wxWidgets/interface/strconv.h

/////////////////////////////////////////////////////////////////////////////
// Name:        strconv.h
// Purpose:     interface of wxMBConvUTF7
// Author:      wxWidgets team
// RCS-ID:      $Id$
// Licence:     wxWindows license
/////////////////////////////////////////////////////////////////////////////

/**
    @class wxMBConv
    @wxheader{strconv.h}

    This class is the base class of a hierarchy of classes capable of
    converting text strings between multibyte (SBCS or DBCS) encodings and
    Unicode.

    This is an abstract base class which defines the operations implemented by
    all different conversion classes. The derived classes don't add any new
    operations of their own (except, possibly, some non-default constructors)
    and so you should simply use this class ToWChar() and FromWChar() (or
    cMB2WC() and cWC2MB()) methods with the objects of the derived class.

    In the documentation for this and related classes please notice that
    length of the string refers to the number of characters in the string
    not counting the terminating @c NUL, if any. While the size of the string
    is the total number of bytes in the string, including any trailing @c NUL.
    Thus, length of wide character string @c L"foo" is 3 while its size can
    be either 8 or 16 depending on whether @c wchar_t is 2 bytes (as
    under Windows) or 4 (Unix).

    @library{wxbase}
    @category{conv}

    @see wxCSConv, wxEncodingConverter, @ref overview_mbconv "wxMBConv classes overview"
*/
class wxMBConv
{
public:
    /**
        Trivial default constructor.
    */
    wxMBConv();

    /**
        This pure virtual function is overridden in each of the derived classes
        to return a new copy of the object it is called on.

        It is used for copying the conversion objects while preserving their
        dynamic type.
    */
    virtual wxMBConv* Clone() const = 0;

    /**
        This function returns 1 for most of the multibyte encodings in which the
        string is terminated by a single @c NUL, 2 for UTF-16 and 4 for UTF-32 for
        which the string is terminated with 2 and 4 @c NUL characters respectively.
        The other cases are not currently supported and @c wxCONV_FAILED
        (defined as -1) is returned for them.
    */
    size_t GetMBNulLen() const;

    /**
        Returns the maximal value which can be returned by GetMBNulLen() for
        any conversion object.

        Currently this value is 4.

        This method can be used to allocate the buffer with enough space for the
        trailing @c NUL characters for any encoding.
    */
    const size_t GetMaxMBNulLen();

    /**
        Convert multibyte string to a wide character one.

        This is the most general function for converting a multibyte string to
        a wide string, cMB2WC() may be often more convenient, however this
        function is the most efficient one as it allows to avoid any
        unnecessary copying.

        The main case is when @a dst is not @NULL and @a srcLen is not
        @c wxNO_LEN (which is defined as @c (size_t)-1): then the function
        converts exactly @a srcLen bytes starting at @a src into wide string
        which it output to @e dst. If the length of the resulting wide
        string is greater than @e dstLen, an error is returned. Note that if
        @a srcLen bytes don't include @c NUL characters, the resulting wide
        string is not @c NUL-terminated neither.

        If @a srcLen is @c wxNO_LEN, the function supposes that the string is
        properly (i.e. as necessary for the encoding handled by this
        conversion) @c NUL-terminated and converts the entire string, including
        any trailing @c NUL bytes. In this case the wide string is also @c
        NUL-terminated.

        Finally, if @a dst is @NULL, the function returns the length of the
        needed buffer.

        Example of use of this function:
        @code
        size_t dstLen = conv.ToWChar(NULL, 0, src);
        if ( dstLen == wxCONV_FAILED )
            ... handle error ...
        wchar_t *dst = new wchar_t[dstLen];
        if ( conv.ToWChar(dst, dstLen, src) == wxCONV_FAILED )
            ... handle error ...
        @endcode

        Notice that when passing the explicit source length the output will
        @e not be @c NUL terminated if you pass @c strlen(str) as parameter.
        Either leave @a srcLen as default @c wxNO_LEN or add one to @c strlen
        result if you want the output to be @c NUL terminated.

