// replacement does not provide a constant time size() method, so be careful to
// use empty() when you really want to know if it's empty.
//
-// The ilist class is implemented by allocating a 'tail' node when the list is
-// created (using ilist_traits<>::createSentinel()). This tail node is
-// absolutely required because the user must be able to compute end()-1. Because
-// of this, users of the direct next/prev links will see an extra link on the
-// end of the list, which should be ignored.
+// The ilist class is implemented as a circular list. The list itself contains
+// a sentinel node, whose Next points at begin() and whose Prev points at
+// rbegin(). The sentinel node itself serves as end() and rend().
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_ADT_ILIST_H
#define LLVM_ADT_ILIST_H
+#include "llvm/ADT/ilist_node.h"
#include "llvm/Support/Compiler.h"
#include <algorithm>
#include <cassert>
template<typename NodeTy, typename Traits> class iplist;
template<typename NodeTy> class ilist_iterator;
-/// An access class for next/prev on ilist_nodes.
+/// An access class for ilist_node private API.
///
/// This gives access to the private parts of ilist nodes. Nodes for an ilist
/// should friend this class if they inherit privately from ilist_node.
///
-/// It's strongly discouraged to *use* this class outside of ilist
+/// It's strongly discouraged to *use* this class outside of the ilist
/// implementation.
struct ilist_node_access {
- template <typename NodeTy> static NodeTy *getPrev(NodeTy *N) {
+ template <typename T> static ilist_node<T> *getNodePtr(T *N) { return N; }
+ template <typename T> static const ilist_node<T> *getNodePtr(const T *N) {
+ return N;
+ }
+
+ template <typename T> static ilist_node<T> *getPrev(ilist_node<T> *N) {
return N->getPrev();
}
- template <typename NodeTy> static NodeTy *getNext(NodeTy *N) {
+ template <typename T> static ilist_node<T> *getNext(ilist_node<T> *N) {
return N->getNext();
}
- template <typename NodeTy> static const NodeTy *getPrev(const NodeTy *N) {
+ template <typename T> static const ilist_node<T> *getPrev(const ilist_node<T> *N) {
return N->getPrev();
}
- template <typename NodeTy> static const NodeTy *getNext(const NodeTy *N) {
+ template <typename T> static const ilist_node<T> *getNext(const ilist_node<T> *N) {
return N->getNext();
}
- template <typename NodeTy> static void setPrev(NodeTy *N, NodeTy *Prev) {
+ template <typename T> static void setPrev(ilist_node<T> *N, ilist_node<T> *Prev) {
N->setPrev(Prev);
}
- template <typename NodeTy> static void setNext(NodeTy *N, NodeTy *Next) {
+ template <typename T> static void setNext(ilist_node<T> *N, ilist_node<T> *Next) {
N->setNext(Next);
}
- template <typename NodeTy> static void setPrev(NodeTy *N, std::nullptr_t) {
+ template <typename T> static void setPrev(ilist_node<T> *N, std::nullptr_t) {
N->setPrev(nullptr);
}
- template <typename NodeTy> static void setNext(NodeTy *N, std::nullptr_t) {
+ template <typename T> static void setNext(ilist_node<T> *N, std::nullptr_t) {
N->setNext(nullptr);
}
};
static const bool value = sizeof(test<TraitsT>(nullptr)) == sizeof(Yes);
};
-template <class TraitsT, class NodeT> struct HasObsoleteCustomization {
- static const bool value = HasGetNext<TraitsT, NodeT>::value;
-};
-
-} // end namespace ilist_detail
-
-template<typename NodeTy>
-struct ilist_traits;
-
-/// ilist_sentinel_traits - A fragment for template traits for intrusive list
-/// that provides default sentinel implementations for common operations.
-///
-/// ilist_sentinel_traits implements a lazy dynamic sentinel allocation
-/// strategy. The sentinel is stored in the prev field of ilist's Head.
