boost/date_time/tz_db_base.hpp
#ifndef DATE_TIME_TZ_DB_BASE_HPP__
#define DATE_TIME_TZ_DB_BASE_HPP__
/* Copyright (c) 2003-2005 CrystalClear Software, Inc.
* 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: 2008-11-12 14:37:53 -0500 (Wed, 12 Nov 2008) $
*/
#include <map>
#include <vector>
#include <string>
#include <sstream>
#include <fstream>
#include <stdexcept>
#include <boost/tokenizer.hpp>
#include <boost/shared_ptr.hpp>
#include <boost/throw_exception.hpp>
#include <boost/date_time/compiler_config.hpp>
#include <boost/date_time/time_zone_names.hpp>
#include <boost/date_time/time_zone_base.hpp>
#include <boost/date_time/time_parsing.hpp>
namespace boost {
namespace date_time {
//! Exception thrown when tz database cannot locate requested data file
class data_not_accessible : public std::logic_error
{
public:
data_not_accessible() :
std::logic_error(std::string("Unable to locate or access the required datafile."))
{}
data_not_accessible(const std::string& filespec) :
std::logic_error(std::string("Unable to locate or access the required datafile. Filespec: " + filespec))
{}
};
//! Exception thrown when tz database locates incorrect field structure in data file
class bad_field_count : public std::out_of_range
{
public:
bad_field_count(const std::string& s) :
std::out_of_range(s)
{}
};
//! Creates a database of time_zones from csv datafile
/*! The csv file containing the zone_specs used by the
* tz_db_base is intended to be customized by the
* library user. When customizing this file (or creating your own) the
* file must follow a specific format.
*
* This first line is expected to contain column headings and is therefore
* not processed by the tz_db_base.
*
* Each record (line) must have eleven fields. Some of those fields can
* be empty. Every field (even empty ones) must be enclosed in
* double-quotes.
* Ex:
* @code
* "America/Phoenix" <- string enclosed in quotes
* "" <- empty field
* @endcode
*
* Some fields represent a length of time. The format of these fields
* must be:
* @code
* "{+|-}hh:mm[:ss]" <- length-of-time format
* @endcode
* Where the plus or minus is mandatory and the seconds are optional.
*
* Since some time zones do not use daylight savings it is not always
* necessary for every field in a zone_spec to contain a value. All
* zone_specs must have at least ID and GMT offset. Zones that use
* daylight savings must have all fields filled except:
* STD ABBR, STD NAME, DST NAME. You should take note
* that DST ABBR is mandatory for zones that use daylight savings
* (see field descriptions for further details).
*
* ******* Fields and their description/details *********
*
* ID:
* Contains the identifying string for the zone_spec. Any string will
* do as long as it's unique. No two ID's can be the same.
*
* STD ABBR:
* STD NAME:
* DST ABBR:
* DST NAME:
* These four are all the names and abbreviations used by the time
* zone being described. While any string will do in these fields,
* care should be taken. These fields hold the strings that will be
* used in the output of many of the local_time classes.
* Ex:
* @code
* time_zone nyc = tz_db.time_zone_from_region("America/New_York");
* local_time ny_time(date(2004, Aug, 30), IS_DST, nyc);
* cout << ny_time.to_long_string() << endl;
* // 2004-Aug-30 00:00:00 Eastern Daylight Time
* cout << ny_time.to_short_string() << endl;
* // 2004-Aug-30 00:00:00 EDT
* @endcode
*
* NOTE: The exact format/function names may vary - see local_time
* documentation for further details.
*
* GMT offset:
* This is the number of hours added to utc to get the local time
* before any daylight savings adjustments are made. Some examples
* are: America/New_York offset -5 hours, & Africa/Cairo offset +2 hours.
* The format must follow the length-of-time format described above.
*
* DST adjustment:
* The amount of time added to gmt_offset when daylight savings is in
* effect. The format must follow the length-of-time format described
* above.
*
* DST Start Date rule:
* This is a specially formatted string that describes the day of year
* in which the transition take place. It holds three fields of it's own,
* separated by semicolons.
* The first field indicates the "nth" weekday of the month. The possible
* values are: 1 (first), 2 (second), 3 (third), 4 (fourth), 5 (fifth),
* and -1 (last).
