text: // Ceres Solver - A fast non-linear least squares minimizer
  // Copyright 2010, 2011, 2012 Google Inc. All rights reserved.
  // http://code.google.com/p/ceres-solver/
  //
  // 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.
  //
  // Author: jorg@google.com (Jorg Brown)
  //
  // 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, and make_scoped_ptr.
  
  #ifndef CERES_PUBLIC_INTERNAL_SCOPED_PTR_H_
  #define CERES_PUBLIC_INTERNAL_SCOPED_PTR_H_
  
  #include <assert.h>
  #include <stdlib.h>
  #include <cstddef>
  
  namespace ceres {
  namespace internal {
  
  template <class C> class scoped_ptr;
  template <class C, class Free> class scoped_ptr_malloc;
  template <class C> class scoped_array;
  
  template <class C>
  scoped_ptr<C> make_scoped_ptr(C *);
  
  // A scoped_ptr<T> is like a T*, except that the destructor of scoped_ptr<T>
  // automatically deletes the pointer it holds (if any). That is, scoped_ptr<T>
  // owns the T object that it points to. Like a T*, a scoped_ptr<T> may hold
  // either NULL or a pointer to a T object. Also like T*, scoped_ptr<T> is
  // thread-compatible, and once you dereference it, you get the threadsafety
  // guarantees of T.
  //
  // The size of a scoped_ptr is small: sizeof(scoped_ptr<C>) == sizeof(C*)
  template <class C>
  class scoped_ptr {
   public:
  
    // The element type
    typedef C element_type;
  
    // Constructor.  Defaults to intializing with NULL.
    // There is no way to create an uninitialized scoped_ptr.
    // The input parameter must be allocated with new.
    explicit scoped_ptr(C* p = NULL) : ptr_(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_ptr() {
      enum { type_must_be_complete = sizeof(C) };
      delete ptr_;
    }
  
    // 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 != ptr_) {
        enum { type_must_be_complete = sizeof(C) };
        delete ptr_;
        ptr_ = p;
      }
    }
  
    // Accessors to get the owned object.
    // operator* and operator-> will assert() 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_; }
  
    // Comparison operators.
    // These return whether a scoped_ptr and a raw pointer refer to
    // the same object, not just to two different but equal objects.
    bool operator==(const C* p) const { return ptr_ == p; }
    bool operator!=(const C* p) const { return ptr_ != p; }
  
    // Swap two scoped pointers.
    void swap(scoped_ptr& p2) {
      C* tmp = ptr_;
      ptr_ = p2.ptr_;
      p2.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() {
      C* retVal = ptr_;
      ptr_ = NULL;
      return retVal;
    }
  
   private:
    C* ptr_;
  
    // google3 friend class that can access copy ctor (although if it actually
    // calls a copy ctor, there will be a problem) see below
    friend scoped_ptr<C> make_scoped_ptr<C>(C *p);
  
    // Forbid comparison of scoped_ptr types.  If C2 != C, it totally doesn't
    // make sense, and if C2 == C, it still doesn't make sense because you should
    // never have the same object owned by two different scoped_ptrs.
    template <class C2> bool operator==(scoped_ptr<C2> const& p2) const;
    template <class C2> bool operator!=(scoped_ptr<C2> const& p2) const;
  
    // Disallow evil constructors
    scoped_ptr(const scoped_ptr&);
    void operator=(const scoped_ptr&);
  };
  
  // Free functions
  template <class C>
  inline void swap(scoped_ptr<C>& p1, scoped_ptr<C>& p2) {
    p1.swap(p2);
  }
  
  template <class C>
  inline bool operator==(const C* p1, const scoped_ptr<C>& p2) {
    return p1 == p2.get();
  }
  
  template <class C>
  inline bool operator==(const C* p1, const scoped_ptr<const C>& p2) {
    return p1 == p2.get();
  }
  
  template <class C>
  inline bool operator!=(const C* p1, const scoped_ptr<C>& p2) {
    return p1 != p2.get();
  }
  
  template <class C>
  inline bool operator!=(const C* p1, const scoped_ptr<const C>& p2) {
    return p1 != p2.get();
  }
  
  template <class C>
  scoped_ptr<C> make_scoped_ptr(C *p) {
    // This does nothing but to return a scoped_ptr of the type that the passed
    // pointer is of.  (This eliminates the need to specify the name of T when
    // making a scoped_ptr that is used anonymously/temporarily.)  From an
    // access control point of view, we construct an unnamed scoped_ptr here
    // which we return and thus copy-construct.  Hence, we need to have access
    // to scoped_ptr::scoped_ptr(scoped_ptr const &).  However, it is guaranteed
    // that we never actually call the copy constructor, which is a good thing
    // as we would call the temporary's object destructor (and thus delete p)
    // if we actually did copy some object, here.
    return scoped_ptr<C>(p);
  }
  
  // scoped_array<C> is like scoped_ptr<C>, except that the caller must allocate
  // with new [] and the destructor deletes objects with delete [].
  //
  // As with scoped_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 = NULL) : 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 = 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[](std::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_;
    }
  
    // Comparison operators.
    // These return whether a scoped_array and a raw pointer refer to
    // the same array, not just to two different but equal arrays.
    bool operator==(const C* p) const { return array_ == p; }
    bool operator!=(const 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_ = NULL;
      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>
  inline void swap(scoped_array<C>& p1, scoped_array<C>& p2) {
    p1.swap(p2);
  }
  
  template <class C>
  inline bool operator==(const C* p1, const scoped_array<C>& p2) {
    return p1 == p2.get();
  }
  
  template <class C>
  inline bool operator==(const C* p1, const scoped_array<const C>& p2) {
    return p1 == p2.get();
  }
  
  template <class C>
  inline bool operator!=(const C* p1, const scoped_array<C>& p2) {
    return p1 != p2.get();
  }
  
  template <class C>
  inline bool operator!=(const C* p1, const scoped_array<const C>& p2) {
    return p1 != p2.get();
  }
  
  // This class wraps the c library function free() in a class that can be
  // passed as a template argument to scoped_ptr_malloc below.
  class ScopedPtrMallocFree {
   public:
    inline void operator()(void* x) const {
      free(x);
    }
  };
  
  }  // namespace internal
  }  // namespace ceres
  
  #endif  // CERES_PUBLIC_INTERNAL_SCOPED_PTR_H_
  