bsonobjiterator.h

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/*    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 bson {

    class BSONObjIterator {
    public:
        BSONObjIterator(const BSONObj& jso) {
            int sz = jso.objsize();
            if ( sz == 0 ) {
                _pos = _theend = 0;
                return;
            }
            _pos = jso.objdata() + 4;
            _theend = jso.objdata() + sz - 1;
        }

        BSONObjIterator() {
            _pos    = NULL ;
            _theend = NULL ;
        }

        BSONObjIterator( const char * start , const char * end ) {
            _pos = start + 4;
            _theend = end - 1;
        }

        bool more() { return _pos < _theend; }

        bool moreWithEOO() { return _pos <= _theend; }

        BSONElement next( bool checkEnd ) {
            assert( _pos <= _theend );
            BSONElement e( _pos, checkEnd ? (int)(_theend + 1 - _pos) : -1 );
            _pos += e.size( checkEnd ? (int)(_theend + 1 - _pos) : -1 );
            return e;
        }
        BSONElement next() {
            assert( _pos <= _theend );
            BSONElement e(_pos);
            _pos += e.size();
            return e;
        }
        void operator++() { next(); }
        void operator++(int) { next(); }

        BSONElement operator*() {
            assert( _pos <= _theend );
            return BSONElement(_pos);
        }

    private:
        const char* _pos;
        const char* _theend;
    };

#define BSONOBJITERSORTED_DFTFIELDS 100
    class BSONObjIteratorSorted {
    public:
        BSONObjIteratorSorted( const BSONObj& o );

        ~BSONObjIteratorSorted() {
            assert( _fields );
            if ( _fields != &_staticFields[0] )
               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;
        const char *_staticFields[BSONOBJITERSORTED_DFTFIELDS] ;
        int _nfields;
        int _cur;
    };

/*#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) ; ) */
}