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qchar.cpp

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**
** Copyright (C) 1992-2007 Trolltech ASA. All rights reserved.
**
** This file is part of the QtCore module of the Qt Toolkit.
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** License version 2.0 as published by the Free Software Foundation
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// Don't define it while compiling this module, or USERS of Qt will
// not be able to link.
#ifdef QT_NO_CAST_FROM_ASCII
#undef QT_NO_CAST_FROM_ASCII
#endif
#ifdef QT_NO_CAST_TO_ASCII
#undef QT_NO_CAST_TO_ASCII
#endif
#include "qchar.h"
#include "qdatastream.h"
#include "qunicodetables_p.h"
#include "qtextcodec.h"

#ifndef QT_NO_CODEC_FOR_C_STRINGS
#ifdef QT_NO_TEXTCODEC
#define QT_NO_CODEC_FOR_C_STRINGS
#endif
#endif

/*! \class QLatin1Char
    \brief The QLatin1Char class provides an 8-bit ASCII/Latin-1 character.

    \ingroup text

    This class is only useful to avoid the codec for C strings business
    in the QChar(ch) constructor. You can avoid it by writing
    QChar(ch, 0).

    \sa QChar, QLatin1String, QString
*/

/*!
    \fn const char QLatin1Char::toLatin1() const

    Converts a Latin-1 character to an 8-bit ASCII representation of
    the character.
*/

/*!
    \fn const ushort QLatin1Char::unicode() const

    Converts a Latin-1 character to an 16-bit-encoded Unicode representation
    of the character.
*/

/*!
    \fn QLatin1Char::QLatin1Char(char c)

    Constructs a Latin-1 character for \a c. This constructor should be
    used when the encoding of the input character is known to be Latin-1.
*/

/*!
    \class QChar
    \brief The QChar class provides a 16-bit Unicode character.

    \ingroup text
    \reentrant

    In Qt, Unicode characters are 16-bit entities without any markup
    or structure. This class represents such an entity. It is
    lightweight, so it can be used everywhere. Most compilers treat
    it like a \c{unsigned short}.

    QChar provides a full complement of testing/classification
    functions, converting to and from other formats, converting from
    composed to decomposed Unicode, and trying to compare and
    case-convert if you ask it to.

    The classification functions include functions like those in the
    standard C++ header <cctype> (formerly <ctype.h>), but
    operating on the full range of Unicode characters. They all
    return true if the character is a certain type of character;
    otherwise they return false. These classification functions are
    isNull() (returns true if the character is '\\0'), isPrint()
    (true if the character is any sort of printable character,
    including whitespace), isPunct() (any sort of punctation),
    isMark() (Unicode Mark), isLetter() (a letter), isNumber() (any
    sort of numeric character, not just 0-9), isLetterOrNumber(), and
    isDigit() (decimal digits). All of these are wrappers around
    category() which return the Unicode-defined category of each
    character.

    QChar also provides direction(), which indicates the "natural"
    writing direction of this character. The joining() function
    indicates how the character joins with its neighbors (needed
    mostly for Arabic) and finally hasMirrored(), which indicates
    whether the character needs to be mirrored when it is printed in
    its "unnatural" writing direction.

    Composed Unicode characters (like \aring) can be converted to
    decomposed Unicode ("a" followed by "ring above") by using
    decomposition().

    In Unicode, comparison is not necessarily possible and case
    conversion is very difficult at best. Unicode, covering the
    "entire" world, also includes most of the world's case and
    sorting problems. operator==() and friends will do comparison
    based purely on the numeric Unicode value (code point) of the
    characters, and toUpper() and toLower() will do case changes when
    the character has a well-defined uppercase/lowercase equivalent.
    For locale-dependent comparisons, use
    QString::localeAwareCompare().

    The conversion functions include unicode() (to a scalar),
    toLatin1() (to scalar, but converts all non-Latin-1 characters to
    0), row() (gives the Unicode row), cell() (gives the Unicode
    cell), digitValue() (gives the integer value of any of the
    numerous digit characters), and a host of constructors.

    QChar provides constructors and cast operators that make it easy
    to convert to and from traditional 8-bit \c{char}s. If you
    defined \c QT_NO_CAST_FROM_ASCII and \c QT_NO_CAST_TO_ASCII, as
    explained in the QString documentation, you will need to
    explicitly call fromAscii() or fromLatin1(), or use QLatin1Char,
    to construct a QChar from an 8-bit \c char, and you will need to
    call toAscii() or toLatin1() to get the 8-bit value back.

