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mongodb/db/jsobjmanipulator.h

80 lines
2.8 KiB
C++

/** jsobjManipulator.h */
/**
* Copyright (C) 2009 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/>.
*/
#pragma once
#include "jsobj.h"
#include "repl.h"
namespace mongo {
/** Manipulate the binary representation of a BSONElement in-place.
Careful, this casts away const.
*/
class BSONElementManipulator {
public:
BSONElementManipulator( const BSONElement &element ) :
element_( element ) {
}
/** Replace a Timestamp type with a Date type initialized to
OpTime::now().asDate()
*/
void initTimestamp() {
massert( "Expected CurrentTime type", element_.type() == Timestamp );
unsigned long long &timestamp = *( reinterpret_cast< unsigned long long* >( value() ) );
if ( timestamp == 0 )
timestamp = OpTime::now().asDate();
}
/** Change the value, in place, of the number. */
void setNumber(double d) {
if ( element_.type() == NumberDouble ) *reinterpret_cast< double * >( value() ) = d;
else if ( element_.type() == NumberInt ) *reinterpret_cast< int * >( value() ) = (int) d;
}
/** Replace the type and value of the element with the type and value of e,
preserving the original fieldName */
void replaceTypeAndValue( const BSONElement &e ) {
*data() = e.type();
memcpy( value(), e.value(), e.valuesize() );
}
static void lookForTimestamps( const BSONObj& obj ){
// If have a Timestamp field as the first or second element,
// update it to a Date field set to OpTime::now().asDate(). The
// replacement policy is a work in progress.
BSONObjIterator i( obj );
for( int j = 0; i.more() && j < 2; ++j ) {
BSONElement e = i.next();
if ( e.eoo() )
break;
if ( e.type() == Timestamp ){
BSONElementManipulator( e ).initTimestamp();
break;
}
}
}
private:
char *data() { return nonConst( element_.rawdata() ); }
char *value() { return nonConst( element_.value() ); }
static char *nonConst( const char *s ) { return const_cast< char * >( s ); }
const BSONElement element_;
};
} // namespace mongo