Line data    Source code

       1             : // Copyright (c) 2022-2023  Made to Order Software Corp.  All Rights Reserved
       2             : //
       3             : // https://snapwebsites.org/project/snapdev
       4             : // contact@m2osw.com
       5             : //
       6             : // This program is free software: you can redistribute it and/or modify
       7             : // it under the terms of the GNU General Public License as published by
       8             : // the Free Software Foundation, either version 3 of the License, or
       9             : // (at your option) any later version.
      10             : //
      11             : // This program is distributed in the hope that it will be useful,
      12             : // but WITHOUT ANY WARRANTY; without even the implied warranty of
      13             : // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      14             : // GNU General Public License for more details.
      15             : //
      16             : // You should have received a copy of the GNU General Public License
      17             : // along with this program.  If not, see <https://www.gnu.org/licenses/>.
      18             : #pragma once
      19             : 
      20             : /** \file
      21             :  * \brief Convert a numeric or string literal to a 128 bit value.
      22             :  *
      23             :  * These functions transform string literals or numeric literals to 128 bit
      24             :  * values as supported by g++. We support signed and unsigned in decimal,
      25             :  * hexadecimal, octal, and binary.
      26             :  */
      27             : 
      28             : // C++
      29             : //
      30             : #include    <cstring>
      31             : #include    <limits>
      32             : 
      33             : 
      34             : namespace snapdev
      35             : {
      36             : namespace literals
      37             : {
      38             : 
      39             : /** \brief Convert a literal to a signed __int128.
      40             :  *
      41             :  * This function converts a literal string to a signed __int128 integer
      42             :  * number.
      43             :  *
      44             :  * \code
      45             :  * using namespace snapdev::literals;
      46             :  *
      47             :  * __int128 value = "0xabcd000000000000"_int128;
      48             :  * \endcode
      49             :  *
      50             :  * \todo
      51             :  * Make sure that the first '\0' represents the end of the string.
      52             :  *
      53             :  * \todo
      54             :  * Support the negative (and positive) sign at the start of the string
      55             :  * (with number literal, it is viewed as an operator so it works as is,
      56             :  * with with string literals, we have to handle those ourselves).
      57             :  *
      58             :  * \param[in] literal  A 128 bit literal number.
      59             :  *
      60             :  * \return The __int128 number.
      61             :  *
      62             :  * \sa operator ""_uint128()
      63             :  */
      64             : #pragma GCC diagnostic push
      65             : #pragma GCC diagnostic ignored "-Wpedantic"
      66        1408 : constexpr __int128 operator ""_int128(char const * literal, std::size_t len)
      67             : {
      68        1408 :     __int128 result(0);
      69        1408 :     __int128 base(10);
      70             : 
      71        1408 :     if(len == 0)
      72             :     {
      73           0 :         throw std::invalid_argument("A string literal of a int128 must be at least one cahracter.");
      74             :     }
      75             : 
      76        1408 :     if(*literal == '0')
      77             :     {
      78           0 :         ++literal;
      79           0 :         if(*literal == '\0')
      80             :         {
      81           0 :             return result;
      82             :         }
      83           0 :         if(*literal == 'x'
      84           0 :         || *literal == 'X')
      85             :         {
      86             :             // parse an hexadecimal number
      87             :             //
      88           0 :             base = 16;
      89           0 :             ++literal;
      90           0 :             if(*literal == '\0')
      91             :             {
      92           0 :                 throw std::invalid_argument("0x must be followed by at least one hexadecimal digit.");
      93             :             }
      94             :         }
      95           0 :         else if(*literal == 'b'
      96           0 :              || *literal == 'B')
      97             :         {
      98             :             // parse a binary number
      99             :             //
     100           0 :             base = 2;
     101           0 :             ++literal;
     102           0 :             if(*literal == '\0')
     103             :             {
     104           0 :                 throw std::invalid_argument("0b must be followed by at least one binary digit.");
     105             :             }
     106             :         }
     107             :         else
     108             :         {
     109             :             // parse an octal number
     110             :             //
     111           0 :             base = 8;
     112             :         }
     113             :     }
     114             :     // else -- parse a decimal number
     115             : 
     116             :     for(;;)
     117             :     {
     118        2816 :         char const c(*literal++);
     119        2816 :         if(c == '\0')
     120             :         {
     121             :             // valid
     122             :             //
     123        1408 :             return result;
     124             :         }
     125        1408 :         int digit(std::numeric_limits<int>::max());
     126        1408 :         if(c >= '0' && c <= '9')
     127             :         {
     128        1408 :             digit = c - '0';
     129             :         }
     130           0 :         else if(c >= 'a' && c <= 'f')
     131             :         {
     132           0 :             digit = c - ('a' - 10);
     133             :         }
     134           0 :         else if(c >= 'A' && c <= 'F')
     135             :         {
     136           0 :             digit = c - ('A' - 10);
     137             :         }
     138        1408 :         if(digit >= base)
     139             :         {
     140           0 :             throw std::domain_error(
     141           0 :                   std::string("digit '")
     142           0 :                 + c
     143           0 :                 + "' too large for the selected base");
     144             :         }
     145             : 
     146        1408 :         __int128 const old(result);
     147        1408 :         result = result * base + digit;
     148        1408 :         if(result < old)
     149             :         {
     150             :             // overflow
     151             :             //
     152             :             // IMPORTANT NOTE: This test works because we do not deal with
     153             :             // the '-' sign which the C++ compiler handles for us
     154             :             //
     155           0 :             throw std::domain_error("signed __int128 literal too large.");
     156             :         }
     157        1408 :     }
     158             : 
     159             :     return result;
     160             : }
     161             : #pragma GCC diagnostic pop
     162             : 
     163             : 
     164             : /** \brief Convert a literal number to an __int128.
