luaqalculator/qalculator.cpp

#include <lua.hpp>
#include <libqalculate/qalculate.h>
#include <string>

const char* qalculate(const char* input, bool exact_mode) {
    Calculator* c = new Calculator();
    c->loadExchangeRates();
    c->loadGlobalDefinitions();
    c->loadLocalDefinitions();
    std::string Input = input;
    std::string Output;
    if (exact_mode) {
        default_user_evaluation_options.approximation = APPROXIMATION_EXACT;
    } else {
        default_user_evaluation_options.approximation = APPROXIMATION_APPROXIMATE;
    }
    Output = c->calculateAndPrint(Input,2000,default_user_evaluation_options);
    delete c;
    char * output = new char [Output.length()+1];
    Output.copy(output,Output.length());
    output[Output.length()] = "\0"[0];
    return output;
}

extern "C" 
int l_qalc(lua_State* L) {
    const char * input = luaL_checkstring(L, 1);
    bool exact_mode = lua_toboolean(L, 2);
    const char * output = qalculate(input, exact_mode);
    lua_pushstring(L, output);
    return 1;
}

extern "C"
int luaopen_libqalculator(lua_State* L) {
    static const struct luaL_Reg library [] =
    {
        {"qalc", l_qalc},
        {NULL, NULL}
    };
    luaL_register(L, "qalc", library);
    return 1;
}