        @param dst
            Pointer to output buffer of the size of at least @a dstLen or @NULL.
        @param dstLen
            Maximal number of characters to be written to the output buffer if
            @dst is non-@NULL, unused otherwise.
        @param src
            Point to the source string, must not be @NULL.
        @param
            The number of characters of the source string to convert or @c
            wxNO_LEN (default parameter) to convert everything up to and
            including the terminating @c NUL character(s).
        @return
            The number of character written (or which would have been written
            if it were non-@NULL) to @a dst or @c wxCONV_FAILED on error.
    */
    virtual size_t ToWChar(wchar_t* dst, size_t dstLen,
                           const char* src,
                           size_t srcLen = wxNO_LEN) const;

    /**
        Converts wide character string to multibyte.

        This function has the same semantics as ToWChar() except that it
        converts a wide string to multibyte one. As with ToWChar(), it may be
        more convenient to use cWC2MB() when working with @c NUL terminated
        strings.

        @param dst
            Pointer to output buffer of the size of at least @a dstLen or @NULL.
        @param dstLen
            Maximal number of characters to be written to the output buffer if
            @dst is non-@NULL, unused otherwise.
        @param src
            Point to the source string, must not be @NULL.
        @param
            The number of characters of the source string to convert or @c
            wxNO_LEN (default parameter) to convert everything up to and
            including the terminating @c NUL character.
        @return
            The number of character written (or which would have been written
            if it were non-@NULL) to @a dst or @c wxCONV_FAILED on error.
    */
    virtual size_t FromWChar(char* dst, size_t dstLen,
                             const wchar_t* src,
                             size_t srcLen = wxNO_LEN) const;

    //@{
    /**
        Converts from multibyte encoding to Unicode by calling MB2WC() and
        allocating a temporary wxWCharBuffer to hold the result.

        The first overload takes a @c NUL-terminated input string. The second
        one takes a string of exactly the specified length and the string may
        include or not the trailing @c NUL character(s). If the string is not
        @c NUL-terminated, a temporary @c NUL-terminated copy of it suitable
        for passing to wxMBConv::MB2WC is made, so it is more efficient to
        ensure that the string is does have the appropriate number of @c NUL
        bytes (which is usually 1 but may be 2 or 4 for UTF-16 or UTF-32, see
        wxMBConv::GetMBNulLen), especially for long strings.

        If @a outLen is not-@NULL, it receives the length of the converted
        string.
    */
    const wxWCharBuffer cMB2WC(const char* in) const;
    const wxWCharBuffer cMB2WC(const char* in, size_t inLen, size_t *outLen) const;
    //@}

    //@{
    /**
        Converts from multibyte encoding to the current wxChar type (which
        depends on whether wxUSE_UNICODE is set to 1).

        If wxChar is char, it returns the parameter unaltered. If wxChar is
        wchar_t, it returns the result in a wxWCharBuffer. The macro wxMB2WXbuf
        is defined as the correct return type (without const).
    */
    const char* cMB2WX(const char* psz) const;
    const wxWCharBuffer cMB2WX(const char* psz) const;
    //@}

    //@{
    /**
        Converts from Unicode to multibyte encoding by calling WC2MB and
        allocating a temporary wxCharBuffer to hold the result.

        The second overload of this function allows to convert a string of the
        given length @e inLen, whether it is @c NUL-terminated or not (for wide
        character strings, unlike for the multibyte ones, a single @c NUL is
        always enough). But notice that just as with @ref wxMBConv::mb2wc
        cMB2WC, it is more efficient to pass an already terminated string to
        this function as otherwise a copy is made internally. If @a outLen is
        not-@NULL, it receives the length of the converted string.
    */
    const wxCharBuffer cWC2MB(const wchar_t* in) const;
    const wxCharBuffer cWC2MB(const wchar_t* in, size_t inLen, size_t *outLen) const;
    //@}

    //@{
    /**
        Converts from Unicode to the current wxChar type.

        If wxChar is wchar_t, it returns the parameter unaltered. If wxChar is
        char, it returns the result in a wxCharBuffer. The macro wxWC2WXbuf is
        defined as the correct return type (without const).
    */
    const wchar_t* cWC2WX(const wchar_t* psz) const;
    const wxCharBuffer cWC2WX(const wchar_t* psz) const;
    //@}

    //@{
    /**
        Converts from the current wxChar type to multibyte encoding.

