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// bsonobjiterator.h
/* Copyright 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/>.
*
* 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 <boost/preprocessor/cat.hpp> // like the ## operator but works with __LINE__
#include "mongo/bson/bsonobj.h"
#include "mongo/base/disallow_copying.h"
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.
The BSONObj must stay in scope for the duration of the iterator's execution.
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 (MONGO_unlikely(sz == 0)) {
_pos = _theend = 0;
return;
}
_pos = jso.objdata() + 4;
_theend = jso.objdata() + sz - 1;
}
BSONObjIterator(const char* start, const char* end) {
_pos = start + 4;
_theend = end - 1;
}
/** @return true if more elements exist to be enumerated. */
bool more() {
return _pos < _theend;
}
/** @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) {
verify(_pos <= _theend);
int maxLen = -1;
if (checkEnd) {
maxLen = _theend + 1 - _pos;
verify(maxLen > 0);
}
BSONElement e(_pos, maxLen);
int esize = e.size(maxLen);
massert(16446, "BSONElement has bad size", esize > 0);
_pos += esize;
return e;
}
BSONElement next() {
verify(_pos <= _theend);
BSONElement e(_pos);
_pos += e.size();
return e;
}
void operator++() {
next();
}
void operator++(int) {
next();
}
BSONElement operator*() {
verify(_pos <= _theend);
return BSONElement(_pos);
}
private:
const char* _pos;
const char* _theend;
};
/** Base class implementing ordered iteration through BSONElements. */
class BSONIteratorSorted {
MONGO_DISALLOW_COPYING(BSONIteratorSorted);
public:
~BSONIteratorSorted() {
verify(_fields);
delete[] _fields;
_fields = 0;
}
bool more() {
return _cur < _nfields;
}
BSONElement next() {
verify(_fields);
if (_cur < _nfields)
return BSONElement(_fields[_cur++]);
return BSONElement();
}
protected:
class ElementFieldCmp;
BSONIteratorSorted(const BSONObj& o, const ElementFieldCmp& cmp);
private:
const char** _fields;
int _nfields;
int _cur;
};
/** Provides iteration of a BSONObj's BSONElements in lexical field order. */
class BSONObjIteratorSorted : public BSONIteratorSorted {
public:
BSONObjIteratorSorted(const BSONObj& object);
};
/**
* Provides iteration of a BSONArray's BSONElements in numeric field order.
* The elements of a bson array should always be numerically ordered by field name, but this
* implementation re-sorts them anyway.
*/
class BSONArrayIteratorSorted : public BSONIteratorSorted {
public:
BSONArrayIteratorSorted(const BSONArray& array);
};
/** 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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