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


#if !defined(PLATFORMUTILS_HPP)
#define PLATFORMUTILS_HPP

#include <xercesc/util/XMLException.hpp>
#include <xercesc/util/PanicHandler.hpp>

XERCES_CPP_NAMESPACE_BEGIN

class XMLMsgLoader;
class XMLNetAccessor;
class XMLTransService;
class MemoryManager;
class XMLMutex;

//
//  For internal use only
//
//  This class provides a simple abstract API via which lazily evaluated
//  data can be cleaned up.
//
class XMLUTIL_EXPORT XMLDeleter
{
public :
    virtual ~XMLDeleter();

protected :
    XMLDeleter();

private :
    XMLDeleter(const XMLDeleter&);
    XMLDeleter& operator=(const XMLDeleter&);
};


/**
  * Utilities that must be implemented in a platform-specific way.
  *
  * This class contains methods that must be implemented in a platform
  * specific manner. The actual implementations of these methods are
  * available in the per-platform files indide <code>src/util/Platforms
  * </code>.
  */
class XMLUTIL_EXPORT XMLPlatformUtils
{
public :

    /** @name Public Static Data */
    //@{

    /** The network accessor
      *
      * This is provided by the per-platform driver, so each platform can
      * choose what actual implementation it wants to use. The object must
      * be dynamically allocated.
      *
      * <i>Note that you may optionally, if your platform driver does not
      * install a network accessor, set it manually from your client code
      * after calling Initialize(). This works because this object is
      * not required during initialization, and only comes into play during
      * actual XML parsing.</i>
      */
    static XMLNetAccessor*      fgNetAccessor;

    /** The transcoding service.
      *
      * This is provided by the per platform driver, so each platform can
      * choose what implemenation it wants to use. When the platform
      * independent initialization code needs to get a transcoding service
      * object, it will call <code>makeTransService()</code> to ask the
      * per-platform code to create one. Only one transcoding service
      * object is reqeusted per-process, so it is shared and synchronized
      * among parser instances within that process.
      */
    static XMLTransService*     fgTransService;
#ifdef OS390
    static XMLTransService*     fgTransService2;
#endif

    /** The Panic Handler
      *
      *   This is the application provided panic handler. 
      */
    static PanicHandler*        fgUserPanicHandler;
    
    /** The Panic Handler
      *
      *   This is the default panic handler. 
      */    
    static PanicHandler*        fgDefaultPanicHandler;

    /** The configurable memory manager
      *
      *   This is the pluggable memory manager. If it is not provided by an
      *   application, a default implementation is used.
      */
    static MemoryManager*       fgMemoryManager;
    
    /** The array-allocating memory manager
      *
      *   This memory manager always allocates memory by calling the
      *   global new[] operator. It may be used to allocate memory
      *   where such memory needs to be deletable by calling delete [].
      *   Since this allocator is always guaranteed to do the same thing
      *   there is no reason, nor facility, to override it.
      */
    static MemoryManager*       fgArrayMemoryManager;

    static XMLMutex*            fgAtomicMutex;
    
    //@}


    /** @name Initialization amd Panic methods */
    //@{

    /** Perform per-process parser initialization
      *
      * Initialization <b>must</b> be called first in any client code.
      *
      * The locale is set iff the Initialize() is invoked for the very first time,
      * to ensure that each and every message loaders, in the process space, share
      * the same locale.
      *
      * All subsequent invocations of Initialize(), with a different locale, have
      * no effect on the message loaders, either instantiated, or to be instantiated.
      *
      * To set to a different locale, client application needs to Terminate() (or
      * multiple Terminate() in the case where multiple Initialize() have been invoked
      * before), followed by Initialize(new_locale).
      *
      * The default locale is "en_US".
      *
      * nlsHome: user specified location where MsgLoader retrieves error message files.
      *          the discussion above with regard to locale, applies to this nlsHome
      *          as well.
      *
      * panicHandler: application's panic handler, application owns this handler.
      *               Application shall make sure that the plugged panic handler persists 
      *               through the call to XMLPlatformUtils::terminate().       
      *
      * memoryManager: plugged-in memory manager which is owned by user
      *                applications. Applications must make sure that the
      *                plugged-in memory manager persist through the call to
      *                XMLPlatformUtils::terminate()
      */
    static void Initialize(const char*          const locale = XMLUni::fgXercescDefaultLocale
                         , const char*          const nlsHome = 0
                         ,       PanicHandler*  const panicHandler = 0
                         ,       MemoryManager* const memoryManager = 0
                         ,       bool                 toInitStatics = false);

