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Add posix-style time zone example: ptz.h
This commit is contained in:
Howard Hinnant
592
include/date/ptz.h
Normal file
592
include/date/ptz.h
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@ -0,0 +1,592 @@
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#ifndef PTZ_H
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#define PTZ_H
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// The MIT License (MIT)
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//
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// Copyright (c) 2017 Howard Hinnant
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//
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// Permission is hereby granted, free of charge, to any person obtaining a copy
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// of this software and associated documentation files (the "Software"), to deal
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// in the Software without restriction, including without limitation the rights
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// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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// copies of the Software, and to permit persons to whom the Software is
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// furnished to do so, subject to the following conditions:
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//
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// The above copyright notice and this permission notice shall be included in all
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// copies or substantial portions of the Software.
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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// SOFTWARE.
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// This header allows Posix-style time zones as specified for TZ here:
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// http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap08.html#tag_08_03
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//
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// Posix::time_zone can be constructed with a posix-style string and then used in
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// a zoned_time like so:
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//
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// zoned_time<system_clock::duration, Posix::time_zone> zt{"EST5EDT,M3.2.0,M11.1.0",
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// system_clock::now()};
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// or:
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//
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// Posix::time_zone tz{"EST5EDT,M3.2.0,M11.1.0"};
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// zoned_time<system_clock::duration, Posix::time_zone> zt{tz, system_clock::now()};
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//
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// Note, Posix-style time zones are not recommended for all of the reasons described here:
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// https://stackoverflow.com/tags/timezone/info
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//
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// They are provided here as a non-trivial custom time zone example, and if you really
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// have to have Posix time zones, you're welcome to use this one.
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#include "date/tz.h"
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#include <cctype>
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#include <ostream>
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#include <string>
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namespace Posix
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{
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namespace detail
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{
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#if HAS_STRING_VIEW
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using string_t = std::string_view;
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#else // !HAS_STRING_VIEW
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using string_t = std::string;
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#endif // !HAS_STRING_VIEW
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class rule;
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void throw_invalid(const string_t& s, unsigned i, const string_t& message);
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unsigned read_date(const string_t& s, unsigned i, rule& r);
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unsigned read_name(const string_t& s, unsigned i, std::string& name);
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unsigned read_signed_time(const string_t& s, unsigned i, std::chrono::seconds& t);
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unsigned read_unsigned_time(const string_t& s, unsigned i, std::chrono::seconds& t);
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unsigned read_unsigned(const string_t& s, unsigned i, unsigned limit, unsigned& u);
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class rule
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{
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enum {off, J, M, N};
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date::month m_;
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date::weekday wd_;
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unsigned short n_ : 14;
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unsigned short mode_ : 2;
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std::chrono::duration<std::int32_t> time_ = std::chrono::hours{2};
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public:
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rule() : mode_(off) {}
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bool ok() const {return mode_ != off;}
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date::local_seconds operator()(date::year y) const;
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friend std::ostream& operator<<(std::ostream& os, const rule& r);
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friend unsigned read_date(const string_t& s, unsigned i, rule& r);
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};
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inline
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date::local_seconds
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rule::operator()(date::year y) const
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{
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using namespace date;
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using sec = std::chrono::seconds;
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date::local_seconds t;
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switch (mode_)
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{
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case J:
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t = local_days{y/jan/0} + days{n_ + (y.is_leap() && n_ > 59)} + sec{time_};
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break;
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case M:
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t = (n_ == 5 ? local_days{y/m_/wd_[last]} : local_days{y/m_/wd_[n_]}) + sec{time_};
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break;
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case N:
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t = local_days{y/jan/1} + days{n_} + sec{time_};
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break;
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default:
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assert(!"rule called with bad mode");
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}
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return t;
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}
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inline
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std::ostream&
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operator<<(std::ostream& os, const rule& r)
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{
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switch (r.mode_)
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{
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case rule::J:
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os << 'J' << r.n_ << date::format(" %T", r.time_);
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break;
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case rule::M:
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if (r.n_ == 5)
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os << r.m_/r.wd_[date::last];
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else
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os << r.m_/r.wd_[r.n_];
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os << date::format(" %T", r.time_);
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break;
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case rule::N:
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os << r.n_ << date::format(" %T", r.time_);
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break;
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default:
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break;
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}
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return os;
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}
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} // namespace detail
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class time_zone
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{
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std::string std_abbrev_;
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std::string dst_abbrev_ = {};
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std::chrono::seconds offset_;
