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//===- llvm/ADT/NullablePtr.h - A pointer that allows null ------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file defines and implements the NullablePtr class.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_ADT_NULLABLEPTR_H
#define LLVM_ADT_NULLABLEPTR_H
#include "llvm/Support/type_traits.h"
#include <cassert>
#include <cstddef>
namespace llvm {
/// NullablePtr pointer wrapper - NullablePtr is used for APIs where a
/// potentially-null pointer gets passed around that must be explicitly handled
/// in lots of places. By putting a wrapper around the null pointer, it makes
/// it more likely that the null pointer case will be handled correctly.
template<class T>
class NullablePtr {
T *Ptr;
struct PlaceHolder {};
public:
NullablePtr(T *P = 0) : Ptr(P) {}
template<typename OtherT>
NullablePtr(NullablePtr<OtherT> Other,
typename enable_if<
is_base_of<T, OtherT>,
PlaceHolder
>::type = PlaceHolder()) : Ptr(Other.getPtrOrNull()) {}
bool isNull() const { return Ptr == 0; }
bool isNonNull() const { return Ptr != 0; }
/// get - Return the pointer if it is non-null.
const T *get() const {
assert(Ptr && "Pointer wasn't checked for null!");
return Ptr;
}
/// get - Return the pointer if it is non-null.
T *get() {
assert(Ptr && "Pointer wasn't checked for null!");
return Ptr;
}
T *getPtrOrNull() { return Ptr; }
const T *getPtrOrNull() const { return Ptr; }
};
} // end namespace llvm
#endif
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