include/llvm/ADT/OwningPtr.h

//===- 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