    /** Perform per-process parser termination
      *
      * The termination call is currently optional, to aid those dynamically
      * loading the parser to clean up before exit, or to avoid spurious
      * reports from leak detectors.
      */
    static void Terminate();

    /** The panic mechanism.
      *
      * If, during initialization, we cannot even get far enough along
      * to get transcoding up or get message loading working, we call
      * this method.</p>
      *
      * Each platform can implement it however they want. This method will
      * delegate the panic handling to a user specified panic handler or
      * in the absence of it, the default panic handler.
      *
      * In case the default panic handler does not support a particular
      * platform, the platform specific panic hanlding shall be implemented
      * here </p>.
      * 
      * @param reason The enumeration that defines the cause of the failure
      */
    static void panic
    (
        const   PanicHandler::PanicReasons    reason
    );
    
    //@}

    /** @name File Methods */
    //@{

    /** Get the current file position
      *
      * This must be implemented by the per-platform driver, which should
      * use local file services to deterine the current position within
      * the passed file.
      *
      * Since the file API provided here only reads, if the host platform
      * supports separate read/write positions, only the read position is
      * of any interest, and hence should be the one returned.
      *
      * @param theFile The file handle
      * @param manager The MemoryManager to use to allocate objects
      */
    static unsigned int curFilePos(FileHandle theFile
        , MemoryManager* const manager  = XMLPlatformUtils::fgMemoryManager);

    /** Closes the file handle
      *
      * This must be implemented by the per-platform driver, which should
      * use local file services to close the passed file handle, and to
      * destroy the passed file handle and any allocated data or system
      * resources it contains.
      *
      * @param theFile The file handle to close
      * @param manager The MemoryManager to use to allocate objects
      */
    static void closeFile(FileHandle theFile
        , MemoryManager* const manager  = XMLPlatformUtils::fgMemoryManager);

    /** Returns the file size
      *
      * This must be implemented by the per-platform driver, which should
      * use local file services to determine the current size of the file
      * represented by the passed handle.
      *
      * @param theFile The file handle whose size you want
      * @param manager The MemoryManager to use to allocate objects
      * @return Returns the size of the file in bytes
      */
    static unsigned int fileSize(FileHandle theFile
        , MemoryManager* const manager  = XMLPlatformUtils::fgMemoryManager);

    /** Opens the file
      *
      * This must be implemented by the per-platform driver, which should
      * use local file services to open passed file. If it fails, a
      * null handle pointer should be returned.
      *
      * @param fileName The string containing the name of the file
      * @param manager The MemoryManager to use to allocate objects
      * @return The file handle of the opened file
      */
    static FileHandle openFile(const char* const fileName
        , MemoryManager* const manager  = XMLPlatformUtils::fgMemoryManager);

    /** Opens a named file
      *
      * This must be implemented by the per-platform driver, which should
      * use local file services to open the passed file. If it fails, a
      * null handle pointer should be returned.
      *
      * @param fileName The string containing the name of the file
      * @param manager The MemoryManager to use to allocate objects
      * @return The file handle of the opened file
      */
    static FileHandle openFile(const XMLCh* const fileName
        , MemoryManager* const manager  = XMLPlatformUtils::fgMemoryManager);

    /** Open a named file to write
      *
      * This must be implemented by the per-platform driver, which should
      * use local file services to open passed file. If it fails, a
      * null handle pointer should be returned.
      *
      * @param fileName The string containing the name of the file
      * @param manager The MemoryManager to use to allocate objects
      * @return The file handle of the opened file
      */
    static FileHandle openFileToWrite(const char* const fileName
        , MemoryManager* const manager  = XMLPlatformUtils::fgMemoryManager);