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/**
* Copyright (C) 2018-present MongoDB, Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the Server Side Public License, version 1,
* as published by MongoDB, Inc.
*
* 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
* Server Side Public License for more details.
*
* You should have received a copy of the Server Side Public License
* along with this program. If not, see
* <http://www.mongodb.com/licensing/server-side-public-license>.
*
* 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 Server Side 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 <string>
#include <boost/optional.hpp>
#include "mongo/bson/bsonobj.h"
namespace mongo {
/**
* A BSONField holds the name and the type intended for a given BSON element. The
* class helps documenting and enforcing that field's type.
*
* Example usages:
*
* In a header file:
* // Determines the types for the fields used in a collection.
* static const std::string MyColl;
* struct MyCollFields {
* static BSONField<std::string> name;
* static BSONField<bool> draining;
* static BSONField<int> count;
* };
*
* In a cpp file:
* const std::string MyColl = "my_collection_name";
*
* // determines the names used for the fields
* BSONField<std::string> MyCollFields::name("_id");
* BSONField<bool> MyCollFields::draining("draining");
* BSONField<int> MyCollFields::count("count");
*
* // Use BSONField::operator()(const T&) to instantiate a typed element for the field:
* BSONObj obj = BSON(MyCollFields::name("id_for_this_doc") <<
* MyCollFields::draining(true) <<
* MyCollFields::count(0));
*
* // Use BSONField::gt() and friends to construct a basic query predicate over the field:
* BSONObj obj = BSON(MyCollFields::count.gt(10));
*
* // Use BSONField::operator()() to retrieve the name of the field:
* BSONObj obj = BSON(MyCollFields::draining() << 1);
*/
template <typename T>
class BSONFieldValue {
public:
BSONFieldValue(const std::string& name, const T& t) : _name(name), _t(t) {}
const T& value() const {
return _t;
}
const std::string& name() const {
return _name;
}
private:
std::string _name;
T _t;
};
template <typename T>
class BSONField {
public:
BSONField(const std::string& name) : _name(name) {}
BSONField(const std::string& name, const T& defaultVal) : _name(name), _default(defaultVal) {}
BSONFieldValue<T> make(const T& t) const {
return BSONFieldValue<T>(_name, t);
}
BSONFieldValue<T> operator()(const T& t) const {
return BSONFieldValue<T>(_name, t);
}
const std::string& name() const {
return _name;
}
const T& getDefault() const {
return *_default;
}
bool hasDefault() const {
return bool(_default);
}
std::string operator()() const {
return _name;
}
BSONFieldValue<BSONObj> query(const char* q, const T& t) const;
BSONFieldValue<BSONObj> gt(const T& t) const {
return query("$gt", t);
}
BSONFieldValue<BSONObj> lt(const T& t) const {
return query("$lt", t);
}
BSONFieldValue<BSONObj> ne(const T& t) const {
return query("$ne", t);
}
private:
std::string _name;
boost::optional<T> _default;
};
} // namespace mongo
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