Add LuaBridge library.

Add some docs on how to add C++ classes to Lua.
wheybags · Mar 19, 2020 · 66f38f6 · 66f38f6
1 parent 7d7987e
commit 66f38f6
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Showing 10 changed files with 101 additions and 234 deletions.
diff --git a/apps/freeablo/fagui/console/console.cpp b/apps/freeablo/fagui/console/console.cpp
@@ -10,10 +10,10 @@ namespace FAGui
     static const char* nullFile = "/dev/null";
 #endif
     static char consoleStdoutBuffer[BUFSIZ];
-    std::unique_ptr<Console> Console::mInstance = nullptr;
+    std::shared_ptr<Console> Console::mInstance = nullptr;
     static std::stringstream consoleCout;
 
-    Console::Console() : mBuffer({}), bufferLen(0), inputLen(0), mScript({})
+    Console::Console() : mBuffer({}), bufferLen(0), inputLen(0), mScript(Script::LuaScript::getInstance())
     {
         std::cout.rdbuf(consoleCout.rdbuf());
         freopen(nullFile, "a", stdout);
@@ -26,7 +26,7 @@ namespace FAGui
         fclose(stdout);
     }
 
-    std::unique_ptr<Console>& Console::getInstance()
+    std::shared_ptr<Console> Console::getInstance()
     {
         if (!mInstance)
             mInstance = std::unique_ptr<Console>(new Console());
@@ -61,7 +61,7 @@ namespace FAGui
         bufferLen += inputLen;
         inputLen = 0;
 
-        mScript.eval(command.c_str());
+        mScript->eval(command.c_str());
         std::string msg = ">> ";
         msg.append(consoleStdoutBuffer, strlen(consoleStdoutBuffer));
         std::memset(consoleStdoutBuffer, '\0', BUFSIZ);

diff --git a/apps/freeablo/fagui/console/console.h b/apps/freeablo/fagui/console/console.h
@@ -15,11 +15,11 @@ namespace FAGui
         static constexpr size_t inputSize = 512;
         char mInput[inputSize];
         int inputLen;
-        Script::LuaScript mScript;
-        static std::unique_ptr<Console> mInstance;
+        std::shared_ptr<Script::LuaScript> mScript;
+        static std::shared_ptr<Console> mInstance;
 
     public:
-        static std::unique_ptr<Console>& getInstance();
+        static std::shared_ptr<Console> getInstance();
         ~Console();
 
         char* getInput() { return mInput; };

diff --git a/apps/freeablo/fagui/guimanager.cpp b/apps/freeablo/fagui/guimanager.cpp
@@ -530,7 +530,7 @@ namespace FAGui
 
     void GuiManager::consolePanel(nk_context* ctx)
     {
-        auto& c = Console::getInstance();
+        auto c = Console::getInstance();
         drawPanel(ctx,
                   PanelType::console,
                   [&]() {

diff --git a/components/CMakeLists.txt b/components/CMakeLists.txt
@@ -157,5 +157,5 @@ add_library(Script
   script/luascript.h
 )
 
-target_link_libraries(Script lua Filesystem Misc)
+target_link_libraries(Script lua LuaBridge Misc)
 set_target_properties(Script PROPERTIES COMPILE_FLAGS "${FA_COMPILER_FLAGS}")
diff --git a/components/script/luascript.cpp b/components/script/luascript.cpp
@@ -5,6 +5,8 @@
 
 namespace Script
 {
+    std::shared_ptr<LuaScript> LuaScript::mInstance = nullptr;
+
     LuaScript::LuaScript() : mState(luaL_newstate()) { luaL_openlibs(mState); }
 
     LuaScript::~LuaScript()
@@ -13,117 +15,6 @@ namespace Script
             lua_close(mState);
     }
 
