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| <!DOCTYPE library PUBLIC "-//Boost//DTD BoostBook XML V1.0//EN" |
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| <!-- Copyright (c) 2001-2006 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) |
| --> |
| |
| <section id="date_time.posix_time.time_period"> |
| <title>Time Period</title> |
| |
| <link linkend="time_period_intro">Introduction</link> -- |
| <link linkend="time_period_header">Header</link> -- |
| <link linkend="time_period_constr">Construction</link> -- |
| <link linkend="time_period_mutators">Mutators</link> -- |
| <link linkend="time_period_accessors">Accessors</link> -- |
| <link linkend="time_period_to_string">Conversion To String</link> -- |
| <link linkend="time_period_operators">Operators</link> |
| |
| <anchor id="time_period_intro" /> |
| <bridgehead renderas="sect3">Introduction</bridgehead> |
| <para> |
| The class boost::posix_time::time_period provides direct representation for ranges between two times. Periods provide the ability to simplify some types of calculations by simplifying the conditional logic of the program. |
| </para> |
| <para> |
| A period that is created with beginning and end points being equal, or with a duration of zero, is known as a zero length period. Zero length periods are considered invalid (it is perfectly legal to construct an invalid period). For these periods, the <code>last</code> point will always be one unit less that the <code>begin</code> point. |
| </para> |
| <para> |
| The <link linkend="date_time.examples.time_periods">time periods example</link> provides an example of using time periods. |
| </para> |
| |
| <anchor id="time_period_header" /> |
| <bridgehead renderas="sect3">Header</bridgehead> |
| <para> |
| <programlisting>#include "boost/date_time/posix_time/posix_time.hpp" //include all types plus i/o |
| or |
| #include "boost/date_time/posix_time/posix_time_types.hpp" //no i/o just types</programlisting> |
| </para> |
| |
| <anchor id="time_period_constr" /> |
| <bridgehead renderas="sect3">Construction</bridgehead> |
| <para> |
| <informaltable frame="all"> |
| <tgroup cols="2"> |
| <thead> |
| <row> |
| <entry valign="top" morerows="1">Syntax</entry> |
| <entry>Description</entry> |
| </row> |
| <row> |
| <entry>Example</entry> |
| </row> |
| </thead> |
| <tbody> |
| <row> |
| <entry valign="top" morerows="1"><screen>time_period(ptime, |
| ptime)</screen></entry> |
| <entry> Create a period as [begin, end). If end is <= begin then the period will be defined as invalid.</entry> |
| </row> |
| <row> |
| <entry><screen>date d(2002,Jan,01); |
| ptime t1(d, seconds(10)); //10 sec after midnight |
| ptime t2(d, hours(10)); //10 hours after midnight |
| time_period tp(t1, t2);</screen> |
| </entry> |
| </row> |
| |
| <row> |
| <entry valign="top" morerows="1"><screen>time_period(ptime, |
| time_duration)</screen></entry> |
| <entry> Create a period as [begin, begin+len) where end would be begin+len. If len is <= zero then the period will be defined as invalid.</entry> |
| </row> |
| <row> |
| <entry><screen>date d(2002,Jan,01); |
| ptime t(d, seconds(10)); //10 sec after midnight |
| time_period tp(t, hours(3));</screen> |
| </entry> |
| </row> |
| |
| <row> |
| <entry valign="top" morerows="1"><screen>time_period(time_period rhs)</screen></entry> |
| <entry> Copy constructor</entry> |
| </row> |
| <row> |
| <entry><screen>time_period tp1(tp);</screen></entry> |
| </row> |
| </tbody> |
| </tgroup> |
| </informaltable> |
| </para> |
| |
| |
| <anchor id="time_period_mutators" /> |
| <bridgehead renderas="sect3">Mutators</bridgehead> |
| <para> |
| <informaltable frame="all"> |
| <tgroup cols="2"> |
| <thead> |
| <row> |
| <entry valign="top" morerows="1">Syntax</entry> |
| <entry>Description</entry> |
| </row> |
| <row> |
| <entry>Example</entry> |
| </row> |
| </thead> |
| <tbody> |
| |
| <row> |
| <entry valign="top" morerows="1"><screen>time_period shift(time_duration)</screen></entry> |
| <entry>Add duration to both begin and end.</entry> |
| </row> |
| <row> |
| <entry> |
| <screen> |
| time_period tp(ptime(date(2005,Jan,1),hours(1)), hours(2)); |
| tp.shift(minutes(5)); |
| // tp == 2005-Jan-01 01:05:00 to 2005-Jan-01 03:05:00 |
| </screen> |