    \sa QString, Unicode, QLatin1Char
*/

/*!
    \enum QChar::UnicodeVersion

    Specifies which version of the \l{http://www.unicode.org/}{Unicode standard}
    introduced a certain character.

    \value Unicode_1_1  Version 1.1.
    \value Unicode_2_0  Version 2.0.
    \value Unicode_2_1_2  Version 2.1.2.
    \value Unicode_3_0  Version 3.0.
    \value Unicode_3_1  Version 3.1.
    \value Unicode_3_2  Version 3.2.
    \value Unicode_4_0  Version 4.0.
    \value Unicode_Unassigned  The value is not assigned to any character
        in version 4.0 of Unicode.

    \sa unicodeVersion()
*/

/*!
    \enum QChar::Category

    This enum maps the Unicode character categories.

    The following characters are normative in Unicode:

    \value Mark_NonSpacing  Unicode class name Mn

    \value Mark_SpacingCombining  Unicode class name Mc

    \value Mark_Enclosing  Unicode class name Me

    \value Number_DecimalDigit  Unicode class name Nd

    \value Number_Letter  Unicode class name Nl

    \value Number_Other  Unicode class name No

    \value Separator_Space  Unicode class name Zs

    \value Separator_Line  Unicode class name Zl

    \value Separator_Paragraph  Unicode class name Zp

    \value Other_Control  Unicode class name Cc

    \value Other_Format  Unicode class name Cf

    \value Other_Surrogate  Unicode class name Cs

    \value Other_PrivateUse  Unicode class name Co

    \value Other_NotAssigned  Unicode class name Cn


    The following categories are informative in Unicode:

    \value Letter_Uppercase  Unicode class name Lu

    \value Letter_Lowercase  Unicode class name Ll

    \value Letter_Titlecase  Unicode class name Lt

    \value Letter_Modifier  Unicode class name Lm

    \value Letter_Other Unicode class name Lo

    \value Punctuation_Connector  Unicode class name Pc

    \value Punctuation_Dash  Unicode class name Pd

    \value Punctuation_Open  Unicode class name Ps

    \value Punctuation_Close  Unicode class name Pe

    \value Punctuation_InitialQuote  Unicode class name Pi

    \value Punctuation_FinalQuote  Unicode class name Pf

    \value Punctuation_Other  Unicode class name Po

    \value Symbol_Math  Unicode class name Sm

    \value Symbol_Currency  Unicode class name Sc

    \value Symbol_Modifier  Unicode class name Sk

    \value Symbol_Other  Unicode class name So

    \value NoCategory  Qt cannot find an appropriate category for the character.

    \omitvalue Punctuation_Dask

    \sa category()
*/

/*!
    \enum QChar::Direction

    This enum type defines the Unicode direction attributes. See the
    \l{http://www.unicode.org/}{Unicode Standard} for a description
    of the values.

    In order to conform to C/C++ naming conventions "Dir" is prepended
    to the codes used in the Unicode Standard.

    \value DirAL
    \value DirAN
    \value DirB
    \value DirBN
    \value DirCS
    \value DirEN
    \value DirES
    \value DirET
    \value DirL
    \value DirLRE
    \value DirLRO
    \value DirNSM
    \value DirON
    \value DirPDF
    \value DirR
    \value DirRLE
    \value DirRLO
    \value DirS
    \value DirWS

    \sa direction()
*/

/*!
    \enum QChar::Decomposition

    This enum type defines the Unicode decomposition attributes. See
    the \l{http://www.unicode.org/}{Unicode Standard} for a
    description of the values.

    \value NoDecomposition
    \value Canonical
    \value Circle
    \value Compat
    \value Final
    \value Font
    \value Fraction
    \value Initial
    \value Isolated
    \value Medial
    \value Narrow
    \value NoBreak
    \value Small
    \value Square
    \value Sub
    \value Super
    \value Vertical
    \value Wide

    \omitvalue Single

    \sa decomposition()
*/

/*!
    \enum QChar::Joining

    This enum type defines the Unicode joining attributes. See the
    \l{http://www.unicode.org/}{Unicode Standard} for a description
    of the values.

    \value Center
    \value Dual
    \value OtherJoining
    \value Right

    \sa joining()
*/

/*!
    \enum QChar::CombiningClass

    \internal

    This enum type defines names for some of the Unicode combining
    classes. See the \l{http://www.unicode.org/}{Unicode Standard}
    for a description of the values.

