister) {
+        lua_register(L, name, functionPtr);
+        qDebug() << "LUA: Register function" << name;
+    }
+}

src/Lib/Script/LuaFreeFunctions.hh

+#pragma once
+
+#include "../Utils.hh"
+
+struct lua_State;
+
+namespace Vivy::Script::FreeFunctions
+{
+void registerFunctions(lua_State *) noexcept;
+}