File indexing completed on 2024-04-21 05:18:10

 /*  -*- c++ -*-
     kmime_charfreq.h
 
     KMime, the KDE Internet mail/usenet news message library.
     SPDX-FileCopyrightText: 2001-2002 Marc Mutz <mutz@kde.org>
 
     SPDX-License-Identifier: LGPL-2.0-or-later
 */
 /**
   @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.
 */
 
 #pragma once
 
 #include <QByteArray>
 #undef None
 
 #include <limits>
 
 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 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(QByteArrayView buf);
 
     /**
       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.
     */
     [[nodiscard]] Type type() const;
 
     /**
       Returns true if the data #Type is EightBitData; false otherwise.
     */
     [[nodiscard]] bool isEightBitData() const;
 
     /**
       Returns true if the data #Type is EightBitText; false otherwise.
     */
     [[nodiscard]] bool isEightBitText() const;
 
     /**
       Returns true if the data #Type is SevenBitData; false otherwise.
     */
     [[nodiscard]] bool isSevenBitData() const;
 
     /**
       Returns true if the data #Type is SevenBitText; false otherwise.
     */
     [[nodiscard]] bool isSevenBitText() const;
 
     /**
       Returns true if the data contains trailing whitespace. i.e.,
       if any line ends with space (' ') or tab ('\\t').
     */
     [[nodiscard]] bool hasTrailingWhitespace() const;
 
     /**
       Returns true if the data contains a line that starts with "From ".
     */
     [[nodiscard]] bool hasLeadingFrom() const;
 
     /**
       Returns the percentage of printable characters in the data.
       The result is undefined if the number of data characters is zero.
     */
     [[nodiscard]] 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.
     */
     [[nodiscard]] float controlCodesRatio() const;
 
   private:
     uint mNUL = 0;       // count of NUL chars
     uint mCTL = 0;       // count of CTLs (incl. DEL, excl. CR, LF, HT)
     uint mCR = 0;        // count of CR chars
     uint mLF = 0;        // count of LF chars
     uint mCRLF = 0;      // count of LFs, preceded by CRs
     uint mPrintable = 0; // count of printable US-ASCII chars (SPC..~)
     uint mEightBit = 0;  // count of other latin1 chars (those with 8th bit set)
     uint mTotal = 0;     // count of all chars
     uint mLineMin = std::numeric_limits<uint>::max(); // minimum line length
     uint mLineMax = 0;   // maximum line length
     bool mTrailingWS = false;  // does the buffer contain trailing whitespace?
     bool mLeadingFrom = false; // does the buffer contain lines starting with "From "?
 
     /**
       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