-///
-template<typename NodeTy>
-struct ilist_sentinel_traits {
- /// createSentinel - create the dynamic sentinel
- static NodeTy *createSentinel() { return new NodeTy(); }
-
- /// destroySentinel - deallocate the dynamic sentinel
- static void destroySentinel(NodeTy *N) { delete N; }
-
- /// provideInitialHead - when constructing an ilist, provide a starting
- /// value for its Head
- /// @return null node to indicate that it needs to be allocated later
- static NodeTy *provideInitialHead() { return nullptr; }
-
- /// ensureHead - make sure that Head is either already
- /// initialized or assigned a fresh sentinel
- /// @return the sentinel
- static NodeTy *ensureHead(NodeTy *&Head) {
- if (!Head) {
- Head = ilist_traits<NodeTy>::createSentinel();
- ilist_traits<NodeTy>::noteHead(Head, Head);
- ilist_node_access::setNext(Head, nullptr);
- return Head;
- }
- return ilist_node_access::getPrev(Head);
- }
-
- /// noteHead - stash the sentinel into its default location
- static void noteHead(NodeTy *NewHead, NodeTy *Sentinel) {
- ilist_node_access::setPrev(NewHead, Sentinel);
- }
-};
-
-template <typename NodeTy> class ilist_half_node;
-template <typename NodeTy> class ilist_node;
+/// Type trait to check for a traits class that has a createSentinel member (as
+/// a canary for any of the ilist_sentinel_traits API).
+template <class TraitsT> struct HasCreateSentinel {
+ typedef char Yes[1];
+ typedef char No[2];
-/// Traits with an embedded ilist_node as a sentinel.
-template <typename NodeTy> struct ilist_embedded_sentinel_traits {
- /// Get hold of the node that marks the end of the list.
- ///
- /// FIXME: This downcast is UB. See llvm.org/PR26753.
- LLVM_NO_SANITIZE("object-size")
- NodeTy *createSentinel() const {
- // Since i(p)lists always publicly derive from their corresponding traits,
- // placing a data member in this class will augment the i(p)list. But since
- // the NodeTy is expected to be publicly derive from ilist_node<NodeTy>,
- // there is a legal viable downcast from it to NodeTy. We use this trick to
- // superimpose an i(p)list with a "ghostly" NodeTy, which becomes the
- // sentinel. Dereferencing the sentinel is forbidden (save the
- // ilist_node<NodeTy>), so no one will ever notice the superposition.
- return static_cast<NodeTy *>(&Sentinel);
- }
- static void destroySentinel(NodeTy *) {}
-
- NodeTy *provideInitialHead() const { return createSentinel(); }
- NodeTy *ensureHead(NodeTy *) const { return createSentinel(); }
- static void noteHead(NodeTy *, NodeTy *) {}
+ template <class U>
+ static Yes &test(U *I, decltype(I->createSentinel()) * = 0);
+ template <class> static No &test(...);
-private:
- mutable ilist_node<NodeTy> Sentinel;
+public:
+ static const bool value = sizeof(test<TraitsT>(nullptr)) == sizeof(Yes);
};
-/// Trait with an embedded ilist_half_node as a sentinel.
-template <typename NodeTy> struct ilist_half_embedded_sentinel_traits {
- /// Get hold of the node that marks the end of the list.
- ///
- /// FIXME: This downcast is UB. See llvm.org/PR26753.
- LLVM_NO_SANITIZE("object-size")
- NodeTy *createSentinel() const {
- // See comment in ilist_embedded_sentinel_traits::createSentinel().
- return static_cast<NodeTy *>(&Sentinel);
- }
- static void destroySentinel(NodeTy *) {}
-
- NodeTy *provideInitialHead() const { return createSentinel(); }
- NodeTy *ensureHead(NodeTy *) const { return createSentinel(); }
- static void noteHead(NodeTy *, NodeTy *) {}
-
-private:
- mutable ilist_half_node<NodeTy> Sentinel;
+template <class TraitsT, class NodeT> struct HasObsoleteCustomization {
+ static const bool value =
+ HasGetNext<TraitsT, NodeT>::value || HasCreateSentinel<TraitsT>::value;
};
-/// Traits with an embedded full node as a sentinel.
-template <typename NodeTy> struct ilist_full_embedded_sentinel_traits {
- /// Get hold of the node that marks the end of the list.
- NodeTy *createSentinel() const { return &Sentinel; }
- static void destroySentinel(NodeTy *) {}
+} // end namespace ilist_detail
- NodeTy *provideInitialHead() const { return createSentinel(); }
- NodeTy *ensureHead(NodeTy *) const { return createSentinel(); }
- static void noteHead(NodeTy *, NodeTy *) {}
+template <typename NodeTy> struct ilist_traits;
-private:
- mutable NodeTy Sentinel;
-};
+// TODO: Delete uses from subprojects, then delete these.
