tbx/include/utils/print.h

/*!
 * \file utils/print.h
 * \brief
 *      A CRTP base class to provide print interface
 *
 * \copyright Copyright (C) 2021 Christos Choutouridis <christos@choutouridis.net>
 *
 * <dl class=\"section copyright\"><dt>License</dt><dd>
 * The MIT License (MIT)
 *
 * 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.
 * </dd></dl>
 */

#ifndef TBX_UTILS_PRINT_H_
#define TBX_UTILS_PRINT_H_

#include <core/core.h>
#include <core/crtp.h>

#include <cstring>
#include <math.h>
#include <string_view>
#include <type_traits>
#include <utility>
#include <limits>

namespace tbx {

    /*!
     * \class Print
     * \brief
     *      A CRTP print interface
     *
     * Requirements:
     *  - size_t write_impl(const Char_t* buffer, size_t size) : Return the number of \c Char_t written
     *  - size_t write_(const Char_t ch) : Return the number of \c Char_t written (normally one).
     *
     * \tparam Impl_t       The derived type
     * \tparam Char_t       The char type to use
     */
    template <typename Impl_t, typename Char_t>
    class Print {
        _CRTP_IMPL(Impl_t);

    public:
        using value_type        = Char_t;
        using pointer_type      = Char_t*;
        using iterator_type     = Char_t*;
        using const_iterator_type = const Char_t*;
        using difference_type   = std::ptrdiff_t;
        using size_type         = size_t;
        using str_view_t        = std::basic_string_view<Char_t>;

        //! Enumerator for number base formating
        enum class Base {
            BIN =2, OCT =8, DEC =10, HEX =16
        };

    private:
        //! \name CRTP requirements
        //! @{
        size_t write_(const Char_t* buffer, size_t size) {
            return impl().write_impl(buffer, size);
        }
        size_t write_(const Char_t ch) {
            return impl().write_impl(ch);
        }
        //! @}

    protected:
        Print() noexcept = default;     //!< Construct from derived only

    private:
        //! Helper tool to convert strong enums to their underlying type
        template <typename E>
        constexpr typename std::underlying_type_t<E> value(E e) noexcept {
            return static_cast<typename std::underlying_type_t<E>>(e);
        }

        size_t print_unsigned(unsigned long n, Base base);  // integer conversion base tool
        size_t print_double(double number, uint8_t digits); // double conversion base tool

    public:
        /*!
         * \brief
         *      Prints a string view
         * \param str   The string view to print
         * \return      The number of printed \c Char_t
         */
        size_t print(const str_view_t str) {
            return write_(str.data(), str.size());
        }

        /*!
         * \brief
         *      Prints a string
         * \param str   Pointer to string to print
         * \return      The number of printed \c Char_t
         */
        size_t print(const Char_t* str) {
            if (str == nullptr)
                return 0;
            return write_(str, std::strlen(str));
        }

        /*!
         * \brief
         *      Prints a buffer of size \c size. If there is a null termination
         *      before the end of the buffer, prints up to termination.
         *
         * \param str       Pointer to string buffer to print
         * \param size      The size of buffer
         * \return      The number of printed \c Char_t
         */
        size_t print(const Char_t* str, size_t size) {
            if (str == nullptr)
                return 0;
            return write_(str, size);
        }

        /*!
         * \brief
         *      Prints a \c Char_t
         * \param ch    The Char_t to print
         * \return      The number of printed \c Char_t
         */
        size_t print(Char_t ch) {
            return write_ (ch);
        }

        /*!
         * \brief
         *      Convert and print a long.
         * \param n     The number to print
         * \param base  The number base to use for conversion.
         * \return      The number of printed \c Char_t
         */
        size_t print(long n, Base base =Base::DEC) {
            size_t cnt =0;
            if (n < 0) {
                n = -n;
                cnt = write_ ('-');
            }
            return cnt + print_unsigned((unsigned long)n, base);
        }

        /*!
         * \brief
         *      Convert and print an int.
         * \param n     The number to print
         * \param base  The number base to use for conversion.
         * \return      The number of printed \c Char_t
         */
        size_t print(int n, Base base= Base::DEC) {
            return print ((long)n, base);
        }

