1#ifndef DATE_TIME_C_LOCAL_TIME_ADJUSTOR_HPP__
2#define DATE_TIME_C_LOCAL_TIME_ADJUSTOR_HPP__
3
4/* Copyright (c) 2002,2003,2005 CrystalClear Software, Inc.
5 * Use, modification and distribution is subject to the
6 * Boost Software License, Version 1.0. (See accompanying
7 * file LICENSE_1_0.txt or http://www.boost.org/LICENSE_1_0.txt)
8 * Author: Jeff Garland, Bart Garst
9 * $Date$
10 */
11
12/*! @file c_local_time_adjustor.hpp
13 Time adjustment calculations based on machine
14*/
15
16#include <stdexcept>
17#include <boost/throw_exception.hpp>
18#include <boost/date_time/compiler_config.hpp>
19#include <boost/date_time/c_time.hpp>
20#include <boost/numeric/conversion/cast.hpp>
21
22namespace boost {
23namespace date_time {
24
25 //! Adjust to / from utc using the C API
26 /*! Warning!!! This class assumes that timezone settings of the
27 * machine are correct. This can be a very dangerous assumption.
28 */
29 template<class time_type>
30 class c_local_adjustor {
31 public:
32 typedef typename time_type::time_duration_type time_duration_type;
33 typedef typename time_type::date_type date_type;
34 typedef typename date_type::duration_type date_duration_type;
35 //! Convert a utc time to local time
36 static time_type utc_to_local(const time_type& t)
37 {
38 date_type time_t_start_day(1970,1,1);
39 time_type time_t_start_time(time_t_start_day,time_duration_type(0,0,0));
40 if (t < time_t_start_time) {
41 boost::throw_exception(e: std::out_of_range("Cannot convert dates prior to Jan 1, 1970"));
42 BOOST_DATE_TIME_UNREACHABLE_EXPRESSION(return time_t_start_time); // should never reach
43 }
44 date_duration_type dd = t.date() - time_t_start_day;
45 time_duration_type td = t.time_of_day();
46 uint64_t t2 = static_cast<uint64_t>(dd.days())*86400 +
47 static_cast<uint64_t>(td.hours())*3600 +
48 static_cast<uint64_t>(td.minutes())*60 +
49 td.seconds();
50 // detect y2038 issue and throw instead of proceed with bad time
51 std::time_t tv = boost::numeric_cast<std::time_t>(arg: t2);
52 std::tm tms, *tms_ptr;
53 tms_ptr = c_time::localtime(t: &tv, result: &tms);
54 date_type d(static_cast<unsigned short>(tms_ptr->tm_year + 1900),
55 static_cast<unsigned short>(tms_ptr->tm_mon + 1),
56 static_cast<unsigned short>(tms_ptr->tm_mday));
57 time_duration_type td2(tms_ptr->tm_hour,
58 tms_ptr->tm_min,
59 tms_ptr->tm_sec,
60 t.time_of_day().fractional_seconds());
61
62 return time_type(d,td2);
63 }
64 };
65
66
67
68} } //namespace date_time
69
70
71
72#endif
73

source code of boost/libs/date_time/include/boost/date_time/c_local_time_adjustor.hpp