lua_common.hpp

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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.
*/
 
/**
 * Common callbacks and functions to manipulate config, vconfig, tstring
 * in lua, and macros to get them from the stack.
 */
 
#pragma once
 
struct lua_State;
class t_string;
class vconfig;
 
#include "config.hpp"
#include "variable_info.hpp"
#include "map/location.hpp"
 
#include <string>
#include <string_view>
#include <vector>
 
namespace lua_common {
    int intf_textdomain(lua_State *L);
    int intf_tovconfig(lua_State* L);
 
    std::string register_gettext_metatable(lua_State *L);
    std::string register_tstring_metatable(lua_State *L);
    std::string register_vconfig_metatable(lua_State *L);
 
}
 
/**
 * Shallow wrapper around lua_geti which pops the top variable from the
 * Lua stack when destroyed. This is meant to be used in local contexts
 * for quick cleanup of the stack variable.
 *
 * @todo support different get* functions?
 */
class scoped_lua_argument
{
public:
    scoped_lua_argument(lua_State* L, int arg_index);
    scoped_lua_argument(lua_State* L, int value_index, int arg_index);
 
    ~scoped_lua_argument();
 
    scoped_lua_argument(const scoped_lua_argument&) = delete;
    scoped_lua_argument& operator=(const scoped_lua_argument&) = delete;
 
private:
    lua_State* const state_;
};
 
void* operator new(std::size_t sz, lua_State *L, int nuv = 0);
void operator delete(void* p, lua_State *L, int nuv);
 
/**
 * Efficiently creates new LUA "named tuples" with the specified field
 * names. Use the @a push method to create a new empty tuple instance
 * at the top of the stack.
 *
 * All tuples have some fixed layout and the total set of layouts is
 * small (10-ish). So, we simply store the meta table the LUA registry
 * once and then keep reusing it. Saves tons of construction effort.
 * For maximum reuse, you should create static instances of this class.
 *
 * @note It is perfectly fine to have multiple instances of this
 * class produce the same named tuple structure; the registry mechanism
 * will ensure that there is a single common metatable not all of them.
 */
class lua_named_tuple_builder
{
public:
 
    lua_named_tuple_builder(const std::vector<std::string>& names);
 
    /**
     * Push an empty "named tuple" onto the stack.
     * A named tuple is an array where each index can also be accessed by name.
     * Once it's pushed, you can set the elements, eg with lua_rawseti.
     */
    void push(lua_State *L) const;
 
private:
 
    static int impl_get(lua_State* L);
    static int impl_set(lua_State* L);
    static int impl_dir(lua_State* L);
    static int impl_tostring(lua_State* L);
    static int impl_compare(lua_State* L);
 
    static std::string build_key(const std::vector<std::string>& names);
 
    static constexpr std::string_view base_name_ = "named tuple";
 
    const std::vector<std::string> names_;
    const std::string key_;
};
 
/**
 * Like luaL_getmetafield, but returns false if key is an empty string
 * or begins with two underscores.
 */
bool luaW_getmetafield(lua_State *L, int idx, const char* key);
 
/**
 * Pushes a vconfig on the top of the stack.
 */
void luaW_pushvconfig(lua_State *L, const vconfig& cfg);
 
/**
 * Pushes a t_string on the top of the stack.
 */
void luaW_pushtstring(lua_State *L, const t_string& v);
 
/**
 * Converts an attribute value into a Lua object pushed at the top of the stack.
 */
void luaW_pushscalar(lua_State *L, const config::attribute_value& v);
 
/**
 * Converts the value at the top of the stack to an attribute value
 */
bool luaW_toscalar(lua_State *L, int index, config::attribute_value& v);
 
/**
 * Converts a scalar to a translatable string.
 */
bool luaW_totstring(lua_State *L, int index, t_string &str);
 
/**
 * Converts a scalar to a translatable string.
 */
t_string luaW_checktstring(lua_State *L, int index);
 
/*
 * Test if a scalar is either a plain or translatable string.
 * Also returns true if it's a number since that's convertible to string.
 */
bool luaW_iststring(lua_State* L, int index);
 
/**
 * Converts a config object to a Lua table.
 * The destination table should be at the top of the stack on entry. It is
 * still at the top on exit.
 */
void luaW_filltable(lua_State *L, const config& cfg);
 
/**
 * Get the keys of a "named tuple" from the stack.
 * Returns an empty array if the stack element is not a named tuple.
 */
std::vector<std::string> luaW_to_namedtuple(lua_State* L, int idx);
 