    \value Combining_Above
    \value Combining_AboveAttached
    \value Combining_AboveLeft
    \value Combining_AboveLeftAttached
    \value Combining_AboveRight
    \value Combining_AboveRightAttached
    \value Combining_Below
    \value Combining_BelowAttached
    \value Combining_BelowLeft
    \value Combining_BelowLeftAttached
    \value Combining_BelowRight
    \value Combining_BelowRightAttached
    \value Combining_DoubleAbove
    \value Combining_DoubleBelow
    \value Combining_IotaSubscript
    \value Combining_Left
    \value Combining_LeftAttached
    \value Combining_Right
    \value Combining_RightAttached
*/

/*!
    \enum QChar::SpecialCharacter

    \value Null A QChar with this value isNull().
    \value Nbsp Non-breaking space.
    \value ReplacementCharacter
    \value ObjectReplacementCharacter
    \value ByteOrderMark
    \value ByteOrderSwapped
    \value ParagraphSeparator
    \value LineSeparator

    \omitvalue null
    \omitvalue replacement
    \omitvalue byteOrderMark
    \omitvalue byteOrderSwapped
    \omitvalue nbsp
*/

/*!
    \fn void QChar::setCell(uchar cell)
    \internal
*/

/*!
    \fn void QChar::setRow(uchar row)
    \internal
*/

/*!
    \fn QChar::QChar()

    Constructs a null QChar ('\\0').

    \sa isNull()
*/

/*!
    \fn QChar::QChar(QLatin1Char ch)

    Constructs a QChar corresponding to ASCII/Latin-1 character \a ch.
*/

/*!
    \fn QChar::QChar(SpecialCharacter ch)

    Constructs a QChar for the predefined character value \a ch.
*/

/*!
    Constructs a QChar corresponding to ASCII/Latin-1 character \a
    ch.
*/
00403 QChar::QChar(char ch)
{
#ifndef QT_NO_CODEC_FOR_C_STRINGS
    if (QTextCodec::codecForCStrings())
        // #####
        ucs =  QTextCodec::codecForCStrings()->toUnicode(&ch, 1).at(0).unicode();
    else
#endif
        ucs = uchar(ch);
}

/*!
    Constructs a QChar corresponding to ASCII/Latin-1 character \a ch.
*/
00417 QChar::QChar(uchar ch)
{
#ifndef QT_NO_CODEC_FOR_C_STRINGS
    if (QTextCodec::codecForCStrings()) {
        // #####
        char c = char(ch);
        ucs =  QTextCodec::codecForCStrings()->toUnicode(&c, 1).at(0).unicode();
    } else
#endif
        ucs = ch;
}

/*!
    \fn QChar::QChar(uchar cell, uchar row)

    Constructs a QChar for Unicode cell \a cell in row \a row.

    \sa cell(), row()
*/

/*!
    \fn QChar::QChar(ushort code)

    Constructs a QChar for the character with Unicode code point \a
    code.
*/


/*!
    \fn QChar::QChar(short code)

    Constructs a QChar for the character with Unicode code point \a
    code.
*/


/*!
    \fn QChar::QChar(uint code)

    Constructs a QChar for the character with Unicode code point \a
    code.
*/


/*!
    \fn QChar::QChar(int code)

    Constructs a QChar for the character with Unicode code point \a
    code.
*/


/*!
    \fn bool QChar::isNull() const

    Returns true if the character is the Unicode character 0x0000
    ('\\0'); otherwise returns false.
*/

/*!
    \fn uchar QChar::cell() const

    Returns the cell (least significant byte) of the Unicode
    character.

    \sa row()
*/

/*!
    \fn uchar QChar::row() const

    Returns the row (most significant byte) of the Unicode character.

    \sa cell()
*/

/*!
    Returns true if the character is a printable character; otherwise
    returns false. This is any character not of category Cc or Cn.

    Note that this gives no indication of whether the character is
    available in a particular font.
*/
00500 bool QChar::isPrint() const
{
    Category c = QUnicodeTables::category(*this);
    return c != Other_Control && c != Other_NotAssigned;
}

/*!
    Returns true if the character is a separator character
    (Separator_* categories); otherwise returns false.
*/
00510 bool QChar::isSpace() const
{
    return QUnicodeTables::isSpace(*this);
}

/*!
    Returns true if the character is a mark (Mark_* categories);
    otherwise returns false.
*/
00519 bool QChar::isMark() const
{
    Category c = QUnicodeTables::category(*this);
    return c >= Mark_NonSpacing && c <= Mark_Enclosing;
}

/*!
    Returns true if the character is a punctuation mark (Punctuation_*
    categories); otherwise returns false.
*/
00529 bool QChar::isPunct() const
{
    Category c = QUnicodeTables::category(*this);
    return (c >= Punctuation_Connector && c <= Punctuation_Other);
}

/*!
    Returns true if the character is a letter (Letter_* categories);
    otherwise returns false.
*/
00539 bool QChar::isLetter() const
{
    Category c = QUnicodeTables::category(*this);
    return (c >= Letter_Uppercase && c <= Letter_Other);
}

/*!
    Returns true if the character is a number (Number_* categories,
    not just 0-9); otherwise returns false.

