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378 lines
11 KiB
378 lines
11 KiB
#ifndef DATE_TIME_PERIOD_HPP___ |
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#define DATE_TIME_PERIOD_HPP___ |
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/* Copyright (c) 2002,2003 CrystalClear Software, Inc. |
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* Use, modification and distribution is subject to the |
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* Boost Software License, Version 1.0. (See accompanying |
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* file LICENSE_1_0.txt or http://www.boost.org/LICENSE_1_0.txt) |
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* Author: Jeff Garland, Bart Garst |
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* $Date$ |
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*/ |
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/*! \file period.hpp |
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This file contain the implementation of the period abstraction. This is |
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basically the same idea as a range. Although this class is intended for |
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use in the time library, it is pretty close to general enough for other |
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numeric uses. |
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*/ |
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#include <boost/operators.hpp> |
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#include <boost/date_time/compiler_config.hpp> |
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namespace boost { |
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namespace date_time { |
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//!Provides generalized period type useful in date-time systems |
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/*!This template uses a class to represent a time point within the period |
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and another class to represent a duration. As a result, this class is |
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not appropriate for use when the number and duration representation |
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are the same (eg: in the regular number domain). |
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A period can be specified by providing either the begining point and |
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a duration or the begining point and the end point( end is NOT part |
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of the period but 1 unit past it. A period will be "invalid" if either |
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end_point <= begin_point or the given duration is <= 0. Any valid period |
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will return false for is_null(). |
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Zero length periods are also considered invalid. Zero length periods are |
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periods where the begining and end points are the same, or, the given |
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duration is zero. For a zero length period, the last point will be one |
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unit less than the begining point. |
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In the case that the begin and last are the same, the period has a |
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length of one unit. |
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The best way to handle periods is usually to provide a begining point and |
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a duration. So, day1 + 7 days is a week period which includes all of the |
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first day and 6 more days (eg: Sun to Sat). |
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*/ |
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template<class point_rep, class duration_rep> |
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class BOOST_SYMBOL_VISIBLE period : private |
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boost::less_than_comparable<period<point_rep, duration_rep> |
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, boost::equality_comparable< period<point_rep, duration_rep> |
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> > |
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{ |
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public: |
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typedef point_rep point_type; |
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typedef duration_rep duration_type; |
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period(point_rep first_point, point_rep end_point); |
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period(point_rep first_point, duration_rep len); |
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point_rep begin() const; |
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point_rep end() const; |
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point_rep last() const; |
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duration_rep length() const; |
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bool is_null() const; |
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bool operator==(const period& rhs) const; |
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bool operator<(const period& rhs) const; |
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void shift(const duration_rep& d); |
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void expand(const duration_rep& d); |
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bool contains(const point_rep& point) const; |
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bool contains(const period& other) const; |
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bool intersects(const period& other) const; |
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bool is_adjacent(const period& other) const; |
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bool is_before(const point_rep& point) const; |
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bool is_after(const point_rep& point) const; |
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period intersection(const period& other) const; |
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period merge(const period& other) const; |
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period span(const period& other) const; |
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private: |
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point_rep begin_; |
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point_rep last_; |
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}; |
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//! create a period from begin to last eg: [begin,end) |
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/*! If end <= begin then the period will be invalid |
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*/ |
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template<class point_rep, class duration_rep> |
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inline |
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period<point_rep,duration_rep>::period(point_rep first_point, |
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point_rep end_point) : |
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begin_(first_point), |
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last_(end_point - duration_rep::unit()) |
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{} |
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//! create a period as [begin, begin+len) |
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/*! If len is <= 0 then the period will be invalid |
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*/ |
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template<class point_rep, class duration_rep> |
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inline |
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period<point_rep,duration_rep>::period(point_rep first_point, duration_rep len) : |
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begin_(first_point), |
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last_(first_point + len-duration_rep::unit()) |
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{ } |
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//! Return the first element in the period |
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template<class point_rep, class duration_rep> |
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inline |
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point_rep period<point_rep,duration_rep>::begin() const |
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{ |
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return begin_; |
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} |
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//! Return one past the last element |