+template <typename NodeTy> struct ilist_sentinel_traits {};
+template <typename NodeTy> struct ilist_embedded_sentinel_traits {};
+template <typename NodeTy> struct ilist_half_embedded_sentinel_traits {};
+template <typename NodeTy> struct ilist_full_embedded_sentinel_traits {};
/// ilist_node_traits - A fragment for template traits for intrusive list
/// that provides default node related operations.
/// for all common operations.
///
template <typename NodeTy>
-struct ilist_default_traits : public ilist_sentinel_traits<NodeTy>,
- public ilist_node_traits<NodeTy> {};
+struct ilist_default_traits : public ilist_node_traits<NodeTy> {};
// Template traits for intrusive list. By specializing this template class, you
// can change what next/prev fields are used to store the links...
typedef node_type &node_reference;
private:
- pointer NodePtr;
+ node_pointer NodePtr = nullptr;
public:
/// Create from an ilist_node.
- explicit ilist_iterator(node_reference N)
- : NodePtr(static_cast<NodeTy *>(&N)) {}
+ explicit ilist_iterator(node_reference N) : NodePtr(&N) {}
explicit ilist_iterator(pointer NP) : NodePtr(NP) {}
explicit ilist_iterator(reference NR) : NodePtr(&NR) {}
- ilist_iterator() : NodePtr(nullptr) {}
+ ilist_iterator() = default;
// This is templated so that we can allow constructing a const iterator from
// a nonconst iterator...
const ilist_iterator<node_ty> &RHS,
typename std::enable_if<std::is_convertible<node_ty *, NodeTy *>::value,
void *>::type = nullptr)
- : NodePtr(RHS.getNodePtrUnchecked()) {}
+ : NodePtr(RHS.getNodePtr()) {}
// This is templated so that we can allow assigning to a const iterator from
// a nonconst iterator...
template <class node_ty>
const ilist_iterator &operator=(const ilist_iterator<node_ty> &RHS) {
- NodePtr = RHS.getNodePtrUnchecked();
+ NodePtr = RHS.getNodePtr();
return *this;
}
void reset(pointer NP) { NodePtr = NP; }
// Accessors...
- reference operator*() const { return *NodePtr; }
+ reference operator*() const {
+ assert(!NodePtr->isKnownSentinel());
+ return static_cast<NodeTy &>(*getNodePtr());
+ }
pointer operator->() const { return &operator*(); }
// Comparison operators
/// Get the underlying ilist_node.
node_pointer getNodePtr() const { return static_cast<node_pointer>(NodePtr); }
-
- // Internal interface, do not use...
- pointer getNodePtrUnchecked() const { return NodePtr; }
};
// Allow ilist_iterators to convert into pointers to a node automatically when
//===----------------------------------------------------------------------===//
//
-/// iplist - The subset of list functionality that can safely be used on nodes
-/// of polymorphic types, i.e. a heterogeneous list with a common base class that
-/// holds the next/prev pointers. The only state of the list itself is a single
-/// pointer to the head of the list.
-///
-/// This list can be in one of three interesting states:
-/// 1. The list may be completely unconstructed. In this case, the head
-/// pointer is null. When in this form, any query for an iterator (e.g.
-/// begin() or end()) causes the list to transparently change to state #2.
-/// 2. The list may be empty, but contain a sentinel for the end iterator. This
-/// sentinel is created by the Traits::createSentinel method and is a link
-/// in the list. When the list is empty, the pointer in the iplist points
-/// to the sentinel. Once the sentinel is constructed, it
-/// is not destroyed until the list is.
-/// 3. The list may contain actual objects in it, which are stored as a doubly
-/// linked list of nodes. One invariant of the list is that the predecessor
-/// of the first node in the list always points to the last node in the list,
-/// and the successor pointer for the sentinel (which always stays at the
-/// end of the list) is always null.
-///
+/// The subset of list functionality that can safely be used on nodes of
+/// polymorphic types, i.e. a heterogeneous list with a common base class that
+/// holds the next/prev pointers. The only state of the list itself is an
+/// ilist_sentinel, which holds pointers to the first and last nodes in the
+/// list.
template <typename NodeTy, typename Traits = ilist_traits<NodeTy>>
class iplist : public Traits, ilist_node_access {
// TODO: Drop this assertion and the transitive type traits anytime after
static_assert(!ilist_detail::HasObsoleteCustomization<Traits, NodeTy>::value,
"ilist customization points have changed!");
- mutable NodeTy *Head;
+ ilist_sentinel<NodeTy> Sentinel;
- // Use the prev node pointer of 'head' as the tail pointer. This is really a
- // circularly linked list where we snip the 'next' link from the sentinel node
- // back to the first node in the list (to preserve assertions about going off
- // the end of the list).
