// -*- c++ -*-
//------------------------------------------------------------------------------
//                               AutoPtr.h
//------------------------------------------------------------------------------
//  Copyright (C) 1999,2005  Vladislav Grinchenko
//
//  This library is free software; you can redistribute it and/or
//  modify it under the terms of the GNU Library General Public
//  License as published by the Free Software Foundation; either
//  version 2 of the License, or (at your option) any later version. 
//------------------------------------------------------------------------------
#ifndef AUTO_PTR_H
#define AUTO_PTR_H

#include <cstdlib>				// NULL definition

/** @file AutoPtr.h 

   AutoPtr is a local implementation of STL's auto_ptr that makes dynamic
   memory handling a bit easier.
*/

namespace ASSA {

/**
 * @class AutoPtrRef
 *
 * A wrapper class to provide AutoPtr with reference semantics.
 * An AutoPtr can be assigned (or constructed from) the result of 
 * a function which returns an AutoPtr by value (rvalue).
 */
template<typename R> class AutoPtrRef {
public:
	explicit AutoPtrRef (R* p_) : m_ptr (p_) { /* no-op */ }
	
	R* m_ptr;
};
 
/** 
	@class AutoPtr

	AutoPtr is based on SGI implementation of a auto_ptr template that 
	makes memory handling a little bit easier.

	AutoPtr interface does not completely confirm to that of auto_ptr as 
	specified in C++ Standard. 
*/

template<class X> class AutoPtr {
private:
    /// Pointer to the object we own
    X* m_ptr;

public:
    /** 
	 *  Construct an AutoPtr from a raw pointer.
	 *  The word 'explicit' disallows implicit construction of objects, 
	 *  for example in function  calls. 
	 *  @param p_ pointer (defaults to NULL) to assume ownerwhip for.
     */
    explicit AutoPtr (X* p_ = 0) : m_ptr (p_) { /* no-op */ }

    /** 
	 *  Construct AutoPtr from another AutoPtr.
	 *  @param a_ AutoPtr object that gives up its ownership.
     */
    AutoPtr (AutoPtr& a_) : m_ptr (a_.release ()) {/* no-op */ }

    /** 
	 *  Construct AutoPtr from another AutoPtr of different (but related)
	 *  type. A pointer to T must be convertible to a pointer to X.
	 *  @note Nonconstant parameter
	 *  @param a_ AutoPtr object that is released of ownership.
     */
	template<typename T> 
	AutoPtr (AutoPtr<T>& a_) : m_ptr (a_.release ()) { /* no-op */ }

    /** 
	 *  Assignment operator deletes memory it owns 
     *  and transfers the ownership from a_ to itself.
     *  @param a_ another AutoPtr of the same type.
     */
    AutoPtr& operator= (AutoPtr& a_)  {
		reset (a_.release ());
		return *this;
    }

    /** 
	 *  Assignment from another AutoPtr of a different but related type.
	 *  @note Nonconstant parameter
     *  @param a_ AutoPtr to assume ownership of
     */
    template<class T> AutoPtr& operator=(AutoPtr<T>& a_) {
		reset (a_.release ());
		return *this;
	}

    /** 
     *  When AutoPtr goes out of scope, the object it owns is deleted.
	 *  Not owning anything has no effect.
     */
    ~AutoPtr () { 
		if (m_ptr) { 
			delete m_ptr; 
		}  
	}
    
	/**
	 * Smart pointer dereferencing.
	 */
    X& operator*() const  { return *m_ptr; }

	/**
	 * Smart pointer dereferencing.
	 */
    X* operator->() const  { return m_ptr; }
	
    /** 
	 *  Get a raw memory pointer without changing ownership status. 
     *  Usefull when you need to pass a pointer to the function.
	 *  @return The raw pointer being managed.
     */
    X* get () const { return m_ptr; }

	/**
	 *  Give up the ownership of the memory. When AutoPtr gets
	 *  out of scope, nothing happens. The caller becomes responsible
	 *  for the memory management.
	 */
	X* release () {
		X* tmp = m_ptr;
		m_ptr = NULL;
		return tmp;
	}
	
    /** 
     *  Forcibly delete the managed object and assume the ownership
	 *  of a_.
     */
	void reset (X* p_ = 0) {
		if (p_ != m_ptr) {
			delete m_ptr;
			m_ptr = p_;
		}
	}

	/** @{
	 *  @brief Automagic conversions
	 *
	 *  These operations convert an AutoPtr into/from an AutoPtrRef
	 *  as needed. This allows on-the-fly conversion between AutoPtr 
	 *  of different but related types (parent/child):
	 *  @code
	 *     AutoPtr<Derived> FooReturnsAutoPtr () { ... };
	 *
	 *     AutoPtr<Base> aptr = FooReturnsAutoPtr ();
	 *  @endcode
	 */
	AutoPtr (AutoPtrRef<X> ref_) : m_ptr (ref_.m_ptr) { /* no-op */ }

	AutoPtr& operator=(AutoPtrRef<X> ref_) {
		if (ref_.m_ptr != get ()) {
			delete m_ptr;
			m_ptr = ref_.m_ptr;
		}
		return *this;
	}
	
	template<typename T>
	operator AutoPtrRef<T> () { return AutoPtrRef<T> (release ()); }

	template<typename T>
	operator AutoPtr<T> () { return AutoPtr<T> (release ()); }
	
	/** @} */
};

