xapian-core/common/parseint.h

   1 /** @file
   2  * @brief Parse signed and unsigned type from string and check for trailing characters.
   3  */
   4 /* Copyright (C) 2019 Olly Betts
   5  * Copyright (C) 2019 Vaibhav Kansagara
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License as published by
   9  * the Free Software Foundation; either version 2 of the License, or
  10  * (at your option) any later version.
  11  *
  12  * This program is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  * GNU General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU General Public License
  18  * along with this program; if not, write to the Free Software
  19  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
  20  */
  21 #ifndef XAPIAN_INCLUDED_PARSEINT_H
  22 #define XAPIAN_INCLUDED_PARSEINT_H
  23
  24 #include "overflow.h"
  25 #include <limits>
  26
  27 template<typename T>
  28 bool parse_unsigned(const char* p, T& res)
  29 {
  30     res = 0;
  31     do {
  32         unsigned char digit = *p - '0';
  33         if (digit > 9 ||
  34             mul_overflows(res, unsigned(10), res) ||
  35             add_overflows(res, digit, res)) {
  36             return false;
  37         }
  38     } while (*++p);
  39     return true;
  40 }
  41
  42 template<typename T>
  43 bool parse_signed(const char* p, T& res)
  44 {
  45     typedef typename std::make_unsigned<T>::type unsigned_type;
  46     unsigned_type temp = 0;
  47     if (*p == '-' && parse_unsigned(++p, temp) &&
  48         // casting the min signed value to unsigned gives us its absolute value.
  49         temp <= unsigned_type(std::numeric_limits<T>::min())) {
  50         res = -temp;
  51         return true;
  52     } else if (parse_unsigned(p, temp) &&
  53                temp <= unsigned_type(std::numeric_limits<T>::max())) {
  54         res = temp;
  55         return true;
  56     }
  57     return false;
  58 }
  59
  60 #endif