/**
 * Converts a map location object to a Lua table pushed at the top of the stack.
 */
void luaW_pushlocation(lua_State *L, const map_location& loc);
 
/**
 * Converts an optional table or pair of integers to a map location object.
 * @param L the pointer to the lua interpreter.
 * @param index stack position of the table or first integer.
 * @param loc the location to write to.
 * @return false if a map location couldn't be matched.
 */
bool luaW_tolocation(lua_State *L, int index, map_location &loc);
 
/**
 * Converts an optional table or pair of integers to a map location object.
 * @note If a pair of integers was found, the first one will be removed
 *       from the stack when the function returns.
 */
map_location luaW_checklocation(lua_State *L, int index);
 
/**
 * Converts a set of map locations to a Lua table pushed at the top of the stack.
 */
int luaW_push_locationset(lua_State* L, const std::set<map_location>& locs);
 
/**
 * Converts a table of integer pairs to a set of map location objects.
 */
std::set<map_location> luaW_check_locationset(lua_State* L, int idx);
 
/**
 * Converts a config object to a Lua table pushed at the top of the stack.
 */
void luaW_pushconfig(lua_State *L, const config& cfg);
 
/**
 * Converts an optional table or vconfig to a config object.
 * @param L the pointer to the lua interpreter.
 * @param index stack position of the table.
 * @param cfg the config to write the data to.
 * @return false if some attributes had not the proper type.
 * @note If the table has holes in the integer keys or floating-point keys,
 *       some keys will be ignored and the error will go undetected.
 */
bool luaW_toconfig(lua_State *L, int index, config &cfg);
 
/**
 * Converts an optional table or vconfig to a config object.
 */
config luaW_checkconfig(lua_State *L, int index);
 
/**
 * Gets an optional vconfig from either a table or a userdata.
 * @return false in case of failure.
 */
bool luaW_tovconfig(lua_State *L, int index, vconfig &vcfg);
 
/**
 * Gets an optional vconfig from either a table or a userdata.
 * @param L the pointer to the lua interpreter.
 * @param index the location in the current lua execution stack to look at.
 * @param allow_missing true if missing values are allowed; the function
 *        then returns an unconstructed vconfig.
 */
vconfig luaW_checkvconfig(lua_State *L, int index, bool allow_missing = false);
 
/**
 * Like the two-argument version, but if it was a vconfig, also
 * returns a pointer to that vconfig.
 */
config luaW_checkconfig(lua_State *L, int index, const vconfig*& vcfg);
 
/**
 * Pushes the value found by following the variadic names (char *), if the
 * value is not nil.
 * @return true if an element was pushed.
 */
bool luaW_getglobal(lua_State *L, const std::vector<std::string>& path);
 
/**
 * Pushes the value found by following the variadic names (char *), if the
 * value is not nil.
 * @return true if an element was pushed.
 */
template<typename... T>
bool luaW_getglobal(lua_State *L, T... path) {
    return luaW_getglobal(L, std::vector<std::string> {path...} );
}
 
bool luaW_toboolean(lua_State *L, int n);
 
 
bool luaW_pushvariable(lua_State *L, variable_access_const& v);
 
bool luaW_checkvariable(lua_State *L, variable_access_create& v, int n);
 
bool luaW_tableget(lua_State *L, int index, const char* key);
 
std::string_view luaW_tostring(lua_State *L, int index);
std::string_view luaW_tostring_or_default(lua_State *L, int index, std::string_view def = std::string_view());
 
/**
 * Displays a message in the chat window.
 */
void chat_message(const std::string& caption, const std::string& msg);
 
/**
 * Calls a Lua function stored below its @a nArgs arguments at the top of the stack.
 * @param L the pointer to the lua interpreter.
 * @param nArgs
 * @param nRets LUA_MULTRET for unbounded return values.
 * @param allow_wml_error controls where any stack traces are output.
 * @return true if the call was successful and @a nRets return values are available.
 */
bool luaW_pcall(lua_State *L, int nArgs, int nRets, bool allow_wml_error = false);
 
// Don't use these directly
void push_error_handler(lua_State *L);
int luaW_pcall_internal(lua_State *L, int nArgs, int nRets);
 
int luaW_type_error(lua_State *L, int narg, const char *tname);
int luaW_type_error(lua_State *L, int narg, const char* kpath, const char *tname);
 
struct luaW_PrintStack { lua_State* L; };
luaW_PrintStack luaW_debugstack(lua_State* L);
std::ostream& operator<<(std::ostream& os, const luaW_PrintStack&);
 
