SimControl/include/CommService/Convert.hpp

#ifndef NETWORKBUFFCONVERT
#define NETWORKBUFFCONVERT

#include <cstring>
#include <stdexcept>
#include <vector>
#include <string>

namespace CommService {


    class Convert{

      public:
        /*
      * @brief template function to byte swap int/uint datatypes - used for endianess conversion
      *
      * @param v - pointer to a variable of some int/uint datatype - in place byte swapped
      */
        template <typename T> 
        static void swapBytes(T *v) {
        for (unsigned int i = 0;  i < sizeof(T)/2;  ++i)
        {
            std::swap(((char *)v)[i], ((char *)v)[sizeof(T)-1-i]);
            }
        }

        /**
        * @brief function to convert a std::vector<unsigned char> to an simple datatype
        *
        * this is the partner function to fromSimpleToByteArray.
        * it extracts the simple datatype like int, double, etc. from the vector and
        * returns it
        *
        * @param v - the vector to convert to a simple datatype
        * @return simple datatype
        * @throw std::invalid_argument: "the bytevector is too small to fit the datatype"
        */
        template<typename T>
        static  T fromByteArrayToSimple(std::vector<unsigned char> &bytes)
        {
          T convVariable;
          if(bytes.size() < sizeof(T))
          {
            throw(std::invalid_argument(std::string(__FILE__) + ":" + std::string(__PRETTY_FUNCTION__) + ":" + std::to_string(__LINE__) + ": the bytevector is too small to fit the datatype"));
          }
          std::memcpy(reinterpret_cast<unsigned char*>(&convVariable),bytes.data(),sizeof(T));
          #ifndef IS_BIG_ENDIAN
          swapBytes(&convVariable);
          #endif
          return std::move(convVariable);
        }



        /**
        * @brief template for converting of simple datatypes to a byte_array, including endianness conversion to big endian
        *
        * @param variable - the variable to convert to a byte vector, needs to be int/uint datatype
        *
        * @return the std::vector<unsigned char>
        */
        template<typename T>
        static std::vector<unsigned char> fromSimpleToByteArray(T &variable)
        {
          std::vector<unsigned char> bytes;
          bytes.clear();
          bytes.resize(sizeof(T));

          #ifndef IS_BIG_ENDIAN
          T convVariable = variable;
          swapBytes(&convVariable);
          std::memcpy(bytes.data(),reinterpret_cast<const unsigned char*>(&convVariable),sizeof(T));
          #else
          std::memcpy(bytes.data(),reinterpret_cast<const unsigned char*>(&variable),sizeof(T));
          #endif

          return bytes;
        }


        /**
        * @brief function to convert a container of a simple datatype to a std::vector<unsigned char>
        *
        * this is the partner function to fromByteArrayToSimpleContainer.
        * the number of container elements is prepended to the std::vector and the simple datatype
        * elements follow.
        *
        * @param data - the container of a simple datatype
        *
        * @return the std::vector<unsigned char>;
        */
        template<class T>
        static std::vector<unsigned char> fromSimpleContainerToByteArray(T &data)
        {
          std::vector<unsigned char> bytes;
          std::vector<unsigned char> convert;

          uint32_t size=data.size();
          bytes=fromSimpleToByteArray(size);

          for(auto it = data.begin(); it!=data.end(); ++it)
          {
            convert=fromSimpleToByteArray(*it);
            bytes.insert(std::end(bytes), std::begin(convert), std::end(convert));
          }

          return bytes;
        }


        /**
        * @brief function to convert a std::vector<unsigned char> to a container of simple datatype elements
        *
        * this is the partner function to fromSimpleContainerToByteArray. It takes the
        * first 4 byte of the vector as an uint32_t element count and parses the all the elements
        * from the vector.
        *
        * @param v - the vector to convert to a container of simple datatype elements
        *
        * @return the container
        */
        template<class T, typename S>
        static T fromByteArrayToSimpleContainer(std::vector<unsigned char> &v)
        {
          T data;
          uint32_t size = fromByteArrayToSimple<S>(v);
          v.erase(v.begin(), v.begin()+sizeof(size));
          for(uint32_t i=0; i<size; i++)
          {
            S convert = fromByteArrayToSimple<S>(v);
            v.erase(v.begin(), v.begin()+sizeof(convert));
            data.push_back(convert);
          }

          return std::move(data);
        }

        
        /**
        * @brief function to convert a std::string to an std::vector<unsigned char>
        *
        * for converting the string, first the length of the string is converted as
        * an uint32_t into the std::vector to be able to correctly parse the string
        * in a larger vector.
        *
        * @param variable - the std::string to convert
        *
        * @return the std::vector<unsigned char>
        */
        static std::vector<unsigned char> fromStringToByteArray(const std::string &variable)
        {
        std::vector<unsigned char> bytes;

        uint32_t size=variable.length();

        bytes=fromSimpleToByteArray(size);
        bytes.insert(std::end(bytes),std::begin(variable), std::end(variable));

        return bytes;
        }

        /**
        * @brief function to convert a std::vector<unsigned char> to an std::string
        *
        * this is the partner function to fromStringToByteArray. It takes the
        * first 4 byte of the vector as an uint32_t string length identifier and
        * uses the following length chars as the string
        *
        * @param v - the vector to convert to a string
        * @return the string read from the vector
        * @throw std::invalid_argument: "vector too short for <X> chars"
        */
        static std::string fromByteArrayToString(std::vector<unsigned char> &v)
        {
        uint32_t length=fromByteArrayToSimple<uint32_t>(v);

        if (v.size()-sizeof(uint32_t) < length)
        {
            throw(std::invalid_argument(std::string(__FILE__) + ":" + std::string(__PRETTY_FUNCTION__) + ":" + std::to_string(__LINE__) + ": vector too short for " + std::to_string(length) + " chars"));
        }

        std::string str(v.begin()+sizeof(uint32_t), v.begin()+sizeof(uint32_t)+length) ;

        return str;
        }


        /**
        * @brief function to convert a container of strings to a std::vector<unsigned char>
        *
        * @param data - the container of std::string
        *
        * @return the std::vector<unsigned char>
        */
        template<class T>
        static std::vector<unsigned char> fromStringContainerToByteArray(T &data)
        {
          std::vector<unsigned char> bytes;
          std::vector<unsigned char> convert;

          uint32_t size=data.size();
          bytes=fromSimpleToByteArray(size);

          for(auto it = data.begin(); it!=data.end(); ++it)
          {
            convert=fromStringToByteArray(*it);
            bytes.insert(std::end(bytes), std::begin(convert), std::end(convert));
          }

          return bytes;
        }


        /**
        * @brief function to convert a std::vector<unsigned char> to a container of strings
        *
        * @param data - the container of std::string
        *
        * @return the std::vector<unsigned char>
        */
        template<class T>
        static T fromByteArrayToStringContainer(std::vector<unsigned char> &v)
        {
          T data;
          uint32_t size = fromByteArrayToSimple<uint32_t>(v);
          v.erase(v.begin(), v.begin()+sizeof(size));

          for(uint32_t i=0; i<size; i++)
          {
            std::string convert = fromByteArrayToString(v);
            data.push_back(convert);
          }

          return std::move(data);
        }


    };
};
#endif