// Copyright (c) 2012 The Chromium Authors. All rights reserved.

// Use of this source code is governed by a BSD-style license that can be

// found in the LICENSE.txt file.

// 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.  There are two main classes you will use, which correspond

// to the operators new/delete and new[]/delete[].

//

// Example usage (gscoped_ptr):

//   {

//     gscoped_ptr<Foo> foo(new Foo("wee"));

//   }  // foo goes out of scope, releasing the pointer with it.

//

//   {

//     gscoped_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.

//

// Example usage (gscoped_array):

//   {

//     gscoped_array<Foo> foo(new Foo[100]);

//     foo.get()->Method();  // Foo::Method on the 0th element.

//     foo[10].Method();     // Foo::Method on the 10th element.

//   }

//

// These scopers also implement part of the functionality of C++11 unique_ptr

// in that they are "movable but not copyable."  You can use the scopers in

// the parameter and return types of functions to signify ownership transfer

// in to and out of a function.  When calling a function that has a scoper

// as the argument type, it must be called with the result of an analogous

// scoper's Pass() function or another function that generates a temporary;

// passing by copy will NOT work.  Here is an example using gscoped_ptr:

//

//   void TakesOwnership(gscoped_ptr<Foo> arg) {

//     // Do something with arg

//   }

//   gscoped_ptr<Foo> CreateFoo() {

//     // No need for calling Pass() because we are constructing a temporary

//     // for the return value.

//     return gscoped_ptr<Foo>(new Foo("new"));

//   }

//   gscoped_ptr<Foo> PassThru(gscoped_ptr<Foo> arg) {

//     return std::move(arg);

//   }

//

//   {

//     gscoped_ptr<Foo> ptr(new Foo("yay"));  // ptr manages Foo("yay").

//     TakesOwnership(std::move(ptr));           // ptr no longer owns Foo("yay").

//     gscoped_ptr<Foo> ptr2 = CreateFoo();   // ptr2 owns the return Foo.

//     gscoped_ptr<Foo> ptr3 =                // ptr3 now owns what was in ptr2.

//         PassThru(std::move(ptr2));            // ptr2 is correspondingly NULL.

//   }

//

// Notice that if you do not call Pass() when returning from PassThru(), or

// when invoking TakesOwnership(), the code will not compile because scopers

// are not copyable; they only implement move semantics which require calling

// the Pass() function to signify a destructive transfer of state. CreateFoo()

// is different though because we are constructing a temporary on the return

// line and thus can avoid needing to call Pass().

//

// Pass() properly handles upcast in assignment, i.e. you can assign

// gscoped_ptr<Child> to gscoped_ptr<Parent>:

//

//   gscoped_ptr<Foo> foo(new Foo());

//   gscoped_ptr<FooParent> parent = std::move(foo);

//

// PassAs<>() should be used to upcast return value in return statement:

//

//   gscoped_ptr<Foo> CreateFoo() {

//     gscoped_ptr<FooChild> result(new FooChild());

//     return result.PassAs<Foo>();

//   }

//

// Note that PassAs<>() is implemented only for gscoped_ptr, but not for

// gscoped_array. This is because casting array pointers may not be safe.

//

// -------------------------------------------------------------------------

// Cloudera notes: this should be used in preference to std::unique_ptr since

// it offers a ::release() method like unique_ptr. We unfortunately cannot

// just use unique_ptr because it has an inconsistent implementation in

// some of the older compilers we have to support.

// -------------------------------------------------------------------------

// This is an implementation designed to match the anticipated future TR2

// implementation of the scoped_ptr class, and its closely-related brethren,

// scoped_array, scoped_ptr_malloc.

#pragma once

#include <assert.h>

#include <stddef.h>

#include <stdlib.h>

#include <algorithm> // For std::swap().

#include <type_traits>

#include "gutil/basictypes.h"

#include "gutil/move.h"

#include "gutil/template_util.h"

namespace doris {

namespace subtle {

class RefCountedBase;

class RefCountedThreadSafeBase;

} // namespace subtle

// 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 gscoped_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 COMPILE_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) };

        COMPILE_ASSERT((std::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 gscoped_ptr<int[10]>.

