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util/IntrusiveList: add type alias "Hook"

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By casting to SafeLinkIntrusiveListHook if appropriate, this fixes a
bug in the erase() method, where erase() calls
IntrusiveListHook::unlink() instead of
SafeLinkIntrusiveListHook::unlink().
This commit is contained in:
Max Kellermann
2021-02-25 13:43:33 +01:00
parent f5f296b13a
commit a6eb264770
1 changed files with 24 additions and 10 deletions
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34
src/util/IntrusiveList.hxx
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@@ -99,28 +99,42 @@ public:
template<typename T> template<typename T>
class IntrusiveList { class IntrusiveList {
/**
* Detect the hook type; this is important because
* SafeLinkIntrusiveListHook::unlink() needs to clear the
* "next" pointer. This is a template to postpone the type
* checks, to allow forward-declared types.
*/
template<typename U>
struct HookDetection {
static_assert(std::is_base_of_v<IntrusiveListHook, U>);
using type = std::conditional_t<std::is_base_of_v<SafeLinkIntrusiveListHook, U>,
SafeLinkIntrusiveListHook,
IntrusiveListHook>;
};
template<typename U>
using Hook = typename HookDetection<U>::type;
IntrusiveListNode head{&head, &head}; IntrusiveListNode head{&head, &head};
static constexpr T *Cast(IntrusiveListNode *node) noexcept { static constexpr T *Cast(IntrusiveListNode *node) noexcept {
static_assert(std::is_base_of<IntrusiveListHook, T>::value); auto *hook = &Hook<T>::Cast(*node);
auto *hook = &IntrusiveListHook::Cast(*node);
return static_cast<T *>(hook); return static_cast<T *>(hook);
} }
static constexpr const T *Cast(const IntrusiveListNode *node) noexcept { static constexpr const T *Cast(const IntrusiveListNode *node) noexcept {
static_assert(std::is_base_of<IntrusiveListHook, T>::value); const auto *hook = &Hook<T>::Cast(*node);
const auto *hook = &IntrusiveListHook::Cast(*node);
return static_cast<const T *>(hook); return static_cast<const T *>(hook);
} }
static constexpr IntrusiveListHook &ToHook(T &t) noexcept { static constexpr auto &ToHook(T &t) noexcept {
static_assert(std::is_base_of<IntrusiveListHook, T>::value); return static_cast<Hook<T> &>(t);
return t;
} }
static constexpr const IntrusiveListHook &ToHook(const T &t) noexcept { static constexpr const auto &ToHook(const T &t) noexcept {
static_assert(std::is_base_of<IntrusiveListHook, T>::value); return static_cast<const Hook<T> &>(t);
return t;
} }
static constexpr IntrusiveListNode &ToNode(T &t) noexcept { static constexpr IntrusiveListNode &ToNode(T &t) noexcept {