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Temporal: various changes to int62_t and timeline types based on code review

This commit is contained in:
Paul Davis 2020-08-10 15:24:46 -06:00
parent 67de08e78d
commit c75fc64306
2 changed files with 44 additions and 81 deletions
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92
libs/temporal/temporal/timeline.h
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@ -1,20 +1,20 @@
/*
Copyright (C) 2020 Paul Davis
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
* Copyright (C) 2020 Paul Davis
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#ifndef __libtemporal_timeline_h__
#define __libtemporal_timeline_h__
@ -101,32 +101,32 @@ class timepos_t : public int62_t {
timepos_t operator+(Temporal::Beats const &b ) const { if (is_beats()) return timepos_t (ticks() + b.to_ticks()); return expensive_add (b); }
/* operator-() poses severe and thorny problems for a class that represents position on a timeline.
If the value of the class is a simple scalar, then subtraction can be used for both:
1) movement backwards along the timeline
2) computing the distance between two positions
But timepos_t is not a simple scalar, and neither is timecnt_t, and these two operations are quite different.
1) movement backwards along the timeline should result in another timepos_t
2) the distance between two positions is a timecnt_t
so already we have a hint that we would need at least:
timepos_t operator- (timecnt_t const &); ... compute new position
timecnt_t operator- (timepos_t const &); ... compute distance
But what happens we try to use more explicit types. What does this expression mean:
timepos_t pos;
pos - Beats (3);
is this computing a new position 3 beats earlier than pos? or is it computing the distance between
pos and the 3rd beat?
For this reason, we do not provide any operator-() methods, but instead require the use of
explicit methods with clear semantics.
*
* If the value of the class is a simple scalar, then subtraction can be used for both:
*
* 1) movement backwards along the timeline
* 2) computing the distance between two positions
*
* But timepos_t is not a simple scalar, and neither is timecnt_t, and these two operations are quite different.
*
* 1) movement backwards along the timeline should result in another timepos_t
* 2) the distance between two positions is a timecnt_t
*
* so already we have a hint that we would need at least:
*
* timepos_t operator- (timecnt_t const &); ... compute new position
* timecnt_t operator- (timepos_t const &); ... compute distance
*
* But what happens we try to use more explicit types. What does this expression mean:
*
* timepos_t pos;
* pos - Beats (3);
*
* is this computing a new position 3 beats earlier than pos? or is it computing the distance between
* pos and the 3rd beat?
*
* For this reason, we do not provide any operator-() methods, but instead require the use of
* explicit methods with clear semantics.
*/
/* computes the distance between this timepos_t and @param p
@ -161,12 +161,6 @@ class timepos_t : public int62_t {
timepos_t & shift_earlier (Temporal::Beats const &);
timepos_t & shift_earlier (Temporal::BBT_Offset const &);
timepos_t operator/(ratio_t const &) const;
timepos_t operator*(ratio_t const &) const;
timepos_t & operator*=(ratio_t const &);
timepos_t & operator/=(ratio_t const &);
timepos_t & operator+=(timecnt_t const & d);
timepos_t & operator+=(samplepos_t);
timepos_t & operator+=(Temporal::Beats const &);
@ -235,6 +229,8 @@ class timepos_t : public int62_t {
timepos_t expensive_add (superclock_t s) const;
using int62_t::operator int64_t;
using int62_t::operator-;
using int62_t::operator-=;
};

33
libs/temporal/timeline.cc
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@ -257,39 +257,6 @@ timepos_t::_ticks () const
return _beats().to_ticks();
}
timepos_t
timepos_t::operator/(ratio_t const & n) const
{
assert (n >= 0); /* do not allow a position to become negative via division */
/* note: v / (N/D) = (v * D) / N */
return timepos_t (is_beats(), int_div_round (val() * n.denominator(), n.numerator()));
}
timepos_t
timepos_t::operator*(ratio_t const & n) const
{
assert (n >= 0); /* do not allow a position to become negative via multiplication */
return timepos_t (is_beats(), int_div_round (val() * n.numerator(), n.denominator()));
}
timepos_t &
timepos_t::operator/=(ratio_t const & n)
{
assert (n >= 0); /* do not allow a position to become negative via division */
v = build (flagged(), int_div_round (val() * n.numerator(), n.denominator()));
return *this;
}
timepos_t &
timepos_t::operator*=(ratio_t const & n)
{
assert (n >= 0); /* do not allow a position to become negative via multiplication */
v = build (flagged(), int_div_round (val() * n.denominator(), n.numerator()));
return *this;
}
timepos_t
timepos_t::expensive_add (Beats const & b) const
{