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//===- llvm/ADT/polymorphic_ptr.h - Smart copyable owned ptr ----*- C++ -*-===// |
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// |
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// The LLVM Compiler Infrastructure |
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// |
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// This file is distributed under the University of Illinois Open Source |
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// License. See LICENSE.TXT for details. |
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// |
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//===----------------------------------------------------------------------===// |
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/// \file |
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/// This file provides a polymorphic_ptr class template. See the class comments |
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/// for details about this API, its intended use cases, etc. |
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/// |
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/// The primary motivation here is to work around the necessity of copy |
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/// semantics in C++98. This is typically used where any actual copies are |
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/// incidental or unnecessary. As a consequence, it is expected to cease to be |
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/// useful and be removed when we can directly rely on move-only types. |
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/// |
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//===----------------------------------------------------------------------===// |
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|
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#ifndef LLVM_ADT_POLYMORPHIC_PTR_H |
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#define LLVM_ADT_POLYMORPHIC_PTR_H |
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|
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#include "llvm/Support/Compiler.h" |
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|
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namespace llvm { |
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|
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/// \brief An owning, copyable polymorphic smart pointer. |
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/// |
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/// This pointer exists to provide copyable owned smart pointer. Rather than |
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/// shared ownership semantics, it has unique ownership semantics and deep copy |
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/// semantics. It is copyable by requiring that the underlying type exposes |
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/// a method which can produce a (heap allocated) clone. |
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/// |
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/// Note that in almost all scenarios use of this could be avoided if we could |
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/// build move-only containers of a std::unique_ptr, but until then this |
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/// provides an effective way to place polymorphic objects in a container. |
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template <typename T> class polymorphic_ptr { |
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T *ptr; |
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|
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public: |
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polymorphic_ptr(T *ptr = 0) : ptr(ptr) {} |
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polymorphic_ptr(const polymorphic_ptr &arg) : ptr(arg ? arg->clone() : 0) {} |
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#if LLVM_HAS_RVALUE_REFERENCES |
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polymorphic_ptr(polymorphic_ptr &&arg) : ptr(arg.take()) {} |
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#endif |
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~polymorphic_ptr() { delete ptr; } |
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|
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polymorphic_ptr &operator=(polymorphic_ptr arg) { |
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swap(arg); |
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return *this; |
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} |
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polymorphic_ptr &operator=(T *arg) { |
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if (arg != ptr) { |
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delete ptr; |
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ptr = arg; |
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} |
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return *this; |
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} |
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|
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T &operator*() const { return *ptr; } |
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T *operator->() const { return ptr; } |
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LLVM_EXPLICIT operator bool() const { return ptr != 0; } |
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bool operator!() const { return ptr == 0; } |
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|
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T *get() const { return ptr; } |
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|
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T *take() { |
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T *tmp = ptr; |
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ptr = 0; |
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return tmp; |
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} |
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|
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void swap(polymorphic_ptr &arg) { |
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T *tmp = ptr; |
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ptr = arg.ptr; |
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arg.ptr = tmp; |
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} |
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}; |
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|
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template <typename T> |
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void swap(polymorphic_ptr<T> &lhs, polymorphic_ptr<T> &rhs) { |
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lhs.swap(rhs); |
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} |
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|
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template <typename T, typename U> |
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bool operator==(const polymorphic_ptr<T> &lhs, const polymorphic_ptr<U> &rhs) { |
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return lhs.get() == rhs.get(); |
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} |
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|
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template <typename T, typename U> |
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bool operator!=(const polymorphic_ptr<T> &lhs, const polymorphic_ptr<U> &rhs) { |
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return lhs.get() != rhs.get(); |
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} |
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|
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template <typename T, typename U> |
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bool operator==(const polymorphic_ptr<T> &lhs, U *rhs) { |
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return lhs.get() == rhs; |
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} |
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|
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template <typename T, typename U> |
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bool operator!=(const polymorphic_ptr<T> &lhs, U *rhs) { |
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return lhs.get() != rhs; |
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} |
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|
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template <typename T, typename U> |
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bool operator==(T *lhs, const polymorphic_ptr<U> &rhs) { |
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return lhs == rhs.get(); |
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} |
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|
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template <typename T, typename U> |
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bool operator!=(T *lhs, const polymorphic_ptr<U> &rhs) { |
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return lhs != rhs.get(); |
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} |
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|
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} |
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|
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#endif |