LuaTable.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_TABLE_H
#define LUA_TABLE_H

#include <vector>

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

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

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

    /**
     * Opens a Lua-table
     * @param name Name of the table inside loaded Lua-state
     * @return true on success, false on error
     */
    bool Open(const std::string &name) {
        if ((not this->Lua.get() or not this->Lua.get()->Lua()))
            return false;

        if (lua_istable(this->Lua.get()->Lua(), -1)) {
#ifdef LUA_ADAPTER_DEBUG
            std::cout << "\t" << LUA_ADAPTER_PREFIX << "opening nested table '"
                      << name << "' ... ";
#endif
            lua_getfield(this->Lua.get()->Lua(), -1, name.c_str());

            if (lua_isnil(this->Lua.get()->Lua(), -1)) {
                lua_pop(this->Lua.get()->Lua(), 1);
                return false;
            }

            if (lua_istable(this->Lua.get()->Lua(), -1)) {
#ifdef LUA_ADAPTER_DEBUG
                std::cout << "ok!" << std::endl;
#endif
                return true;
            }
            return false;
        }
        lua_getglobal(this->Lua.get()->Lua(), name.c_str());  // void

        if (lua_istable(this->Lua.get()->Lua(), -1)) {
#ifdef LUA_ADAPTER_DEBUG
            std::cout << LUA_ADAPTER_PREFIX << "open table '" << name << "'"
                      << std::endl;
#endif
            return true;
        }

        lua_pop(this->Lua.get()->Lua(), 1);
        return false;
    }

    /**
     * Get the length of the current (opened) table
     * (tables with integer keys and without 'nil-holes')
     * @return the length of the table
     */
    int Length() {
        int result{0};
        if (not this->Lua.get() or not this->Lua.get()->Lua() or
                not lua_istable(this->Lua.get()->Lua(), -1))
            return result;

        lua_len(this->Lua.get()->Lua(), -1);
        result = lua_tointeger(this->Lua.get()->Lua(), -1);
        lua_pop(this->Lua.get()->Lua(), 1);
        return result;
    }

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

    /**
     * Gets a field from an opened table
     * @param name of the field
     * @param r value of the field
     * @return true on success, false on error
     */
    template <typename R>
    bool Get(const char *name, R &r) {
        if (not this->Lua.get() or not this->Lua.get()->Lua() or
                not lua_istable(this->Lua.get()->Lua(), -1))
            return false;

        lua_getfield(this->Lua.get()->Lua(), -1, name);

        if (this->convert(r) == false) {
            lua_pop(this->Lua.get()->Lua(), 1);
            return false;
        }
#ifdef LUA_ADAPTER_DEBUG
        std::cout << "\t" << LUA_ADAPTER_PREFIX << "got field '" << name << "' = '"
                  << r << "'" << std::endl;
#endif
        lua_pop(this->Lua.get()->Lua(), 1);
        return true;
    }

    /**
     * Gets a field from an opened table
     * @param i i-th field (starting at 1)
     * @param r value of the field
     * @return true on success, false on error
     */
    template <typename R>
    bool Get(unsigned short int i, R &r) {
        if (not this->Lua.get() or not this->Lua.get()->Lua() or
                not lua_istable(this->Lua.get()->Lua(), -1) or (i < 1))
            return false;
        lua_rawgeti(this->Lua.get()->Lua(), -1, i);

        if (this->convert(r) == false) {
            lua_pop(this->Lua.get()->Lua(), 1);
            return false;
        }

#ifdef LUA_ADAPTER_DEBUG
        std::cout << "\t" << LUA_ADAPTER_PREFIX << "got " << i << "th field  = '"
                  << r << "'" << std::endl;
#endif
        lua_pop(this->Lua.get()->Lua(), 1);
        return true;
    }
    /**
     * Gets a field value from an opened n-dimensional table.
     * Example: lua_identity ={
     *               {1, 0, 0},
     *               {0, 1, 0},
     *               {0, 0, 1},
     *           }  *
     * @param m table-indeces. e.g. {1,2} for first 0 from example table above.
     * @param r value of the field
     * @return true on success, false on error
     */
    template <typename R>
    bool Get(const std::vector<unsigned short int> &m, R &r) {
        if (not this->Lua.get() or not this->Lua.get()->Lua()) return false;
        for (auto &v : m)
            if (lua_istable(this->Lua.get()->Lua(), -1))
                lua_rawgeti(this->Lua.get()->Lua(), -1, v);

        const bool Result{this->convert(r)};
#ifdef LUA_ADAPTER_DEBUG
        if (Result)
            std::cout << "\t" << LUA_ADAPTER_PREFIX
                      << "got field "
                      " = '"
                      << r << "'" << std::endl;
#endif
        while (lua_gettop(this->Lua.get()->Lua()) > 1)
            lua_pop(this->Lua.get()->Lua(), 1);
        return Result;
    }

    /**
     *Closes a table
     *(This is important to prevents "stack-smashing".)
     */
    void Close() {
        if (this->Lua.get() and this->Lua.get()->Lua())
            lua_pop(this->Lua.get()->Lua(), 1);
    }

private:
    template <typename R>
    bool convert(R &r) {
        if (not this->Lua.get() or not this->Lua.get()->Lua()) return false;
        if (lua_isnumber(this->Lua.get()->Lua(), -1) and
                !lua_isinteger(this->Lua.get()->Lua(), -1)) {
            if constexpr (std::is_same_v<double, R> or std::is_same_v<R, float>)
                r = lua_tonumber(this->Lua.get()->Lua(), -1);
        } else if (lua_isinteger(this->Lua.get()->Lua(), -1)) {
            if constexpr (std::is_same_v<R, int>)
                r = lua_tointeger(this->Lua.get()->Lua(), -1);
        } else if (lua_isboolean(this->Lua.get()->Lua(), -1)) {
            if constexpr (std::is_same_v<R, bool>)
                r = lua_toboolean(this->Lua.get()->Lua(), -1);
        } else if (lua_isstring(this->Lua.get()->Lua(), -1)) {
            if constexpr (std::is_same_v<R, std::string>)
                r = lua_tostring(this->Lua.get()->Lua(), -1);
        } else
            return false;
        return true;
    }
    std::shared_ptr<LuaState> Lua;
};
#endif