Merge to XFA: Switch from nonstd::unique_ptr to std::unique_ptr.

third_party/base/nonstd_unique_ptr.h

-// Copyright 2013 Google Inc. All Rights Reserved.
-//
-// Redistribution and use in source and binary forms, with or without
-// modification, are permitted provided that the following conditions are
-// met:
-//
-//     * Redistributions of source code must retain the above copyright
-// notice, this list of conditions and the following disclaimer.
-//     * Redistributions in binary form must reproduce the above
-// copyright notice, this list of conditions and the following disclaimer
-// in the documentation and/or other materials provided with the
-// distribution.
-//     * Neither the name of Google Inc. nor the names of its
-// contributors may be used to endorse or promote products derived from
-// this software without specific prior written permission.
-//
-// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
-// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
-// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
-// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
-// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
-// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
-// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
-// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
-// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
-// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
-// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
-
-// This is a copy of breakpad's standalone scoped_ptr, which has been
-// renamed to nonstd::unique_ptr, and from which more complicated classes
-// have been removed. The reset() method has also been tweaked to more
-// closely match c++11, and an implicit conversion to bool has been added.
-
-// Scopers help you manage ownership of a pointer, helping you easily manage the
-// a pointer within a scope, and automatically destroying the pointer at the
-// end of a scope.
-//
-// A unique_ptr<T> is like a T*, except that the destructor of unique_ptr<T>
-// automatically deletes the pointer it holds (if any).
-// That is, unique_ptr<T> owns the T object that it points to.
-// Like a T*, a unique_ptr<T> may hold either NULL or a pointer to a T object.
-// Also like T*, unique_ptr<T> is thread-compatible, and once you
-// dereference it, you get the thread safety guarantees of T.
-//
-// Example usage (unique_ptr):
-//   {
-//     unique_ptr<Foo> foo(new Foo("wee"));
-//   }  // foo goes out of scope, releasing the pointer with it.
-//
-//   {
-//     unique_ptr<Foo> foo;          // No pointer managed.
-//     foo.reset(new Foo("wee"));    // Now a pointer is managed.
-//     foo.reset(new Foo("wee2"));   // Foo("wee") was destroyed.
-//     foo.reset(new Foo("wee3"));   // Foo("wee2") was destroyed.
-//     foo->Method();                // Foo::Method() called.
-//     foo.get()->Method();          // Foo::Method() called.
-//     SomeFunc(foo.release());      // SomeFunc takes ownership, foo no longer
-//                                   // manages a pointer.
-//     foo.reset(new Foo("wee4"));   // foo manages a pointer again.
-//     foo.reset();                  // Foo("wee4") destroyed, foo no longer
-//                                   // manages a pointer.
-//   }  // foo wasn't managing a pointer, so nothing was destroyed.
-//
-// The size of a unique_ptr is small: sizeof(unique_ptr<C>) == sizeof(C*)
-
-#ifndef NONSTD_UNIQUE_PTR_H_
-#define NONSTD_UNIQUE_PTR_H_
-
-// This is an implementation designed to match the anticipated future C++11
-// implementation of the unique_ptr class.
-
-#include <assert.h>
-#include <stddef.h>
-#include <stdlib.h>
-
-#include <ostream>
-#include <utility>
-
-#include "template_util.h"
-
-namespace nonstd {
-
-// Function object which deletes its parameter, which must be a pointer.
-// If C is an array type, invokes 'delete[]' on the parameter; otherwise,
-// invokes 'delete'. The default deleter for unique_ptr<T>.
-template <class T>
-struct DefaultDeleter {
-  DefaultDeleter() {}
-  template <typename U>
-  DefaultDeleter(const DefaultDeleter<U>& other) {
-    // IMPLEMENTATION NOTE: C++11 20.7.1.1.2p2 only provides this constructor
-    // if U* is implicitly convertible to T* and U is not an array type.
-    //
-    // Correct implementation should use SFINAE to disable this
-    // constructor. However, since there are no other 1-argument constructors,
-    // using a static_assert() based on is_convertible<> and requiring
-    // complete types is simpler and will cause compile failures for equivalent
-    // misuses.
-    //
-    // Note, the is_convertible<U*, T*> check also ensures that U is not an
-    // array. T is guaranteed to be a non-array, so any U* where U is an array
-    // cannot convert to T*.
-    enum { T_must_be_complete = sizeof(T) };
-    enum { U_must_be_complete = sizeof(U) };
-    static_assert((pdfium::base::is_convertible<U*, T*>::value),
-                  "U_ptr_must_implicitly_convert_to_T_ptr");
-  }
-  inline void operator()(T* ptr) const {
-    enum { type_must_be_complete = sizeof(T) };
-    delete ptr;
-  }
-};
-
-// Specialization of DefaultDeleter for array types.
-template <class T>
-struct DefaultDeleter<T[]> {
-  inline void operator()(T* ptr) const {
-    enum { type_must_be_complete = sizeof(T) };
-    delete[] ptr;
-  }
-
- private:
-  // Disable this operator for any U != T because it is undefined to execute
-  // an array delete when the static type of the array mismatches the dynamic
-  // type.