    \sa isDigit()
*/
00551 bool QChar::isNumber() const
{
    Category c = QUnicodeTables::category(*this);
    return c >= Number_DecimalDigit && c <= Number_Other;
}

/*!
    Returns true if the character is a letter or number (Letter_* or
    Number_* categories); otherwise returns false.
*/
00561 bool QChar::isLetterOrNumber() const
{
    Category c = QUnicodeTables::category(*this);
    return (c >= Letter_Uppercase && c <= Letter_Other)
        || (c >= Number_DecimalDigit && c <= Number_Other);
}


/*!
    Returns true if the character is a decimal digit
    (Number_DecimalDigit); otherwise returns false.
*/
00573 bool QChar::isDigit() const
{
    return (QUnicodeTables::category(*this) == Number_DecimalDigit);
}


/*!
    Returns true if the character is a symbol (Symbol_* categories);
    otherwise returns false.
*/
00583 bool QChar::isSymbol() const
{
    Category c = QUnicodeTables::category(*this);
    return c >= Symbol_Math && c <= Symbol_Other;
}

/*!
    Returns the numeric value of the digit, or -1 if the character is
    not a digit.
*/
00593 int QChar::digitValue() const
{
    return QUnicodeTables::digitValue(ucs);
}

/*!
    Returns the character's category.
*/
00601 QChar::Category QChar::category() const
{
    return QUnicodeTables::category(*this);
}

/*!
    Returns the character's direction.
*/
00609 QChar::Direction QChar::direction() const
{
     return QUnicodeTables::direction(*this);
}

/*!
    \preliminary

    Returns information about the joining properties of the character
    (needed for certain languages such as Arabic).
*/
00620 QChar::Joining QChar::joining() const
{
    return QUnicodeTables::joining(*this);
}


/*!
    Returns true if the character should be reversed if the text
    direction is reversed; otherwise returns false.

    \sa mirroredChar()
*/
00632 bool QChar::hasMirrored() const
{
    return QUnicodeTables::mirrored(*this);
}

/*!
    \fn bool QChar::isLower() const

    Returns true if the character is a lowercase letter, i.e.
    category() is Letter_Lowercase.

    \sa isUpper(), toLower(), toUpper()
*/

/*!
    \fn bool QChar::isUpper() const

    Returns true if the character is an uppercase letter, i.e.
    category() is Letter_Uppercase.

    \sa isLower(), toUpper(), toLower()
*/

/*!
    Returns the mirrored character if this character is a mirrored
    character; otherwise returns the character itself.

    \sa hasMirrored()
*/
00661 QChar QChar::mirroredChar() const
{
    return QUnicodeTables::mirroredChar(*this);
}

/*!
    Decomposes a character into its parts. Returns an empty string if
    no decomposition exists.
*/
00670 QString QChar::decomposition() const
{
    return QUnicodeTables::decomposition(ucs);
}

/*!
    Returns the tag defining the composition of the character. Returns
    QChar::Single if no decomposition exists.
*/
00679 QChar::Decomposition QChar::decompositionTag() const
{
    return QUnicodeTables::decompositionTag(ucs);
}

/*!
    Returns the combining class for the character as defined in the
    Unicode standard. This is mainly useful as a positioning hint for
    marks attached to a base character.

    The Qt text rendering engine uses this information to correctly
    position non-spacing marks around a base character.
*/
00692 unsigned char QChar::combiningClass() const
{
    return QUnicodeTables::combiningClass(*this);
}


/*!
    Returns the Unicode version that introduced this character.
*/
00701 QChar::UnicodeVersion QChar::unicodeVersion() const
{
    return QUnicodeTables::unicodeVersion(ucs);
}


/*!
    Returns the lowercase equivalent if the character is uppercase;
    otherwise returns the character itself.
*/
00711 QChar QChar::toLower() const
{
     return QUnicodeTables::lower(*this);
}

/*!
    Returns the uppercase equivalent if the character is lowercase;
    otherwise returns the character itself.
*/
00720 QChar QChar::toUpper() const
{
     return QUnicodeTables::upper(*this);
}

/*!
    \fn char QChar::latin1() const

    Use toLatin1() instead.
*/

/*!
    \fn char QChar::ascii() const

    Use toAscii() instead.
*/

/*!
    \fn char QChar::toLatin1() const

    Returns the Latin-1 character equivalent to the QChar, or 0. This
    is mainly useful for non-internationalized software.

