lua_rng.cpp

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/*
    Copyright (C) 2014 - 2025
    by Chris Beck <render787@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_rng.hpp"
 
#include "log.hpp"
#include "mt_rng.hpp"
#include "scripting/lua_kernel_base.hpp"
#include "scripting/lua_common.hpp" // for new(L)
#include "scripting/push_check.hpp"
 
#include <string>
 
#include "lua/wrapper_lauxlib.h"
 
static lg::log_domain log_lua("scripting/lua");
#define ERR_LUA LOG_STREAM(err, log_lua)
 
// Begin lua rng bindings
namespace lua_rng {
 
using randomness::mt_rng;
 
static const char * Rng = "Rng";
 
int impl_rng_create(lua_State* L)
{
    uint32_t seed = lua_kernel_base::get_lua_kernel<lua_kernel_base>(L).get_random_seed();
    new(L) mt_rng(seed);
    luaL_setmetatable(L, Rng);
 
    return 1;
}
 
int impl_rng_destroy(lua_State* L)
{
    mt_rng * d = static_cast< mt_rng *> (luaL_testudata(L, 1, Rng));
    if (d == nullptr) {
        ERR_LUA << "rng_destroy called on data of type: " << lua_typename( L, lua_type( L, 1 ) );
        ERR_LUA << "This may indicate a memory leak, please report at bugs.wesnoth.org";
        lua_pushstring(L, "Rng object garbage collection failure");
        lua_error(L);
    } else {
        d->~mt_rng();
    }
    return 0;
}
 
int impl_rng_seed(lua_State* L)
{
    mt_rng * rng = static_cast<mt_rng *>(luaL_checkudata(L, 1, Rng));
    std::string seed = luaL_checkstring(L, 2);
 
    rng->seed_random(seed);
    return 0;
}
 
int impl_rng_draw(lua_State* L)
{
    mt_rng * rng = static_cast<mt_rng *>(luaL_checkudata(L, 1, Rng));
 
    lua_pushnumber(L, rng->get_next_random());
    return 1;
}
 
static int impl_rng_tostring(lua_State* L)
{
    mt_rng* rng = static_cast<mt_rng*>(luaL_checkudata(L, 1, Rng));
    luaW_getglobal(L, "string", "format");
    lua_pushstring(L, "Rng: %#x");
    lua_pushinteger(L, rng->get_random_seed());
    lua_call(L, 2, 1);
    return 1;
}
 
static int impl_rng_dir(lua_State* L)
{
    static const std::vector<std::string> fields = {"draw", "seed"};
    lua_push(L, fields);
    return 1;
}
 
// End Lua Rng bindings
 
void load_tables(lua_State* L)
{
    // Create the global Rng table, with create() as its only element
    lua_createtable(L, 0, 1);
    lua_pushcfunction(L, &impl_rng_create);
    lua_setfield(L, -2, "create");
    lua_setglobal(L, Rng);
 
    // Create the metatable for Rng objects
    luaL_newmetatable(L, Rng);
    static luaL_Reg const meta_callbacks[] {
        { "__gc",           &impl_rng_destroy},
        { "__tostring",     &impl_rng_tostring},
        { "__dir",          &impl_rng_dir},
        { nullptr, nullptr }
    };
    luaL_setfuncs(L, meta_callbacks, 0);
 
    static luaL_Reg const callbacks[] {
        { "seed",       &impl_rng_seed},
        { "draw",       &impl_rng_draw},
        { nullptr, nullptr }
    };
    luaL_newlibtable(L, callbacks);
    luaL_setfuncs(L, callbacks, 0);
 
    lua_setfield(L, -2, "__index");
    lua_pushstring(L, Rng);
    lua_setfield(L, -2, "__metatable");
    lua_pop(L, 1);
}
 
} // end namespace lua_map_rng