-    void LuaScript::printError(const std::string& variable, const std::string& reason)
-    {
-#ifdef NDEBUG
-        (void)variable;
-        (void)reason;
-#else
-        std::cerr << "Can't get variable " << variable << ".\nReason: " << reason << "\n";
-#endif
-    }
-
-    template <> std::string LuaScript::luaGetDefault<std::string>() { return "null"; }
-
-    template <> bool LuaScript::luaGet<bool>(const std::string& variable)
-    {
-        (void)variable;
-        return static_cast<bool>(lua_toboolean(mState, -1));
-    }
-    template <> int LuaScript::luaGet<int>(const std::string& variable)
-    {
-        (void)variable;
-        return static_cast<int>(lua_tointeger(mState, -1));
-    }
-    template <> int64_t LuaScript::luaGet<int64_t>(const std::string& variable)
-    {
-        (void)variable;
-        return static_cast<int64_t>(lua_tointeger(mState, -1));
-    }
-
-    template <> FixedPoint LuaScript::luaGet<FixedPoint>(const std::string& variable)
-    {
-        (void)variable;
-        return static_cast<FixedPoint>(luaL_checknumber(mState, 1));
-    }
-
-    template <> std::string LuaScript::luaGet<std::string>(const std::string& variable)
-    {
-        std::string ret = "null";
-
-        release_assert(lua_isstring(mState, -1));
-
-        if (lua_isstring(mState, -1))
-            ret = std::string(lua_tostring(mState, -1));
-        else
-            printError(variable, "Not a string");
-
-        return ret;
-    }
-
-    bool LuaScript::luaGetToStack(const std::string& variable, int& level)
-    {
-        level = 0;
-        std::string var{};
-
-        for (char c : variable)
-        {
-            if (c == '.')
-            {
-                if (level == 0)
-                {
-                    lua_getglobal(mState, var.c_str());
-                }
-
-                else
-                {
-                    lua_getfield(mState, -1, var.c_str());
-                }
-
-                if (lua_isnil(mState, -1))
-                {
-                    printError(variable, var + " is not defined");
-                    return false;
-                }
-
-                else
-                {
-                    var = "";
-                    ++level;
-                }
-            }
-
-            else
-            {
-                var += c;
-            }
-        }
-
-        if (level == 0)
-        {
-            lua_getglobal(mState, var.c_str());
-        }
-
-        else
-        {
-            lua_getfield(mState, -1, var.c_str());
-        }
-
-        if (lua_isnil(mState, -1))
-        {
-            printError(variable, var + " is not defined");
-            return false;
-        }
-
-        return true;
-    }
-
-    void LuaScript::clean()
-    {
-        int n = lua_gettop(mState);
-        lua_pop(mState, n);
-    }
-
     void LuaScript::runScript(const std::string& path)
     {
         lua_settop(mState, 0);
@@ -146,4 +37,7 @@ namespace Script
             lua_pop(mState, 1);
         }
     }
+
+    template <> float LuaScript::get<float>(const std::string &variable) = delete;
+    template <> double LuaScript::get<double>(const std::string &variable) = delete;
 }
diff --git a/components/script/luascript.h b/components/script/luascript.h
@@ -11,105 +11,53 @@
 #include "lua.h"
 #include "lualib.h"
 
+#include "LuaBridge/LuaBridge.h"
+#include "LuaBridge/Vector.h"
+
 namespace Script
 {
     class LuaScript
     {
         lua_State* mState;
+        static std::shared_ptr<LuaScript> mInstance;
 
     public:
-        LuaScript();
         ~LuaScript();
 
-        template <typename T> void registerGlobalType();
+        template <typename T> void registerType();
 
         template <typename Func> void registerGlobalFunction(const std::string& functionName, Func&& func)
         {
-            lua_pushcfunction(mState, func);
-            lua_setglobal(mState, functionName.c_str());
+            luabridge::getGlobalNamespace(mState).addFunction(functionName.c_str(), func);
         }
 
