You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
147 lines
4.5 KiB
147 lines
4.5 KiB
/* Copyright (c) 2013, 2019, Oracle and/or its affiliates. All rights reserved.
|
|
|
|
This program is free software; you can redistribute it and/or modify
|
|
it under the terms of the GNU General Public License, version 2.0,
|
|
as published by the Free Software Foundation.
|
|
|
|
This program is also distributed with certain software (including
|
|
but not limited to OpenSSL) that is licensed under separate terms,
|
|
as designated in a particular file or component or in included license
|
|
documentation. The authors of MySQL hereby grant you an additional
|
|
permission to link the program and your derivative works with the
|
|
separately licensed software that they have included with MySQL.
|
|
|
|
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 General Public License, version 2.0, for more details.
|
|
|
|
You should have received a copy of the GNU General Public License
|
|
along with this program; if not, write to the Free Software
|
|
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA */
|
|
|
|
#ifndef TEMPLATE_UTILS_INCLUDED
|
|
#define TEMPLATE_UTILS_INCLUDED
|
|
|
|
#include <stddef.h>
|
|
|
|
#include "my_dbug.h"
|
|
|
|
/**
|
|
@file include/template_utils.h
|
|
*/
|
|
|
|
/**
|
|
Clears a container, but deletes all objects that the elements point to first.
|
|
@tparam Container_type Container of pointers.
|
|
*/
|
|
template <typename Container_type>
|
|
void delete_container_pointers(Container_type &container) {
|
|
typename Container_type::iterator it1 = container.begin();
|
|
typename Container_type::iterator it2 = container.end();
|
|
for (; it1 != it2; ++it1) {
|
|
delete (*it1);
|
|
}
|
|
container.clear();
|
|
}
|
|
|
|
/**
|
|
Clears a container, but frees all objects that the elements point to first.
|
|
@tparam Container_type Container of pointers.
|
|
*/
|
|
template <typename Container_type>
|
|
void my_free_container_pointers(Container_type &container) {
|
|
typename Container_type::iterator it1 = container.begin();
|
|
typename Container_type::iterator it2 = container.end();
|
|
for (; it1 != it2; ++it1) {
|
|
my_free(*it1);
|
|
}
|
|
container.clear();
|
|
}
|
|
|
|
/**
|
|
Casts from one pointer type, to another, without using
|
|
reinterpret_cast or C-style cast:
|
|
foo *f; bar *b= pointer_cast<bar*>(f);
|
|
This avoids having to do:
|
|
foo *f; bar *b= static_cast<bar*>(static_cast<void*>(f));
|
|
*/
|
|
template <typename T>
|
|
inline T pointer_cast(void *p) {
|
|
return static_cast<T>(p);
|
|
}
|
|
|
|
template <typename T>
|
|
inline const T pointer_cast(const void *p) {
|
|
return static_cast<T>(p);
|
|
}
|
|
|
|
/**
|
|
Casts from one pointer type to another in a type hierarchy.
|
|
In debug mode, we verify the cast is indeed legal.
|
|
|
|
@tparam Target The descendent type, must be a pointer type.
|
|
@tparam Source The parent type.
|
|
|
|
@param arg The pointer to be down-cast.
|
|
|
|
@return A pointer of type Target.
|
|
*/
|
|
template <typename Target, typename Source>
|
|
inline Target down_cast(Source *arg) {
|
|
DBUG_ASSERT(NULL != dynamic_cast<Target>(arg));
|
|
return static_cast<Target>(arg);
|
|
}
|
|
|
|
/**
|
|
Casts from one reference type to another in a type hierarchy.
|
|
In debug mode, we verify the cast is indeed legal.
|
|
|
|
@tparam Target The descendent type, must be a reference type.
|
|
@tparam Source The parent type.
|
|
|
|
@param arg The reference to be down-cast.
|
|
|
|
@return A reference of type Target.
|
|
*/
|
|
template <typename Target, typename Source>
|
|
inline Target down_cast(Source &arg) {
|
|
// We still use the pointer version of dynamic_cast, as the
|
|
// reference-accepting version throws exceptions, and we don't want to deal
|
|
// with that.
|
|
DBUG_ASSERT(dynamic_cast<typename std::remove_reference<Target>::type *>(
|
|
&arg) != nullptr);
|
|
return static_cast<Target>(arg);
|
|
}
|
|
|
|
/**
|
|
Sometimes the compiler insists that types be the same and does not do any
|
|
implicit conversion. For example:
|
|
Derived1 *a;
|
|
Derived2 *b; // Derived1 and 2 are children classes of Base
|
|
Base *x= cond ? a : b; // Error, need to force a cast.
|
|
|
|
Use:
|
|
Base *x= cond ? implicit_cast<Base*>(a) : implicit_cast<Base*>(b);
|
|
static_cast would work too, but would be less safe (allows any
|
|
pointer-to-pointer conversion, not only up-casts).
|
|
*/
|
|
template <typename To>
|
|
inline To implicit_cast(To x) {
|
|
return x;
|
|
}
|
|
|
|
/**
|
|
Utility to allow returning values from functions which can fail
|
|
(until we have std::optional).
|
|
*/
|
|
template <class VALUE_TYPE>
|
|
struct ReturnValueOrError {
|
|
/** Value returned from function in the normal case. */
|
|
VALUE_TYPE value;
|
|
|
|
/** True if an error occured. */
|
|
bool error;
|
|
};
|
|
|
|
#endif // TEMPLATE_UTILS_INCLUDED
|
|
|