src/framework/XMLBufferMgr.hpp

/*
 * The Apache Software License, Version 1.1
 * 
 * Copyright (c) 1999 The Apache Software Foundation.  All rights 
 * reserved.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer. 
 * 
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 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 * 
 * 3. The end-user documentation included with the redistribution,
 *    if any, must include the following acknowledgment:  
 *       "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.
 * 
 * 4. The names "Xerces" and "Apache Software Foundation" must
 *    not be used to endorse or promote products derived from this
 *    software without prior written permission. For written 
 *    permission, please contact apache\@apache.org.
 * 
 * 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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 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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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
 * on the Apache Software Foundation, please see
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/**
 * $Log$
 * Revision 1.1  1999/11/09 01:08:30  twl
 * Initial revision
 *
 * Revision 1.2  1999/11/08 20:44:36  rahul
 * Swat for adding in Product name and CVS comment log variable.
 *
 */


#if !defined(XMLBUFFERMGR_HPP)
#define XMLBUFFERMGR_HPP

#include <util/XML4CDefs.hpp>
#include <framework/XMLBuffer.hpp>

class XMLBufBid;


//
//  There are many places where XMLBuffer objects are needed. In order to
//  avoid either constantly creating and destroying them or maintaining a
//  fixed set and worry about accidental reuse, a buffer manager can provide
//  a pool of them which can be temporarily used and then put back into the
//  pool. This provides a good compromise between performance and easier
//  maintenance.
//
class XMLPARSER_EXPORT XMLBufferMgr
{
public :
    // -----------------------------------------------------------------------
    //  Constructors and Destructor
    // -----------------------------------------------------------------------
    XMLBufferMgr();
    ~XMLBufferMgr();


    // -----------------------------------------------------------------------
    //  Buffer management
    // -----------------------------------------------------------------------
    XMLBuffer& bidOnBuffer();
    void releaseBuffer(XMLBuffer& toRelease);


private :
    // -----------------------------------------------------------------------
    //  Private data members
    //
    //  fBufCount
    //      The count of buffers that have been allocated so far.
    //
    //  fBufList;
    //      The list of pointers to buffers that are loaned out. There will
    //      never be a lot of them, so a flat list is good enough.
    // -----------------------------------------------------------------------
    unsigned int    fBufCount;
    XMLBuffer**     fBufList;
};


//
//  XMLBufBid is a scoped based janitor that allows the scanner code to ask
//  for a buffer on a scoped basis and then insure that it gets freed back
//  into the pool no matter how the scope is exited (exception or normal exit.)
//
class XMLBufBid
{
public :
    // -----------------------------------------------------------------------
    //  Constructors and Destructor
    // -----------------------------------------------------------------------
    XMLBufBid(XMLBufferMgr* const srcMgr) :

        fBuffer(srcMgr->bidOnBuffer())
        , fMgr(srcMgr)
    {
    }

    ~XMLBufBid()
    {
        fMgr->releaseBuffer(fBuffer);
    }



    // -----------------------------------------------------------------------
    //  Buffer access
    // -----------------------------------------------------------------------
    void append(const XMLCh toAppend)
    {
        fBuffer.append(toAppend);
    }

    void append(const XMLCh* const toAppend, const unsigned int count = 0)
    {
        fBuffer.append(toAppend, count);
    }

    const XMLBuffer& getBuffer() const
    {
        return fBuffer;
    }

    XMLBuffer& getBuffer()
    {
        return fBuffer;
    }

    const XMLCh* getRawBuffer() const
    {
        fBuffer.fBuffer[fBuffer.fIndex] = 0;
        return fBuffer.fBuffer;
    }

    XMLCh* getRawBuffer()
    {
        fBuffer.fBuffer[fBuffer.fIndex] = 0;
        return fBuffer.fBuffer;
    }

    unsigned int getLen() const
    {
        return fBuffer.fIndex;
    }

    bool isEmpty()
    {
        return (fBuffer.fIndex == 0);
    }

    void reset()
    {
        fBuffer.reset();
    }

    void set(const XMLCh* const chars, const unsigned int count = 0)
    {
        fBuffer.set(chars, count);
    }


private :
    // -----------------------------------------------------------------------
    //  Private data members
    //
    //  fBuffer
    //      This is the buffer we got, and which we will release.
    //
    //  fMgr
    //      This is the buffer manager we got the buffer from. This is needed
    //      to release the buffer later.
    // -----------------------------------------------------------------------
    XMLBuffer&          fBuffer;
    XMLBufferMgr* const fMgr;
};

#endif