整理

include/boost/date_time/c_local_time_adjustor.hpp

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+#ifndef DATE_TIME_C_LOCAL_TIME_ADJUSTOR_HPP__
+#define DATE_TIME_C_LOCAL_TIME_ADJUSTOR_HPP__
+
+/* Copyright (c) 2002,2003,2005 CrystalClear Software, Inc.
+ * Use, modification and distribution is subject to the 
+ * Boost Software License, Version 1.0. (See accompanying
+ * file LICENSE_1_0.txt or http://www.boost.org/LICENSE_1_0.txt)
+ * Author: Jeff Garland, Bart Garst
+ * $Date$
+ */
+
+/*! @file c_local_time_adjustor.hpp
+  Time adjustment calculations based on machine
+*/
+
+#include <stdexcept>
+#include <boost/throw_exception.hpp>
+#include <boost/date_time/compiler_config.hpp>
+#include <boost/date_time/c_time.hpp>
+#include <boost/numeric/conversion/cast.hpp>
+
+namespace boost {
+namespace date_time {
+
+  //! Adjust to / from utc using the C API
+  /*! Warning!!! This class assumes that timezone settings of the
+   *  machine are correct.  This can be a very dangerous assumption.
+   */
+  template<class time_type>
+  class c_local_adjustor {
+  public:
+    typedef typename time_type::time_duration_type time_duration_type;
+    typedef typename time_type::date_type date_type;
+    typedef typename date_type::duration_type date_duration_type;
+    //! Convert a utc time to local time
+    static time_type utc_to_local(const time_type& t)
+    {
+      date_type time_t_start_day(1970,1,1);
+      time_type time_t_start_time(time_t_start_day,time_duration_type(0,0,0));
+      if (t < time_t_start_time) {
+        boost::throw_exception(std::out_of_range("Cannot convert dates prior to Jan 1, 1970"));
+        BOOST_DATE_TIME_UNREACHABLE_EXPRESSION(return time_t_start_time); // should never reach
+      }
+      date_duration_type dd = t.date() - time_t_start_day;
+      time_duration_type td = t.time_of_day();
+      uint64_t t2 = static_cast<uint64_t>(dd.days())*86400 +
+                    static_cast<uint64_t>(td.hours())*3600 +
+                    static_cast<uint64_t>(td.minutes())*60 +
+                    td.seconds();
+      // detect y2038 issue and throw instead of proceed with bad time
+      std::time_t tv = boost::numeric_cast<std::time_t>(t2);
+      std::tm tms, *tms_ptr;
+      tms_ptr = c_time::localtime(&tv, &tms);
+      date_type d(static_cast<unsigned short>(tms_ptr->tm_year + 1900),
+                  static_cast<unsigned short>(tms_ptr->tm_mon + 1),
+                  static_cast<unsigned short>(tms_ptr->tm_mday));
+      time_duration_type td2(tms_ptr->tm_hour,
+                             tms_ptr->tm_min,
+                             tms_ptr->tm_sec,
+                             t.time_of_day().fractional_seconds());
+      
+      return time_type(d,td2);
+    }
+  };
+
+
+
+} } //namespace date_time
+
+
+
+#endif