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template<class point_rep, class duration_rep> |
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inline |
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point_rep period<point_rep,duration_rep>::end() const |
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{ |
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return last_ + duration_rep::unit(); |
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} |
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//! Return the last item in the period |
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template<class point_rep, class duration_rep> |
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inline |
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point_rep period<point_rep,duration_rep>::last() const |
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{ |
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return last_; |
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} |
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//! True if period is ill formed (length is zero or less) |
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template<class point_rep, class duration_rep> |
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inline |
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bool period<point_rep,duration_rep>::is_null() const |
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{ |
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return end() <= begin_; |
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} |
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//! Return the length of the period |
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template<class point_rep, class duration_rep> |
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inline |
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duration_rep period<point_rep,duration_rep>::length() const |
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{ |
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if(last_ < begin_){ // invalid period |
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return last_+duration_rep::unit() - begin_; |
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} |
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else{ |
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return end() - begin_; // normal case |
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} |
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} |
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//! Equality operator |
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template<class point_rep, class duration_rep> |
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inline |
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bool period<point_rep,duration_rep>::operator==(const period& rhs) const |
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{ |
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return ((begin_ == rhs.begin_) && |
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(last_ == rhs.last_)); |
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} |
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//! Strict as defined by rhs.last <= lhs.last |
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template<class point_rep, class duration_rep> |
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inline |
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bool period<point_rep,duration_rep>::operator<(const period& rhs) const |
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{ |
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return (last_ < rhs.begin_); |
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} |
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//! Shift the start and end by the specified amount |
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template<class point_rep, class duration_rep> |
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inline |
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void period<point_rep,duration_rep>::shift(const duration_rep& d) |
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{ |
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begin_ = begin_ + d; |
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last_ = last_ + d; |
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} |
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/** Expands the size of the period by the duration on both ends. |
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* |
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*So before expand |
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*@code |
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* |
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* [-------] |
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* ^ ^ ^ ^ ^ ^ ^ |
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* 1 2 3 4 5 6 7 |
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* |
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*@endcode |
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* After expand(2) |
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*@code |
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* |
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* [----------------------] |
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* ^ ^ ^ ^ ^ ^ ^ |
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* 1 2 3 4 5 6 7 |
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* |
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*@endcode |
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*/ |
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template<class point_rep, class duration_rep> |
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inline |
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void period<point_rep,duration_rep>::expand(const duration_rep& d) |
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{ |
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begin_ = begin_ - d; |
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last_ = last_ + d; |
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} |
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//! True if the point is inside the period, zero length periods contain no points |
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template<class point_rep, class duration_rep> |
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inline |
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bool period<point_rep,duration_rep>::contains(const point_rep& point) const |
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{ |
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return ((point >= begin_) && |
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(point <= last_)); |
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} |
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//! True if this period fully contains (or equals) the other period |
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template<class point_rep, class duration_rep> |
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inline |
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bool period<point_rep,duration_rep>::contains(const period<point_rep,duration_rep>& other) const |
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{ |
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return ((begin_ <= other.begin_) && (last_ >= other.last_)); |
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} |
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//! True if periods are next to each other without a gap. |
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/* In the example below, p1 and p2 are adjacent, but p3 is not adjacent |
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* with either of p1 or p2. |
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*@code |
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* [-p1-) |
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* [-p2-) |
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* [-p3-) |
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*@endcode |
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*/ |
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template<class point_rep, class duration_rep> |
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inline |
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bool |
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period<point_rep,duration_rep>::is_adjacent(const period<point_rep,duration_rep>& other) const |
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{ |
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return (other.begin() == end() || |
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begin_ == other.end()); |
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} |
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//! True if all of the period is prior or t < start |
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/* In the example below only point 1 would evaluate to true. |
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*@code |
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* [---------]) |