    COMPILE_ASSERT(sizeof(T) == -1, do_not_use_array_with_size_as_type);

};

// Function object which invokes 'free' on its parameter, which must be

// a pointer. Can be used to store malloc-allocated pointers in gscoped_ptr:

//

// gscoped_ptr<int, doris::FreeDeleter> foo_ptr(

//     static_cast<int*>(malloc(sizeof(int))));

struct FreeDeleter {

    inline void operator()(void* ptr) const { free(ptr); }

};

namespace internal {

template <typename T>

struct IsNotRefCounted {

    enum {

        value = !std::is_convertible<T*, doris::subtle::RefCountedBase*>::value &&

                !std::is_convertible<T*, doris::subtle::RefCountedThreadSafeBase*>::value

    };

};

// Minimal implementation of the core logic of gscoped_ptr, suitable for

// reuse in both gscoped_ptr and its specializations.

template <class T, class D>

class gscoped_ptr_impl {

public:

    explicit gscoped_ptr_impl(T* p) : data_(p) {}

    // Initializer for deleters that have data parameters.

    gscoped_ptr_impl(T* p, const D& d) : data_(p, d) {}

    // Templated constructor that destructively takes the value from another

    // gscoped_ptr_impl.

    template <typename U, typename V>

    gscoped_ptr_impl(gscoped_ptr_impl<U, V>* other)

            : data_(other->release(), other->get_deleter()) {

        // We do not support move-only deleters.  We could modify our move

        // emulation to have base::subtle::move() and base::subtle::forward()

        // functions that are imperfect emulations of their C++11 equivalents,

        // but until there's a requirement, just assume deleters are copyable.

    }

    template <typename U, typename V>

    void TakeState(gscoped_ptr_impl<U, V>* other) {

        // See comment in templated constructor above regarding lack of support

        // for move-only deleters.

        reset(other->release());

        get_deleter() = other->get_deleter();

    }

    ~gscoped_ptr_impl() {

        if (data_.ptr != NULL) {

            // Not using get_deleter() saves one function call in non-optimized

            // builds.

            static_cast<D&>(data_)(data_.ptr);

        }

    }

    void reset(T* p) {

        // This is a self-reset, which is no longer allowed: http://crbug.com/162971

        if (p != NULL && p == data_.ptr) abort();

        // Note that running data_.ptr = p can lead to undefined behavior if

        // get_deleter()(get()) deletes this. In order to pevent this, reset()

        // should update the stored pointer before deleting its old value.

        //

        // However, changing reset() to use that behavior may cause current code to

        // break in unexpected ways. If the destruction of the owned object

        // dereferences the gscoped_ptr when it is destroyed by a call to reset(),

        // then it will incorrectly dispatch calls to |p| rather than the original

        // value of |data_.ptr|.

        //

        // During the transition period, set the stored pointer to NULL while

        // deleting the object. Eventually, this safety check will be removed to

        // prevent the scenario initially described from occuring and

        // http://crbug.com/176091 can be closed.

        T* old = data_.ptr;

        data_.ptr = NULL;

        if (old != NULL) static_cast<D&>(data_)(old);

        data_.ptr = p;

    }

    T* get() const { return data_.ptr; }

    D& get_deleter() { return data_; }

    const D& get_deleter() const { return data_; }

    void swap(gscoped_ptr_impl& p2) {

        // Standard swap idiom: 'using std::swap' ensures that std::swap is

        // present in the overload set, but we call swap unqualified so that

        // any more-specific overloads can be used, if available.

        using std::swap;

        swap(static_cast<D&>(data_), static_cast<D&>(p2.data_));

        swap(data_.ptr, p2.data_.ptr);

    }

    T* release() {

        T* old_ptr = data_.ptr;

        data_.ptr = NULL;

        return old_ptr;

    }

private:

    // Needed to allow type-converting constructor.

    template <typename U, typename V>

    friend class gscoped_ptr_impl;

    // 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(T* ptr_in) : ptr(ptr_in) {}

        Data(T* ptr_in, D other) : D(std::move(other)), ptr(ptr_in) {}

        T* ptr;

    };

    Data data_;

    DISALLOW_COPY_AND_ASSIGN(gscoped_ptr_impl);

};

} // namespace internal

} // namespace doris

// A gscoped_ptr<T> is like a T*, except that the destructor of gscoped_ptr<T>

// automatically deletes the pointer it holds (if any).

// That is, gscoped_ptr<T> owns the T object that it points to.

