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6f8b468cb6
This is just good to do and hopefully will help prevent people from forgetting to check in the future by annotating the API explicitly as returning a potentially nullptr. Swift SVN r25364
68 lines
2.0 KiB
C++
68 lines
2.0 KiB
C++
//===- NullablePtr.h - A pointer that allows null ---------------*- C++ -*-===//
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//
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// This source file is part of the Swift.org open source project
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//
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// Copyright (c) 2014 - 2015 Apple Inc. and the Swift project authors
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// Licensed under Apache License v2.0 with Runtime Library Exception
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//
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// See http://swift.org/LICENSE.txt for license information
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// See http://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
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//
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//===----------------------------------------------------------------------===//
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//
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// This file defines and implements the NullablePtr class.
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//
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//===----------------------------------------------------------------------===//
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#ifndef SWIFT_BASIC_NULLABLEPTR_H
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#define SWIFT_BASIC_NULLABLEPTR_H
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#include <cassert>
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#include <cstddef>
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#include <type_traits>
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namespace swift {
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/// NullablePtr pointer wrapper - NullablePtr is used for APIs where a
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/// potentially-null pointer gets passed around that must be explicitly handled
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/// in lots of places. By putting a wrapper around the null pointer, it makes
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/// it more likely that the null pointer case will be handled correctly.
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template<class T>
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class NullablePtr {
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T *Ptr;
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struct PlaceHolder {};
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public:
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NullablePtr(T *P = 0) : Ptr(P) {}
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template<typename OtherT>
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NullablePtr(NullablePtr<OtherT> Other,
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typename std::enable_if<
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std::is_convertible<OtherT, T>::value,
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PlaceHolder
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>::type = PlaceHolder()) : Ptr(Other.getPtrOrNull()) {}
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bool isNull() const { return Ptr == 0; }
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bool isNonNull() const { return Ptr != 0; }
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/// get - Return the pointer if it is non-null.
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const T *get() const {
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assert(Ptr && "Pointer wasn't checked for null!");
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return Ptr;
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}
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/// get - Return the pointer if it is non-null.
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T *get() {
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assert(Ptr && "Pointer wasn't checked for null!");
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return Ptr;
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}
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T *getPtrOrNull() { return Ptr; }
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const T *getPtrOrNull() const { return Ptr; }
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explicit operator bool() const { return Ptr; }
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};
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} // end namespace swift
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#endif
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