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// bsonobjiterator.h
/* Copyright 2009 10gen Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#pragma once
#include <boost/preprocessor/cat.hpp> // like the ## operator but works with __LINE__
namespace mongo {
/** iterator for a BSONObj
Note each BSONObj ends with an EOO element: so you will get more() on an empty
object, although next().eoo() will be true.
todo: we may want to make a more stl-like iterator interface for this
with things like begin() and end()
*/
class BSONObjIterator {
public:
/** Create an iterator for a BSON object.
*/
BSONObjIterator(const BSONObj& jso) {
int sz = jso.objsize();
if ( sz == 0 ) {
_pos = _theend = 0;
return;
}
_pos = jso.objdata() + 4;
_theend = jso.objdata() + sz;
}
BSONObjIterator( const char * start , const char * end ) {
_pos = start + 4;
_theend = end;
}
/** @return true if more elements exist to be enumerated. */
bool more() { return _pos < _theend && _pos[0]; }
/** @return true if more elements exist to be enumerated INCLUDING the EOO element which is always at the end. */
bool moreWithEOO() { return _pos < _theend; }
/** @return the next element in the object. For the final element, element.eoo() will be true. */
BSONElement next( bool checkEnd = false ) {
assert( _pos < _theend );
BSONElement e( _pos, checkEnd ? (int)(_theend - _pos) : -1 );
_pos += e.size( checkEnd ? (int)(_theend - _pos) : -1 );
return e;
}
void operator++() { next(); }
void operator++(int) { next(); }
BSONElement operator*() {
assert( _pos < _theend );
return BSONElement(_pos, -1);
}
private:
const char* _pos;
const char* _theend;
};
class BSONObjIteratorSorted {
public:
BSONObjIteratorSorted( const BSONObj& o );
~BSONObjIteratorSorted() {
assert( _fields );
delete[] _fields;
_fields = 0;
}
bool more() {
return _cur < _nfields;
}
BSONElement next() {
assert( _fields );
if ( _cur < _nfields )
return BSONElement( _fields[_cur++] );
return BSONElement();
}
private:
const char ** _fields;
int _nfields;
int _cur;
};
/** Similar to BOOST_FOREACH
*
* because the iterator is defined outside of the for, you must use {} around
* the surrounding scope. Don't do this:
*
* if (foo)
* BSONForEach(e, obj)
* doSomething(e);
*
* but this is OK:
*
* if (foo) {
* BSONForEach(e, obj)
* doSomething(e);
* }
*
*/
#define BSONForEach(e, obj) \
BSONObjIterator BOOST_PP_CAT(it_,__LINE__)(obj); \
for ( BSONElement e; \
(BOOST_PP_CAT(it_,__LINE__).more() ? \
(e = BOOST_PP_CAT(it_,__LINE__).next(), true) : \
false) ; \
/*nothing*/ )
}
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