| </entry> |
| </row> |
| |
| <row> |
| <entry valign="top" morerows="1"><screen>time_period expand(days)</screen></entry> |
| <entry>Subtract duration from begin and add duration to end.</entry> |
| </row> |
| <row> |
| <entry> |
| <screen> |
| time_period tp(ptime(date(2005,Jan,1),hours(1)), hours(2)); |
| tp.expand(minutes(5)); |
| // tp == 2005-Jan-01 00:55:00 to 2005-Jan-01 03:05:00 |
| </screen> |
| </entry> |
| </row> |
| |
| </tbody> |
| </tgroup> |
| </informaltable> |
| </para> |
| |
| |
| <anchor id="time_period_accessors" /> |
| <bridgehead renderas="sect3">Accessors</bridgehead> |
| <para> |
| <informaltable frame="all"> |
| <tgroup cols="2"> |
| <thead> |
| <row> |
| <entry valign="top" morerows="1">Syntax</entry> |
| <entry>Description</entry> |
| </row> |
| <row> |
| <entry>Example</entry> |
| </row> |
| </thead> |
| <tbody> |
| <row> |
| <entry valign="top" morerows="1"><screen>ptime begin()</screen></entry> |
| <entry>Return first time of period.</entry> |
| </row> |
| <row> |
| <entry><screen>date d(2002,Jan,01); |
| ptime t1(d, seconds(10)); //10 sec after midnight |
| ptime t2(d, hours(10)); //10 hours after midnight |
| time_period tp(t1, t2); |
| tp.begin(); // --> 2002-Jan-01 00:00:10</screen> |
| </entry> |
| </row> |
| |
| <row> |
| <entry valign="top" morerows="1"><screen>ptime last()</screen></entry> |
| <entry>Return last time in the period</entry> |
| </row> |
| <row> |
| <entry><screen>date d(2002,Jan,01); |
| ptime t1(d, seconds(10)); //10 sec after midnight |
| ptime t2(d, hours(10)); //10 hours after midnight |
| time_period tp(t1, t2); |
| tp.last();// --> 2002-Jan-01 09:59:59.999999999</screen> |
| </entry> |
| </row> |
| |
| <row> |
| <entry valign="top" morerows="1"><screen>ptime end()</screen></entry> |
| <entry> Return one past the last in period</entry> |
| </row> |
| <row> |
| <entry><screen>date d(2002,Jan,01); |
| ptime t1(d, seconds(10)); //10 sec after midnight |
| ptime t2(d, hours(10)); //10 hours after midnight |
| time_period tp(t1, t2); |
| tp.last(); // --> 2002-Jan-01 10:00:00</screen> |
| </entry> |
| </row> |
| |
| <row> |
| <entry valign="top" morerows="1"><screen>time_duration length()</screen></entry> |
| <entry>Return the length of the time period.</entry> |
| </row> |
| <row> |
| <entry><screen>date d(2002,Jan,01); |
| ptime t1(d); //midnight |
| time_period tp(t1, hours(1)); |
| tp.length() --> 1 hour</screen> |
| </entry> |
| </row> |
| |
| <row> |
| <entry valign="top" morerows="1"><screen>bool is_null()</screen></entry> |
| <entry>True if period is not well formed. eg: end is less than or equal to begin.</entry> |
| </row> |
| <row> |
| <entry><screen>date d(2002,Jan,01); |
| ptime t1(d, hours(12)); // noon on Jan 1st |
| ptime t2(d, hours(9)); // 9am on Jan 1st |
| time_period tp(t1, t2); |
| tp.is_null(); // true</screen> |
| </entry> |
| </row> |
| |
| <row> |
| <entry valign="top" morerows="1"><screen>bool contains(ptime)</screen></entry> |
| <entry>True if ptime is within the period. Zero length periods cannot contain any points.</entry> |
| </row> |
| <row> |
| <entry><screen>date d(2002,Jan,01); |
| ptime t1(d, seconds(10)); //10 sec after midnight |
| ptime t2(d, hours(10)); //10 hours after midnight |
| ptime t3(d, hours(2)); //2 hours after midnight |
| time_period tp(t1, t2); |
| tp.contains(t3); // true |
| time_period tp2(t1, t1); |
| tp2.contains(t1); // false</screen> |
| </entry> |
| </row> |
| |
| <row> |
| <entry valign="top" morerows="1"><screen>bool contains(time_period)</screen></entry> |
| <entry>True if period is within the period</entry> |
| </row> |
| <row> |
| <entry><screen>time_period tp1(ptime(d,hours(1)), |
| ptime(d,hours(12))); |
| time_period tp2(ptime(d,hours(2)), |
| ptime(d,hours(4))); |
| tp1.contains(tp2); // --> true |
| tp2.contains(tp1); // --> false</screen> |
| </entry> |
| </row> |
| |
| <row> |
| <entry valign="top" morerows="1"><screen>bool intersects(time_period)</screen></entry> |
| <entry> True if periods overlap</entry> |
| </row> |
| <row> |
| <entry><screen>time_period tp1(ptime(d,hours(1)), |
| ptime(d,hours(12))); |
| time_period tp2(ptime(d,hours(2)), |
| ptime(d,hours(4))); |
| tp2.intersects(tp1); // --> true</screen> |
| </entry> |
| </row> |
| |
| <row> |
