include/llvm/ADT/ilist_node_base.h

   1 //===- llvm/ADT/ilist_node_base.h - Intrusive List Node Base -----*- C++ -*-==//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 #ifndef LLVM_ADT_ILIST_NODE_BASE_H
  10 #define LLVM_ADT_ILIST_NODE_BASE_H
  11
  12 #include "llvm/ADT/PointerIntPair.h"
  13
  14 namespace llvm {
  15
  16 /// Base class for ilist nodes.
  17 ///
  18 /// Optionally tracks whether this node is the sentinel.
  19 template <bool EnableSentinelTracking> class ilist_node_base;
  20
  21 template <> class ilist_node_base<false> {
  22   ilist_node_base *Prev = nullptr;
  23   ilist_node_base *Next = nullptr;
  24
  25 public:
  26   void setPrev(ilist_node_base *Prev) { this->Prev = Prev; }
  27   void setNext(ilist_node_base *Next) { this->Next = Next; }
  28   ilist_node_base *getPrev() const { return Prev; }
  29   ilist_node_base *getNext() const { return Next; }
  30
  31   bool isKnownSentinel() const { return false; }
  32   void initializeSentinel() {}
  33 };
  34
  35 template <> class ilist_node_base<true> {
  36   PointerIntPair<ilist_node_base *, 1> PrevAndSentinel;
  37   ilist_node_base *Next = nullptr;
  38
  39 public:
  40   void setPrev(ilist_node_base *Prev) { PrevAndSentinel.setPointer(Prev); }
  41   void setNext(ilist_node_base *Next) { this->Next = Next; }
  42   ilist_node_base *getPrev() const { return PrevAndSentinel.getPointer(); }
  43   ilist_node_base *getNext() const { return Next; }
  44
  45   bool isSentinel() const { return PrevAndSentinel.getInt(); }
  46   bool isKnownSentinel() const { return isSentinel(); }
  47   void initializeSentinel() { PrevAndSentinel.setInt(true); }
  48 };
  49
  50 } // end namespace llvm
  51
  52 #endif // LLVM_ADT_ILIST_NODE_BASE_H