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// projection.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 "pch.h"
#include "jsobj.h"
namespace mongo {
/**
used for doing field limiting
*/
class FieldMatcher {
public:
FieldMatcher()
: _include(true)
, _special(false)
, _includeID(true)
, _skip(0)
, _limit(-1)
{}
/**
* called once per lifetime
*/
void init( const BSONObj& spec );
/**
* @return the spec init was called with
*/
BSONObj getSpec() const { return _source; }
/**
* appends e to b if user wants it
* will descend into e if needed
*/
void append( BSONObjBuilder& b , const BSONElement& e ) const;
/**
* transforms in according to spec
* NOTE: this will stricy obey _id, which is not true
* for normal queries
*/
BSONObj transform( const BSONObj& in ) const;
/**
* @return if _id should be returned
*/
bool includeID() { return _includeID; }
private:
void add( const string& field, bool include );
void add( const string& field, int skip, int limit );
void appendArray( BSONObjBuilder& b , const BSONObj& a , bool nested=false) const;
bool _include; // true if default at this level is to include
bool _special; // true if this level can't be skipped or included without recursing
//TODO: benchmark vector<pair> vs map
typedef map<string, boost::shared_ptr<FieldMatcher> > FieldMap;
FieldMap _fields;
BSONObj _source;
bool _includeID;
// used for $slice operator
int _skip;
int _limit;
};
}
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