Add back() and pop_back() methods to SetVector

Move clear to the end of the class
Add assertions

llvm-svn: 15203

llvm/include/Support/SetVector.h

@@ -19,6 +19,7 @@
 
 #include <set>
 #include <vector>
+#include <cassert>
 
 namespace llvm {
 
@@ -44,16 +45,10 @@ public:
 
   /// @brief Initialize a SetVector with a range of elements
   template<typename It>
-  SetVector( It Start, It End ) {
+  SetVector(It Start, It End) {
     insert(Start, End);
   }
 
-  /// @brief Completely clear the SetVector
-  void clear() {
-    set_.clear();
-    vector_.clear();
-  }
-
   /// @brief Determine if the SetVector is empty or not.
   bool empty() const {
     return vector_.empty();
@@ -84,35 +79,54 @@ public:
     return vector_.end();
   }
 
+  /// @brief Return the last element of the SetVector.
+  const T &back() const {
+    assert(!empty() && "Cannot call back() on empty SetVector!");
+    return vector_.back();
+  }
+
   /// @brief Index into the SetVector.
   const_reference operator[](size_type n) const {
-      return vector_[n];
+    assert(n < vector_.size() && "SetVector access out of range!");
+    return vector_[n];
   }
 
   /// @returns true iff the element was inserted into the SetVector.
   /// @brief Insert a new element into the SetVector.
-  bool insert( const value_type& X ) {
+  bool insert(const value_type &X) {
     bool result = set_.insert(X).second;
-    if ( result ) {
+    if (result)
       vector_.push_back(X);
-    }
     return result;
   }
 
   /// @brief Insert a range of elements into the SetVector.
   template<typename It>
-  void insert( It Start, It End ) {
+  void insert(It Start, It End) {
     for (; Start != End; ++Start)
-      if ( set_.insert(*Start).second )
+      if (set_.insert(*Start).second)
         vector_.push_back(*Start);
   }
 
   /// @returns 0 if the element is not in the SetVector, 1 if it is.
   /// @brief Count the number of elements of a given key in the SetVector.
-  size_type count( const key_type& key ) const {
+  size_type count(const key_type &key) const {
     return set_.count(key);
   }
 
+  /// @brief Completely clear the SetVector
+  void clear() {
+    set_.clear();
+    vector_.clear();
+  }
+
+  /// @brief Remove the last element of the SetVector.
+  void pop_back() {
+    assert(!empty() && "Cannot remove an element from an empty SetVector!");
+    set_.erase(back());
+    vector_.pop_back();
+  }
+
 private:
   set_type set_;         ///< The set.
   vector_type vector_;   ///< The vector.