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// checked_cast.h
/**
* Copyright (C) 2015 MongoDB 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 <memory>
#include "mongo/util/assert_util.h"
#include "mongo/util/debug_util.h"
namespace mongo {
/**
* Similar to static_cast, but in debug builds uses RTTI to confirm that the cast
* is legal at runtime.
*/
template <bool>
struct checked_cast_impl;
template <>
struct checked_cast_impl<false> {
template <typename T, typename U>
static T cast(const U& u) {
return static_cast<T>(u);
}
template <typename T, typename U>
static T cast(U& u) {
return static_cast<T>(u);
}
};
template <>
struct checked_cast_impl<true> {
template <typename T, typename U>
static T cast(U* u) {
if (!u) {
return NULL;
}
T t = dynamic_cast<T>(u);
invariant(t);
return t;
}
template <typename T, typename U>
static T cast(const U& u) {
return dynamic_cast<T>(u);
}
template <typename T, typename U>
static T cast(U& u) {
return dynamic_cast<T>(u);
}
};
template <typename T, typename U>
T checked_cast(const U& u) {
return checked_cast_impl<kDebugBuild>::cast<T>(u);
};
template <typename T, typename U>
T checked_cast(U& u) {
return checked_cast_impl<kDebugBuild>::cast<T>(u);
};
/**
* Similar to static_pointer_cast, but in debug builds uses RTTI to confirm that the cast
* is legal at runtime.
*/
template <bool>
struct checked_pointer_cast_impl;
template <>
struct checked_pointer_cast_impl<false> {
template <typename T, typename U>
static std::shared_ptr<T> cast(const std::shared_ptr<U>& u) {
return std::static_pointer_cast<T>(u);
}
};
template <>
struct checked_pointer_cast_impl<true> {
template <typename T, typename U>
static std::shared_ptr<T> cast(const std::shared_ptr<U>& u) {
if (!u) {
return nullptr;
}
std::shared_ptr<T> t = std::dynamic_pointer_cast<T>(u);
invariant(t);
return t;
}
};
template <typename T, typename U>
std::shared_ptr<T> checked_pointer_cast(const std::shared_ptr<U>& u) {
return checked_pointer_cast_impl<kDebugBuild>::cast<T>(u);
};
} // namespace mongo
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