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std::chrono::seconds save_ = std::chrono::hours{1};
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detail::rule start_rule_;
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detail::rule end_rule_;
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public:
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explicit time_zone(const detail::string_t& name);
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template <class Duration>
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date::sys_info get_info(date::sys_time<Duration> st) const;
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template <class Duration>
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date::local_info get_info(date::local_time<Duration> tp) const;
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template <class Duration>
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date::sys_time<typename std::common_type<Duration, std::chrono::seconds>::type>
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to_sys(date::local_time<Duration> tp) const;
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template <class Duration>
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date::sys_time<typename std::common_type<Duration, std::chrono::seconds>::type>
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to_sys(date::local_time<Duration> tp, date::choose z) const;
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template <class Duration>
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date::local_time<typename std::common_type<Duration, std::chrono::seconds>::type>
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to_local(date::sys_time<Duration> tp) const;
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friend std::ostream& operator<<(std::ostream& os, const time_zone& z);
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const time_zone* operator->() const {return this;}
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};
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inline
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time_zone::time_zone(const detail::string_t& s)
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{
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using namespace detail;
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auto i = read_name(s, 0, std_abbrev_);
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i = read_signed_time(s, i, offset_);
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offset_ = -offset_;
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if (i != s.size())
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{
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i = read_name(s, i, dst_abbrev_);
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if (i != s.size())
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{
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if (s[i] != ',')
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i = read_signed_time(s, i, save_);
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if (i != s.size())
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{
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if (s[i] != ',')
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throw_invalid(s, i, "Expecting end of string or ',' to start rule");
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++i;
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i = read_date(s, i, start_rule_);
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if (i == s.size() || s[i] != ',')
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throw_invalid(s, i, "Expecting ',' and then the ending rule");
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++i;
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i = read_date(s, i, end_rule_);
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if (i != s.size())
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throw_invalid(s, i, "Found unexpected trailing characters");
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}
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}
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}
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}
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template <class Duration>
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date::sys_info
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time_zone::get_info(date::sys_time<Duration> st) const
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{
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using namespace date;
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using namespace std::chrono;
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sys_info r{};
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r.offset = offset_;
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if (start_rule_.ok())
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{
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auto y = year_month_day{floor<days>(st)}.year();
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auto start = sys_seconds{(start_rule_(y) - offset_).time_since_epoch()};
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auto end = sys_seconds{(end_rule_(y) - (offset_ + save_)).time_since_epoch()};
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if (start <= st && st < end)
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{
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r.begin = start;
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r.end = end;
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r.offset += save_;
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r.save = ceil<minutes>(save_);
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r.abbrev = dst_abbrev_;
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}
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else if (st < start)
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{
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r.begin = sys_seconds{(end_rule_(y-years{1}) -
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(offset_ + save_)).time_since_epoch()};
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r.end = start;
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r.abbrev = std_abbrev_;
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}
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else // st >= end
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{
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r.begin = end;
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r.end = sys_seconds{(start_rule_(y+years{1}) - offset_).time_since_epoch()};
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r.abbrev = std_abbrev_;
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}
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}
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else // constant offset
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{
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r.begin = sys_days{year::min()/jan/1};
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r.end = sys_days{year::max()/dec/last};
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r.abbrev = std_abbrev_;
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}
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return r;
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}
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template <class Duration>
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date::local_info
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time_zone::get_info(date::local_time<Duration> tp) const
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{
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using namespace date;
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using namespace std::chrono;
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local_info r{};
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if (start_rule_.ok())
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{
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auto y = year_month_day{floor<days>(tp)}.year();
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auto start = sys_seconds{(start_rule_(y) - offset_).time_since_epoch()};
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auto end = sys_seconds{(end_rule_(y) - (offset_ + save_)).time_since_epoch()};
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auto utcs = sys_seconds{floor<seconds>(tp - offset_).time_since_epoch()};
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auto utcd = sys_seconds{floor<seconds>(tp - (offset_ + save_)).time_since_epoch()};
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if ((utcs < start) != (utcd < start))
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{
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r.first.begin = sys_seconds{(end_rule_(y-years{1}) -
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(offset_ + save_)).time_since_epoch()};
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r.first.end = start;
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r.first.offset = offset_;
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r.first.abbrev = std_abbrev_;
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r.second.begin = start;
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r.second.end = end;
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r.second.abbrev = dst_abbrev_;
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r.second.offset = offset_ + save_;
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r.second.save = ceil<minutes>(save_);
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r.result = save_ > seconds{0} ? local_info::nonexistent
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: local_info::ambiguous;
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}
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else if ((utcs < end) != (utcd < end))
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{
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r.first.begin = start;
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r.first.end = end;
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r.first.offset = offset_ + save_;
