245 lines
8.5 KiB
C++
245 lines
8.5 KiB
C++
/* Copyright (c) 2013, 2024, Oracle and/or its affiliates.
|
|
|
|
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 designed to work 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 either included with
|
|
the program or referenced in the documentation.
|
|
|
|
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 <assert.h>
|
|
#include <ctype.h>
|
|
#include <stddef.h>
|
|
#include <algorithm>
|
|
#include <iterator>
|
|
#include <optional>
|
|
#include <type_traits>
|
|
|
|
/**
|
|
@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>
|
|
constexpr T pointer_cast(void *p) {
|
|
return static_cast<T>(p);
|
|
}
|
|
|
|
template <typename T>
|
|
constexpr 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) {
|
|
static_assert(
|
|
!std::is_base_of<typename std::remove_pointer<Target>::type,
|
|
Source>::value,
|
|
"Do not use down_cast for upcasts; use implicit_cast or nothing");
|
|
assert(nullptr != 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.
|
|
static_assert(
|
|
!std::is_base_of<typename std::remove_reference<Target>::type,
|
|
Source>::value,
|
|
"Do not use down_cast for upcasts; use implicit_cast or nothing");
|
|
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 occurred. */
|
|
bool error;
|
|
};
|
|
|
|
/**
|
|
Number of elements in a constant C array.
|
|
*/
|
|
template <class T, size_t N>
|
|
constexpr size_t array_elements(T (&)[N]) noexcept {
|
|
return N;
|
|
}
|
|
|
|
namespace myu {
|
|
/**
|
|
Split a range into sub ranges delimited by elements satisfying a predicate.
|
|
Examines the elements from first to last, exclusive. Each time an element
|
|
which satisfies the splitting predicate is encountered, the action argument's
|
|
operator() is invoked with the starting and past-the-end iterators for the
|
|
current sub-range, even if this is empty. When iteration is complete, action()
|
|
is called on the range between the start of the last subrange and last.
|
|
|
|
It must be possible to pass a single element with type const
|
|
InputIt::value_type to is_split_element. It must be possible to pass two
|
|
InputIt arguments to action.
|
|
|
|
@param first Beginning of the range to split.
|
|
@param last End of the range to split.
|
|
@param pred Callable which will be invoked on each element in
|
|
turn to determine if it is a splitting element.
|
|
@param action Callable which will be invoked with the beginning
|
|
and one-past-the-end iterators for each subrange.
|
|
*/
|
|
template <class InputIt, class Pred, class Action>
|
|
inline void Split(InputIt first, InputIt last, Pred &&pred, Action &&action) {
|
|
while (first != last) {
|
|
InputIt split = std::find_if(first, last, std::forward<Pred>(pred));
|
|
action(first, split); // Called even for empty subranges, action must
|
|
// discard if not wanted
|
|
if (split == last) return;
|
|
first = split + 1;
|
|
}
|
|
}
|
|
|
|
/**
|
|
Search backwards for the first occurrence of an element which does not satisfy
|
|
the trimming predicate, and return an InputIt to the element after it.
|
|
|
|
@param first Beginning of the range to search.
|
|
@param last End of the range to search.
|
|
@param pred Callable which can be applied to a dereferenced InputIt and which
|
|
returns true if the element should be trimmed.
|
|
|
|
@returns InputIt referencing the first element of sub range satisfying the
|
|
trimming predicate at the end of the range. last if no elements
|
|
satisfy the trimming predicate.
|
|
*/
|
|
template <class InputIt, class Pred>
|
|
inline InputIt FindTrimmedEnd(InputIt first, InputIt last, Pred &&pred) {
|
|
return std::find_if_not(std::make_reverse_iterator(last),
|
|
std::make_reverse_iterator(first),
|
|
std::forward<Pred>(pred))
|
|
.base();
|
|
}
|
|
|
|
/**
|
|
Searches for a sub range such that no elements before or after fail to
|
|
satisfy the trimming predicate.
|
|
|
|
@param first Beginning of the range to search.
|
|
@param last End of the range to search.
|
|
@param pred Callable which can be applied to a dereferenced InputIt and which
|
|
returns true if the element should be trimmed.
|
|
|
|
@returns Pair of iterators denoting the sub range which does not include the
|
|
leading and trailing sub ranges matching the trimming predicate.
|
|
{last, last} if all elements match the trimming predicate.
|
|
*/
|
|
template <class InputIt, class Pred>
|
|
inline std::pair<InputIt, InputIt> FindTrimmedRange(InputIt first, InputIt last,
|
|
Pred &&pred) {
|
|
InputIt f = std::find_if_not(first, last, std::forward<Pred>(pred));
|
|
return {f, FindTrimmedEnd(f, last, std::forward<Pred>(pred))};
|
|
}
|
|
|
|
/** Convenience lambdas for common predicates. */
|
|
const auto IsSpace = [](char c) { return isspace(c); };
|
|
const auto IsComma = [](char c) { return c == ','; };
|
|
|
|
} // namespace myu
|
|
#endif // TEMPLATE_UTILS_INCLUDED
|