AK+Everywhere: Reduce the number of template parameters of IntrusiveList

This makes the user-facing type only take the node member pointer, and
lets the compiler figure out the other needed types from that.

3 files changed, 67 insertions, 48 deletions

diff --git a/AK/IntrusiveList.h b/AK/IntrusiveList.h
index d7dc93c9b3..b485443980 100644
--- a/AK/IntrusiveList.h
+++ b/AK/IntrusiveList.h
@@ -13,29 +13,34 @@
 #include <AK/Noncopyable.h>
 #include <AK/StdLibExtras.h>
 
-namespace AK {
+namespace AK::Detail {
 
-namespace Detail {
 template<typename T, typename Container = RawPtr<T>>
 class IntrusiveListNode;
-}
+
+struct ExtractIntrusiveListTypes {
+    template<typename V, typename Container, typename T>
+    static V value(IntrusiveListNode<V, Container> T::*x);
+    template<typename V, typename Container, typename T>
+    static Container container(IntrusiveListNode<V, Container> T::*x);
+};
 
 template<typename T, typename Container = RawPtr<T>>
-using IntrusiveListNode = Detail::IntrusiveListNode<T, typename Detail::SubstituteIntrusiveContainerType<T, Container>::Type>;
+using SubstitutedIntrusiveListNode = IntrusiveListNode<T, typename Detail::SubstituteIntrusiveContainerType<T, Container>::Type>;
 
 template<typename T, typename Container>
 class IntrusiveListStorage {
 private:
-    friend class Detail::IntrusiveListNode<T, Container>;
+    friend class IntrusiveListNode<T, Container>;
 
-    template<class T_, typename Container_, IntrusiveListNode<T_, Container_> T_::*member>
+    template<class T_, typename Container_, SubstitutedIntrusiveListNode<T_, Container_> T_::*member>
     friend class IntrusiveList;
 
-    IntrusiveListNode<T, Container>* m_first { nullptr };
-    IntrusiveListNode<T, Container>* m_last { nullptr };
+    SubstitutedIntrusiveListNode<T, Container>* m_first { nullptr };
+    SubstitutedIntrusiveListNode<T, Container>* m_last { nullptr };
 };
 
-template<class T, typename Container, IntrusiveListNode<T, Container> T::*member>
+template<class T, typename Container, SubstitutedIntrusiveListNode<T, Container> T::*member>
 class IntrusiveList {
     AK_MAKE_NONCOPYABLE(IntrusiveList);
     AK_MAKE_NONMOVABLE(IntrusiveList);
@@ -144,12 +149,10 @@ private:
     static T* prev(T* current);
     static const T* next(const T* current);
     static const T* prev(const T* current);
-    static T* node_to_value(IntrusiveListNode<T, Container>& node);
+    static T* node_to_value(SubstitutedIntrusiveListNode<T, Container>& node);
     IntrusiveListStorage<T, Container> m_storage;
 };
 
-namespace Detail {
-
 template<typename T, typename Container>
 class IntrusiveListNode {
 public:
@@ -159,23 +162,21 @@ public:
 
     static constexpr bool IsRaw = IsPointer<Container>;
 
-    // Note: For some reason, clang does not consider `member` as declared here, and as declared above (`IntrusiveListNode<T, Container> T::*`)
+    // Note: For some reason, clang does not consider `member` as declared here, and as declared above (`SubstitutedIntrusiveListNode<T, Container> T::*`)
     //       to be of equal types. so for now, just make the members public on clang.
 #ifndef __clang__
 private:
-    template<class T_, typename Container_, IntrusiveListNode<T_, Container_> T_::*member>
-    friend class ::AK::IntrusiveList;
+    template<class T_, typename Container_, SubstitutedIntrusiveListNode<T_, Container_> T_::*member>
+    friend class ::AK::Detail::IntrusiveList;
 #endif
 
     IntrusiveListStorage<T, Container>* m_storage = nullptr;
-    IntrusiveListNode<T, Container>* m_next = nullptr;
-    IntrusiveListNode<T, Container>* m_prev = nullptr;
+    SubstitutedIntrusiveListNode<T, Container>* m_next = nullptr;
+    SubstitutedIntrusiveListNode<T, Container>* m_prev = nullptr;
     [[no_unique_address]] SelfReferenceIfNeeded<Container, IsRaw> m_self;
 };
 