- NodeTy *getTail() { return this->ensureHead(Head); }
- const NodeTy *getTail() const { return this->ensureHead(Head); }
- void setTail(NodeTy *N) const { this->noteHead(Head, N); }
-
- /// CreateLazySentinel - This method verifies whether the sentinel for the
- /// list has been created and lazily makes it if not.
- void CreateLazySentinel() const {
- this->ensureHead(Head);
- }
+ typedef ilist_node<NodeTy> node_type;
+ typedef const ilist_node<NodeTy> const_node_type;
static bool op_less(NodeTy &L, NodeTy &R) { return L < R; }
static bool op_equal(NodeTy &L, NodeTy &R) { return L == R; }
- // No fundamental reason why iplist can't be copyable, but the default
- // copy/copy-assign won't do.
+ // Copying intrusively linked nodes doesn't make sense.
iplist(const iplist &) = delete;
void operator=(const iplist &) = delete;
typedef std::reverse_iterator<const_iterator> const_reverse_iterator;
typedef std::reverse_iterator<iterator> reverse_iterator;
- iplist() : Head(this->provideInitialHead()) {}
- ~iplist() {
- if (!Head) return;
- clear();
- Traits::destroySentinel(getTail());
- }
+ iplist() = default;
+ ~iplist() { clear(); }
// Iterator creation methods.
- iterator begin() {
- CreateLazySentinel();
- return iterator(Head);
- }
- const_iterator begin() const {
- CreateLazySentinel();
- return const_iterator(Head);
- }
- iterator end() {
- CreateLazySentinel();
- return iterator(getTail());
- }
- const_iterator end() const {
- CreateLazySentinel();
- return const_iterator(getTail());
- }
+ iterator begin() { return ++iterator(Sentinel); }
+ const_iterator begin() const { return ++const_iterator(Sentinel); }
+ iterator end() { return iterator(Sentinel); }
+ const_iterator end() const { return const_iterator(Sentinel); }
// reverse iterator creation methods.
reverse_iterator rbegin() { return reverse_iterator(end()); }
// Miscellaneous inspection routines.
size_type max_size() const { return size_type(-1); }
- bool LLVM_ATTRIBUTE_UNUSED_RESULT empty() const {
- return !Head || Head == getTail();
- }
+ bool LLVM_ATTRIBUTE_UNUSED_RESULT empty() const { return Sentinel.empty(); }
// Front and back accessor functions...
reference front() {
assert(!empty() && "Called front() on empty list!");
- return *Head;
+ return *begin();
}
const_reference front() const {
assert(!empty() && "Called front() on empty list!");
- return *Head;
+ return *begin();
}
reference back() {
assert(!empty() && "Called back() on empty list!");
- return *this->getPrev(getTail());
+ return *--end();
}
const_reference back() const {
assert(!empty() && "Called back() on empty list!");
- return *this->getPrev(getTail());
+ return *--end();
}
void swap(iplist &RHS) {
assert(0 && "Swap does not use list traits callback correctly yet!");
- std::swap(Head, RHS.Head);
+ std::swap(Sentinel, RHS.Sentinel);
}
iterator insert(iterator where, NodeTy *New) {
- NodeTy *CurNode = where.getNodePtrUnchecked();
- NodeTy *PrevNode = this->getPrev(CurNode);
- this->setNext(New, CurNode);
- this->setPrev(New, PrevNode);
-
- if (CurNode != Head) // Is PrevNode off the beginning of the list?
- this->setNext(PrevNode, New);
- else
- Head = New;
- this->setPrev(CurNode, New);
+ node_type *NewN = this->getNodePtr(New);
+ node_type *Next = where.getNodePtr();
+ node_type *Prev = this->getPrev(Next);
+ this->setNext(NewN, Next);
+ this->setPrev(NewN, Prev);
+ this->setNext(Prev, NewN);
+ this->setPrev(Next, NewN);
this->addNodeToList(New); // Notify traits that we added a node...
return iterator(New);
NodeTy *remove(iterator &IT) {
assert(IT != end() && "Cannot remove end of list!");
NodeTy *Node = &*IT;
- NodeTy *NextNode = this->getNext(Node);
- NodeTy *PrevNode = this->getPrev(Node);
+ node_type *Base = this->getNodePtr(Node);
+ node_type *Next = this->getNext(Base);
+ node_type *Prev = this->getPrev(Base);
- if (Node != Head) // Is PrevNode off the beginning of the list?