-  //
-  // References:
-  //   C++98 [expr.delete]p3
-  //   http://cplusplus.github.com/LWG/lwg-defects.html#938
-  template <typename U>
-  void operator()(U* array) const;
-};
-
-template <class T, int n>
-struct DefaultDeleter<T[n]> {
-  // Never allow someone to declare something like unique_ptr<int[10]>.
-  static_assert(sizeof(T) == -1, "do_not_use_array_with_size_as_type");
-};
-
-namespace internal {
-
-// Common implementation for both pointers to elements and pointers to
-// arrays. These are differentiated below based on the need to invoke
-// delete vs. delete[] as appropriate.
-template <class C, class D>
-class unique_ptr_base {
- public:
-  // The element type
-  typedef C element_type;
-
-  explicit unique_ptr_base(C* p) : data_(p) {}
-
-  // Initializer for deleters that have data parameters.
-  unique_ptr_base(C* p, const D& d) : data_(p, d) {}
-
-  // Move constructor.
-  unique_ptr_base(unique_ptr_base<C, D>&& that)
-      : data_(that.release(), that.get_deleter()) {}
-
-  ~unique_ptr_base() {
-    enum { type_must_be_complete = sizeof(C) };
-    if (data_.ptr != nullptr) {
-      // Not using get_deleter() saves one function call in non-optimized
-      // builds.
-      static_cast<D&>(data_)(data_.ptr);
-    }
-  }
-
-  void reset(C* p = nullptr) {
-    C* old = data_.ptr;
-    data_.ptr = p;
-    if (old != nullptr)
-      static_cast<D&>(data_)(old);
-  }
-
-  C* get() const { return data_.ptr; }
-  D& get_deleter() { return data_; }
-  const D& get_deleter() const { return data_; }
-
-  // Comparison operators.
-  // These return whether two unique_ptr refer to the same object, not just to
-  // two different but equal objects.
-  bool operator==(C* p) const { return data_.ptr == p; }
-  bool operator!=(C* p) const { return data_.ptr != p; }
-
-  // Swap two unique pointers.
-  void swap(unique_ptr_base& p2) {
-    Data tmp = data_;
-    data_ = p2.data_;
-    p2.data_ = tmp;
-  }
-
-  // Release a pointer.
-  // The return value is the current pointer held by this object.
-  // If this object holds a NULL pointer, the return value is NULL.
-  // After this operation, this object will hold a NULL pointer,
-  // and will not own the object any more.
-  C* release() {
-    C* ptr = data_.ptr;
-    data_.ptr = nullptr;
-    return ptr;
-  }
-
-  // Allow promotion to bool for conditional statements.
-  explicit operator bool() const { return data_.ptr != nullptr; }
-
- protected:
-  // Use the empty base class optimization to allow us to have a D
-  // member, while avoiding any space overhead for it when D is an
-  // empty class.  See e.g. http://www.cantrip.org/emptyopt.html for a good
-  // discussion of this technique.
-  struct Data : public D {
-    explicit Data(C* ptr_in) : ptr(ptr_in) {}
-    Data(C* ptr_in, const D& other) : D(other), ptr(ptr_in) {}
-    C* ptr;
-  };
-
-  Data data_;
-};
-
-}  // namespace internal
-
-// Implementation for ordinary pointers using delete.
-template <class C, class D = DefaultDeleter<C>>
-class unique_ptr : public internal::unique_ptr_base<C, D> {
- public:
-  // Constructor.  Defaults to initializing with nullptr.
-  unique_ptr() : internal::unique_ptr_base<C, D>(nullptr) {}
-
-  // Constructor.  Takes ownership of p.
-  explicit unique_ptr(C* p) : internal::unique_ptr_base<C, D>(p) {}
-
-  // Constructor.  Allows initialization of a stateful deleter.
-  unique_ptr(C* p, const D& d) : internal::unique_ptr_base<C, D>(p, d) {}
-
-  // Constructor.  Allows construction from a nullptr.
-  unique_ptr(decltype(nullptr)) : internal::unique_ptr_base<C, D>(nullptr) {}
-
-  // Move constructor.
-  unique_ptr(unique_ptr&& that)
-      : internal::unique_ptr_base<C, D>(std::move(that)) {}
-
-  // operator=.  Allows assignment from a nullptr. Deletes the currently owned
-  // object, if any.
-  unique_ptr& operator=(decltype(nullptr)) {
-    this->reset();
-    return *this;
-  }
-
-  // Move assignment.
-  unique_ptr<C>& operator=(unique_ptr<C>&& that) {
-    this->reset(that.release());
-    return *this;
-  }
-
-  // Accessors to get the owned object.
-  // operator* and operator-> will assert() if there is no current object.
-  C& operator*() const {
-    assert(this->data_.ptr != nullptr);
-    return *this->data_.ptr;
-  }
-  C* operator->() const {
-    assert(this->data_.ptr != nullptr);
-    return this->data_.ptr;
-  }
-
-  // Comparison operators.
-  // These return whether two unique_ptr refer to the same object, not just to
-  // two different but equal objects.