-}
-
-template<class T, typename Container, IntrusiveListNode<T, Container> T::*member>
+template<class T, typename Container, SubstitutedIntrusiveListNode<T, Container> T::*member>
 inline typename IntrusiveList<T, Container, member>::Iterator& IntrusiveList<T, Container, member>::Iterator::erase()
 {
     auto old = m_value;
@@ -184,26 +185,26 @@ inline typename IntrusiveList<T, Container, member>::Iterator& IntrusiveList<T,
     return *this;
 }
 
-template<class T, typename Container, IntrusiveListNode<T, Container> T::*member>
+template<class T, typename Container, SubstitutedIntrusiveListNode<T, Container> T::*member>
 inline IntrusiveList<T, Container, member>::~IntrusiveList()
 {
     clear();
 }
 
-template<class T, typename Container, IntrusiveListNode<T, Container> T::*member>
+template<class T, typename Container, SubstitutedIntrusiveListNode<T, Container> T::*member>
 inline void IntrusiveList<T, Container, member>::clear()
 {
     while (m_storage.m_first)
         m_storage.m_first->remove();
 }
 
-template<class T, typename Container, IntrusiveListNode<T, Container> T::*member>
+template<class T, typename Container, SubstitutedIntrusiveListNode<T, Container> T::*member>
 inline bool IntrusiveList<T, Container, member>::is_empty() const
 {
     return m_storage.m_first == nullptr;
 }
 
-template<class T, typename Container, IntrusiveListNode<T, Container> T::*member>
+template<class T, typename Container, SubstitutedIntrusiveListNode<T, Container> T::*member>
 inline size_t IntrusiveList<T, Container, member>::size_slow() const
 {
     size_t size = 0;
@@ -214,7 +215,7 @@ inline size_t IntrusiveList<T, Container, member>::size_slow() const
     return size;
 }
 
-template<class T, typename Container, IntrusiveListNode<T, Container> T::*member>
+template<class T, typename Container, SubstitutedIntrusiveListNode<T, Container> T::*member>
 inline void IntrusiveList<T, Container, member>::append(T& n)
 {
     remove(n);
@@ -233,7 +234,7 @@ inline void IntrusiveList<T, Container, member>::append(T& n)
         m_storage.m_first = &nnode;
 }
 
-template<class T, typename Container, IntrusiveListNode<T, Container> T::*member>
+template<class T, typename Container, SubstitutedIntrusiveListNode<T, Container> T::*member>
 inline void IntrusiveList<T, Container, member>::prepend(T& n)
 {
     remove(n);
@@ -252,7 +253,7 @@ inline void IntrusiveList<T, Container, member>::prepend(T& n)
         m_storage.m_last = &nnode;
 }
 
-template<class T, typename Container, IntrusiveListNode<T, Container> T::*member>
+template<class T, typename Container, SubstitutedIntrusiveListNode<T, Container> T::*member>
 inline void IntrusiveList<T, Container, member>::insert_before(T& bn, T& n)
 {
     remove(n);
@@ -274,7 +275,7 @@ inline void IntrusiveList<T, Container, member>::insert_before(T& bn, T& n)
         new_node.m_self.reference = &n;
 }
 
-template<class T, typename Container, IntrusiveListNode<T, Container> T::*member>
+template<class T, typename Container, SubstitutedIntrusiveListNode<T, Container> T::*member>
 inline void IntrusiveList<T, Container, member>::remove(T& n)
 {
     auto& nnode = n.*member;
@@ -282,20 +283,20 @@ inline void IntrusiveList<T, Container, member>::remove(T& n)
         nnode.remove();
 }
 
-template<class T, typename Container, IntrusiveListNode<T, Container> T::*member>
+template<class T, typename Container, SubstitutedIntrusiveListNode<T, Container> T::*member>
 inline bool IntrusiveList<T, Container, member>::contains(const T& n) const
 {
     auto& nnode = n.*member;
     return nnode.m_storage == &m_storage;
 }
 
