lua_widget.cpp

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/*
   Copyright (C) 2009 - 2018 by Guillaume Melquiond <guillaume.melquiond@gmail.com>
   Part of the Battle for Wesnoth Project https://www.wesnoth.org/

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2 of the License, or
   (at your option) any later version.
   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY.

   See the COPYING file for more details.
*/

#include "scripting/lua_widget.hpp"
#include "scripting/lua_widget_attributes.hpp"

#include "log.hpp"
#include "gui/widgets/widget.hpp"
#include "scripting/lua_common.hpp"
#include "scripting/lua_unit.hpp"
#include "scripting/lua_unit_type.hpp"
#include "scripting/lua_ptr.hpp"
#include "scripting/push_check.hpp"


#include "lua/lauxlib.h"
#include "lua/lua.h"                    // for lua_State, lua_settop, etc

#include <type_traits>

static const char widgetKey[] = "widget";
static char widgetdataKey[] = "widgetdata";

void luaW_pushwidget(lua_State* L, gui2::widget& w)
{
    new(L) lua_ptr<gui2::widget>(w);
    luaL_setmetatable(L, widgetKey);
}

gui2::widget& luaW_checkwidget(lua_State* L, int n)
{
    lua_ptr<gui2::widget>& lp =  *static_cast<lua_ptr<gui2::widget>*>(luaL_checkudata(L, n, widgetKey));
    auto ptr = lp.get_ptr();
    if(!ptr) {
        luaL_argerror(L, n, "widget was deleted");
    }
    return *ptr;
}

lua_ptr<gui2::widget>& luaW_checkwidget_ptr(lua_State* L, int n)
{
    lua_ptr<gui2::widget>& lp =  *static_cast<lua_ptr<gui2::widget>*>(luaL_checkudata(L, n, widgetKey));
    auto ptr = lp.get_ptr();
    if(!ptr) {
        luaL_argerror(L, n, "widget was deleted");
    }
    return lp;
}


bool luaW_iswidget(lua_State* L, int index)
{
    return luaL_testudata(L, index, widgetKey) != nullptr;
}


static void luaW_pushwidgettablecontainer(lua_State* L)
{
    lua_pushlightuserdata(L, &widgetdataKey[0]);
    lua_rawget(L, LUA_REGISTRYINDEX);
    if(lua_isnoneornil(L, -1)) {
        lua_pop(L, 1);
        lua_createtable(L, 0, 0);
        lua_pushlightuserdata(L, &widgetdataKey[0]);
        lua_pushvalue(L , -2);
        lua_rawset(L, LUA_REGISTRYINDEX);
    }
}

void luaW_pushwindowtable(lua_State* L,  gui2::window* owner)
{
    luaW_pushwidgettablecontainer(L);
    lua_pushlightuserdata(L, owner);
    lua_rawget(L, -2);
    if(lua_isnoneornil(L, -1))
    {
        //stack: windowstable, nil
        lua_pop(L, 1);
        //stack: windowstable
        lua_createtable(L, 1, 0);
        //stack: windowstable, {}
        lua_pushlightuserdata(L, owner);
        //stack: windowtable, {}, wg_id
        lua_pushvalue(L, -2);
        //stack: windowtable, {}, wg_id, {}
        lua_rawset(L, -4);
        //stack: windowtable, {}
    }
    lua_remove(L, lua_absindex(L, -2));
}

void luaW_clearwindowtable(lua_State* L, gui2::window* owner)
{
    luaW_pushwidgettablecontainer(L);
    lua_pushlightuserdata(L, owner);
    lua_pushnil(L);
    lua_rawset(L, -3);
    lua_pop(L, 1);
}


void luaW_pushwidgettable(lua_State* L, gui2::widget* wg, gui2::window* owner)
{
    luaW_pushwindowtable(L, owner);
    lua_pushlightuserdata(L, wg);
    lua_rawget(L, -2);
    if(lua_isnoneornil(L, -1))
    {
        //stack: windowtable, nil
        lua_pop(L, 1);
        //stack: windowtable
        lua_createtable(L, 1, 0);
        //stack: windowtable, {}
        luaW_pushwidget(L, *wg);
        //stack: windowtable, {}, wg
        lua_rawseti(L, -2, 1);
        //stack: windowtable, { wg},
        lua_pushlightuserdata(L, wg);
        //stack: windowtable, { wg}, wg_id
        lua_pushvalue(L, -2);
        //stack: windowtable, { wg}, wg_id, {wg}
        lua_rawset(L, -4);
        //stack: windowtable, { wg}
    }
    lua_remove(L, lua_absindex(L, -2));
}


bool luaW_setwidgetcallback(lua_State* L, gui2::widget* wg, gui2::window* owner, std::string_view name)
{
    //stack: function
    luaW_pushwidgettable(L, wg, owner);
    //stack: function, {}
    lua_push(L, name);
    //stack: function, {}, name
    lua_rawget(L, -2);
    // function, old_function
    bool existed_already = !lua_isnoneornil(L, -1);
    lua_pop(L, 1);
    // function,
    lua_push(L, name);
    //stack: function, {}, name
    lua_rotate(L, lua_absindex(L, -3), -1);
    //stack: {}, name, function
    lua_rawset(L, -3);
    //stack: {name = function}
    lua_pop(L, 1);
    return existed_already;
}

void luaW_getwidgetcallback(lua_State* L, gui2::widget* wg, gui2::window* owner, std::string_view name)
{
    luaW_pushwidgettable(L, wg, owner);
    //stack: {name = function},
    lua_push(L, name);
    //stack: {name = function}, name
    lua_rawget(L, -2);
    //stack: {name = function}, function
    lua_remove(L, lua_absindex(L, -2));
    //stack: function
}

void luaW_callwidgetcallback(lua_State* L, gui2::widget* wg, gui2::window* owner, std::string_view name)
{
    luaW_getwidgetcallback(L, wg, owner, name);
    assert(lua_isfunction(L, -1));
    luaW_pushwidget(L, *wg);
    lua_call(L, 1, 0);
}


static int impl_widget_collect(lua_State* L)
{
    lua_ptr<gui2::widget>* w = static_cast<lua_ptr<gui2::widget>*>(luaL_checkudata(L, 1, widgetKey));
    w->~lua_ptr<gui2::widget>();
    return 0;
}


namespace lua_widget {
    void register_metatable(lua_State* L)
    {

        luaL_newmetatable(L, widgetKey);
        lua_pushcfunction(L, lua_widget::impl_widget_get);
        lua_setfield(L, -2, "__index");
        lua_pushcfunction(L, lua_widget::impl_widget_set);
        lua_setfield(L, -2, "__newindex");
        lua_pushcfunction(L, impl_widget_collect);
        lua_setfield(L, -2, "__gc");
        lua_pushstring(L, widgetKey);
        lua_setfield(L, -2, "__metatable");
    }
}