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r.first.save = ceil<minutes>(save_);
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r.first.abbrev = dst_abbrev_;
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r.second.begin = end;
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r.second.end = sys_seconds{(start_rule_(y+years{1}) -
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offset_).time_since_epoch()};
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r.second.abbrev = std_abbrev_;
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r.second.offset = offset_;
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r.result = save_ > seconds{0} ? local_info::ambiguous
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: local_info::nonexistent;
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}
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else if (utcs < start)
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{
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r.first.begin = sys_seconds{(end_rule_(y-years{1}) -
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(offset_ + save_)).time_since_epoch()};
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r.first.end = start;
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r.first.offset = offset_;
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r.first.abbrev = std_abbrev_;
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}
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else if (utcs < end)
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{
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r.first.begin = start;
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r.first.end = end;
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r.first.offset = offset_ + save_;
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r.first.save = ceil<minutes>(save_);
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r.first.abbrev = dst_abbrev_;
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}
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else
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{
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r.first.begin = end;
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r.first.end = sys_seconds{(start_rule_(y+years{1}) -
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offset_).time_since_epoch()};
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r.first.abbrev = std_abbrev_;
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r.first.offset = offset_;
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}
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}
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else // constant offset
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{
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r.first.begin = sys_days{year::min()/jan/1};
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r.first.end = sys_days{year::max()/dec/last};
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r.first.abbrev = std_abbrev_;
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r.first.offset = offset_;
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}
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return r;
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}
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template <class Duration>
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date::sys_time<typename std::common_type<Duration, std::chrono::seconds>::type>
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time_zone::to_sys(date::local_time<Duration> tp) const
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{
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using namespace date;
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auto i = get_info(tp);
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if (i.result == local_info::nonexistent)
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throw nonexistent_local_time(tp, i);
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else if (i.result == local_info::ambiguous)
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throw ambiguous_local_time(tp, i);
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return sys_time<Duration>{tp.time_since_epoch()} - i.first.offset;
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}
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template <class Duration>
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date::sys_time<typename std::common_type<Duration, std::chrono::seconds>::type>
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time_zone::to_sys(date::local_time<Duration> tp, date::choose z) const
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{
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using namespace date;
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auto i = get_info(tp);
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if (i.result == local_info::nonexistent)
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{
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return i.first.end;
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}
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else if (i.result == local_info::ambiguous)
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{
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if (z == choose::latest)
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return sys_time<Duration>{tp.time_since_epoch()} - i.second.offset;
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}
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return sys_time<Duration>{tp.time_since_epoch()} - i.first.offset;
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}
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template <class Duration>
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date::local_time<typename std::common_type<Duration, std::chrono::seconds>::type>
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time_zone::to_local(date::sys_time<Duration> tp) const
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{
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using namespace date;
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using namespace std::chrono;
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using LT = local_time<typename std::common_type<Duration, seconds>::type>;
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auto i = get_info(tp);
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return LT{(tp + i.offset).time_since_epoch()};
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}
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inline
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std::ostream&
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operator<<(std::ostream& os, const time_zone& z)
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{
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using date::operator<<;
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os << '{';
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os << z.std_abbrev_ << ", " << z.dst_abbrev_ << date::format(", %T, ", z.offset_)
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<< date::format("%T, [", z.save_) << z.start_rule_ << ", " << z.end_rule_ << ")}";
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return os;
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}
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namespace detail
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{
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inline
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void
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throw_invalid(const string_t& s, unsigned i, const string_t& message)
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{
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throw std::runtime_error(std::string("Invalid time_zone initializer.\n") +
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std::string(message) + ":\n" +
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s + '\n' +
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"\x1b[1;32m" +
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std::string(i, '~') + '^' +
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std::string(s.size()-i-1, '~') +
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"\x1b[0m");
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}
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inline
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unsigned
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read_date(const string_t& s, unsigned i, rule& r)
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{
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using namespace date;
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if (i == s.size())
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throw_invalid(s, i, "Expected rule but found end of string");
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if (s[i] == 'J')
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{
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++i;
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unsigned n;
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i = read_unsigned(s, i, 3, n);
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r.mode_ = rule::J;
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r.n_ = n;
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}
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else if (s[i] == 'M')
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{
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++i;
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unsigned m;
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i = read_unsigned(s, i, 2, m);
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if (i == s.size() || s[i] != '.')
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throw_invalid(s, i, "Expected '.' after month");
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++i;
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unsigned n;
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i = read_unsigned(s, i, 1, n);
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if (i == s.size() || s[i] != '.')
