/*
 * The Apache Software License, Version 1.1
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 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
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 * 4. The names "Xerces" and "Apache Software Foundation" must
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 * 5. Products derived from this software may not be called "Apache",
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 * 
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
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 * ====================================================================
 * 
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation, and was
 * originally based on software copyright (c) 1999, International
 * Business Machines, Inc., http://www.ibm.com .  For more information
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 * <http://www.apache.org/>.
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/*
 *  $Id: XMLRecognizer.hpp,v 1.8 2000/08/30 22:21:28 andyh Exp $
 */

#if !defined(XMLRECOGNIZER_HPP)
#define XMLRECOGNIZER_HPP

/**
 *  This class provides some simple code to recognize the encodings of
 *  XML files. This recognition only does very basic sensing of the encoding
 *  in a broad sense. Basically its just enough to let us get started and
 *  read the XMLDecl line. The scanner, once it reads the XMLDecl, will
 *  tell the reader any actual encoding string it found and the reader can
 *  update itself to be more specific at that point.
 */
class XMLPARSER_EXPORT XMLRecognizer
{
public :
    // -----------------------------------------------------------------------
    //  Class types
    //
    //  This enum represents the various encoding families that we have to
    //  deal with individually at the scanner level. This does not indicate
    //  the exact encoding, just the rough family that would let us scan
    //  the XML/TextDecl to find the encoding string.
    //
    //  The 'L's and 'B's stand for little or big endian. We conditionally
    //  create versions that will automatically map to the local UTF-16 and
    //  UCS-4 endian modes.
    //
    //  OtherEncoding means that its some transcoder based encoding, i.e. not
    //  one of the ones that we do internally. Its a special case and should
    //  never be used directly outside of the reader.
    //
    //  NOTE: Keep this in sync with the name map array in the Cpp file!!
    // -----------------------------------------------------------------------
    enum Encodings
    {
        EBCDIC          = 0
        , UCS_4B        = 1
        , UCS_4L        = 2
        , US_ASCII      = 3
        , UTF_8         = 4
        , UTF_16B       = 5
        , UTF_16L       = 6

        , Encodings_Count
        , Encodings_Min = EBCDIC
        , Encodings_Max = UTF_16L

        , OtherEncoding = 999

        #if defined(ENDIANMODE_BIG)
        , Def_UTF16     = UTF_16B
        , Def_UCS4      = UCS_4B
        #else
        , Def_UTF16     = UTF_16L
        , Def_UCS4      = UCS_4L
        #endif
    };


    // -----------------------------------------------------------------------
    //  Public, const static data
    //
    //  These are the byte sequences for each of the encodings that we can
    //  auto sense, and their lengths.
    // -----------------------------------------------------------------------
    static const char           fgASCIIPre[];
    static const unsigned int   fgASCIIPreLen;
    static const XMLByte        fgEBCDICPre[];
    static const unsigned int   fgEBCDICPreLen;
    static const XMLByte        fgUTF16BPre[];
    static const XMLByte        fgUTF16LPre[];
    static const unsigned int   fgUTF16PreLen;
    static const XMLByte        fgUCS4BPre[];
    static const XMLByte        fgUCS4LPre[];
    static const unsigned int   fgUCS4PreLen;
    static const char           fgUTF8BOM[];
    static const unsigned int   fgUTF8BOMLen;


    // -----------------------------------------------------------------------
    //  Encoding recognition methods
    // -----------------------------------------------------------------------
    static Encodings basicEncodingProbe
    (
        const   XMLByte* const      rawBuffer
        , const unsigned int        rawByteCount
    );

    static Encodings encodingForName
    (
        const   XMLCh* const    theEncName
    );

    static const XMLCh* nameForEncoding(const Encodings theEncoding);


protected :
    // -----------------------------------------------------------------------
    //  Unimplemented constructors, operators, and destructor
    //
    //  This class is effectively being used as a namespace for some static
    //  methods.
    //
    //   (these functions are protected rather than private only to get rid of
    //    some annoying compiler warnings.)
    //
    // -----------------------------------------------------------------------
    XMLRecognizer();
    ~XMLRecognizer();
    void operator=(const XMLRecognizer&);
};

#endif
