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/*
* for reference:
* - James F. Allen, Maintaining Knowledge about Temporal Intervals, CACM November 1983, Vol. 26, No. 11
* - https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6188649/
*/
#include <u.h>
#include <libc.h>
#include "interval.h"
static int
interval_before(Interval *i, Interval *ii)
{
return i->t1 < ii->t0;
}
static int
interval_equals(Interval *i, Interval *ii)
{
return i->t0 == ii->t0 &&
i->t1 == ii->t1;
}
static int
interval_overlaps(Interval *i, Interval *ii)
{
return i->t0 < ii->t0 &&
i->t1 > ii->t0 &&
i->t1 < ii->t1;
}
static int
interval_meets(Interval *i, Interval *ii)
{
return i->t1 == ii->t0;
}
static int
interval_during(Interval *i, Interval *ii)
{
return (i->t0 > ii->t0 && i->t1 <= ii->t1) ||
(i->t0 >= ii->t0 && i->t1 < ii->t1);
}
static int
interval_intersects(Interval *i, Interval *ii)
{
return i->equals(i, ii) ||
i->overlaps(i, ii) ||
ii->overlaps(ii, i) ||
i->during(i, ii) ||
ii->during(ii, i);
}
Interval *
mkinterval(uvlong t0, uvlong t1)
{
Interval *i;
assert(t0 <= t1);
i = malloc(sizeof(Interval));
if(i == nil)
sysfatal("mkinterval: %r");
i->t0 = t0;
i->t1 = t1;
i->∆t = t1-t0;
i->before = interval_before;
i->equals = interval_equals;
i->overlaps = interval_overlaps;
i->meets = interval_meets;
i->during = interval_during;
i->intersects = interval_intersects;
return i;
}
void
rminterval(Interval *i)
{
free(i);
}
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