        If wxChar is char, it returns the parameter unaltered. If wxChar is
        wchar_t, it returns the result in a wxCharBuffer. The macro wxWX2MBbuf
        is defined as the correct return type (without const).
    */
    const char* cWX2MB(const wxChar* psz) const;
    const wxCharBuffer cWX2MB(const wxChar* psz) const;
    //@}

    //@{
    /**
        Converts from the current wxChar type to Unicode.

        If wxChar is wchar_t, it returns the parameter unaltered. If wxChar is
        char, it returns the result in a wxWCharBuffer. The macro wxWX2WCbuf is
        defined as the correct return type (without const).
    */
    const wchar_t* cWX2WC(const wxChar* psz) const;
    const wxWCharBuffer cWX2WC(const wxChar* psz) const;
    //@}

    /**
        @deprecated This function is deprecated, please use ToWChar() instead.

        Converts from a string @a in in multibyte encoding to Unicode putting up to
        @a outLen characters into the buffer @e out.

        If @a out is @NULL, only the length of the string which would result
        from the conversion is calculated and returned. Note that this is the
        length and not size, i.e. the returned value does not include the
        trailing @c NUL. But when the function is called with a non-@NULL @a
        out buffer, the @a outLen parameter should be one more to allow to
        properly @c NUL-terminate the string.

        @param out
            The output buffer, may be @NULL if the caller is only
            interested in the length of the resulting string
        @param in
            The NUL-terminated input string, cannot be @NULL
        @param outLen
            The length of the output buffer but including
            NUL, ignored if out is @NULL

        @return The length of the converted string excluding the trailing NUL.
    */
    virtual size_t MB2WC(wchar_t* out, const char* in, size_t outLen) const;

    /**
        @deprecated This function is deprecated, please use FromWChar() instead.

        Converts from Unicode to multibyte encoding.
        The semantics of this function (including the return value meaning) is
        the same as for wxMBConv::MB2WC. Notice that when the function is
        called with a non-@NULL buffer, the @a n parameter should be the size
        of the buffer and so it should take into account the trailing @c NUL,
        which might take two or four bytes for some encodings (UTF-16 and
        UTF-32) and not one.
    */
    virtual size_t WC2MB(char* buf, const wchar_t* psz, size_t n) const;
};


/**
    @class wxMBConvUTF7
    @wxheader{strconv.h}

    This class converts between the UTF-7 encoding and Unicode.
    It has one predefined instance, @b wxConvUTF7.

    Notice that, unlike all the other conversion objects, this converter is
    stateful, i.e. it remembers its state from the last call to its ToWChar()
    or FromWChar() and assumes it is called on the continuation of the same
    string when the same method is called again. This assumption is only made
    if an explicit length is specified as parameter to these functions as if an
    entire @c NUL terminated string is processed the state doesn't need to be
    remembered.

    This also means that, unlike the other predefined conversion objects,
    @b wxConvUTF7 is @em not thread-safe.

    @library{wxbase}
    @category{conv}

    @see wxMBConvUTF8, @ref overview_mbconv "wxMBConv classes overview"
*/
class wxMBConvUTF7 : public wxMBConv
{
};



/**
    @class wxMBConvUTF8
    @wxheader{strconv.h}

    This class converts between the UTF-8 encoding and Unicode.
    It has one predefined instance, @b wxConvUTF8.

    @library{wxbase}
    @category{conv}

    @see wxMBConvUTF7, @ref overview_mbconv "wxMBConv classes overview"
*/
class wxMBConvUTF8 : public wxMBConv
{
};



/**
    @class wxMBConvUTF16
    @wxheader{strconv.h}

    This class is used to convert between multibyte encodings and UTF-16 Unicode
    encoding (also known as UCS-2).

    Unlike UTF-8 encoding, UTF-16 uses words and not bytes and hence depends
    on the byte ordering: big or little endian. Hence this class is provided in
    two versions: wxMBConvUTF16LE and wxMBConvUTF16BE and wxMBConvUTF16 itself
    is just a typedef for one of them (native for the given platform, e.g. LE
    under Windows and BE under Mac).