    \sa toAscii(), unicode(), QTextCodec::codecForCStrings()
*/

/*!
    Returns the character value of the QChar obtained using the current
    codec used to read C strings, or 0 if the character is not representable
    using this codec. The default codec handles Latin-1 encoded text,
    but this can be changed to assist developers writing source code using
    other encodings.

    The main purpose of this function is to preserve ASCII characters used
    in C strings. This is mainly useful for developers of non-internationalized
    software.

    \sa toLatin1(), unicode(), QTextCodec::codecForCStrings()
*/
00759 const char QChar::toAscii() const
{
#ifndef QT_NO_CODEC_FOR_C_STRINGS
    if (QTextCodec::codecForCStrings())
        // #####
        return QTextCodec::codecForCStrings()->fromUnicode(QString(*this)).at(0);
#endif
    return ucs > 0xff ? 0 : char(ucs);
}

/*!
    \fn QChar QChar::fromLatin1(char c)

    Converts the Latin-1 character \a c to its equivalent QChar. This
    is mainly useful for non-internationalized software.

    \sa fromAscii(), unicode(), QTextCodec::codecForCStrings()
*/

/*!
    Converts the ASCII character \a c to its equivalent QChar. This
    is mainly useful for non-internationalized software.

    An alternative is to use QLatin1Char.

    \sa fromLatin1(), unicode(), QTextCodec::codecForCStrings()
*/
00786 QChar QChar::fromAscii(char c)
{
#ifndef QT_NO_CODEC_FOR_C_STRINGS
    if (QTextCodec::codecForCStrings())
        // #####
        return QTextCodec::codecForCStrings()->toUnicode(&c, 1).at(0).unicode();
#endif
    return QChar(ushort((uchar)c));
}

#ifndef QT_NO_DATASTREAM
/*!
  \relates QChar

  Writes the char \a chr to the stream \a out.

  \sa {Format of the QDataStream operators}
 */

00805 QDataStream &operator<<(QDataStream &out, const QChar &chr)
{
    out << quint16(chr.unicode());
    return out;
}


/*!
  \relates QChar

  Reads a char from the stream \a in into char \a chr.

  \sa {Format of the QDataStream operators}
 */

00820 QDataStream &operator>>(QDataStream &in, QChar &chr)
{
    quint16 u;
    in >> u;
    chr.unicode() = ushort(u);
    return in;
}
#endif

/*!
    \fn ushort & QChar::unicode()

    Returns a reference to the numeric Unicode value of the QChar.
*/

/*!
    \fn ushort QChar::unicode() const

    \overload
*/

/*****************************************************************************
  Documentation of QChar related functions
 *****************************************************************************/

/*!
    \fn bool operator==(QChar c1, QChar c2)

    \relates QChar

    Returns true if \a c1 and \a c2 are the same Unicode character;
    otherwise returns false.
*/

/*!
    \fn int operator!=(QChar c1, QChar c2)

    \relates QChar

    Returns true if \a c1 and \a c2 are not the same Unicode
    character; otherwise returns false.
*/

/*!
    \fn int operator<=(QChar c1, QChar c2)

    \relates QChar

    Returns true if the numeric Unicode value of \a c1 is less than
    or equal to that of \a c2; otherwise returns false.
*/

/*!
    \fn int operator>=(QChar c1, QChar c2)

    \relates QChar

    Returns true if the numeric Unicode value of \a c1 is greater than
    or equal to that of \a c2; otherwise returns false.
*/

/*!
    \fn int operator<(QChar c1, QChar c2)

    \relates QChar

    Returns true if the numeric Unicode value of \a c1 is less than
    that of \a c2; otherwise returns false.
*/

/*!
    \fn int operator>(QChar c1, QChar c2)

    \relates QChar

    Returns true if the numeric Unicode value of \a c1 is greater than
    that of \a c2; otherwise returns false.
*/

/*!
    \fn bool QChar::mirrored() const

    Use hasMirrored() instead.
*/

/*!
    \fn QChar QChar::lower() const

    Use toLower() instead.
*/

/*!
    \fn QChar QChar::upper() const

    Use toUpper() instead.
*/

/*!
    \fn bool QChar::networkOrdered()

    See if QSysInfo::ByteOrder == QSysInfo::BigEndian instead.
*/

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