Add ImmutableMap::getMaxElement(), a method that returns the <key,value> pair in a ImmutableMap that has the highest ranked key.

llvm-svn: 65326

2 files changed, 16 insertions, 0 deletions

diff --git a/llvm/include/llvm/ADT/ImmutableMap.h b/llvm/include/llvm/ADT/ImmutableMap.h
index 07cdb56a9ab..00d59028aa0 100644
--- a/llvm/include/llvm/ADT/ImmutableMap.h
+++ b/llvm/include/llvm/ADT/ImmutableMap.h
@@ -202,6 +202,13 @@ public:
 
     return 0;
   }
+  
+  /// getMaxElement - Returns the <key,value> pair in the ImmutableMap for
+  ///  which key is the highest in the ordering of keys in the map.  This
+  ///  method returns NULL if the map is empty.
+  value_type* getMaxElement() const {
+    return Root ? &(Root->getMaxElement()) : 0;
+  }
 
   //===--------------------------------------------------===//
   // Utility methods.
diff --git a/llvm/include/llvm/ADT/ImmutableSet.h b/llvm/include/llvm/ADT/ImmutableSet.h
index ba1262b077c..be274dbe675 100644
--- a/llvm/include/llvm/ADT/ImmutableSet.h
+++ b/llvm/include/llvm/ADT/ImmutableSet.h
@@ -86,6 +86,15 @@ public:
 
     return NULL;
   }
+  
+  /// getMaxElement - Find the subtree associated with the highest ranged
+  ///  key value.
+  ImutAVLTree* getMaxElement() {
+    ImutAVLTree *T = this;
+    ImutAVLTree *Right = T->getRight();    
+    while (Right) { T = Right; Right = T->getRight(); }
+    return T;
+  }
 
   /// size - Returns the number of nodes in the tree, which includes
   ///  both leaves and non-leaf nodes.