// Like a T*, a gscoped_ptr<T> may hold either NULL or a pointer to a T object.

// Also like T*, gscoped_ptr<T> is thread-compatible, and once you

// dereference it, you get the thread safety guarantees of T.

//

// The size of gscoped_ptr is small. On most compilers, when using the

// DefaultDeleter, sizeof(gscoped_ptr<T>) == sizeof(T*). Custom deleters will

// increase the size proportional to whatever state they need to have. See

// comments inside gscoped_ptr_impl<> for details.

//

// Current implementation targets having a strict subset of  C++11's

// unique_ptr<> features. Known deficiencies include not supporting move-only

// deleteres, function pointers as deleters, and deleters with reference

// types.

template <class T, class D = doris::DefaultDeleter<T>>

class gscoped_ptr {

    MOVE_ONLY_TYPE_FOR_CPP_03(gscoped_ptr, RValue)

    COMPILE_ASSERT(doris::internal::IsNotRefCounted<T>::value,

                   T_is_refcounted_type_and_needs_scoped_refptr);

public:

    // The element and deleter types.

    typedef T element_type;

    typedef D deleter_type;

    // Constructor.  Defaults to initializing with NULL.

    gscoped_ptr() : impl_(NULL) {}

    // Constructor.  Takes ownership of p.

    explicit gscoped_ptr(element_type* p) : impl_(p) {}

    // Constructor.  Allows initialization of a stateful deleter.

    gscoped_ptr(element_type* p, const D& d) : impl_(p, d) {}

    // Constructor.  Allows construction from a gscoped_ptr rvalue for a

    // convertible type and deleter.

    //

    // IMPLEMENTATION NOTE: C++11 unique_ptr<> keeps this constructor distinct

    // from the normal move constructor. By C++11 20.7.1.2.1.21, this constructor

    // has different post-conditions if D is a reference type. Since this

    // implementation does not support deleters with reference type,

    // we do not need a separate move constructor allowing us to avoid one

    // use of SFINAE. You only need to care about this if you modify the

    // implementation of gscoped_ptr.

    template <typename U, typename V>

    gscoped_ptr(gscoped_ptr<U, V> other) : impl_(&other.impl_) {

        COMPILE_ASSERT(!std::is_array<U>::value, U_cannot_be_an_array);

    }

    // Constructor.  Move constructor for C++03 move emulation of this type.

    gscoped_ptr(RValue rvalue) : impl_(&rvalue.object->impl_) {}

    // operator=.  Allows assignment from a gscoped_ptr rvalue for a convertible

    // type and deleter.

    //

    // IMPLEMENTATION NOTE: C++11 unique_ptr<> keeps this operator= distinct from

    // the normal move assignment operator. By C++11 20.7.1.2.3.4, this templated

    // form has different requirements on for move-only Deleters. Since this

    // implementation does not support move-only Deleters, we do not need a

    // separate move assignment operator allowing us to avoid one use of SFINAE.

    // You only need to care about this if you modify the implementation of

    // gscoped_ptr.

    template <typename U, typename V>

    gscoped_ptr& operator=(gscoped_ptr<U, V> rhs) {

        COMPILE_ASSERT(!std::is_array<U>::value, U_cannot_be_an_array);

        impl_.TakeState(&rhs.impl_);

        return *this;

    }

    // Reset.  Deletes the currently owned object, if any.

    // Then takes ownership of a new object, if given.

    void reset(element_type* p = NULL) { impl_.reset(p); }

    // Accessors to get the owned object.

    // operator* and operator-> will assert() if there is no current object.

    element_type& operator*() const {

        assert(impl_.get() != NULL);

        return *impl_.get();

    }

    element_type* operator->() const {

        assert(impl_.get() != NULL);

        return impl_.get();

    }

    element_type* get() const { return impl_.get(); }

    // Access to the deleter.

    deleter_type& get_deleter() { return impl_.get_deleter(); }

    const deleter_type& get_deleter() const { return impl_.get_deleter(); }

    // Allow gscoped_ptr<element_type> to be used in boolean expressions, but not

    // implicitly convertible to a real bool (which is dangerous).

private:

    typedef doris::internal::gscoped_ptr_impl<element_type, deleter_type> gscoped_ptr::*Testable;

public:

    operator Testable() const { return impl_.get() ? &gscoped_ptr::impl_ : NULL; }

    // Comparison operators.