    @library{wxbase}
    @category{conv}

    @see wxMBConvUTF8, wxMBConvUTF32, @ref overview_mbconv "wxMBConv classes overview"
*/
class wxMBConvUTF16 : public wxMBConv
{
};


/**
    @class wxMBConvUTF32
    @wxheader{strconv.h}

    This class is used to convert between multibyte encodings and UTF-32
    Unicode encoding (also known as UCS-4).
    Unlike UTF-8 encoding, UTF-32 uses (double) words and not bytes and hence
    depends on the byte ordering: big or little endian. Hence this class is
    provided in two versions: wxMBConvUTF32LE and wxMBConvUTF32BE and
    wxMBConvUTF32 itself is just a typedef for one of them (native for the
    given platform, e.g. LE under Windows and BE under Mac).

    @library{wxbase}
    @category{conv}

    @see wxMBConvUTF8, wxMBConvUTF16, @ref overview_mbconv "wxMBConv classes overview"
*/
class wxMBConvUTF32 : public wxMBConv
{
};




/**
    @class wxCSConv
    @wxheader{strconv.h}

    This class converts between any character set supported by the system and
    Unicode.

    Please notice that this class uses system-provided conversion functions,
    e.g. @c MultiByteToWideChar() and @c WideCharToMultiByte() under MSW and @c
    iconv(3) under Unix systems and as such may support different encodings and
    different encoding names on different platforms (although all relatively
    common encodings are supported should be supported everywhere).

    It has one predefined instance, @b wxConvLocal, for the default user
    character set.

    @library{wxbase}
    @category{conv}

    @see wxMBConv, wxEncodingConverter, @ref overview_mbconv "wxMBConv classes overview"
*/
class wxCSConv : public wxMBConv
{
public:
    /**
        Constructor.

        You can specify the name of the character set you want to convert
        from/to. If the character set name is not recognized, ISO 8859-1 is
        used as fall back, use IsOk() to test for this.

        @param charset The name of the encoding, shouldn't be empty.
    */
    wxCSConv(const wxString& charset);

    /**
        Constructor.

        You can specify an encoding constant for the character set you want to
        convert from/to. Use IsOk() after construction to check whether the
        encoding is supported by the current system.

        @param encoding Any valid (i.e. not wxFONTENCODING_MAX) font encoding.
    */
    wxCSConv(wxFontEncoding encoding);

    /**
        Returns @true if the charset (or the encoding) given at constructor is
        really available to use.

        Returns @false if ISO 8859-1 will be used instead.

        Note this does not mean that a given string will be correctly
        converted. A malformed string may still make conversion functions
        return @c wxCONV_FAILED.

        @since 2.8.2
    */
    bool IsOk() const;
};



/**
    @class wxMBConvFile
    @wxheader{strconv.h}

    This class used to define the class instance @b wxConvFileName, but
    nowadays @b wxConvFileName is either of type wxConvLibc (on most platforms)
    or wxConvUTF8 (on MacOS X).

    @b wxConvFileName converts filenames between filesystem multibyte encoding
    and Unicode. @b wxConvFileName can also be set to a something else at
    run-time which is used e.g. by wxGTK to use a class which checks the
    environment variable @b G_FILESYSTEM_ENCODING indicating that filenames
    should not be interpreted as UTF8 and also for converting invalid UTF8
    characters (e.g. if there is a filename in iso8859_1) to strings with octal
    values.

    Since some platforms (such as Win32) use Unicode in the filenames,
    and others (such as Unix) use multibyte encodings, this class should only
    be used directly if wxMBFILES is defined to 1. A convenience macro,
    @c wxFNCONV, is defined to @c wxConvFileName->cWX2MB in this case. You
    could use it like this:

    @code
    wxChar *name = wxT("rawfile.doc");
    FILE *fil = fopen(wxFNCONV(name), "r");
    @endcode

    (although it would be better to just use wxFopen(name, "r") in this
    particular case, you only need to use this class for functions taking file
    names not wrapped by wxWidgets.)

    @library{wxbase}
    @category{conv}

    @see @ref overview_mbconv "wxMBConv classes overview"
*/
class wxMBConvFile : public wxMBConv
{
public:
};