membufinputsource.hpp

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/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

/*
 * $Id: MemBufInputSource.hpp 568078 2007-08-21 11:43:25Z amassari $
 */


#if !defined(MEMBUFINPUTSOURCE_HPP)
#define MEMBUFINPUTSOURCE_HPP

#include <xercesc/sax/InputSource.hpp>

XERCES_CPP_NAMESPACE_BEGIN

class BinInputStream;


/**
 *  This class is a derivative of the standard InputSource class. It provides
 *  for the parser access to data stored in a memory buffer. The type of
 *  buffer and its host specific attributes are of little concern here. The
 *  only real requirement is that the memory be readable by the current
 *  process.
 *
 *  Note that the memory buffer size is expressed in <b>bytes</b>, not in
 *  characters. If you pass it text data, you must account for the bytes
 *  per character when indicating the buffer size.
 *
 *  As with all InputSource derivatives. The primary objective of an input
 *  source is to create an input stream via which the parser can spool in
 *  data from the referenced source. In this case, there are two options
 *  available.
 *
 *  The passed buffer can be adopted or merely referenced. If it is adopted,
 *  then it must be dynamically allocated and will be destroyed when the
 *  input source is destroyed (no reference counting!.) If not adopted, the
 *  caller must insure that it remains valid until the input source object
 *  is destroyed.
 *
 *  The other option indicates whether each stream created for this input
 *  source should get its own copy of the data, or whether it should just
 *  stream the data directly from this object's copy of the data. The same
 *  rules apply here, in that the buffer must either be copied by the
 *  stream or it must remain valid until the stream is destroyed.
 */
class XMLPARSER_EXPORT MemBufInputSource : public InputSource
{
public :
    // -----------------------------------------------------------------------
    //  Constructors and Destructor
    // -----------------------------------------------------------------------

    /** @name Constructors */
    //@{

    /**
      * A memory buffer input source is constructed from a buffer of byte
      * data, and the count of bytes in that buffer. The parser will parse
      * from this memory buffer until it has eaten the indicated number of
      * bytes.
      *
      * Note that the system id provided serves two purposes. Firstly it is
      * going to be displayed in error messages as the source of the error.
      * And secondly, any entities which are refered to from this entity
      * via relative paths/URLs will be relative to this fake system id.
      *
      * @param  srcDocBytes     The actual data buffer to be parsed from.
      * @param  byteCount       The count of bytes (not characters, bytes!)
      *                         in the buffer.
      * @param  bufId           A fake system id for the buffer.
      * @param  adoptBuffer     Indicates whether this object should adopt
      *                         the buffer (i.e. become responsible for 
      * deletion) or just
      *                         use it in place.
      * @param  manager         Pointer to the memory manager to be used to
      *                         allocate objects.
      */
    MemBufInputSource
    (
        const   XMLByte* const  srcDocBytes
        , const unsigned int    byteCount
        , const XMLCh* const    bufId
        , const bool            adoptBuffer = false
        , MemoryManager* const  manager = XMLPlatformUtils::fgMemoryManager
    );

    /**
      * This constructor is identical to the previous one, except that it takes
      * the fake system id in local code page form and transcodes it internally.
      */
    MemBufInputSource
    (
        const   XMLByte* const  srcDocBytes
        , const unsigned int    byteCount
        , const char* const     bufId
        , const bool            adoptBuffer = false
        , MemoryManager* const  manager = XMLPlatformUtils::fgMemoryManager
    );
    //@}

    /** @name Destructor */
    //@{
    /**
      * If the buffer was adopted, the copy made during construction is deleted
      * at this point.
      */
    ~MemBufInputSource();
    //@}


    // -----------------------------------------------------------------------
    //  Virtual input source interface
    // -----------------------------------------------------------------------

    /** @name Virtual methods */
    //@{

    /**
      * This method will return a binary input stream derivative that will
      * parse from the memory buffer. If setCopyBufToStream() has been set,
      * then the stream will make its own copy. Otherwise, it will use the
      * buffer as is (in which case it must remain valid until the stream
      * is no longer in use, i.e. the parse completes.)
      *
      * @return A dynamically allocated binary input stream derivative that
      *         can parse from the memory buffer.
      */
    BinInputStream* makeStream() const;

    //@}


    // -----------------------------------------------------------------------
    //  Setter methods
    // -----------------------------------------------------------------------

    /** @name Setter methods */

    //@{

    /**
      * By default, for safety's sake, each newly created stream from this
      * input source will make its own copy of the buffer to stream from. This
      * avoids having to deal with aliasing of the buffer for simple work. But,
      * for higher performance applications or for large buffers, this is
      * obviously not optimal.
      *
      * In such cases, you can call this method to turn off that default
      * action. Once turned off, the streams will just get a pointer to the
      * buffer and parse directly from that. In this case, you must insure that
      * the buffer remains valid for as long as any parse events are still
      * using it.
      *
      * @param  newState    The new boolean flag state to set.
      */
    void setCopyBufToStream(const bool newState);

    /**
      * This methods allows the MemBufInputSource to be used for more than
      * one input source, instead of destructing/constructing another
      * MemBufInputSource.
      *
      * @param  srcDocBytes     The actual data buffer to be parsed from.
      * @param  byteCount       The count of bytes (not characters, bytes!)
      *                         in the buffer.     
      */
    void resetMemBufInputSource(const   XMLByte* const  srcDocBytes
                                , const unsigned int    byteCount);
    //@}


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

    // -----------------------------------------------------------------------
    //  Private data members
    //
    //  fAdopted
    //      Indicates whether the buffer is adopted or not. If so, then it
    //      is destroyed when the input source is destroyed.
    //
    //  fByteCount
    //      The size of the source document.
    //
    //  fCopyBufToStream
    //      This defaults to true (the safe option), which causes it to
    //      give a copy of the buffer to any streams it creates. If you set
    //      it to false, it will allow the streams to just reference the
    //      buffer (in which case this input source must stay alive as long
    //      as the buffer is in use by the stream.)
    //
    //  fSrcBytes
    //      The source memory buffer that is being spooled from. Whether it
    //      belongs to the this input source or not is controlled by the
    //      fAdopted flag.
    // -----------------------------------------------------------------------
    bool            fAdopted;
    unsigned int    fByteCount;
    bool            fCopyBufToStream;
    const XMLByte*  fSrcBytes;
};


inline void MemBufInputSource::setCopyBufToStream(const bool newState)
{
    fCopyBufToStream = newState;
}

XERCES_CPP_NAMESPACE_END

#endif