    // These return whether two gscoped_ptr refer to the same object, not just to

    // two different but equal objects.

    bool operator==(const element_type* p) const { return impl_.get() == p; }

    bool operator!=(const element_type* p) const { return impl_.get() != p; }

    // Swap two scoped pointers.

    void swap(gscoped_ptr& p2) { impl_.swap(p2.impl_); }

    // 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.

    element_type* release() WARN_UNUSED_RESULT { return impl_.release(); }

    // C++98 doesn't support functions templates with default parameters which

    // makes it hard to write a PassAs() that understands converting the deleter

    // while preserving simple calling semantics.

    //

    // Until there is a use case for PassAs() with custom deleters, just ignore

    // the custom deleter.

    template <typename PassAsType>

    gscoped_ptr<PassAsType> PassAs() {

        return gscoped_ptr<PassAsType>(Pass());

    }

private:

    // Needed to reach into |impl_| in the constructor.

    template <typename U, typename V>

    friend class gscoped_ptr;

    doris::internal::gscoped_ptr_impl<element_type, deleter_type> impl_;

    // Forbid comparison of gscoped_ptr types.  If U != T, it totally

    // doesn't make sense, and if U == T, it still doesn't make sense

    // because you should never have the same object owned by two different

    // gscoped_ptrs.

    template <class U>

    bool operator==(gscoped_ptr<U> const& p2) const;

    template <class U>

    bool operator!=(gscoped_ptr<U> const& p2) const;

};

template <class T, class D>

class gscoped_ptr<T[], D> {

    MOVE_ONLY_TYPE_FOR_CPP_03(gscoped_ptr, RValue)

public:

    // The element and deleter types.

    typedef T element_type;

    typedef D deleter_type;

    // Constructor.  Defaults to initializing with NULL.

    gscoped_ptr() : impl_(NULL) {}

    // 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 NULL, because NULL is an integral expression, not a

    //   pointer to T. Use the no-argument version instead of explicitly

    //   passing NULL.

    // - 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 implicit_cast<const T*>().

    //   However, because of the first bullet in this comment, users MUST

    //   NOT use implicit_cast<Base*>() to upcast the static type of the array.

    explicit gscoped_ptr(element_type* array) : impl_(array) {}

    // Constructor.  Move constructor for C++03 move emulation of this type.

    gscoped_ptr(RValue rvalue) : impl_(&rvalue.object->impl_) {}

    // operator=.  Move operator= for C++03 move emulation of this type.

    gscoped_ptr& operator=(RValue rhs) {

        impl_.TakeState(&rhs.object->impl_);

        return *this;

    }

    // Reset.  Deletes the currently owned array, if any.

    // Then takes ownership of a new object, if given.

    void reset(element_type* array = NULL) { impl_.reset(array); }

    // Accessors to get the owned array.

    element_type& operator[](size_t i) const {

        assert(impl_.get() != NULL);

        return impl_.get()[i];

    }

    element_type* get() const { return impl_.get(); }

    // Access to the deleter.

    deleter_type& get_deleter() { return impl_.get_deleter(); }

    const deleter_type& get_deleter() const { return impl_.get_deleter(); }

    // Allow gscoped_ptr<element_type> to be used in boolean expressions, but not

    // implicitly convertible to a real bool (which is dangerous).

private:

    typedef doris::internal::gscoped_ptr_impl<element_type, deleter_type> gscoped_ptr::*Testable;

public:

    operator Testable() const { return impl_.get() ? &gscoped_ptr::impl_ : NULL; }

    // Comparison operators.

    // These return whether two gscoped_ptr refer to the same object, not just to

    // two different but equal objects.

    bool operator==(element_type* array) const { return impl_.get() == array; }

    bool operator!=(element_type* array) const { return impl_.get() != array; }

    // Swap two scoped pointers.

    void swap(gscoped_ptr& p2) { impl_.swap(p2.impl_); }

    // 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.

    element_type* release() WARN_UNUSED_RESULT { return impl_.release(); }

private:

    // Force element_type to be a complete type.

    enum { type_must_be_complete = sizeof(element_type) };

    // Actually hold the data.

    doris::internal::gscoped_ptr_impl<element_type, deleter_type> impl_;

    // 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 gscoped_ptr(U* array);

    explicit gscoped_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);

