X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=include%2Fllvm%2FADT%2Filist_node.h;h=f0080035cb885157e0a80b9e0300227e21ad3300;hb=c5252da873d547a19069eaf9030fec203f128f66;hp=dae7475ffa01222cf7c05b8990d30fb1b331a461;hpb=9c01f2dd0b20e09f4edef832620a188eda62ff5a;p=oota-llvm.git

diff --git a/include/llvm/ADT/ilist_node.h b/include/llvm/ADT/ilist_node.h
index dae7475ffa0..f0080035cb8 100644
--- a/include/llvm/ADT/ilist_node.h
+++ b/include/llvm/ADT/ilist_node.h
@@ -18,28 +18,87 @@
 namespace llvm {
 
 template<typename NodeTy>
-struct ilist_nextprev_traits;
+struct ilist_traits;
 
+/// ilist_half_node - Base class that provides prev services for sentinels.
+///
 template<typename NodeTy>
-struct ilist_traits;
+class ilist_half_node {
+  friend struct ilist_traits<NodeTy>;
+  NodeTy *Prev;
+protected:
+  NodeTy *getPrev() { return Prev; }
+  const NodeTy *getPrev() const { return Prev; }
+  void setPrev(NodeTy *P) { Prev = P; }
+  ilist_half_node() : Prev(0) {}
+};
+
+template<typename NodeTy>
+struct ilist_nextprev_traits;
 
 /// ilist_node - Base class that provides next/prev services for nodes
 /// that use ilist_nextprev_traits or ilist_default_traits.
 ///
 template<typename NodeTy>
-class ilist_node {
-private:
+class ilist_node : private ilist_half_node<NodeTy> {
   friend struct ilist_nextprev_traits<NodeTy>;
   friend struct ilist_traits<NodeTy>;
-  NodeTy *Prev, *Next;
-  NodeTy *getPrev() { return Prev; }
+  NodeTy *Next;
   NodeTy *getNext() { return Next; }
-  const NodeTy *getPrev() const { return Prev; }
   const NodeTy *getNext() const { return Next; }
-  void setPrev(NodeTy *N) { Prev = N; }
   void setNext(NodeTy *N) { Next = N; }
 protected:
-  ilist_node() : Prev(0), Next(0) {}
+  ilist_node() : Next(0) {}
+
+public:
+  /// @name Adjacent Node Accessors
+  /// @{
+
+  /// \brief Get the previous node, or 0 for the list head.
+  NodeTy *getPrevNode() {
+    NodeTy *Prev = this->getPrev();
+
+    // Check for sentinel.
+    if (!Prev->getNext())
+      return 0;
+
+    return Prev;
+  }
+
+  /// \brief Get the previous node, or 0 for the list head.
+  const NodeTy *getPrevNode() const {
+    const NodeTy *Prev = this->getPrev();
+
+    // Check for sentinel.
+    if (!Prev->getNext())
+      return 0;
+
+    return Prev;
+  }
+
+  /// \brief Get the next node, or 0 for the list tail.
+  NodeTy *getNextNode() {
+    NodeTy *Next = getNext();
+
+    // Check for sentinel.
+    if (!Next->getNext())
+      return 0;
+
+    return Next;
+  }
+
+  /// \brief Get the next node, or 0 for the list tail.
+  const NodeTy *getNextNode() const {
+    const NodeTy *Next = getNext();
+
+    // Check for sentinel.
+    if (!Next->getNext())
+      return 0;
+
+    return Next;
+  }
+
+  /// @}
 };
 
 } // End llvm namespace