add new smart pointer for clang.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@45261 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/ADT/OwningPtr.h

@@ -0,0 +1,79 @@
+//===- llvm/ADT/OwningPtr.h - Smart ptr that owns the pointee ---*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file was developed by Chris Lattner and is distributed under the
+// University of Illinois Open Source License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file defines and implements the OwningPtr class.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_ADT_OWNING_PTR_H
+#define LLVM_ADT_OWNING_PTR_H
+
+#include <cassert>
+
+namespace llvm {
+
+/// OwningPtr smart pointer - OwningPtr mimics a built-in pointer except that it
+/// guarantees deletion of the object pointed to, either on destruction of the
+/// OwningPtr or via an explicit reset().  Once created, ownership of the
+/// pointee object can be taken away from OwningPtr by using the take method.
+template<class T> 
+class OwningPtr {
+  OwningPtr(OwningPtr const &);             // DO NOT IMPLEMENT
+  OwningPtr &operator=(OwningPtr const &); // DO NOT IMPLEMENT
+  T *Ptr;
+public:
+  explicit OwningPtr(T *P = 0) : Ptr(P) {}
+
+  ~OwningPtr() {
+    delete Ptr;
+  }
+
+  /// reset - Change the current pointee to the specified pointer.  Note that
+  /// calling this with any pointer (including a null pointer) deletes the
+  /// current pointer.
+  void reset(T *P = 0) { 
+    if (P == Ptr) return;
+    T *Tmp = Ptr;
+    Ptr = P;
+    delete Tmp;
+  }
+
+  /// take - Reset the owning pointer to null and return its pointer.  This does
+  /// not delete the pointer before returning it.
+  T *take() { 
+    T *Tmp = Ptr;
+    Ptr = 0;
+    return Tmp;
+  }
+  
+  T &operator*() const {
+    assert(Ptr && "Cannot dereference null pointer");
+    return *Ptr;
+  }
+
+  T *operator->() const { return Ptr; }
+  T *get() const { return Ptr; }
+  operator bool() const { return Ptr != 0; }
+  bool operator!() const { return Ptr == 0; }
+
+  void swap(OwningPtr &RHS) {
+    T *Tmp = RHS.Ptr;
+    RHS.Ptr = Ptr;
+    Ptr = Tmp;
+  }
+};
+
+template<class T>
+inline void swap(OwningPtr<T> &a, OwningPtr<T> &b) {
+  a.swap(b);
+}
+
+} // end namespace llvm
+
+#endif