-        template <typename T> void pushObject(T& obj, const char* varName)
+        template <typename T> void pushGlobalObject(T& obj, const char* varName)
         {
-            static bool registered = false;
-            if (!registered)
-            {
-                registerGlobalType<T>();
-                registered = true;
-            }
-
-            T** udata = reinterpret_cast<T**>(lua_newuserdata(mState, sizeof(T*)));
-            (*udata) = &obj;
-            const std::string typeName = typeid(T).name();
-            luaL_setmetatable(mState, typeName.substr(1).c_str());
+            registerType<T>();
+            luabridge::push(mState, obj);
             lua_setglobal(mState, varName);
         }
 
         template <typename T> T get(const std::string& variable)
         {
-            release_assert(mState);
-            int level;
-
-            T result;
-            if (luaGetToStack(variable, level))
-                result = luaGet<T>(variable);
-
-            else
-                result = luaGetDefault<T>();
-
-            lua_pop(mState, level + 1);
-            return result;
-        }
-
-        template <typename T> std::vector<T> getVector(const std::string& variable)
-        {
-            std::vector<T> ret;
-            lua_getglobal(mState, variable.c_str());
-            if (lua_isnil(mState, -1))
-            {
-                return {};
-            }
-
-            lua_pushnil(mState);
-
-            while (lua_next(mState, -2))
-            {
-                T aux;
-                if constexpr (std::is_same<T, std::string>::value)
-                {
-                    ret.push_back(lua_tostring(mState, -1));
-                }
-
-                else
-                {
-                    ret.push_back(static_cast<T>(lua_tonumber(mState, -1)));
-                }
-
-                lua_pop(mState, 1);
-            }
-
-            clean();
-            return ret;
+            luabridge::LuaRef ret = luabridge::getGlobal(mState, variable.c_str());
+            return ret.cast<T>();
         }
 
         void runScript(const std::string& path);
         void eval(const char* script);
 
-    private:
-        bool luaGetToStack(const std::string& variable, int& level);
-
-        void clean();
-
-        void printError(const std::string& variable, const std::string& reason);
+        static std::shared_ptr<LuaScript> getInstance()
+        {
+            if (!mInstance)
+                mInstance = std::shared_ptr<LuaScript>(new LuaScript());
 
-        template <typename T> T luaGet(const std::string& variable = "");
+            return mInstance;
+        }
 
-        template <typename T> T luaGetDefault() { return {}; }
+        operator lua_State*() { return mState; }
 
-        template <typename Func> void pushFunction(Func&& f, const char* funcName)
-        {
-            lua_pushcfunction(mState, f);
-            lua_setfield(mState, -2, funcName);
-        }
+    private:
+        LuaScript();
     };
 }
diff --git a/docs/cpp_class_to_lua.md b/docs/cpp_class_to_lua.md
@@ -0,0 +1,47 @@
+## Registering a C++ class into Lua
+
+Suppose you have the following class:
+
+```cpp
+class Greeter
+{
+    const char* msg
+public:
+    Greeter() {}
+    Greeter(const char *msg) {}
+    void hello(const char* name) { std::cout << "Hello, " << name << "\n"; }
+    void print() { std::cout << msg << "\n"; }
+};
+```
+
+If you want to use it inside Lua, you should implement Script::LuaScript::registerType for it:
+
+```cpp
+namespace Script
+{
+    template <> void LuaScript::registerType<Greeter>()
+    {
+        luabridge::getGlobalNamespace(mState)
+            .beginNamespace("example") // optionally, you can wrap the class inside a namespace
+                .beginClass<Greeter>("Greeter")
+                    .addConstructor<void (*)(void)>()
+                    .addConstructor<void (*)(const char*)>()
+                    .addFunction("hello", &Greeter::hello)
+                    .addFunction("print", &Greeter::print)
+                .endClass()
+            .endNamespace();
+    }
+}
+```
+
+Make sure you call 'registerType' before using the class in Lua. Now, to use in Lua:
+
+```lua
+local greeter = example.Greeter()
+greeter:hello("John Smith")
+
+local greeter2 = example.Greeter("Hello world")
+greeter2:print()
+```
+
+For more information, see [LuaBridge Reference](https://vinniefalco.github.io/LuaBridge/Manual.html).
diff --git a/extern/CMakeLists.txt b/extern/CMakeLists.txt
@@ -23,5 +23,6 @@ add_subdirectory(SDL_image)
 add_subdirectory(StormLib)
 add_subdirectory(gtest)
 add_subdirectory(lua)
+add_subdirectory(LuaBridge)
 
 unset(MESSAGE_QUIET)