LuaFunction.hpp

/*
 * Copyright (c) 2015-2023 JlnWntr (jlnwntr@gmail.com)
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

#ifndef LUA_FUNCTION_H
#define LUA_FUNCTION_H

#ifndef LUA_ADAPTER_H
#include "LuaAdapter.hpp"
#endif

static int LUA_ADAPTER_NULL{};
typedef int (*Lua_callback_function)(lua_State *L);

class LuaFunction {
public:
    /**
     * Default constructor
     */
    LuaFunction() : Lua{nullptr} {}

    /**
     * Constructor
     * @param lua uses an existing LuaState
     */
    LuaFunction(lua_State *const lua) : Lua{std::make_shared<LuaState>(lua)} {}
    LuaFunction(LuaAdapter &lua) : Lua{lua.GetLuaState()} {}
    LuaFunction(const LuaFunction &) = delete;

    /**
     * Destructor
     */
    ~LuaFunction() {}

    /**
     * Calls a Lua-function
     * @param f name of the Lua-function
     * @param c number of arguments passed to the Lua-function
     * @param a function arguments
     * @param r new value returned from the called Lua-function
     * @return true on success, false on error
     */
    template <typename A, typename R>
    bool Call(const std::string f, const auto c, const A *const a, R &r) {
        if (not this->Lua.get() or not this->Lua.get()->Lua() or
                not(lua_getglobal(this->Lua.get()->Lua(), f.c_str()) == LUA_TFUNCTION))
            return false;

        for (auto i = 0; i < c; i++) {
            if (not(a + i)) break;
            if constexpr (std::is_same_v<double, A> or std::is_same_v<A, float>)
                lua_pushnumber(this->Lua.get()->Lua(), a[i]);
            else if constexpr (std::is_same_v<A, int>)
                lua_pushinteger(this->Lua.get()->Lua(), a[i]);
            else if constexpr (std::is_same_v<A, std::string>)
                lua_pushlstring(this->Lua.get()->Lua(), a[i].c_str(), a[i].length());
            else if constexpr (std::is_same_v<A, const char*>)
                lua_pushlstring(this->Lua.get()->Lua(), a[i], strlen(a[i]));
            else if constexpr (std::is_same_v<A, bool>)
                lua_pushboolean(this->Lua.get()->Lua(), a[i]);
        }

        if (this->Pcall(c, 1, 0) == false){
            return false;
        }
        if constexpr (std::is_same_v<double, R> or std::is_same_v<R, float>) {
            if (lua_isnumber(this->Lua.get()->Lua(), -1))
                r = lua_tonumber(this->Lua.get()->Lua(), -1);
        } else if constexpr (std::is_same_v<R, int>) {
            if (lua_isinteger(this->Lua.get()->Lua(), -1))
                r = lua_tointeger(this->Lua.get()->Lua(), -1);
        } else if constexpr (std::is_same_v<R, bool>) {
            if (lua_isboolean(this->Lua.get()->Lua(), -1))
                r = lua_toboolean(this->Lua.get()->Lua(), -1);
        } else if constexpr (std::is_same_v<R, std::string>) {
            if (lua_isstring(this->Lua.get()->Lua(), -1))
                r = lua_tostring(this->Lua.get()->Lua(), -1);
        }
        lua_pop(this->Lua.get()->Lua(), 1);
        return true;
    }

    /**
     * Calls a Lua-function
     * @param f name of the Lua-function
     * @param c number of arguments passed to the Lua-function
     * @param a function arguments
     * @return true on success, false on error
     */
    template <typename A>
    bool Test(const std::string f, const auto c, const A *const a) {
        if (not this->Lua.get() or not this->Lua.get()->Lua() or
                not(lua_getglobal(this->Lua.get()->Lua(), f.c_str()) == LUA_TFUNCTION))
            return false;

        for (auto i = 0; i < c; i++) {
            if (not(a + i)) break;
            if constexpr (std::is_same_v<double, A> or std::is_same_v<A, float>)
                lua_pushnumber(this->Lua.get()->Lua(), a[i]);
            else if constexpr (std::is_same_v<A, int>)
                lua_pushinteger(this->Lua.get()->Lua(), a[i]);
            else if constexpr (std::is_same_v<A, std::string>)
                lua_pushlstring(this->Lua.get()->Lua(), a[i].c_str(), a[i].length());
            else if constexpr (std::is_same_v<A, const char*>)
                lua_pushlstring(this->Lua.get()->Lua(), a[i], strlen(a[i]));
            else if constexpr (std::is_same_v<A, bool>)
                lua_pushboolean(this->Lua.get()->Lua(), a[i]);
        }
        return this->Pcall(c, 0, 0);
    }

    /**
     * Calls a Lua-function
     * @param f name of the Lua-function
     * @param a function argument
     * @param r new value returned from the called Lua-function
     * @return true on success, false on error
     */
    template <typename A, typename R>
    bool Call(const std::string f, const A a, R &r = LUA_ADAPTER_NULL) {
        return this->Call(f.c_str(), 1, &a, r);
    }

    /**
     * Calls a Lua-function
     * @param f name of the Lua-function
     * @param a function argument
     * @return true on success, false on error
     */
    template <typename A>
    bool Call(const std::string f, const A a) {
        return this->Call(f.c_str(), a, LUA_ADAPTER_NULL);
    }

    /**
     * Calls a Lua-function
     * @param f name of the Lua-function
     * @return true on success, false on error
     */
    bool Call(const std::string f) {
        if (not this->Lua.get() or not this->Lua.get()->Lua() or
                not(lua_getglobal(this->Lua.get()->Lua(), f.c_str()) == LUA_TFUNCTION))
            return false;
        return this->Pcall(0, 0, 0);
    }

    /**
     * Makes a C-/C++-function available for Lua
     * (It's called pushFunction(), but you're not 'incrementing' the stack)
     * @param function C-/C++-function
     * @param name of the function
     * @return true on success, false on error
     */
    bool Push(Lua_callback_function function, const std::string name) {
        if (not this->Lua.get() or not this->Lua.get()->Lua())
            return false;
        lua_pushcfunction(this->Lua.get()->Lua(), function);
        lua_setglobal(this->Lua.get()->Lua(), name.c_str());
        return true;
    }


private:
    std::shared_ptr<LuaState> Lua;

    /**
     * Calls Lua's pcall and outputs errors.
     * @param argc number of arguments
     * @param results number of results
     * @param msgh message handler (see
     * https://www.lua.org/manual/5.3/manual.html#lua_pcall)
     * @return true on success, false on error
     */
    bool Pcall(int argc, int results, int msgh) {
        if (not this->Lua.get() or not this->Lua.get()->Lua()) return false;
        const int call{lua_pcall(this->Lua.get()->Lua(), argc, results, msgh)};
        if (call == LUA_OK) return true;

#ifdef LUA_ADAPTER_DEBUG
        std::cerr << LUA_ADAPTER_PREFIX << "Error: pcall failed. Code: ";
        std::cerr << call;
        std::cerr << ", '" << lua_tostring(this->Lua.get()->Lua(), -1) << "'\n";
#endif
        lua_pop(this->Lua.get()->Lua(), 1);
        return false;
    }
};
#endif