Function format_buffer

Source/Utils/json.hpp:15313–15381

            JSON_HEDLEY_NON_NULL(1)
                JSON_HEDLEY_RETURNS_NON_NULL
                inline char* format_buffer(char* buf, int len, int decimal_exponent,
                    int min_exp, int max_exp)
            {
                JSON_ASSERT(min_exp < 0);
                JSON_ASSERT(max_exp > 0);

                const int k = len;
                const int n = len + decimal_exponent;

                // v = buf * 10^(n-k)
                // k is the length of the buffer (number of decimal digits)
                // n is the position of the decimal point relative to the start of the buffer.

                if (k <= n && n <= max_exp)
                {
                    // digits[000]
                    // len <= max_exp + 2

                    std::memset(buf + k, '0', static_cast<size_t>(n) - static_cast<size_t>(k));
                    // Make it look like a floating-point number (#362, #378)
                    buf[n + 0] = '.';
                    buf[n + 1] = '0';
                    return buf + (static_cast<size_t>(n) + 2);
                }

                if (0 < n && n <= max_exp)
                {
                    // dig.its
                    // len <= max_digits10 + 1

                    JSON_ASSERT(k > n);

                    std::memmove(buf + (static_cast<size_t>(n) + 1), buf + n, static_cast<size_t>(k) - static_cast<size_t>(n));
                    buf[n] = '.';
                    return buf + (static_cast<size_t>(k) + 1U);
                }

                if (min_exp < n && n <= 0)
                {
                    // 0.[000]digits
                    // len <= 2 + (-min_exp - 1) + max_digits10

                    std::memmove(buf + (2 + static_cast<size_t>(-n)), buf, static_cast<size_t>(k));
                    buf[0] = '0';
                    buf[1] = '.';
                    std::memset(buf + 2, '0', static_cast<size_t>(-n));
                    return buf + (2U + static_cast<size_t>(-n) + static_cast<size_t>(k));
                }

                if (k == 1)
                {
                    // dE+123
                    // len <= 1 + 5

                    buf += 1;
                }
                else
                {