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      1 //===- llvm/ADT/NullablePtr.h - A pointer that allows null ------*- C++ -*-===//
      2 //
      3 //                     The LLVM Compiler Infrastructure
      4 //
      5 // This file is distributed under the University of Illinois Open Source
      6 // License. See LICENSE.TXT for details.
      7 //
      8 //===----------------------------------------------------------------------===//
      9 //
     10 // This file defines and implements the NullablePtr class.
     11 //
     12 //===----------------------------------------------------------------------===//
     13 
     14 #ifndef LLVM_ADT_NULLABLE_PTR_H
     15 #define LLVM_ADT_NULLABLE_PTR_H
     16 
     17 #include <cassert>
     18 #include <cstddef>
     19 
     20 namespace llvm {
     21 /// NullablePtr pointer wrapper - NullablePtr is used for APIs where a
     22 /// potentially-null pointer gets passed around that must be explicitly handled
     23 /// in lots of places.  By putting a wrapper around the null pointer, it makes
     24 /// it more likely that the null pointer case will be handled correctly.
     25 template<class T>
     26 class NullablePtr {
     27   T *Ptr;
     28 public:
     29   NullablePtr(T *P = 0) : Ptr(P) {}
     30 
     31   bool isNull() const { return Ptr == 0; }
     32   bool isNonNull() const { return Ptr != 0; }
     33 
     34   /// get - Return the pointer if it is non-null.
     35   const T *get() const {
     36     assert(Ptr && "Pointer wasn't checked for null!");
     37     return Ptr;
     38   }
     39 
     40   /// get - Return the pointer if it is non-null.
     41   T *get() {
     42     assert(Ptr && "Pointer wasn't checked for null!");
     43     return Ptr;
     44   }
     45 
     46   T *getPtrOrNull() { return Ptr; }
     47   const T *getPtrOrNull() const { return Ptr; }
     48 };
     49 
     50 } // end namespace llvm
     51 
     52 #endif
     53