Interval.cpp
上传用户:romrleung
上传日期:2022-05-23
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文件大小:3k
- /* Copyright (C) 2003 MySQL AB
- 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */
- #include "Interval.hpp"
- #undef min
- #undef max
- Uint32 max(Uint32 a, Uint32 b) { return a > b ? a : b; }
- Uint32 min(Uint32 a, Uint32 b) { return a < b ? a : b; }
- Interval::Interval()
- {
- set(1, 0); // EmptyInterval
- }
- Interval::Interval(Uint32 f, Uint32 l)
- {
- set(f, l);
- }
- bool
- Interval::isEmpty() const
- {
- return (m_first > m_last) ? true : false;
- }
- bool
- Interval::isEqual(Uint32 a, Uint32 b) const
- {
- return (a==m_first && b==m_last);
- }
- bool
- Interval::inInterval(Uint32 a) const
- {
- return (m_first <= a && a <= m_last);
- }
- void
- Interval::set(Uint32 first, Uint32 last)
- {
- m_first = first;
- m_last = last;
- normalize();
- }
- void
- Interval::set(const Interval i)
- {
- m_first = i.first();
- m_last = i.last();
- normalize();
- }
- void
- Interval::setFirst(Uint32 first)
- {
- m_first = first;
- }
- void
- Interval::setLast(Uint32 last)
- {
- m_last = last;
- }
- void
- Interval::onlyLeft(Uint32 n)
- {
- if (size() > n) m_last = m_first + n - 1;
- }
- void
- Interval::onlyUpToValue(Uint32 n)
- {
- m_last = min(n, m_last);
- normalize();
- }
- /*****************************************************************************/
- void
- Interval::normalize()
- {
- if (isEmpty()) {
- m_first = 1;
- m_last = 0;
- }
- }
- /*****************************************************************************/
- bool
- intervalAdd(const Interval a, const Interval b, Interval * r)
- {
- /**
- * Non-empty disjoint intervals
- */
- if (!a.isEmpty() &&
- !b.isEmpty() &&
- (a.last() + 1 < b.first() ||
- b.last() + 1 < a.first()) ) {
- return false; // Illegal add
- }
-
- /**
- * Interval A empty -> return B
- */
- if (a.isEmpty()) {
- r->set(b);
- return true;
- }
- /**
- * Interval B empty -> return A
- */
- if (b.isEmpty()) {
- r->set(a);
- return true;
- }
-
- r->set(min(a.first(), b.first()),
- max(a.last(), b.last()));
- return true;
- }
- /**
- * Subtract the left part of interval 'a' up to last of 'b'.
- *
- * @note This is NOT ordinary arithmetic interval minus.
- * In ordinary arithmetic, [11-25] - [12-15] would be undefined,
- * but here it is [11-25] - [12-15] = [16-25].
- */
- void
- intervalLeftMinus(const Interval a, const Interval b, Interval * r)
- {
- if(b.last() != intervalMax)
- r->set(max(a.first(), b.last()+1), a.last());
- else
- r->set(max(a.first(), intervalMax), a.last());
- }
- void
- intervalCut(const Interval a, const Interval b, Interval * r)
- {
- r->set(max(a.first(), b.first()), min(a.last(), b.last()));
- r->normalize();
- }
- bool
- intervalDisjoint(const Interval a, const Interval b)
- {
- return (a.isEmpty() ||
- b.isEmpty() ||
- a.last() < b.first() ||
- b.last() < a.first());
- }