#define deprecate_attrib(name, prefix, level, version, msg) deprecated_message(prefix "." name, DEP_LEVEL::level, version, msg)
 
#define return_deprecated_attrib(type_macro, name, accessor, prefix, level, version, msg) \
    type_macro(name, ( \
        deprecate_attrib(name, prefix, level, version, msg), \
        accessor \
    ))
 
#define return_tstring_attrib(name, accessor) \
do { \
    if (strcmp(m, (name)) == 0) { \
        luaW_pushtstring(L, (accessor)); \
        return 1; \
    } \
} while(false)
#define return_tstring_attrib_deprecated(name, prefix, level, version, msg, accessor) \
    return_deprecated_attrib(return_tstring_attrib, name, accessor, prefix, level, version, msg)
 
#define return_cstring_attrib(name, accessor) \
do { \
    if (strcmp(m, (name)) == 0) { \
        lua_pushstring(L, (accessor)); \
        return 1; \
    } \
} while(false)
#define return_cstring_attrib_deprecated(name, prefix, level, version, msg, accessor) \
    return_deprecated_attrib(return_cstring_attrib, name, accessor, prefix, level, version, msg)
 
#define return_string_attrib(name, accessor) \
do { \
    if (strcmp(m, (name)) == 0) { \
        const std::string& str = (accessor); \
        lua_pushlstring(L, str.c_str(), str.length()); \
        return 1; \
    } \
} while(false)
#define return_string_attrib_deprecated(name, prefix, level, version, msg, accessor) \
    return_deprecated_attrib(return_string_attrib, name, accessor, prefix, level, version, msg)
 
#define return_int_attrib(name, accessor) \
do { \
    if (strcmp(m, (name)) == 0) { \
        lua_pushinteger(L, (accessor)); \
        return 1; \
    } \
} while(false)
#define return_int_attrib_deprecated(name, prefix, level, version, msg, accessor) \
    return_deprecated_attrib(return_int_attrib, name, accessor, prefix, level, version, msg)
 
#define return_float_attrib(name, accessor) \
do { \
    if (strcmp(m, (name)) == 0) { \
        lua_pushnumber(L, (accessor)); \
        return 1; \
    } \
} while(false)
#define return_float_attrib_deprecated(name, prefix, level, version, msg, accessor) \
    return_deprecated_attrib(return_float_attrib, name, accessor, prefix, level, version, msg)
 
#define return_bool_attrib(name, accessor) \
do { \
    if (strcmp(m, (name)) == 0) { \
        lua_pushboolean(L, (accessor)); \
        return 1; \
    } \
} while(false)
#define return_bool_attrib_deprecated(name, prefix, level, version, msg, accessor) \
    return_deprecated_attrib(return_bool_attrib, name, accessor, prefix, level, version, msg)
 
#define return_cfg_attrib(name, accessor) \
do { \
    if (strcmp(m, (name)) == 0) { \
        config cfg; \
        {accessor;} \
        luaW_pushconfig(L, cfg); \
        return 1; \
    } \
} while(false)
#define return_cfg_attrib_deprecated(name, prefix, level, version, msg, accessor) \
    return_cfg_attrib(name, deprecate_attrib(name, prefix, level, version, msg); accessor)
 
#define return_cfgref_attrib(name, accessor) \
do { \
    if (strcmp(m, (name)) == 0) { \
        luaW_pushconfig(L, (accessor)); \
        return 1; \
    } \
} while(false)
#define return_cfgref_attrib_deprecated(name, prefix, level, version, msg, accessor) \
    return_deprecated_attrib(return_cfgref_attrib, name, accessor, prefix, level, version, msg)
 
#define return_vector_string_attrib(name, accessor) \
do { \
    if (strcmp(m, (name)) == 0) { \
        const std::vector<std::string>& vector = (accessor); \
        lua_createtable(L, vector.size(), 0); \
        int i = 1; \
        for (const std::string& s : vector) { \
            lua_pushlstring(L, s.c_str(), s.length()); \
            lua_rawseti(L, -2, i); \
            ++i; \
        } \
        return 1; \
    } \
} while(false)
#define return_vector_string_attrib_deprecated(name, prefix, level, version, msg, accessor) \
    return_deprecated_attrib(return_vector_string_attrib, name, accessor, prefix, level, version, msg)
 
#define modify_tstring_attrib(name, accessor) \
do { \
    if (strcmp(m, (name)) == 0) { \
        t_string value = luaW_checktstring(L, 3); \
        {accessor;} \
        return 0; \
    } \
} while(false)
#define modify_tstring_attrib_deprecated(name, prefix, level, version, msg, accessor) \
    modify_tstring_attrib(name, deprecate_attrib(name, prefix, level, version, msg); accessor)
 