| <entry valign="top" morerows="1"><screen>time_period intersection(time_period)</screen></entry> |
| <entry>Calculate the intersection of 2 periods. Null if no intersection.</entry> |
| </row> |
| <row> |
| <entry></entry> |
| </row> |
| |
| <row> |
| <entry valign="top" morerows="1"><screen>time_period merge(time_period)</screen></entry> |
| <entry>Returns union of two periods. Null if no intersection.</entry> |
| </row> |
| <row> |
| <entry></entry> |
| </row> |
| |
| <row> |
| <entry valign="top" morerows="1"><screen>time_period span(time_period)</screen></entry> |
| <entry>Combines two periods and any gap between them such that begin = min(p1.begin, p2.begin) and end = max(p1.end , p2.end).</entry> |
| </row> |
| <row> |
| <entry></entry> |
| </row> |
| |
| </tbody> |
| </tgroup> |
| </informaltable> |
| </para> |
| |
| |
| <anchor id="time_period_to_string" /> |
| <bridgehead renderas="sect3">Conversion To String</bridgehead> |
| <para> |
| <informaltable frame="all"> |
| <tgroup cols="2"> |
| <thead> |
| <row> |
| <entry valign="top" morerows="1">Syntax</entry> |
| <entry>Description</entry> |
| </row> |
| <row> |
| <entry>Example</entry> |
| </row> |
| </thead> |
| <tbody> |
| <row> |
| <entry valign="top" morerows="1"><screen>std::string |
| to_simple_string(time_period dp)</screen></entry> |
| <entry>To <code>[YYYY-mmm-DD hh:mm:ss.fffffffff/YYYY-mmm-DD hh:mm:ss.fffffffff]</code> string where <code>mmm</code> is 3 char month name.</entry> |
| </row> |
| <row> |
| <entry><screen>[2002-Jan-01 01:25:10.000000001/ |
| 2002-Jan-31 01:25:10.123456789] |
| // string occupies one line</screen></entry> |
| </row> |
| </tbody> |
| </tgroup> |
| </informaltable> |
| </para> |
| |
| |
| <anchor id="time_period_operators" /> |
| <bridgehead renderas="sect3">Operators</bridgehead> |
| <para> |
| <informaltable frame="all"> |
| <tgroup cols="2"> |
| <thead> |
| <row> |
| <entry valign="top" morerows="1">Syntax</entry> |
| <entry>Description</entry> |
| </row> |
| <row> |
| <entry>Example</entry> |
| </row> |
| </thead> |
| <tbody> |
| <row> |
| <entry valign="top" morerows="1"><screen>operator<<</screen></entry> |
| <entry>Output streaming operator for time duration. Uses facet to output [date time_of_day/date time_of_day]. The default is format is <code>[YYYY-mmm-DD hh:mm:ss.fffffffff/YYYY-mmm-DD hh:mm:ss.fffffffff]</code> string where <code>mmm</code> is 3 char month name and the fractional seconds are left out when zero.</entry> |
| </row> |
| <row> |
| <entry><screen>[2002-Jan-01 01:25:10.000000001/ \ |
| 2002-Jan-31 01:25:10.123456789]</screen></entry> |
| </row> |
| |
| <row> |
| <entry valign="top" morerows="1"><screen>operator>></screen></entry> |
| <entry>Input streaming operator for time duration. Uses facet to read [date time_of_day/date time_of_day]. The default is format is <code>[YYYY-mmm-DD hh:mm:ss.fffffffff/YYYY-mmm-DD hh:mm:ss.fffffffff]</code> string where <code>mmm</code> is 3 char month name and the fractional seconds are left out when zero.</entry> |
| </row> |
| <row> |
| <entry><screen>[2002-Jan-01 01:25:10.000000001/ \ |
| 2002-Jan-31 01:25:10.123456789]</screen></entry> |
| </row> |
| |
| <row> |
| <entry valign="top" morerows="1"><screen>operator==, operator!=</screen></entry> |
| <entry>Equality operators. Periods are equal if p1.begin == p2.begin && p1.last == p2.last</entry> |
| </row> |
| <row> |
| <entry><screen>if (tp1 == tp2) {...</screen></entry> |
| </row> |
| |
| <row> |
| <entry valign="top" morerows="1"><screen>operator<</screen></entry> |
| <entry>Ordering with no overlap. True if tp1.end() less than tp2.begin()</entry> |
| </row> |
| <row> |
| <entry><screen>if (tp1 < tp2) {...</screen></entry> |
| </row> |
| |
| <row> |
| <entry valign="top" morerows="1"><screen>operator></screen></entry> |
| <entry>Ordering with no overlap. True if tp1.begin() greater than tp2.end()</entry> |
| </row> |
| <row> |
| <entry><screen>if (tp1 > tp2) {... etc</screen></entry> |
| </row> |
| |
| <row> |
| <entry valign="top" morerows="1"><screen>operator<=, operator>=</screen></entry> |
| <entry>Defined in terms of the other operators.</entry> |
| </row> |
| <row> |
| <entry></entry> |
| </row> |
| </tbody> |
| </tgroup> |
| </informaltable> |
| </para> |
| |
| </section> |