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* ^ ^ ^ ^ ^ |
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* 1 2 3 4 5 |
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* |
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*@endcode |
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*/ |
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template<class point_rep, class duration_rep> |
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inline |
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bool |
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period<point_rep,duration_rep>::is_after(const point_rep& t) const |
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{ |
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if (is_null()) |
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{ |
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return false; //null period isn't after |
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} |
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return t < begin_; |
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} |
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//! True if all of the period is prior to the passed point or end <= t |
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/* In the example below points 4 and 5 return true. |
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*@code |
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* [---------]) |
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* ^ ^ ^ ^ ^ |
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* 1 2 3 4 5 |
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* |
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*@endcode |
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*/ |
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template<class point_rep, class duration_rep> |
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inline |
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bool |
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period<point_rep,duration_rep>::is_before(const point_rep& t) const |
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{ |
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if (is_null()) |
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{ |
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return false; //null period isn't before anything |
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} |
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return last_ < t; |
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} |
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//! True if the periods overlap in any way |
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/* In the example below p1 intersects with p2, p4, and p6. |
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*@code |
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* [---p1---) |
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* [---p2---) |
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* [---p3---) |
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* [---p4---) |
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* [-p5-) |
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* [-p6-) |
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*@endcode |
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*/ |
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template<class point_rep, class duration_rep> |
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inline |
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bool period<point_rep,duration_rep>::intersects(const period<point_rep,duration_rep>& other) const |
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{ |
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return ( contains(other.begin_) || |
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other.contains(begin_) || |
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((other.begin_ < begin_) && (other.last_ >= begin_))); |
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} |
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//! Returns the period of intersection or invalid range no intersection |
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template<class point_rep, class duration_rep> |
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inline |
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period<point_rep,duration_rep> |
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period<point_rep,duration_rep>::intersection(const period<point_rep,duration_rep>& other) const |
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{ |
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if (begin_ > other.begin_) { |
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if (last_ <= other.last_) { //case2 |
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return *this; |
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} |
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//case 1 |
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return period<point_rep,duration_rep>(begin_, other.end()); |
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} |
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else { |
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if (last_ <= other.last_) { //case3 |
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return period<point_rep,duration_rep>(other.begin_, this->end()); |
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} |
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//case4 |
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return other; |
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} |
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//unreachable |
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} |
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//! Returns the union of intersecting periods -- or null period |
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/*! |
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*/ |
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template<class point_rep, class duration_rep> |
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inline |
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period<point_rep,duration_rep> |
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period<point_rep,duration_rep>::merge(const period<point_rep,duration_rep>& other) const |
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{ |
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if (this->intersects(other)) { |
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if (begin_ < other.begin_) { |
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return period<point_rep,duration_rep>(begin_, last_ > other.last_ ? this->end() : other.end()); |
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} |
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return period<point_rep,duration_rep>(other.begin_, last_ > other.last_ ? this->end() : other.end()); |
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} |
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return period<point_rep,duration_rep>(begin_,begin_); // no intersect return null |
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} |
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//! Combine two periods with earliest start and latest end. |
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/*! Combines two periods and any gap between them such that |
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* start = min(p1.start, p2.start) |
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* end = max(p1.end , p2.end) |
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*@code |
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* [---p1---) |
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* [---p2---) |
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* result: |
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* [-----------p3----------) |
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*@endcode |
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*/ |
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template<class point_rep, class duration_rep> |
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inline |
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period<point_rep,duration_rep> |
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period<point_rep,duration_rep>::span(const period<point_rep,duration_rep>& other) const |
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{ |
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point_rep start((begin_ < other.begin_) ? begin() : other.begin()); |
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point_rep newend((last_ < other.last_) ? other.end() : this->end()); |
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return period<point_rep,duration_rep>(start, newend); |
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} |
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} } //namespace date_time |
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#endif
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