[ADT] Add a 'find_as' operation to DenseSet.

[oota-llvm.git] / include / llvm / ADT / SetVector.h

diff --git a/include/llvm/ADT/SetVector.h b/include/llvm/ADT/SetVector.h
index acc4daf1468f9d237dccef3d85b767ad43e05bc5..1e7d237045aacb6f39621c024aa82931a89d4fae 100644 (file)
--- a/include/llvm/ADT/SetVector.h
+++ b/include/llvm/ADT/SetVector.h
@@ -126,6 +126,30 @@ public:
     return false;
   }
 
+  /// \brief Remove items from the set vector based on a predicate function.
+  ///
+  /// This is intended to be equivalent to the following code, if we could
+  /// write it:
+  ///
+  /// \code
+  ///   V.erase(std::remove_if(V.begin(), V.end(), P), V.end());
+  /// \endcode
+  ///
+  /// However, SetVector doesn't expose non-const iterators, making any
+  /// algorithm like remove_if impossible to use.
+  ///
+  /// \returns true if any element is removed.
+  template <typename UnaryPredicate>
+  bool remove_if(UnaryPredicate P) {
+    typename vector_type::iterator I
+      = std::remove_if(vector_.begin(), vector_.end(),
+                       TestAndEraseFromSet<UnaryPredicate>(P, set_));
+    if (I == vector_.end())
+      return false;
+    vector_.erase(I, vector_.end());
+    return true;
+  }
+
 
   /// \brief Count the number of elements of a given key in the SetVector.
   /// \returns 0 if the element is not in the SetVector, 1 if it is.
@@ -146,7 +170,7 @@ public:
     vector_.pop_back();
   }
   
-  T pop_back_val() {
+  T LLVM_ATTRIBUTE_UNUSED_RESULT pop_back_val() {
     T Ret = back();
     pop_back();
     return Ret;
@@ -161,6 +185,28 @@ public:
   }
 
 private:
+  /// \brief A wrapper predicate designed for use with std::remove_if.
+  ///
+  /// This predicate wraps a predicate suitable for use with std::remove_if to
+  /// call set_.erase(x) on each element which is slated for removal.
+  template <typename UnaryPredicate>
+  class TestAndEraseFromSet {
+    UnaryPredicate P;
+    set_type &set_;
+
+  public:
+    TestAndEraseFromSet(UnaryPredicate P, set_type &set_) : P(P), set_(set_) {}
+
+    template <typename ArgumentT>
+    bool operator()(const ArgumentT &Arg) {
+      if (P(Arg)) {
+        set_.erase(Arg);
+        return true;
+      }
+      return false;
+    }
+  };
+
   set_type set_;         ///< The set.
   vector_type vector_;   ///< The vector.
 };