-template<class T, typename Container, IntrusiveListNode<T, Container> T::*member>
+template<class T, typename Container, SubstitutedIntrusiveListNode<T, Container> T::*member>
 inline Container IntrusiveList<T, Container, member>::first() const
 {
     return m_storage.m_first ? node_to_value(*m_storage.m_first) : nullptr;
 }
 
-template<class T, typename Container, IntrusiveListNode<T, Container> T::*member>
+template<class T, typename Container, SubstitutedIntrusiveListNode<T, Container> T::*member>
 inline Container IntrusiveList<T, Container, member>::take_first()
 {
     if (Container ptr = first()) {
@@ -305,7 +306,7 @@ inline Container IntrusiveList<T, Container, member>::take_first()
     return nullptr;
 }
 
-template<class T, typename Container, IntrusiveListNode<T, Container> T::*member>
+template<class T, typename Container, SubstitutedIntrusiveListNode<T, Container> T::*member>
 inline Container IntrusiveList<T, Container, member>::take_last()
 {
     if (Container ptr = last()) {
@@ -315,13 +316,13 @@ inline Container IntrusiveList<T, Container, member>::take_last()
     return nullptr;
 }
 
-template<class T, typename Container, IntrusiveListNode<T, Container> T::*member>
+template<class T, typename Container, SubstitutedIntrusiveListNode<T, Container> T::*member>
 inline Container IntrusiveList<T, Container, member>::last() const
 {
     return m_storage.m_last ? node_to_value(*m_storage.m_last) : nullptr;
 }
 
-template<class T, typename Container, IntrusiveListNode<T, Container> T::*member>
+template<class T, typename Container, SubstitutedIntrusiveListNode<T, Container> T::*member>
 inline const T* IntrusiveList<T, Container, member>::next(const T* current)
 {
     auto& nextnode = (current->*member).m_next;
@@ -329,7 +330,7 @@ inline const T* IntrusiveList<T, Container, member>::next(const T* current)
     return nextstruct;
 }
 
-template<class T, typename Container, IntrusiveListNode<T, Container> T::*member>
+template<class T, typename Container, SubstitutedIntrusiveListNode<T, Container> T::*member>
 inline const T* IntrusiveList<T, Container, member>::prev(const T* current)
 {
     auto& prevnode = (current->*member).m_prev;
@@ -337,7 +338,7 @@ inline const T* IntrusiveList<T, Container, member>::prev(const T* current)
     return prevstruct;
 }
 
-template<class T, typename Container, IntrusiveListNode<T, Container> T::*member>
+template<class T, typename Container, SubstitutedIntrusiveListNode<T, Container> T::*member>
 inline T* IntrusiveList<T, Container, member>::next(T* current)
 {
     auto& nextnode = (current->*member).m_next;
@@ -345,7 +346,7 @@ inline T* IntrusiveList<T, Container, member>::next(T* current)
     return nextstruct;
 }
 
-template<class T, typename Container, IntrusiveListNode<T, Container> T::*member>
+template<class T, typename Container, SubstitutedIntrusiveListNode<T, Container> T::*member>
 inline T* IntrusiveList<T, Container, member>::prev(T* current)
 {
     auto& prevnode = (current->*member).m_prev;
@@ -353,26 +354,26 @@ inline T* IntrusiveList<T, Container, member>::prev(T* current)
     return prevstruct;
 }
 
-template<class T, typename Container, IntrusiveListNode<T, Container> T::*member>
+template<class T, typename Container, SubstitutedIntrusiveListNode<T, Container> T::*member>
 inline typename IntrusiveList<T, Container, member>::Iterator IntrusiveList<T, Container, member>::begin()
 {
     return m_storage.m_first ? Iterator(node_to_value(*m_storage.m_first)) : Iterator();
 }
 
-template<class T, typename Container, IntrusiveListNode<T, Container> T::*member>
+template<class T, typename Container, SubstitutedIntrusiveListNode<T, Container> T::*member>
 inline typename IntrusiveList<T, Container, member>::ReverseIterator IntrusiveList<T, Container, member>::rbegin()
 {
     return m_storage.m_last ? ReverseIterator(node_to_value(*m_storage.m_last)) : ReverseIterator();
 }
 
