// Copyright 2013 Google LLC
//
// 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 LLC 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.

// scoped_ptr is just a type alias for std::unique_ptr. Mass conversion TBD.

#ifndef COMMON_SCOPED_PTR_H_
#define COMMON_SCOPED_PTR_H_

// This is an implementation designed to match the anticipated future TR2
// implementation of the scoped_array class.

#include <assert.h>
#include <stddef.h>
#include <stdlib.h>

#include <memory>

#include "breakpad/common/scoped_ptr.h"

namespace google_breakpad {

// scoped_array<C> is like std::unique_ptr<C>, except that the caller must allocate
// with new [] and the destructor deletes objects with delete [].
//
// As with std::unique_ptr<C>, a scoped_array<C> either points to an object
// or is NULL.  A scoped_array<C> owns the object that it points to.
// scoped_array<T> is thread-compatible, and once you index into it,
// the returned objects have only the threadsafety guarantees of T.
//
// Size: sizeof(scoped_array<C>) == sizeof(C*)
template <class C>
class scoped_array {
 public:

  // The element type
  typedef C element_type;

  // Constructor.  Defaults to intializing with NULL.
  // There is no way to create an uninitialized scoped_array.
  // The input parameter must be allocated with new [].
  explicit scoped_array(C* p = nullptr) : array_(p) { }

  // Destructor.  If there is a C object, delete it.
  // We don't need to test ptr_ == NULL because C++ does that for us.
  ~scoped_array() {
    enum { type_must_be_complete = sizeof(C) };
    delete[] array_;
  }

  // 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 = nullptr) {
    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_ != nullptr);
    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_;
  }

  // Comparison operators.
  // These return whether two scoped_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(scoped_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() {
    C* retVal = array_;
    array_ = nullptr;
    return retVal;
  }

 private:
  C* array_;

  // Forbid comparison of different scoped_array types.
  template <class C2> bool operator==(scoped_array<C2> const& p2) const;
  template <class C2> bool operator!=(scoped_array<C2> const& p2) const;

  // Disallow evil constructors
  scoped_array(const scoped_array&);
  void operator=(const scoped_array&);
};

// Free functions
template <class C>
void swap(scoped_array<C>& p1, scoped_array<C>& p2) {
  p1.swap(p2);
}

template <class C>
bool operator==(C* p1, const scoped_array<C>& p2) {
  return p1 == p2.get();
}

template <class C>
bool operator!=(C* p1, const scoped_array<C>& p2) {
  return p1 != p2.get();
}

}  // namespace google_breakpad

#endif  // COMMON_SCOPED_PTR_H_