#define modify_string_attrib(name, accessor) \
do { \
    if (strcmp(m, (name)) == 0) { \
        const char *value = luaL_checkstring(L, 3); \
        {accessor;} \
        return 0; \
    } \
} while(false)
#define modify_string_attrib_deprecated(name, prefix, level, version, msg, accessor) \
    modify_string_attrib(name, deprecate_attrib(name, prefix, level, version, msg); accessor)
 
#define modify_int_attrib(name, accessor) \
do { \
    if (strcmp(m, (name)) == 0) { \
        int value = static_cast<int>(luaL_checknumber(L, 3)); \
        {accessor;} \
        return 0; \
    } \
} while(false)
#define modify_int_attrib_deprecated(name, prefix, level, version, msg, accessor) \
    modify_int_attrib(name, deprecate_attrib(name, prefix, level, version, msg); accessor)
 
#define modify_int_attrib_check_range(name, accessor, allowed_min, allowed_max) \
do { \
    if (strcmp(m, (name)) == 0) { \
        int value = static_cast<int>(luaL_checknumber(L, 3)); \
        if (value < (allowed_min) || (allowed_max) < value) return luaL_argerror(L, 3, "out of bounds"); \
        {accessor;} \
        return 0; \
    } \
} while(false)
#define modify_int_attrib_check_range_deprecated(name, prefix, level, version, msg, accessor, allowed_min, allowed_max) \
    modify_int_attrib_check_range(name, deprecate_attrib(name, prefix, level, version, msg); accessor, allowed_min, allowed_max)
 
#define modify_float_attrib(name, accessor) \
do { \
    if (strcmp(m, (name)) == 0) { \
        lua_Number value = luaL_checknumber(L, 3); \
        {accessor;} \
        return 0; \
    } \
} while(false)
#define modify_float_attrib_deprecated(name, prefix, level, version, msg, accessor) \
    modify_float_attrib(name, deprecate_attrib(name, prefix, level, version, msg); accessor)
 
#define modify_float_attrib_check_range(name, accessor, allowed_min, allowed_max) \
do { \
    if (strcmp(m, (name)) == 0) { \
        lua_Number value = luaL_checknumber(L, 3); \
        if (value < (allowed_min) || (allowed_max) < value) return luaL_argerror(L, 3, "out of bounds"); \
        {accessor;} \
        return 0; \
    } \
} while(false)
#define modify_float_attrib_check_range_deprecated(name, prefix, level, version, msg, accessor, allowed_min, allowed_max) \
    modify_float_attrib_check_range(name, deprecate_attrib(name, prefix, level, version, msg); accessor, allowed_min, allowed_max)
 
#define modify_bool_attrib(name, accessor) \
do { \
    if (strcmp(m, (name)) == 0) { \
        bool value = luaW_toboolean(L, 3); \
        {accessor;} \
        return 0; \
    } \
} while(false)
#define modify_bool_attrib_deprecated(name, prefix, level, version, msg, accessor) \
    modify_bool_attrib(name, deprecate_attrib(name, prefix, level, version, msg); accessor)
 
#define modify_cfg_attrib(name, accessor) \
do { \
    if (strcmp(m, (name)) == 0) { \
        const config& cfg = luaW_checkconfig(L, 3); \
        {accessor;} \
        return 0; \
    } \
} while(false)
#define modify_cfg_attrib_deprecated(name, prefix, level, version, msg, accessor) \
    modify_cfg_attrib(name, deprecate_attrib(name, prefix, level, version, msg); accessor)
 
#define modify_vector_string_attrib(name, accessor) \
do { \
    if (strcmp(m, (name)) == 0) { \
        std::vector<std::string> value; \
        char const* message = "table with unnamed indices holding strings expected"; \
        if (!lua_istable(L, 3)) return luaL_argerror(L, 3, message); \
        unsigned length = lua_rawlen(L, 3); \
        for (unsigned i = 1; i <= length; ++i) { \
            lua_rawgeti(L, 3, i); \
            char const* string = lua_tostring(L, 4); \
            if(!string) return luaL_argerror(L, 2 + i, message); \
            value.push_back(string); \
            lua_pop(L, 1); \
        } \
        {accessor;} \
        return 0; \
    } \
} while(false)
#define modify_vector_string_attrib_deprecated(name, prefix, level, version, msg, accessor) \
    modify_vector_string_attrib(name, deprecate_attrib(name, prefix, level, version, msg); accessor)