kmime_charfreq.cpp

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/*
  kmime_charfreq.cpp

  KMime, the KDE Internet mail/usenet news message library.
  Copyright (c) 2001-2002 Marc Mutz <mutz@kde.org>

  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.

  This library 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
  Library General Public License for more details.

  You should have received a copy of the GNU Library General Public License
  along with this library; see the file COPYING.LIB.  If not, write to
  the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  Boston, MA 02110-1301, USA.
*/

#include "kmime_charfreq.h"

using namespace KMime;

//@cond PRIVATE
//class KMime::CharFreq::Private
//{
//  public:
//};
//@endcond

CharFreq::CharFreq( const QByteArray &buf )
  : mNUL( 0 ),
    mCTL( 0 ),
    mCR( 0 ), mLF( 0 ),
    mCRLF( 0 ),
    mPrintable( 0 ),
    mEightBit( 0 ),
    mTotal( 0 ),
    mLineMin( 0xffffffff ),
    mLineMax( 0 ),
    mTrailingWS( false ),
    mLeadingFrom( false )
{
  if ( !buf.isEmpty() ) {
    count( buf.data(), buf.size() );
  }
}

CharFreq::CharFreq( const char *buf, size_t len )
  : mNUL( 0 ),
    mCTL( 0 ),
    mCR( 0 ), mLF( 0 ),
    mCRLF( 0 ),
    mPrintable( 0 ),
    mEightBit( 0 ),
    mTotal( 0 ),
    mLineMin( 0xffffffff ),
    mLineMax( 0 ),
    mTrailingWS( false ),
    mLeadingFrom( false )
{
  if ( buf && len > 0 ) {
    count( buf, len );
  }
}

//@cond PRIVATE
static inline bool isWS( char ch )
{
  return ( ch == '\t' || ch == ' ' );
}
//@endcond

void CharFreq::count( const char *it, size_t len )
{
  const char *end = it + len;
  uint currentLineLength = 0;
  // initialize the prevChar with LF so that From_ detection works w/o
  // special-casing:
  char prevChar = '\n';
  char prevPrevChar = 0;

  for ( ; it != end ; ++it ) {
    ++currentLineLength;
    switch ( *it ) {
    case '\0': ++mNUL; break;
    case '\r': ++mCR;  break;
    case '\n': ++mLF;
      if ( prevChar == '\r' ) {
        --currentLineLength; ++mCRLF;
      }
      if ( currentLineLength >= mLineMax ) {
        mLineMax = currentLineLength-1;
      }
      if ( currentLineLength <= mLineMin ) {
        mLineMin = currentLineLength-1;
      }
      if ( !mTrailingWS ) {
        if ( isWS( prevChar ) ||
             ( prevChar == '\r' && isWS( prevPrevChar ) ) ) {
          mTrailingWS = true;
        }
      }
      currentLineLength = 0;
      break;
    case 'F': // check for lines starting with From_ if not found already:
      if ( !mLeadingFrom ) {
        if ( prevChar == '\n' && end - it >= 5 &&
             !qstrncmp( "From ", it, 5 ) ) {
          mLeadingFrom = true;
        }
      }
      ++mPrintable;
      break;
    default:
    {
      uchar c = *it;
      if ( c == '\t' || ( c >= ' ' && c <= '~' ) ) {
        ++mPrintable;
      } else if ( c == 127 || c < ' ' ) {
        ++mCTL;
      } else {
        ++mEightBit;
      }
    }
    }
    prevPrevChar = prevChar;
    prevChar = *it;
  }

  // consider the length of the last line
  if ( currentLineLength >= mLineMax ) {
    mLineMax = currentLineLength;
  }
  if ( currentLineLength <= mLineMin ) {
    mLineMin = currentLineLength;
  }

  // check whether the last character is tab or space
  if ( isWS( prevChar ) ) {
    mTrailingWS = true;
  }

  mTotal = len;
}

bool CharFreq::isEightBitData() const
{
  return type() == EightBitData;
}

bool CharFreq::isEightBitText() const
{
  return type() == EightBitText;
}

bool CharFreq::isSevenBitData() const
{
  return type() == SevenBitData;
}

bool CharFreq::isSevenBitText() const
{
  return type() == SevenBitText;
}

bool CharFreq::hasTrailingWhitespace() const
{
  return mTrailingWS;
}

bool CharFreq::hasLeadingFrom() const
{
  return mLeadingFrom;
}

CharFreq::Type CharFreq::type() const
{
#if 0
  qDebug( "Total: %d; NUL: %d; CTL: %d;\n"
          "CR: %d; LF: %d; CRLF: %d;\n"
          "lineMin: %d; lineMax: %d;\n"
          "printable: %d; eightBit: %d;\n"
          "trailing whitespace: %s;\n"
          "leading 'From ': %s;\n",
          total, NUL, CTL, CR, LF, CRLF, lineMin, lineMax,
          printable, eightBit,
          mTrailingWS ? "yes" : "no" , mLeadingFrom ? "yes" : "no" );
#endif
  if ( mNUL ) { // must be binary
    return Binary;
  }

  // doesn't contain NUL's:
  if ( mEightBit ) {
    if ( mLineMax > 988 ) {
      return EightBitData; // not allowed in 8bit
    }
    if ( ( mLF != mCRLF && mCRLF > 0 ) || mCR != mCRLF || controlCodesRatio() > 0.2 ) {
      return EightBitData;
    }
    return EightBitText;
  }

  // doesn't contain NUL's, nor 8bit chars:
  if ( mLineMax > 988 ) {
    return SevenBitData;
  }
  if ( ( mLF != mCRLF && mCRLF > 0 ) || mCR != mCRLF || controlCodesRatio() > 0.2 ) {
    return SevenBitData;
  }

  // no NUL, no 8bit chars, no excessive CTLs and no lines > 998 chars:
  return SevenBitText;
}

float CharFreq::printableRatio() const
{
  if ( mTotal ) {
    return float( mPrintable ) / float( mTotal );
  } else {
    return 0;
  }
}

float CharFreq::controlCodesRatio() const
{
  if ( mTotal ) {
    return float( mCTL ) / float( mTotal );
  } else {
    return 0;
  }
}