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throw_invalid(s, i, "Expected '.' after weekday index");
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++i;
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unsigned wd;
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i = read_unsigned(s, i, 1, wd);
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r.mode_ = rule::M;
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r.m_ = month{m};
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r.wd_ = weekday{wd};
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r.n_ = n;
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}
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else if (std::isdigit(s[i]))
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{
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unsigned n;
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i = read_unsigned(s, i, 3, n);
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r.mode_ = rule::N;
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r.n_ = n;
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}
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else
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throw_invalid(s, i, "Expected 'J', 'M', or a digit to start rule");
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||||
if (i != s.size() && s[i] == '/')
|
||||
{
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++i;
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std::chrono::seconds t;
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||||
i = read_unsigned_time(s, i, t);
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r.time_ = t;
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}
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return i;
|
||||
}
|
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inline
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unsigned
|
||||
read_name(const string_t& s, unsigned i, std::string& name)
|
||||
{
|
||||
if (i == s.size())
|
||||
throw_invalid(s, i, "Expected a name but found end of string");
|
||||
if (s[i] == '<')
|
||||
{
|
||||
++i;
|
||||
while (true)
|
||||
{
|
||||
if (i == s.size())
|
||||
throw_invalid(s, i,
|
||||
"Expected to find closing '>', but found end of string");
|
||||
if (s[i] == '>')
|
||||
break;
|
||||
name.push_back(s[i]);
|
||||
++i;
|
||||
}
|
||||
++i;
|
||||
}
|
||||
else
|
||||
{
|
||||
while (i != s.size() && std::isalpha(s[i]))
|
||||
{
|
||||
name.push_back(s[i]);
|
||||
++i;
|
||||
}
|
||||
}
|
||||
if (name.size() < 3)
|
||||
throw_invalid(s, i, "Found name to be shorter than 3 characters");
|
||||
return i;
|
||||
}
|
||||
|
||||
inline
|
||||
unsigned
|
||||
read_signed_time(const string_t& s, unsigned i,
|
||||
std::chrono::seconds& t)
|
||||
{
|
||||
if (i == s.size())
|
||||
throw_invalid(s, i, "Expected to read signed time, but found end of string");
|
||||
bool negative = false;
|
||||
if (s[i] == '-')
|
||||
{
|
||||
negative = true;
|
||||
++i;
|
||||
}
|
||||
else if (s[i] == '+')
|
||||
++i;
|
||||
i = read_unsigned_time(s, i, t);
|
||||
if (negative)
|
||||
t = -t;
|
||||
return i;
|
||||
}
|
||||
|
||||
inline
|
||||
unsigned
|
||||
read_unsigned_time(const string_t& s, unsigned i, std::chrono::seconds& t)
|
||||
{
|
||||
using namespace std::chrono;
|
||||
if (i == s.size())
|
||||
throw_invalid(s, i, "Expected to read unsigned time, but found end of string");
|
||||
unsigned x;
|
||||
i = read_unsigned(s, i, 2, x);
|
||||
t = hours{x};
|
||||
if (i != s.size() && s[i] == ':')
|
||||
{
|
||||
++i;
|
||||
i = read_unsigned(s, i, 2, x);
|
||||
t += minutes{x};
|
||||
if (i != s.size() && s[i] == ':')
|
||||
{
|
||||
++i;
|
||||
i = read_unsigned(s, i, 2, x);
|
||||
t += seconds{x};
|
||||
}
|
||||
}
|
||||
return i;
|
||||
}
|
||||
|
||||
inline
|
||||
unsigned
|
||||
read_unsigned(const string_t& s, unsigned i, unsigned limit, unsigned& u)
|
||||
{
|
||||
if (i == s.size() || !std::isdigit(s[i]))
|
||||
throw_invalid(s, i, "Expected to find a decimal digit");
|
||||
u = static_cast<unsigned>(s[i] - '0');
|
||||
unsigned count = 1;
|
||||
for (++i; count < limit && i != s.size() && std::isdigit(s[i]); ++i, ++count)
|
||||
u = u * 10 + static_cast<unsigned>(s[i] - '0');
|
||||
return i;
|
||||
}
|
||||
|
||||
} // namespace detail
|
||||
|
||||
} // namespace Posix
|
||||
|
||||
namespace date
|
||||
{
|
||||
|
||||
template <>
|
||||
struct zoned_traits<Posix::time_zone>
|
||||
{
|
||||
|
||||
#if HAS_STRING_VIEW
|
||||
|
||||
static
|
||||
Posix::time_zone
|
||||
locate_zone(std::string_view name)
|
||||
{
|
||||
return Posix::time_zone{name};
|
||||
}
|
||||
|
||||
#else // !HAS_STRING_VIEW
|
||||
|
||||
static
|
||||
Posix::time_zone
|
||||
locate_zone(const std::string& name)
|
||||
{
|
||||
return Posix::time_zone{name};
|
||||
}
|
||||
|
||||
static
|
||||
Posix::time_zone
|
||||
locate_zone(const char* name)
|
||||
{
|
||||
return Posix::time_zone{name};
|
||||
}
|
||||
|
||||
#endif // !HAS_STRING_VIEW
|
||||
|
||||
};
|
||||
|
||||
} // namespace date
|
||||
|
||||
#endif // PTZ_H
|
||||
Reference in New Issue
Block a user