vmime/src/encoding.cpp

//
// VMime library (http://vmime.sourceforge.net)
// Copyright (C) 2002-2004 Vincent Richard <vincent@vincent-richard.net>
//
// This program is free software; you can redistribute it and/or
// modify it under the terms of the GNU General Public License as
// published by the Free Software Foundation; either version 2 of
// the License, or (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
// General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
//

#include "encoding.hpp"
#include "encoderFactory.hpp"
#include "contentHandler.hpp"

#include <algorithm>


namespace vmime
{


encoding::encoding()
	: m_name(encodingTypes::SEVEN_BIT)
{
}


encoding::encoding(const string& name)
	: m_name(toLower(name))
{
}


encoding::encoding(const encoding& enc)
	: component(), m_name(enc.m_name)
{
}


void encoding::parse(const string& buffer, const string::size_type position,
	const string::size_type end, string::size_type* newPosition)
{
	m_name = toLower(string(buffer.begin() + position, buffer.begin() + end));

	if (newPosition)
		*newPosition = end;
}


void encoding::generate(utility::outputStream& os, const string::size_type /* maxLineLength */,
	const string::size_type curLinePos, string::size_type* newLinePos) const
{
	os << m_name;

	if (newLinePos)
		*newLinePos = curLinePos + m_name.length();
}


encoder* encoding::getEncoder() const
{
	return (encoderFactory::getInstance()->create(generate()));
}


encoding& encoding::operator=(const encoding& source)
{
	m_name = source.m_name;
	return (*this);
}


encoding& encoding::operator=(const string& name)
{
	m_name = toLower(name);
	return (*this);
}


const bool encoding::operator==(const encoding& value) const
{
	return (toLower(m_name) == value.m_name);
}


const bool encoding::operator!=(const encoding& value) const
{
	return !(*this == value);
}


const encoding encoding::decide
	(const string::const_iterator begin, const string::const_iterator end)
{
	const string::difference_type length = end - begin;
	const string::difference_type count = std::count_if
		(begin, end, std::bind2nd(std::less<unsigned char>(), 127));

	// All is in 7-bit US-ASCII --> 7-bit (or Quoted-Printable...)
	if (length == count)
	{
		// Now, we check if there is any line with more than
		// "lineLengthLimits::convenient" characters (7-bit requires that)
		string::const_iterator p = begin;

		const string::size_type maxLen = lineLengthLimits::convenient;
		string::size_type len = 0;

		for ( ; p != end && len <= maxLen ; )
		{
			if (*p == '\n')
			{
				len = 0;
				++p;

				// May or may not need to be encoded, we don't take
				// any risk (avoid problems with SMTP)
				if (p != end && *p == '.')
					len = maxLen + 1;
			}
			else
			{
				++len;
				++p;
			}
		}

		if (len > maxLen)
			return (encoding(encodingTypes::QUOTED_PRINTABLE));
		else
			return (encoding(encodingTypes::SEVEN_BIT));
	}
	// Less than 20% non US-ASCII --> Quoted-Printable
	else if ((length - count) <= length / 5)
	{
		return (encoding(encodingTypes::QUOTED_PRINTABLE));
	}
	// Otherwise --> Base64
	else
	{
		return (encoding(encodingTypes::BASE64));
	}
}


const encoding encoding::decide(const contentHandler& /* data */)
{
	return (encoding(encodingTypes::BASE64));
}


} // vmime