kde-playground/kdepimlibs/kmime/kmime_charfreq.h

/*  -*- c++ -*-
    kmime_charfreq.h

    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.
*/
/**
  @file
  This file is part of the API for handling @ref MIME data and
  defines the CharFreq class.

  @brief
  Defines the CharFreq class.

  @authors Marc Mutz \<mutz@kde.org\>

  @glossary @anchor Eight-Bit @anchor eight-bit @b 8-bit:
  Data that contains bytes with at least one value greater than 127, or at
  least one NUL byte.

  @glossary @anchor Eight-Bit-Binary @anchor eight-bit-binary @b 8-bit-binary:
  Eight-bit data that contains a high percentage of non-ascii values,
  or lines longer than 998 characters, or stray CRs, or NULs.

  @glossary @anchor Eight-Bit-Text @anchor eight-bit-text @b 8-bit-text:
  Eight-bit data that contains a high percentage of ascii values,
  no lines longer than 998 characters, no NULs, and either only LFs or
  only CRLFs.

  @glossary @anchor Seven-Bit @anchor seven-bit @b 7-Bit:
  Data that contains bytes with all values less than 128, and no NULs.

  @glossary @anchor Seven-Bit-Binary @anchor seven-bit-binary @b 7-bit-binary:
  Seven-bit data that contains a high percentage of non-ascii values,
  or lines longer than 998 characters, or stray CRs.

  @glossary @anchor Seven-Bit-Text @anchor seven-bit-text @b 7-bit-text:
  Seven-bit data that contains a high percentage of ascii values,
  no lines longer than 998 characters, and either only LFs, or only CRLFs.
*/

#ifndef __KMIME_CHARFREQ_H__
#define __KMIME_CHARFREQ_H__

#include <QtCore/QByteArray>
#include "kmime_export.h"
#undef None

namespace KMime {

/**
  @brief
  A class for performing basic data typing using frequency count heuristics.

  This class performs character frequency counts on the provided data which
  are used in heuristics to determine a basic data type.  The data types are:

  - @ref Eight-Bit-Binary
  - @ref Eight-Bit-Text
  - @ref Seven-Bit-Binary
  - @ref Seven-Bit-Text
*/
class KMIME_EXPORT CharFreq
{
  public:
    /**
      Constructs a Character Frequency instance for a buffer @p buf of
      QByteArray data.

      @param buf is a QByteArray containing the data.
    */
    explicit CharFreq( const QByteArray &buf );

    /**
      Constructs a Character Frequency instance for a buffer @p buf of
      chars of length @p len.

      @param buf is a pointer to a character string containing the data.
      @param len is the length of @p buf, in characters.
    */
    CharFreq( const char *buf, size_t len );

    /**
      The different types of data.
    */
    enum Type {
      None = 0,              /**< Unknown */
      EightBitData,          /**< 8bit binary */
      Binary = EightBitData, /**< 8bit binary */
      SevenBitData,          /**< 7bit binary */
      EightBitText,          /**< 8bit text */
      SevenBitText           /**< 7bit text */
    };

    /**
      Returns the data #Type as derived from the class heuristics.
    */
    Type type() const;

    /**
      Returns true if the data #Type is EightBitData; false otherwise.
    */
    bool isEightBitData() const;

    /**
      Returns true if the data #Type is EightBitText; false otherwise.
    */
    bool isEightBitText() const;

    /**
      Returns true if the data #Type is SevenBitData; false otherwise.
    */
    bool isSevenBitData() const;

    /**
      Returns true if the data #Type is SevenBitText; false otherwise.
    */
    bool isSevenBitText() const;

    /**
      Returns true if the data contains trailing whitespace. i.e.,
      if any line ends with space (' ') or tab ('\\t').
    */
    bool hasTrailingWhitespace() const;

    /**
      Returns true if the data contains a line that starts with "From ".
    */
    bool hasLeadingFrom() const;

    /**
      Returns the percentage of printable characters in the data.
      The result is undefined if the number of data characters is zero.
    */
    float printableRatio() const;

    /**
      Returns the percentage of control code characters (CTLs) in the data.
      The result is undefined if the number of data characters is zero.
    */
    float controlCodesRatio() const;

  private:
    //@cond PRIVATE
    uint mNUL;         // count of NUL chars
    uint mCTL;         // count of CTLs (incl. DEL, excl. CR, LF, HT)
    uint mCR;          // count of CR chars
    uint mLF;          // count of LF chars
    uint mCRLF;        // count of LFs, preceded by CRs
    uint mPrintable;   // count of printable US-ASCII chars (SPC..~)
    uint mEightBit;    // count of other latin1 chars (those with 8th bit set)
    uint mTotal;       // count of all chars
    uint mLineMin;     // minimum line length
    uint mLineMax;     // maximum line length
    bool mTrailingWS;  // does the buffer contain trailing whitespace?
    bool mLeadingFrom; // does the buffer contain lines starting with "From "?
    //@endcond

    /**
      Performs the character frequency counts on the data.

      @param buf is a pointer to a character string containing the data.
      @param len is the length of @p buf, in characters.
    */
    void count( const char *buf, size_t len );
};

} // namespace KMime

#endif /* __KMIME_CHARFREQ_H__ */