XML256TableTranscoder.hpp

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 * originally based on software copyright (c) 1999, International
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/*
 * $Log$
 * Revision 1.1  2002/02/01 22:22:13  peiyongz
 * Initial revision
 *
 * Revision 1.1  2000/03/18 00:00:32  roddey
 * Initial updates for two way transcoding support
 *
 */


#ifndef XML256TABLETRANSCODER_HPP
#define XML256TABLETRANSCODER_HPP

#include <xercesc/util/TransService.hpp>

//
//  This class implements the functionality of a common type of transcoder
//  for an 8 bit, single byte encoding based on a set of 'to' and 'from'
//  translation tables. Actual derived classes are trivial and just have to
//  provide us with pointers to their tables and we do all the work.
//
class XMLUTIL_EXPORT XML256TableTranscoder : public XMLTranscoder
{
public :
    // -----------------------------------------------------------------------
    //  Public constructors and destructor
    // -----------------------------------------------------------------------
    virtual ~XML256TableTranscoder();


    // -----------------------------------------------------------------------
    //  The virtual transcoding interface
    // -----------------------------------------------------------------------
    virtual unsigned int transcodeFrom
    (
        const   XMLByte* const          srcData
        , const unsigned int            srcCount
        ,       XMLCh* const            toFill
        , const unsigned int            maxChars
        ,       unsigned int&           bytesEaten
        ,       unsigned char* const    charSizes
    );

    virtual unsigned int transcodeTo
    (
        const   XMLCh* const    srcData
        , const unsigned int    srcCount
        ,       XMLByte* const  toFill
        , const unsigned int    maxBytes
        ,       unsigned int&   charsEaten
        , const UnRepOpts       options
    );

    virtual bool canTranscodeTo
    (
        const   unsigned int    toCheck
    )   const;


protected :
    // -----------------------------------------------------------------------
    //  Hidden constructors
    // -----------------------------------------------------------------------
    XML256TableTranscoder
    (
        const   XMLCh* const                        encodingName
        , const unsigned int                        blockSize
        , const XMLCh* const                        fromTable
        , const XMLTransService::TransRec* const    toTable
        , const unsigned int                        toTableSize
    );


    // -----------------------------------------------------------------------
    //  Protected helper methods
    // -----------------------------------------------------------------------
    XMLByte xlatOneTo
    (
        const   XMLCh       toXlat
    )   const;


private :
    // -----------------------------------------------------------------------
    //  Unimplemented constructors and operators
    // -----------------------------------------------------------------------
    XML256TableTranscoder();
    XML256TableTranscoder(const XML256TableTranscoder&);
    void operator=(const XML256TableTranscoder&);


    // -----------------------------------------------------------------------
    //  Private data members
    //
    //  fFromTable
    //      This is the 'from' table that we were given during construction.
    //      It is a 256 entry table of XMLCh chars. Each entry is the
    //      Unicode code point for the external encoding point of that value.
    //      So fFromTable[N] is the Unicode translation of code point N of
    //      the source encoding.
    //
    //      We don't own this table, we just refer to it. It is assumed that
    //      the table is static, for performance reasons.
    //
    //  fToSize
    //      The 'to' table is variable sized. This indicates how many records
    //      are in it.
    //
    //  fToTable
    //      This is a variable sized table of TransRec structures. It must
    //      be sorted by the intCh field, i.e. the XMLCh field. It is searched
    //      binarily to find the record for a particular Unicode char. Then
    //      that record's extch field is the translation record.
    //
    //      We don't own this table, we just refer to it. It is assumed that
    //      the table is static, for performance reasons.
    //
    //      NOTE: There may be dups of the extCh field, since there might be
    //      multiple Unicode code points which map to the same external code
    //      point. Normally this won't happen, since the parser assumes that
    //      internalization is normalized, but we have to be prepared to do
    //      the right thing if some client code gives us non-normalized data
    //      itself.
    // -----------------------------------------------------------------------
    const XMLCh*                        fFromTable;
    unsigned int                        fToSize;
    const XMLTransService::TransRec*    fToTable;
};

#endif