HexPuller.hpp

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#pragma once
 
#include <AH/STL/utility> // std::forward
#include <AH/STL/vector>  // std::vector
#include <Settings/NamespaceSettings.hpp>
#include <ctype.h> // isxdigit, tolower
 
BEGIN_CS_NAMESPACE
 
template <class CharPuller>
class HexPuller {
  public:
    HexPuller(CharPuller &&puller) : puller(std::forward<CharPuller>(puller)) {}
 
    bool pull(uint8_t &output) {
        uint8_t input;
        while (puller.pull(input)) {
            // If we receive a hexadecimal digit
            if (isxdigit(input)) {
                (char1 ? char2 : char1) = tolower(input);
            }
            // If we received two hex characters
            if (char1 && char2) {
                output = hex2int(char1) << 4 | hex2int(char2);
                char1 = '\0';
                char2 = '\0';
                return true;
            }
            // If we received one hex character followed by whitespace/other
            else if (!isxdigit(input) && char1) {
                output = hex2int(char1);
                char1 = '\0';
                return true;
            }
        }
        return false;
    }
 
  private:
    static uint8_t hex2int(char hex) {
        return hex < 'a' ? hex - '0' : hex - 'a' + 10;
    }
 
  public:
    CharPuller puller;
 
  private:
    char char1 = '\0';
    char char2 = '\0';
};
 
END_CS_NAMESPACE