* The second field indicates the day-of-week from 0-6 (Sun=0).
* The third field indicates the month from 1-12 (Jan=1).
*
* Examples are: "-1;5;9"="Last Friday of September",
* "2;1;3"="Second Monday of March"
*
* Start time:
* Start time is the number of hours past midnight, on the day of the
* start transition, the transition takes place. More simply put, the
* time of day the transition is made (in 24 hours format). The format
* must follow the length-of-time format described above with the
* exception that it must always be positive.
*
* DST End date rule:
* See DST Start date rule. The difference here is this is the day
* daylight savings ends (transition to STD).
*
* End time:
* Same as Start time.
*/
template<class time_zone_type, class rule_type>
class tz_db_base {
public:
/* Having CharT as a template parameter created problems
* with posix_time::duration_from_string. Templatizing
* duration_from_string was not possible at this time, however,
* it should be possible in the future (when poor compilers get
* fixed or stop being used).
* Since this class was designed to use CharT as a parameter it
* is simply typedef'd here to ease converting in back to a
* parameter the future */
typedef char char_type;
typedef typename time_zone_type::base_type time_zone_base_type;
typedef typename time_zone_type::time_duration_type time_duration_type;
typedef time_zone_names_base<char_type> time_zone_names;
typedef boost::date_time::dst_adjustment_offsets<time_duration_type> dst_adjustment_offsets;
typedef std::basic_string<char_type> string_type;
//! Constructs an empty database
tz_db_base() {}
//! Process csv data file, may throw exceptions
/*! May throw data_not_accessible, or bad_field_count exceptions */
void load_from_file(const std::string& pathspec)
{
string_type in_str;
std::string buff;
std::ifstream ifs(pathspec.c_str());
if(!ifs){
boost::throw_exception(data_not_accessible(pathspec));
}
std::getline(ifs, buff); // first line is column headings
while( std::getline(ifs, buff)) {
parse_string(buff);
}
}
//! returns true if record successfully added to map
/*! Takes a region name in the form of "America/Phoenix", and a
* time_zone object for that region. The id string must be a unique
* name that does not already exist in the database. */
bool add_record(const string_type& region,
boost::shared_ptr<time_zone_base_type> tz)
{
typename map_type::value_type p(region, tz);
return (m_zone_map.insert(p)).second;
}
//! Returns a time_zone object built from the specs for the given region
/*! Returns a time_zone object built from the specs for the given
* region. If region does not exist a local_time::record_not_found
* exception will be thrown */
boost::shared_ptr<time_zone_base_type>
time_zone_from_region(const string_type& region) const
{
// get the record
typename map_type::const_iterator record = m_zone_map.find(region);
if(record == m_zone_map.end()){
return boost::shared_ptr<time_zone_base_type>(); //null pointer
}
return record->second;
}
//! Returns a vector of strings holding the time zone regions in the database
std::vector<std::string> region_list() const
{
typedef std::vector<std::string> vector_type;
vector_type regions;
typename map_type::const_iterator itr = m_zone_map.begin();
while(itr != m_zone_map.end()) {
regions.push_back(itr->first);
++itr;
}
return regions;
}
private:
typedef std::map<string_type, boost::shared_ptr<time_zone_base_type> > map_type;
map_type m_zone_map;
// start and end rule are of the same type
typedef typename rule_type::start_rule::week_num week_num;
/* TODO: mechanisms need to be put in place to handle different
* types of rule specs. parse_rules() only handles nth_kday
* rule types. */
//! parses rule specs for transition day rules
rule_type* parse_rules(const string_type& sr, const string_type& er) const
{
using namespace gregorian;
// start and end rule are of the same type,
// both are included here for readability
typedef typename rule_type::start_rule start_rule;
