#ifndef UTIL_HH

#define UTIL_HH

#include <string>

namespace qpdf::util

{

    // This is a collection of useful utility functions for qpdf internal use. They include inline

    // functions, some of which are exposed as regular functions in QUtil. Implementations are in

    // QUtil.cc.

    inline constexpr char

    hex_decode_char(char digit)

    {

        return digit <= '9' && digit >= '0'

            ? char(digit - '0')

            : (digit >= 'a' ? char(digit - 'a' + 10)

                            : (digit >= 'A' ? char(digit - 'A' + 10) : '\20'));

    }

    inline constexpr bool

    is_hex_digit(char ch)

    {

        return hex_decode_char(ch) < '\20';

    }

    inline constexpr bool

    is_space(char ch)

    {

        return ch == ' ' || ch == '\n' || ch == '\r' || ch == '\t' || ch == '\f' || ch == '\v';

    }

    inline bool

    is_digit(char ch)

    {

        return (ch >= '0' && ch <= '9');

    }

    // Returns lower-case hex-encoded version of the char including a leading "#".

    inline std::string

    hex_encode_char(char c)

    {

        static auto constexpr hexchars = "0123456789abcdef";

        return {'#', hexchars[static_cast<unsigned char>(c) >> 4], hexchars[c & 0x0f]};

    }

    // Numerically increment a digit string. Ignore the last 'tail' characters.

    inline void

    increment(std::string& s, int tail = 0)

    {

        auto end = s.rend();

        for (auto it = s.rbegin() + tail; it != end; ++it) {

            ++*it;

            if (*it != ':') {

                return;

            }

            *it = '0';

        }

        s.insert(0, 1, '1');

    }

    std::string random_string(size_t len);

} // namespace qpdf::util

#endif // UTIL_HH