//
// Buffer.h
//
// $Id: //poco/1.4/Foundation/include/Poco/Buffer.h#2 $
//
// Library: Foundation
// Package: Core
// Module:  Buffer
//
// Definition of the Buffer class.
//
// Copyright (c) 2006, Applied Informatics Software Engineering GmbH.
// and Contributors.
//
// Permission is hereby granted, free of charge, to any person or organization
// obtaining a copy of the software and accompanying documentation covered by
// this license (the "Software") to use, reproduce, display, distribute,
// execute, and transmit the Software, and to prepare derivative works of the
// Software, and to permit third-parties to whom the Software is furnished to
// do so, all subject to the following:
// 
// The copyright notices in the Software and this entire statement, including
// the above license grant, this restriction and the following disclaimer,
// must be included in all copies of the Software, in whole or in part, and
// all derivative works of the Software, unless such copies or derivative
// works are solely in the form of machine-executable object code generated by
// a source language processor.
// 
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
// SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
// FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
// ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
// DEALINGS IN THE SOFTWARE.
//


#ifndef Foundation_Buffer_INCLUDED
#define Foundation_Buffer_INCLUDED


#include "Poco/Foundation.h"
#include <cstddef>
#include <cstring>


namespace Poco {


template <class T>
class Buffer
        /// A buffer class that allocates a buffer of a given type and size.
        /// Buffer can be zero-size, resized, copy-constructed and assigned.
        /// Memory allocation, resizing and deallocation is managed automatically.
        ///
        /// This class is useful everywhere where a temporary buffer
        /// is needed.
{
public:
        Buffer(std::size_t size):
                _size(size),
                _ptr(size ? new T[size] : 0)
                /// Creates and allocates the Buffer.
        {
        }
        
        Buffer(): _size(0),     _ptr(0)
                /// Creates the Buffer.
        {
        }
        
        Buffer(const Buffer& other):
                /// Copy constructor.
                _size(other._size),
                _ptr(other._size ? new T[other._size] : 0)
        {
                if (_size)
                        std::memcpy(_ptr, other._ptr, _size * sizeof(T));
        }

        Buffer& operator = (const Buffer& other)
                /// Assignment operator.
                {
                if (this != &other)
                {
                        Buffer tmp(other);
                        swap(tmp);
                }

                return *this;
        }

        ~Buffer()
                /// Destroys the Buffer.
        {
                delete [] _ptr;
        }
        
        void swap(Buffer& other)
                /// Swaps the buffer with another one.
        {
                using std::swap;
                
                swap(_ptr, other._ptr);
                swap(_size, other._size);
        }
        
        std::size_t size() const
		/// Returns the size of the buffer.
	{
                return _size;
        }
        
        void clear()
                /// Sets the contents of the bufer to zero.
        {
                std::memset(_ptr, 0, _size * sizeof(T));
        }

        void resize(std::size_t newSize, bool preserve = false)
                /// Resizes the buffer. If preserve is true, the contents
                /// of the buffer is preserved. If the newSize is smaller
                /// than the current size, data truncation will occur.
                /// 
                /// For efficiency sake, the default behavior is not to
                /// preserve the contents.
        {
                if (preserve) 
                {
                        if (_size == newSize) return;
                        Buffer tmp;
                        tmp = *this;
                        recreate(newSize);
                        std::size_t size = _size < tmp._size ? _size : tmp._size;
                        std::memcpy(_ptr, tmp._ptr, size * sizeof(T));
                        return;
                }
                else if (_size == newSize) 
                {
                        clear();
                        return;
                }

                recreate(newSize);
        }

        void append(const T* buf, std::size_t sz)
                /// Resizes this buffer and appends the argument buffer.
        {
                if (0 == sz) return;
                std::size_t oldSize = _size;
                resize(_size + sz, true);
                std::memcpy(_ptr + oldSize, buf, sz);
        }

        void append(const Buffer& buf)
                /// Resizes this buffer and appends the argument buffer.
        {
                append(buf.begin(), buf.size());
        }

        std::size_t elementSize() const
                /// Returns the size of the buffer element.
        {
                return sizeof(T);
        }

        std::size_t byteCount() const
                /// Returns the total length of the buffer in bytes.
        {
                return _size * sizeof(T);
        }

        T* begin()
                /// Returns a pointer to the beginning of the buffer.
        {
		return _ptr;
	}
	
	const T* begin() const
		/// Returns a pointer to the beginning of the buffer.
	{
		return _ptr;
	}

	T* end()
		/// Returns a pointer to end of the buffer.
	{
		return _ptr + _size;
	}
	
	const T* end() const
		/// Returns a pointer to the end of the buffer.
	{
                return _ptr + _size;
        }
        
        bool isEmpty() const
                /// Return true if buffer is empty.
        {
                return 0 == _size;
        }

        T& operator [] (std::size_t index)
        {
                poco_assert (index < _size);
		
		return _ptr[index];
	}

	const T& operator [] (std::size_t index) const
	{
		poco_assert (index < _size);
		
		return _ptr[index];
        }

private:

        void recreate(std::size_t newSize)
        {
                if (newSize != _size)
                {
                        delete [] _ptr;
                        if (0 == newSize)
                                _ptr = 0;
                        else
                                _ptr = new T[newSize];

                        _size = newSize;
                }
        }

        std::size_t _size;
        T* _ptr;
};


} // namespace Poco


#endif // Foundation_Buffer_INCLUDED