    // Forbid comparison of gscoped_ptr types.  If U != T, it totally

    // doesn't make sense, and if U == T, it still doesn't make sense

    // because you should never have the same object owned by two different

    // gscoped_ptrs.

    template <class U>

    bool operator==(gscoped_ptr<U> const& p2) const;

    template <class U>

    bool operator!=(gscoped_ptr<U> const& p2) const;

};

// Free functions

template <class T, class D>

void swap(gscoped_ptr<T, D>& p1, gscoped_ptr<T, D>& p2) {

    p1.swap(p2);

}

template <class T, class D>

bool operator==(T* p1, const gscoped_ptr<T, D>& p2) {

    return p1 == p2.get();

}

template <class T, class D>

bool operator!=(T* p1, const gscoped_ptr<T, D>& p2) {

    return p1 != p2.get();

}

// DEPRECATED: Use gscoped_ptr<C[]> instead.

//

// gscoped_array<C> is like gscoped_ptr<C>, except that the caller must allocate

// with new [] and the destructor deletes objects with delete [].

//

// As with gscoped_ptr<C>, a gscoped_array<C> either points to an object

// or is NULL.  A gscoped_array<C> owns the object that it points to.

// gscoped_array<T> is thread-compatible, and once you index into it,

// the returned objects have only the thread safety guarantees of T.

//

// Size: sizeof(gscoped_array<C>) == sizeof(C*)

template <class C>

class gscoped_array {

    MOVE_ONLY_TYPE_FOR_CPP_03(gscoped_array, RValue)

public:

    // The element type

    typedef C element_type;

    // Constructor.  Defaults to initializing with NULL.

    // There is no way to create an uninitialized gscoped_array.

    // The input parameter must be allocated with new [].

    explicit gscoped_array(C* p = NULL) : array_(p) {}

    // Constructor.  Move constructor for C++03 move emulation of this type.

    gscoped_array(RValue rvalue) : array_(rvalue.object->release()) {}

    // Destructor.  If there is a C object, delete it.

    // We don't need to test ptr_ == NULL because C++ does that for us.

    ~gscoped_array() {

        enum { type_must_be_complete = sizeof(C) };

        delete[] array_;

    }

    // operator=.  Move operator= for C++03 move emulation of this type.

    gscoped_array& operator=(RValue rhs) {

        reset(rhs.object->release());

        return *this;

    }

    // Reset.  Deletes the current owned object, if any.

    // Then takes ownership of a new object, if given.

    // this->reset(this->get()) works.

    void reset(C* p = NULL) {

        if (p != array_) {

            enum { type_must_be_complete = sizeof(C) };

            delete[] array_;

            array_ = p;

        }

    }

    // Get one element of the current object.

    // Will assert() if there is no current object, or index i is negative.

    C& operator[](ptrdiff_t i) const {

        assert(i >= 0);

        assert(array_ != NULL);

        return array_[i];

    }

    // Get a pointer to the zeroth element of the current object.

    // If there is no current object, return NULL.

    C* get() const { return array_; }

    // Allow gscoped_array<C> to be used in boolean expressions, but not

    // implicitly convertible to a real bool (which is dangerous).

    typedef C* gscoped_array::*Testable;

    operator Testable() const { return array_ ? &gscoped_array::array_ : NULL; }

    // Comparison operators.

    // These return whether two gscoped_array refer to the same object, not just to

    // two different but equal objects.

    bool operator==(C* p) const { return array_ == p; }

    bool operator!=(C* p) const { return array_ != p; }

    // Swap two scoped arrays.

    void swap(gscoped_array& p2) {

        C* tmp = array_;

        array_ = p2.array_;

        p2.array_ = tmp;

    }

    // Release an array.

    // 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() WARN_UNUSED_RESULT {

        C* retVal = array_;

        array_ = NULL;

        return retVal;

    }

private:

    C* array_;

    // Forbid comparison of different gscoped_array types.

    template <class C2>

    bool operator==(gscoped_array<C2> const& p2) const;

    template <class C2>

    bool operator!=(gscoped_array<C2> const& p2) const;

};

// Free functions

template <class C>

void swap(gscoped_array<C>& p1, gscoped_array<C>& p2) {

    p1.swap(p2);

}

template <class C>

bool operator==(C* p1, const gscoped_array<C>& p2) {

    return p1 == p2.get();

}

template <class C>

bool operator!=(C* p1, const gscoped_array<C>& p2) {

    return p1 != p2.get();

}

// DEPRECATED: Use gscoped_ptr<C, doris::FreeDeleter> instead.

