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/**
* Copyright (C) 2013 10gen Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License, version 3,
* as published by the Free Software Foundation.
*
* 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 Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include "mongo/db/query/interval.h"
namespace mongo {
namespace {
/** Returns true if lhs and rhs intersection is not empty */
bool intersects(const Interval& lhs, const Interval& rhs) {
int res = lhs.start.woCompare(rhs.end, false);
if (res > 0) {
return false;
}
else if (res == 0 && (!lhs.startInclusive || !rhs.endInclusive)) {
return false;
}
res = rhs.start.woCompare(lhs.end, false);
if (res > 0) {
return false;
}
else if (res == 0 && (!rhs.startInclusive || !lhs.endInclusive)) {
return false;
}
return true;
}
/** Returns true if lhs and rhs represent the same interval */
bool exact(const Interval& lhs, const Interval& rhs) {
if (lhs.startInclusive != rhs.startInclusive) {
return false;
}
if (lhs.endInclusive != rhs.endInclusive) {
return false;
}
int res = lhs.start.woCompare(rhs.start, false);
if (res != 0) {
return false;
}
res = lhs.end.woCompare(rhs.end, false);
if (res != 0) {
return false;
}
return true;
}
/** Returns true if lhs is fully withing rhs */
bool within(const Interval& lhs, const Interval& rhs) {
int res = lhs.start.woCompare(rhs.start, false);
if (res < 0) {
return false;
}
else if (res == 0 && lhs.startInclusive && !rhs.startInclusive) {
return false;
}
res = lhs.end.woCompare(rhs.end, false);
if (res > 0) {
return false;
}
else if (res == 0 && lhs.endInclusive && !rhs.endInclusive) {
return false;
}
return true;
}
/** Returns true if the start of lhs comes before the start of rhs */
bool precedes(const Interval& lhs, const Interval& rhs) {
int res = lhs.start.woCompare(rhs.start, false);
if (res < 0) {
return true;
}
else if (res == 0 && lhs.startInclusive && !rhs.startInclusive) {
return true;
}
return false;
}
} // unnamed namespace
Interval::Interval()
: _intervalData(BSONObj()), start(BSONElement()), startInclusive(false), end(BSONElement()),
endInclusive(false) { }
Interval::Interval(BSONObj base, bool si, bool ei) {
init(base, si, ei);
}
void Interval::init(BSONObj base, bool si, bool ei) {
dassert(base.nFields() >= 2);
_intervalData = base.getOwned();
BSONObjIterator it(_intervalData);
start = it.next();
end = it.next();
startInclusive = si;
endInclusive = ei;
}
bool Interval::isEmpty() const {
return _intervalData.nFields() == 0;
}
// TODO: shortcut number of comparisons
Interval::IntervalComparison Interval::compare(const Interval& other) const {
//
// Intersect cases
//
// TODO: rewrite this to be member functions so semantics are clearer.
if (intersects(*this, other)) {
if (exact(*this, other)) {
return INTERVAL_EQUALS;
}
if (within(*this, other)) {
return INTERVAL_WITHIN;
}
if (within(other, *this)) {
return INTERVAL_CONTAINS;
}
if (precedes(*this, other)) {
return INTERVAL_OVERLAPS_BEFORE;
}
return INTERVAL_OVERLAPS_AFTER;
}
//
// Non-intersect cases
//
if (precedes(*this, other)) {
// It's not possible for both endInclusive and other.startInclusive to be true because
// the bounds would intersect. Refer to section on "Intersect cases" above.
if ((endInclusive || other.startInclusive) && 0 == end.woCompare(other.start, false)) {
return INTERVAL_PRECEDES_COULD_UNION;
}
return INTERVAL_PRECEDES;
}
return INTERVAL_SUCCEEDS;
}
void Interval::intersect(const Interval& other, IntervalComparison cmp) {
if (cmp == INTERVAL_UNKNOWN) {
cmp = this->compare(other);
}
BSONObjBuilder builder;
switch (cmp) {
case INTERVAL_EQUALS:
case INTERVAL_WITHIN:
break;
case INTERVAL_CONTAINS:
builder.append(other.start);
builder.append(other.end);
init(builder.obj(), other.startInclusive, other.endInclusive);
break;
case INTERVAL_OVERLAPS_AFTER:
builder.append(start);
builder.append(other.end);
init(builder.obj(), startInclusive, other.endInclusive);
break;
case INTERVAL_OVERLAPS_BEFORE:
builder.append(other.start);
builder.append(end);
init(builder.obj(), other.startInclusive, endInclusive);
break;
case INTERVAL_PRECEDES:
case INTERVAL_SUCCEEDS:
*this = Interval();
break;
default:
dassert(false);
}
}
void Interval::combine(const Interval& other, IntervalComparison cmp) {
if (cmp == INTERVAL_UNKNOWN) {
cmp = this->compare(other);
}
BSONObjBuilder builder;
switch (cmp) {
case INTERVAL_EQUALS:
case INTERVAL_CONTAINS:
break;
case INTERVAL_WITHIN:
builder.append(other.start);
builder.append(other.end);
init(builder.obj(), other.startInclusive, other.endInclusive);
break;
case INTERVAL_OVERLAPS_AFTER:
case INTERVAL_SUCCEEDS:
builder.append(other.start);
builder.append(end);
init(builder.obj(), other.startInclusive, endInclusive);
break;
case INTERVAL_OVERLAPS_BEFORE:
case INTERVAL_PRECEDES:
builder.append(start);
builder.append(other.end);
init(builder.obj(), startInclusive, other.endInclusive);
break;
default:
dassert(false);
}
}
// static
string Interval::cmpstr(IntervalComparison c) {
if (c == INTERVAL_EQUALS) {
return "INTERVAL_EQUALS";
}
// 'this' contains the other interval.
if (c == INTERVAL_CONTAINS) {
return "INTERVAL_CONTAINS";
}
// 'this' is contained by the other interval.
if (c == INTERVAL_WITHIN) {
return "INTERVAL_WITHIN";
}
// The two intervals intersect and 'this' is before the other interval.
if (c == INTERVAL_OVERLAPS_BEFORE) {
return "INTERVAL_OVERLAPS_BEFORE";
}
// The two intervals intersect and 'this is after the other interval.
if (c == INTERVAL_OVERLAPS_AFTER) {
return "INTERVAL_OVERLAPS_AFTER";
}
// There is no intersection.
if (c == INTERVAL_PRECEDES) {
return "INTERVAL_PRECEDES";
}
if (c == INTERVAL_PRECEDES_COULD_UNION) {
return "INTERVAL_PRECEDES_COULD_UNION";
}
if (c == INTERVAL_SUCCEEDS) {
return "INTERVAL_SUCCEEDS";
}
if (c == INTERVAL_UNKNOWN) {
return "INTERVAL_UNKNOWN";
}
return "NO IDEA DUDE";
}
void Interval::reverse() {
std::swap(start, end);
std::swap(startInclusive, endInclusive);
}
} // namespace mongo
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