-template<class T, typename Container, IntrusiveListNode<T, Container> T::*member>
+template<class T, typename Container, SubstitutedIntrusiveListNode<T, Container> T::*member>
 inline typename IntrusiveList<T, Container, member>::ConstIterator IntrusiveList<T, Container, member>::begin() const
 {
     return m_storage.m_first ? ConstIterator(node_to_value(*m_storage.m_first)) : ConstIterator();
 }
 
-template<class T, typename Container, IntrusiveListNode<T, Container> T::*member>
-inline T* IntrusiveList<T, Container, member>::node_to_value(IntrusiveListNode<T, Container>& node)
+template<class T, typename Container, SubstitutedIntrusiveListNode<T, Container> T::*member>
+inline T* IntrusiveList<T, Container, member>::node_to_value(SubstitutedIntrusiveListNode<T, Container>& node)
 {
     // Note: Since this might seem odd, here's an explanation on what this function actually does:
     //       `node` is a reference that resides in some part of the actual value (of type T), the
@@ -383,8 +384,6 @@ inline T* IntrusiveList<T, Container, member>::node_to_value(IntrusiveListNode<T
     return bit_cast<T*>(bit_cast<unsigned char*>(&node) - bit_cast<unsigned char*>(member));
 }
 
-namespace Detail {
-
 template<typename T, typename Container>
 inline IntrusiveListNode<T, Container>::~IntrusiveListNode()
 {
@@ -416,13 +415,11 @@ inline bool IntrusiveListNode<T, Container>::is_in_list() const
     return m_storage != nullptr;
 }
 
-}
-
 // Specialise IntrusiveList for NonnullRefPtr
 // By default, intrusive lists cannot contain null entries anyway, so switch to RefPtr
 // and just make the user-facing functions deref the pointers.
 
-template<class T, IntrusiveListNode<T, NonnullRefPtr<T>> T::*member>
+template<class T, SubstitutedIntrusiveListNode<T, NonnullRefPtr<T>> T::*member>
 class IntrusiveList<T, NonnullRefPtr<T>, member> : public IntrusiveList<T, RefPtr<T>, member> {
 public:
     [[nodiscard]] NonnullRefPtr<T> first() const { return *IntrusiveList<T, RefPtr<T>, member>::first(); }
@@ -434,5 +431,18 @@ public:
 
 }
 
+namespace AK {
+
+template<typename T, typename Container = RawPtr<T>>
+using IntrusiveListNode = Detail::SubstitutedIntrusiveListNode<T, Container>;
+
+template<auto member>
+using IntrusiveList = Detail::IntrusiveList<
+    decltype(Detail::ExtractIntrusiveListTypes::value(member)),
+    decltype(Detail::ExtractIntrusiveListTypes::container(member)),
+    member>;
+
+}
+
 using AK::IntrusiveList;
 using AK::IntrusiveListNode;
diff --git a/AK/IntrusiveListRelaxedConst.h b/AK/IntrusiveListRelaxedConst.h
index 9c431972e0..da94b1cc00 100644
--- a/AK/IntrusiveListRelaxedConst.h
+++ b/AK/IntrusiveListRelaxedConst.h
@@ -9,6 +9,7 @@
 #include <AK/IntrusiveList.h>
 
 namespace AK {
+namespace Detail {
 
 template<class T, typename Container, IntrusiveListNode<T, Container> T::*member>
 class IntrusiveListRelaxedConst : public IntrusiveList<T, Container, member> {
@@ -26,4 +27,12 @@ public:
 
 }
 
+template<auto member>
+using IntrusiveListRelaxedConst = Detail::IntrusiveListRelaxedConst<
+    decltype(Detail::ExtractIntrusiveListTypes::value(member)),
+    decltype(Detail::ExtractIntrusiveListTypes::container(member)),
+    member>;
+
+}
+
 using AK::IntrusiveListRelaxedConst;
diff --git a/AK/Queue.h b/AK/Queue.h
index c87750a879..448856a665 100644
--- a/AK/Queue.h
+++ b/AK/Queue.h
@@ -76,7 +76,7 @@ private:
         IntrusiveListNode<QueueSegment> node;
     };
 
-    IntrusiveList<QueueSegment, RawPtr<QueueSegment>, &QueueSegment::node> m_segments;
+    IntrusiveList<&QueueSegment::node> m_segments;
     size_t m_index_into_first { 0 };
     size_t m_size { 0 };
 };