/**
 * @class AutoPtrArrayRef
 *
 * A wrapper class to provide AutoPtr with reference semantics.
 * An AutoPtr can be assigned (or constructed from) the result of 
 * a function which returns an AutoPtr by value (rvalue).
 */
template<typename R> class AutoPtrArrayRef {
public:
	explicit AutoPtrArrayRef (R* p_) : m_ptr (p_) { /* no-op */ }
	
	R* m_ptr;
};

/** 
	@class AutoPtrArray

	@brief AutoPtrArray handles memory management of an array of objects.
*/

template<class X> class AutoPtrArray {
private:
    /// Pointer to the object we own
    X* m_ptr;

public:
    /** 
	 *  Construct an AutoPtrArray from a raw pointer.
	 *  The word 'explicit' disallows implicit construction of objects, 
	 *  for example in function  calls. 
	 *  @param p_ pointer (defaults to NULL) to assume ownerwhip for.
     */
    explicit AutoPtrArray (X* p_ = 0) : m_ptr (p_) { /* no-op */ }

    /** 
	 *  Construct AutoPtrArray from another AutoPtrArray.
	 *  @param a_ AutoPtrArray object that gives up its ownership.
     */
    AutoPtrArray (AutoPtrArray& a_) : m_ptr (a_.release ()) {/* no-op */ }

    /** 
	 *  Construct AutoPtrArray from another AutoPtrArray of different 
	 *  (but related) type. A pointer to T must be convertible to a 
	 *  pointer to X.
	 *  @note Nonconstant paramenter
	 *  @param a_ AutoPtrArray object that is released of ownership.
     */
	template<typename T> 
	AutoPtrArray (AutoPtrArray<T>& a_) 
		: m_ptr (a_.release ()) { /* no-op */ }

    /** 
	 *  Assignment operator deletes memory it owns 
     *  and transfers the ownership from a_ to itself.
	 *  @note Nonconstant parameter
     *  @param a_ another AutoPtrArray of the same type.
     */
    AutoPtrArray& operator= (AutoPtrArray& a_)  {
		reset (a_.release ());
		return *this;
    }

    /** 
	 *  Assignment from another AutoPtrArray of a different but related type.
	 *  @note Nonconstant parameter
     *  @param a_ AutoPtrArray to assume ownership of
     */
    template<class T> 
	AutoPtrArray& operator=(AutoPtrArray<T>& a_) {
		reset (a_.release ());
		return *this;
	}

    /** 
     *  When AutoPtrArray goes out of scope, the object it owns is deleted.
	 *  Not owning anything has no effect.
     */
    ~AutoPtrArray () { 
		if (m_ptr) { 
			delete [] m_ptr; 
		}  
	}
    
	/**
	 * Smart pointer dereferencing.
	 */
    X& operator*() const  { return *m_ptr; }

	/**
	 * Smart pointer dereferencing.
	 */
    X* operator->() const  { return m_ptr; }

	/** 
	 *  Access operator
	 */
	X& operator[] (int i) const {
		X* array = get ();
		return (array [i]);
	}
	
    /** 
	 *  Get a raw memory pointer without changing ownership status. 
     *  Usefull when you need to pass a pointer to the function.
	 *  @return The raw pointer being managed.
     */
    X* get () const  { return m_ptr; }

	/**
	 *  Give up the ownership of the memory. When AutoPtrArray gets
	 *  out of scope, nothing happens. The caller becomes responsible
	 *  for the memory management.
	 */
	X* release () {
		X* tmp = m_ptr;
		m_ptr = NULL;
		return tmp;
	}
	
    /** 
     *  Forcibly delete the managed object and assume the ownership
	 *  of a_.
     */
	void reset (X* p_ = 0) {
		if (p_ != m_ptr) {
			delete [] m_ptr;
			m_ptr = p_;
		}
	}

	/** @{
	 *  @brief Automagic conversions
	 *
	 *  These operations convert an AutoPtrArray into/from an AutoPtrArrayRef
	 *  as needed. This allows on-the-fly conversion between AutoPtrArray 
	 *  of different but related types (parent/child):
	 *  @code
	 *     AutoPtrArray<Derived> FooReturnsAutoPtrArray () { ... };
	 *
	 *     AutoPtrArray<Base> aptr = FooReturnsAutoPtrArray ();
	 *  @endcode
	 */
	AutoPtrArray (AutoPtrArrayRef<X> ref_) : m_ptr (ref_.m_ptr) { /* no-op */ }

	AutoPtrArray& operator=(AutoPtrArrayRef<X> ref_) {
		if (ref_.m_ptr != get ()) {
			delete [] m_ptr;
			m_ptr = ref_.m_ptr;
		}
		return *this;
	}
	
	template<typename T>
	operator AutoPtrArrayRef<T> () { return AutoPtrArrayRef<T> (release ()); }

	template<typename T>
	operator AutoPtrArray<T> () { return AutoPtrArray<T> (release ()); }
	
	/** @} */
};

} // end namespace ASSA

#endif /* AUTO_PTR_H */