        /*!
         * \brief
         *      Convert and print an unsigned long.
         * \param n     The number to print
         * \param base  The number base to use for conversion.
         * \return      The number of printed \c Char_t
         */
        size_t print(unsigned long n, Base base= Base::DEC) {
            return print_unsigned ((unsigned long)n, base);
        }

        /*!
         * \brief
         *      Convert and print an unsigned int.
         * \param n     The number to print
         * \param base  The number base to use for conversion.
         * \return      The number of printed \c Char_t
         */
        size_t print(unsigned int n, Base base= Base::DEC) {
            return print_unsigned ((unsigned long)n, base);
        }

        /*!
         * \brief
         *      Convert and print adouble
         * \param n         The number to print
         * \param digits    The number of decimal digits to print
         * \return          The number of printed \c Char_t
         */
        size_t print(double n, uint8_t digits = 2) {
            return print_double (n, digits);
        }

        /*!
         * \brief
         *      Perfect forwarder to print functionality with a new line termination
         * \tparam Ts   The types of parameters
         * \param args  The arguments to pass
         * \return      The number of printed \c Char_t
         */
        template <typename ...Ts>
        size_t println(Ts&& ...args) {
            size_t r = print (std::forward<Ts>(args)...);
            r += write_ ('\n');
            return r;
        }
    };

    /*!
     * \brief
     *      Converts and prints an unsigned long
     *
     * \tparam Impl_t       The derived type
     * \tparam Char_t       The char type to use
     *
     * \param n     The number to print
     * \param base  The number base to use
     * \return      The number of printed \c Char_t
     */
    template <typename Impl_t, typename Char_t>
    size_t Print<Impl_t, Char_t>::print_unsigned(unsigned long n, Base base) {
        Char_t buf[8 *sizeof(Char_t) * sizeof(long) + 1]; // Assumes 8-bit chars plus zero byte.
        Char_t *str = &buf[sizeof(buf) - 1];

        *str = '\0';

        do {
            Char_t c = n % value(base);
            n /= value(base);

            *--str = c < 10 ? c + '0' : c + 'A' - 10;
        } while(n);

        return write_(str, std::strlen(str));
    }

    /*!
     * \brief
     *      Converts and prints a double
     *
     * \note
     *  Internally, this implementation uses a long to store the integer part of the number.
     *  Thus overflows for numbers bigger than std::numeric_limits<long>::max() / min().
     *  For these numbers it prints "ovf" instead.
     *
     * \tparam Impl_t       The derived type
     * \tparam Char_t       The char type to use
     *
     * \param n         The number to print
     * \param digits    The number of decimal digits to print
     * \return          The number of printed \c Char_t
     */
    template <typename Impl_t, typename Char_t>
    size_t Print<Impl_t, Char_t>::print_double(double number, uint8_t digits)  {
        size_t n = 0;

        if (std::isnan(number))     return print("nan");
        if (std::isinf(number))     return print("inf");
        if (number > (double)std::numeric_limits<long>::max())
            return print ("ovf");
        if (number < (double)std::numeric_limits<long>::min())
            return print ("-ovf");

        // Handle negative numbers
        if (number < 0.0) {
            n += write_ ('-');
            number = -number;
        }

        // Round correctly so that print(1.999, 2) prints as "2.00"
        double rounding = 0.5;
        for (uint8_t i=0; i<digits; ++i)
            rounding /= 10.0;

        number += rounding;

        // Extract the integer part of the number and print it
        unsigned long int_part = (unsigned long)number;
        double remainder       = number - (double)int_part;
        n += print(int_part);

        // Print the decimal point, but only if there are digits beyond
        if (digits > 0) {
            n += print('.');
        }

        // Extract digits from the remainder one at a time
        while (digits-- > 0) {
            remainder *= 10.0;
            unsigned int toPrint = (unsigned int)(remainder);
            n += print(toPrint);
            remainder -= toPrint;
        }

        return n;
    }


}
#endif /* TBX_UTILS_PRINT_H_ */