- this->setNext(PrevNode, NextNode);
- else
- Head = NextNode;
- this->setPrev(NextNode, PrevNode);
- IT.reset(NextNode);
+ this->setNext(Prev, Next);
+ this->setPrev(Next, Prev);
+ IT = iterator(*Next);
this->removeNodeFromList(Node); // Notify traits that we removed a node...
// Set the next/prev pointers of the current node to null. This isn't
// strictly required, but this catches errors where a node is removed from
// an ilist (and potentially deleted) with iterators still pointing at it.
- // When those iterators are incremented or decremented, they will assert on
- // the null next/prev pointer instead of "usually working".
- this->setNext(Node, nullptr);
- this->setPrev(Node, nullptr);
+ // After those iterators are incremented or decremented, they become
+ // default-constructed iterators, and will assert on increment, decrement,
+ // and dereference instead of "usually working".
+ this->setNext(Base, nullptr);
+ this->setPrev(Base, nullptr);
return Node;
}
///
/// This should only be used immediately before freeing nodes in bulk to
/// avoid traversing the list and bringing all the nodes into cache.
- void clearAndLeakNodesUnsafely() {
- if (Head) {
- Head = getTail();
- this->setPrev(Head, Head);
- }
- }
+ void clearAndLeakNodesUnsafely() { Sentinel.reset(); }
private:
// transfer - The heart of the splice function. Move linked list nodes from
void transfer(iterator position, iplist &L2, iterator first, iterator last) {
assert(first != last && "Should be checked by callers");
// Position cannot be contained in the range to be transferred.
- // Check for the most common mistake.
assert(position != first &&
+ // Check for the most common mistake.
"Insertion point can't be one of the transferred nodes");
- if (position != last) {
- // Note: we have to be careful about the case when we move the first node
- // in the list. This node is the list sentinel node and we can't move it.
- NodeTy *ThisSentinel = getTail();
- setTail(nullptr);
- NodeTy *L2Sentinel = L2.getTail();
- L2.setTail(nullptr);
-
- // Remove [first, last) from its old position.
- NodeTy *First = &*first, *Prev = this->getPrev(First);
- NodeTy *Next = last.getNodePtrUnchecked(), *Last = this->getPrev(Next);
- if (Prev)
- this->setNext(Prev, Next);
- else
- L2.Head = Next;
- this->setPrev(Next, Prev);
-
- // Splice [first, last) into its new position.
- NodeTy *PosNext = position.getNodePtrUnchecked();
- NodeTy *PosPrev = this->getPrev(PosNext);
-
- // Fix head of list...
- if (PosPrev)
- this->setNext(PosPrev, First);
- else
- Head = First;
- this->setPrev(First, PosPrev);
-
- // Fix end of list...
- this->setNext(Last, PosNext);
- this->setPrev(PosNext, Last);
-
- this->transferNodesFromList(L2, iterator(First), iterator(PosNext));
-
- // Now that everything is set, restore the pointers to the list sentinels.
- L2.setTail(L2Sentinel);
- setTail(ThisSentinel);
- }
+ if (position == last)
+ return;
+
+ // Get raw hooks to the first and final nodes being transferred.
+ node_type *First = first.getNodePtr();
+ node_type *Final = (--last).getNodePtr();
+
+ // Detach from old list/position.
+ node_type *Prev = this->getPrev(First);
+ node_type *Next = this->getNext(Final);
+ this->setNext(Prev, Next);
+ this->setPrev(Next, Prev);
+
+ // Splice [First, Final] into its new list/position.
+ Next = position.getNodePtr();
+ Prev = this->getPrev(Next);
+ this->setNext(Final, Next);
+ this->setPrev(First, Prev);
+ this->setNext(Prev, First);
+ this->setPrev(Next, Final);
+
+ // Callback. Note that the nodes have moved from before-last to
+ // before-position.
+ this->transferNodesFromList(L2, first, position);
}
public:
//
size_type LLVM_ATTRIBUTE_UNUSED_RESULT size() const {
- if (!Head) return 0; // Don't require construction of sentinel if empty.
return std::distance(begin(), end());
}
return last;
}
- void clear() { if (Head) erase(begin(), end()); }
+ void clear() { erase(begin(), end()); }
// Front and back inserters...
void push_front(NodeTy *val) { insert(begin(), val); }
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