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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/>.
*
* As a special exception, the copyright holders give permission to link the
* code of portions of this program with the OpenSSL library under certain
* conditions as described in each individual source file and distribute
* linked combinations including the program with the OpenSSL library. You
* must comply with the GNU Affero General Public License in all respects for
* all of the code used other than as permitted herein. If you modify file(s)
* with this exception, you may extend this exception to your version of the
* file(s), but you are not obligated to do so. If you do not wish to do so,
* delete this exception statement from your version. If you delete this
* exception statement from all source files in the program, then also delete
* it in the license file.
*/
#pragma once
#include "mongo/db/jsobj.h"
#include "mongo/bson/mutable/document.h"
#include "mongo/bson/mutable/element.h"
namespace mongo {
// Extracts the value for 'pattern' for both 'lhs' and 'rhs' and return true if 'lhs' <
// 'rhs'. We expect that both 'lhs' and 'rhs' be key patterns.
struct PatternElementCmp {
BSONObj sortPattern;
bool useWholeValue;
PatternElementCmp()
: sortPattern(BSONObj())
, useWholeValue(true) {}
PatternElementCmp(const BSONObj& pattern)
: sortPattern(pattern)
, useWholeValue(pattern.hasField("")){
}
bool operator()(const mutablebson::Element& lhs, const mutablebson::Element& rhs) const {
if (useWholeValue) {
const int comparedValue = lhs.compareWithElement( rhs, false );
const bool reversed = (sortPattern.firstElement().number() < 0 );
return (reversed ? comparedValue > 0 : comparedValue < 0);
}
else {
//TODO: Push on to mutable in the future, and to support non-contiguous Elements.
BSONObj lhsObj = lhs.getType() == Object ?
lhs.getValueObject() :
lhs.getValue().wrap("");
BSONObj rhsObj = rhs.getType() == Object ?
rhs.getValueObject() :
rhs.getValue().wrap("");
BSONObj lhsKey = lhsObj.extractFields(sortPattern, true);
BSONObj rhsKey = rhsObj.extractFields(sortPattern, true);
return lhsKey.woCompare(rhsKey, sortPattern) < 0;
}
}
};
} // namespace mongo
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