typedef typename rule_type::end_rule end_rule;
// these are: [start|end] nth, day, month
int s_nth = 0, s_d = 0, s_m = 0;
int e_nth = 0, e_d = 0, e_m = 0;
split_rule_spec(s_nth, s_d, s_m, sr);
split_rule_spec(e_nth, e_d, e_m, er);
typename start_rule::week_num s_wn, e_wn;
s_wn = get_week_num(s_nth);
e_wn = get_week_num(e_nth);
return new rule_type(start_rule(s_wn, s_d, s_m),
end_rule(e_wn, e_d, e_m));
}
//! helper function for parse_rules()
week_num get_week_num(int nth) const
{
typedef typename rule_type::start_rule start_rule;
switch(nth){
case 1:
return start_rule::first;
case 2:
return start_rule::second;
case 3:
return start_rule::third;
case 4:
return start_rule::fourth;
case 5:
case -1:
return start_rule::fifth;
default:
// shouldn't get here - add error handling later
break;
}
return start_rule::fifth; // silence warnings
}
//! splits the [start|end]_date_rule string into 3 ints
void split_rule_spec(int& nth, int& d, int& m, string_type rule) const
{
typedef boost::char_separator<char_type, std::char_traits<char_type> > char_separator_type;
typedef boost::tokenizer<char_separator_type,
std::basic_string<char_type>::const_iterator,
std::basic_string<char_type> > tokenizer;
typedef boost::tokenizer<char_separator_type,
std::basic_string<char_type>::const_iterator,
std::basic_string<char_type> >::iterator tokenizer_iterator;
const char_type sep_char[] = { ';', '\0'};
char_separator_type sep(sep_char);
tokenizer tokens(rule, sep); // 3 fields
tokenizer_iterator tok_iter = tokens.begin();
nth = std::atoi(tok_iter->c_str()); ++tok_iter;
d = std::atoi(tok_iter->c_str()); ++tok_iter;
m = std::atoi(tok_iter->c_str());
}
//! Take a line from the csv, turn it into a time_zone_type.
/*! Take a line from the csv, turn it into a time_zone_type,
* and add it to the map. Zone_specs in csv file are expected to
* have eleven fields that describe the time zone. Returns true if
* zone_spec successfully added to database */
bool parse_string(string_type& s)
{
std::vector<string_type> result;
typedef boost::token_iterator_generator<boost::escaped_list_separator<char_type>, string_type::const_iterator, string_type >::type token_iter_type;
token_iter_type i = boost::make_token_iterator<string_type>(s.begin(), s.end(),boost::escaped_list_separator<char_type>());
token_iter_type end;
while (i != end) {
result.push_back(*i);
i++;
}
enum db_fields { ID, STDABBR, STDNAME, DSTABBR, DSTNAME, GMTOFFSET,
DSTADJUST, START_DATE_RULE, START_TIME, END_DATE_RULE,
END_TIME, FIELD_COUNT };
//take a shot at fixing gcc 4.x error
const unsigned int expected_fields = static_cast<unsigned int>(FIELD_COUNT);
if (result.size() != expected_fields) {
std::ostringstream msg;
msg << "Expecting " << FIELD_COUNT << " fields, got "
<< result.size() << " fields in line: " << s;
boost::throw_exception(bad_field_count(msg.str()));
BOOST_DATE_TIME_UNREACHABLE_EXPRESSION(return false); // should never reach
}
// initializations
bool has_dst = true;
if(result[DSTABBR] == std::string()){
has_dst = false;
}
// start building components of a time_zone
time_zone_names names(result[STDNAME], result[STDABBR],
result[DSTNAME], result[DSTABBR]);
time_duration_type utc_offset =
str_from_delimited_time_duration<time_duration_type,char_type>(result[GMTOFFSET]);
dst_adjustment_offsets adjust(time_duration_type(0,0,0),
time_duration_type(0,0,0),
time_duration_type(0,0,0));
boost::shared_ptr<rule_type> rules;
if(has_dst){
adjust = dst_adjustment_offsets(
str_from_delimited_time_duration<time_duration_type,char_type>(result[DSTADJUST]),
str_from_delimited_time_duration<time_duration_type,char_type>(result[START_TIME]),
str_from_delimited_time_duration<time_duration_type,char_type>(result[END_TIME])
);
rules =
boost::shared_ptr<rule_type>(parse_rules(result[START_DATE_RULE],
result[END_DATE_RULE]));
}
string_type id(result[ID]);
boost::shared_ptr<time_zone_base_type> zone(new time_zone_type(names, utc_offset, adjust, rules));
return (add_record(id, zone));
}
};
} } // namespace
#endif // DATE_TIME_TZ_DB_BASE_HPP__