//

// gscoped_ptr_malloc<> is similar to gscoped_ptr<>, but it accepts a

// second template argument, the functor used to free the object.

template <class C, class FreeProc = doris::FreeDeleter>

class gscoped_ptr_malloc {

    MOVE_ONLY_TYPE_FOR_CPP_03(gscoped_ptr_malloc, RValue)

public:

    // The element type

    typedef C element_type;

    // Constructor.  Defaults to initializing with NULL.

    // There is no way to create an uninitialized gscoped_ptr.

    // The input parameter must be allocated with an allocator that matches the

    // Free functor.  For the default Free functor, this is malloc, calloc, or

    // realloc.

    explicit gscoped_ptr_malloc(C* p = NULL) : ptr_(p) {}

    // Constructor.  Move constructor for C++03 move emulation of this type.

    gscoped_ptr_malloc(RValue rvalue) : ptr_(rvalue.object->release()) {}

    // Destructor.  If there is a C object, call the Free functor.

    ~gscoped_ptr_malloc() { reset(); }

    // operator=.  Move operator= for C++03 move emulation of this type.

    gscoped_ptr_malloc& operator=(RValue rhs) {

        reset(rhs.object->release());

        return *this;

    }

    // Reset.  Calls the Free functor on the current owned object, if any.

    // Then takes ownership of a new object, if given.

    // this->reset(this->get()) works.

    void reset(C* p = NULL) {

        if (ptr_ != p) {

            if (ptr_ != NULL) {

                FreeProc free_proc;

                free_proc(ptr_);

            }

            ptr_ = p;

        }

    }

    // Get the current object.

    // operator* and operator-> will cause an assert() failure if there is

    // no current object.

    C& operator*() const {

        assert(ptr_ != NULL);

        return *ptr_;

    }

    C* operator->() const {

        assert(ptr_ != NULL);

        return ptr_;

    }

    C* get() const { return ptr_; }

    // Allow gscoped_ptr_malloc<C> to be used in boolean expressions, but not

    // implicitly convertible to a real bool (which is dangerous).

    typedef C* gscoped_ptr_malloc::*Testable;

    operator Testable() const { return ptr_ ? &gscoped_ptr_malloc::ptr_ : NULL; }

    // Comparison operators.

    // These return whether a gscoped_ptr_malloc and a plain pointer refer

    // to the same object, not just to two different but equal objects.

    // For compatibility with the boost-derived implementation, these

    // take non-const arguments.

    bool operator==(C* p) const { return ptr_ == p; }

    bool operator!=(C* p) const { return ptr_ != p; }

    // Swap two scoped pointers.

    void swap(gscoped_ptr_malloc& b) {

        C* tmp = b.ptr_;

        b.ptr_ = ptr_;

        ptr_ = 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() WARN_UNUSED_RESULT {

        C* tmp = ptr_;

        ptr_ = NULL;

        return tmp;

    }

private:

    C* ptr_;

    // no reason to use these: each gscoped_ptr_malloc should have its own object

    template <class C2, class GP>

    bool operator==(gscoped_ptr_malloc<C2, GP> const& p) const;

    template <class C2, class GP>

    bool operator!=(gscoped_ptr_malloc<C2, GP> const& p) const;

};

template <class C, class FP>

void swap(gscoped_ptr_malloc<C, FP>& a, gscoped_ptr_malloc<C, FP>& b) {

    a.swap(b);

}

template <class C, class FP>

bool operator==(C* p, const gscoped_ptr_malloc<C, FP>& b) {

    return p == b.get();

}

template <class C, class FP>

bool operator!=(C* p, const gscoped_ptr_malloc<C, FP>& b) {

    return p != b.get();

}

// A function to convert T* into gscoped_ptr<T>

// Doing e.g. make_gscoped_ptr(new FooBarBaz<type>(arg)) is a shorter notation

// for gscoped_ptr<FooBarBaz<type>>(new FooBarBaz<type>(arg))

template <typename T>

gscoped_ptr<T> make_gscoped_ptr(T* ptr) {

    return gscoped_ptr<T>(ptr);

}