-  bool operator==(const C* p) const { return this->get() == p; }
-  bool operator!=(const C* p) const { return this->get() != p; }
-
- private:
-  // Disallow evil constructors. It doesn't make sense to make a copy of
-  // something that's allegedly unique.
-  unique_ptr(const unique_ptr&) = delete;
-  void operator=(const unique_ptr&) = delete;
-
-  // Forbid comparison of unique_ptr types.  If U != C, it totally
-  // doesn't make sense, and if U == C, it still doesn't make sense
-  // because you should never have the same object owned by two different
-  // unique_ptrs.
-  template <class U>
-  bool operator==(unique_ptr<U> const& p2) const;
-  template <class U>
-  bool operator!=(unique_ptr<U> const& p2) const;
-};
-
-// Specialization for arrays using delete[].
-template <class C, class D>
-class unique_ptr<C[], D> : public internal::unique_ptr_base<C, D> {
- public:
-  // Constructor.  Defaults to initializing with nullptr.
-  unique_ptr() : internal::unique_ptr_base<C, D>(nullptr) {}
-
-  // Constructor. Stores the given array. Note that the argument's type
-  // must exactly match T*. In particular:
-  // - it cannot be a pointer to a type derived from T, because it is
-  //   inherently unsafe in the general case to access an array through a
-  //   pointer whose dynamic type does not match its static type (eg., if
-  //   T and the derived types had different sizes access would be
-  //   incorrectly calculated). Deletion is also always undefined
-  //   (C++98 [expr.delete]p3). If you're doing this, fix your code.
-  // - it cannot be const-qualified differently from T per unique_ptr spec
-  //   (http://cplusplus.github.com/LWG/lwg-active.html#2118). Users wanting
-  //   to work around this may use const_cast<const T*>().
-  explicit unique_ptr(C* p) : internal::unique_ptr_base<C, D>(p) {}
-
-  // Constructor.  Allows construction from a nullptr.
-  unique_ptr(decltype(nullptr)) : internal::unique_ptr_base<C, D>(nullptr) {}
-
-  // Move constructor.
-  unique_ptr(unique_ptr&& that)
-      : internal::unique_ptr_base<C, D>(std::move(that)) {}
-
-  // operator=.  Allows assignment from a nullptr. Deletes the currently owned
-  // array, if any.
-  unique_ptr& operator=(decltype(nullptr)) {
-    this->reset();
-    return *this;
-  }
-
-  // Move assignment.
-  unique_ptr<C>& operator=(unique_ptr<C>&& that) {
-    this->reset(that.release());
-    return *this;
-  }
-
-  // Reset.  Deletes the currently owned array, if any.
-  // Then takes ownership of a new object, if given.
-  void reset(C* array = nullptr) {
-    static_cast<internal::unique_ptr_base<C, D>*>(this)->reset(array);
-  }
-
-  // Support indexing since it is holding array.
-  C& operator[](size_t i) { return this->data_.ptr[i]; }
-
-  // Comparison operators.
-  // These return whether two unique_ptr refer to the same object, not just to
-  // two different but equal objects.
-  bool operator==(C* array) const { return this->get() == array; }
-  bool operator!=(C* array) const { return this->get() != array; }
-
- private:
-  // Disable initialization from any type other than element_type*, by
-  // providing a constructor that matches such an initialization, but is
-  // private and has no definition. This is disabled because it is not safe to
-  // call delete[] on an array whose static type does not match its dynamic
-  // type.
-  template <typename U>
-  explicit unique_ptr(U* array);
-  explicit unique_ptr(int disallow_construction_from_null);
-
-  // Disable reset() from any type other than element_type*, for the same
-  // reasons as the constructor above.
-  template <typename U>
-  void reset(U* array);
-  void reset(int disallow_reset_from_null);
-
-  // Disallow evil constructors.  It doesn't make sense to make a copy of
-  // something that's allegedly unique.
-  unique_ptr(const unique_ptr&) = delete;
-  void operator=(const unique_ptr&) = delete;
-
-  // Forbid comparison of unique_ptr types.  If U != C, it totally
-  // doesn't make sense, and if U == C, it still doesn't make sense
-  // because you should never have the same object owned by two different
-  // unique_ptrs.
-  template <class U>
-  bool operator==(unique_ptr<U> const& p2) const;
-  template <class U>
-  bool operator!=(unique_ptr<U> const& p2) const;
-};
-
-// Free functions
-template <class C>
-void swap(unique_ptr<C>& p1, unique_ptr<C>& p2) {
-  p1.swap(p2);
-}
-
-template <class C>
-bool operator==(C* p1, const unique_ptr<C>& p2) {
-  return p1 == p2.get();
-}
-
-template <class C>
-bool operator!=(C* p1, const unique_ptr<C>& p2) {
-  return p1 != p2.get();
-}
-
-template <typename T>
-std::ostream& operator<<(std::ostream& out, const unique_ptr<T>& p) {
-  return out << p.get();
-}
-
-}  // namespace nonstd
-
-#endif  // NONSTD_UNIQUE_PTR_H_