     165             :  *
     166             :  * This function converts a literal number to an __int128. For example:
     167             :  *
     168             :  * \code
     169             :  * using namespace snapdev::literals;
     170             :  *
     171             :  * __int128 value = 123_int128;
     172             :  * \endcode
     173             :  *
     174             :  * \param[in] literal  A literal number.
     175             :  *
     176             :  * \return The literal number converted to an __int128 value.
     177             :  */
     178             : #pragma GCC diagnostic push
     179             : #pragma GCC diagnostic ignored "-Wpedantic"
     180        1408 : constexpr __int128 operator ""_int128(char const * literal)
     181             : {
     182        1408 :     return operator ""_int128(literal, strlen(literal));
     183             : }
     184             : #pragma GCC diagnostic pop
     185             : 
     186             : 
     187             : /** \brief Convert a literal to an unsigned __int128.
     188             :  *
     189             :  * This function converts a literal string to an unsigned __int128 integer
     190             :  * number.
     191             :  *
     192             :  * \todo
     193             :  * Make sure that the first '\0' represents the end of the string.
     194             :  *
     195             :  * \param[in] literal  A 128 bit literal number.
     196             :  *
     197             :  * \return The unsigned __int128 number.
     198             :  *
     199             :  * \sa operator ""_int128()
     200             :  */
     201             : #pragma GCC diagnostic push
     202             : #pragma GCC diagnostic ignored "-Wpedantic"
     203         768 : constexpr unsigned __int128 operator ""_uint128(char const * literal, std::size_t len)
     204             : {
     205         768 :     unsigned __int128 result(0);
     206         768 :     unsigned __int128 base(10);
     207             : 
     208         768 :     if(len == 0)
     209             :     {
     210           0 :         throw std::invalid_argument("A string literal of a uint128 must be at least one cahracter.");
     211             :     }
     212             : 
     213         768 :     if(*literal == '0')
     214             :     {
     215           0 :         ++literal;
     216           0 :         if(*literal == '\0')
     217             :         {
     218           0 :             return result;
     219             :         }
     220           0 :         if(*literal == 'x'
     221           0 :         || *literal == 'X')
     222             :         {
     223             :             // parse an hexadecimal number
     224             :             //
     225           0 :             base = 16;
     226           0 :             ++literal;
     227           0 :             if(*literal == '\0')
     228             :             {
     229           0 :                 throw std::invalid_argument("0x must be followed by at least one hexadecimal digit.");
     230             :             }
     231             :         }
     232           0 :         else if(*literal == 'b'
     233           0 :              || *literal == 'B')
     234             :         {
     235             :             // parse a binary number
     236             :             //
     237           0 :             base = 2;
     238           0 :             ++literal;
     239           0 :             if(*literal == '\0')
     240             :             {
     241           0 :                 throw std::invalid_argument("0b must be followed by at least one binary digit.");
     242             :             }
     243             :         }
     244             :         else
     245             :         {
     246             :             // parse an octal number
     247             :             //
     248           0 :             base = 8;
     249             :         }
     250             :     }
     251             :     // else -- parse a decimal number
     252             : 
     253             :     for(;;)
     254             :     {
     255        1536 :         char const c(*literal++);
     256        1536 :         if(c == '\0')
     257             :         {
     258             :             // valid
     259             :             //
     260         768 :             return result;
     261             :         }
     262         768 :         unsigned int digit(std::numeric_limits<unsigned int>::max());
     263         768 :         if(c >= '0' && c <= '9')
     264             :         {
     265         768 :             digit = c - '0';
     266             :         }
     267           0 :         else if(c >= 'a' && c <= 'f')
     268             :         {
     269           0 :             digit = c - ('a' - 10);
     270             :         }
     271           0 :         else if(c >= 'A' && c <= 'F')
     272             :         {
     273           0 :             digit = c - ('A' - 10);
     274             :         }
     275         768 :         if(digit >= base)
     276             :         {
     277           0 :             throw std::domain_error(
     278           0 :                   std::string("digit '")
     279           0 :                 + c
     280           0 :                 + "' too large for the selected base");
     281             :         }
     282             : 
     283         768 :         unsigned __int128 const old(result);
     284         768 :         result = result * base + digit;
     285         768 :         if(result < old)
     286             :         {
     287             :             // overflow
     288             :             //
     289           0 :             throw std::domain_error("unsigned __int128 literal too large.");
     290             :         }
     291         768 :     }
     292             : 
     293             :     return result;
     294             : }
     295             : #pragma GCC diagnostic pop
     296             : 
     297             : 
     298             : /** \brief Convert a literal number to an unsigned __int128 value.
     299             :  *
     300             :  * This function converts a literal number to an unsigned __int128.
     301             :  * For example:
     302             :  *
     303             :  * \code
     304             :  * using namespace snapdev::literals;
     305             :  *
     306             :  * unsigned __int128 value = 123_uint128;
     307             :  * \endcode
     308             :  *
     309             :  * \param[in] literal  A literal number.
     310             :  *
     311             :  * \return The literal number converted to an unsigned __int128 value.
     312             :  */
     313             : #pragma GCC diagnostic push
     314             : #pragma GCC diagnostic ignored "-Wpedantic"
     315         768 : constexpr unsigned __int128 operator ""_uint128(char const * literal)
     316             : {
     317         768 :     return operator ""_uint128(literal, strlen(literal));
     318             : }
     319             : #pragma GCC diagnostic pop
     320             : 
     321             : 
     322             : 
     323             : } // namespace literals
     324             : } // namespace snapdev
     325             : // vim: ts=4 sw=4 et