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URIStreamOpener.h

//
// URIStreamOpener.h
//
// $Id: //poco/1.3/Foundation/include/Poco/URIStreamOpener.h#2 $
//
// Library: Foundation
// Package: URI
// Module:  URIStreamOpener
//
// Definition of the URIStreamOpener class.
//
// Copyright (c) 2004-2006, Applied Informatics Software Engineering GmbH.
// and Contributors.
//
// Permission is hereby granted, free of charge, to any person or organization
// obtaining a copy of the software and accompanying documentation covered by
// this license (the "Software") to use, reproduce, display, distribute,
// execute, and transmit the Software, and to prepare derivative works of the
// Software, and to permit third-parties to whom the Software is furnished to
// do so, all subject to the following:
// 
// The copyright notices in the Software and this entire statement, including
// the above license grant, this restriction and the following disclaimer,
// must be included in all copies of the Software, in whole or in part, and
// all derivative works of the Software, unless such copies or derivative
// works are solely in the form of machine-executable object code generated by
// a source language processor.
// 
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
// SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
// FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
// ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
// DEALINGS IN THE SOFTWARE.
//


#ifndef Foundation_URIStreamOpener_INCLUDED
#define Foundation_URIStreamOpener_INCLUDED


#include "Poco/Foundation.h"
#include "Poco/Mutex.h"
#include <istream>
#include <map>


namespace Poco {


class URI;
class URIStreamFactory;
class Path;


00057 class Foundation_API URIStreamOpener
      /// The URIStreamOpener class is used to create and open input streams
      /// for resourced identified by Uniform Resource Identifiers.
      ///
      /// For every URI scheme used, a URIStreamFactory must be registered.
      /// A FileStreamFactory is automatically registered for file URIs.
{
public:
      enum
      {
            MAX_REDIRECTS = 10
      };
      
      URIStreamOpener();
            /// Creates the URIStreamOpener and registers a FileStreamFactory
            /// for file URIs.

      ~URIStreamOpener();
            /// Destroys the URIStreamOpener and deletes all registered
            /// URI stream factories.

      std::istream* open(const URI& uri) const;
            /// Tries to create and open an input stream for the resource specified
            /// by the given uniform resource identifier.
            ///
            /// If no URIStreamFactory has been registered for the URI's
            /// scheme, a UnknownURIScheme exception is thrown.
            /// If the stream cannot be opened for any reason, an
            /// IOException is thrown.
            ///
            /// The given URI must be a valid one. This excludes file system paths.
            ///
            /// Whoever calls the method is responsible for deleting
            /// the returned stream.

      std::istream* open(const std::string& pathOrURI) const;
            /// Tries to create and open an input stream for the resource specified
            /// by the given path or uniform resource identifier.
            ///
            /// If the stream cannot be opened for any reason, an
            /// Exception is thrown.
            ///
            /// The method first tries to interpret the given pathOrURI as an URI.
            /// If this fails, the pathOrURI is treated as local filesystem path.
            /// If this also fails, an exception is thrown.
            ///
            /// Whoever calls the method is responsible for deleting
            /// the returned stream.

      std::istream* open(const std::string& basePathOrURI, const std::string& pathOrURI) const;
            /// Tries to create and open an input stream for the resource specified
            /// by the given path or uniform resource identifier.
            ///
            /// pathOrURI is resolved against basePathOrURI (see URI::resolve() and
            /// Path::resolve() for more information).
            ///
            /// If the stream cannot be opened for any reason, an
            /// Exception is thrown.
            ///
            /// Whoever calls the method is responsible for deleting
            /// the returned stream.
            
      void registerStreamFactory(const std::string& scheme, URIStreamFactory* pFactory);
            /// Registers a URIStreamFactory for the given scheme. If another factory
            /// has already been registered for the scheme, an ExistsException is thrown.
            ///
            /// The URIStreamOpener takes ownership of the factory and deletes it when it is
            /// no longer needed (in other words, when the URIStreamOpener is deleted).

      void unregisterStreamFactory(const std::string& scheme);
            /// Unregisters and deletes the URIStreamFactory for the given scheme.
            ///
            /// Throws a NotFoundException if no URIStreamFactory has been registered
            /// for the given scheme.
            
      bool supportsScheme(const std::string& scheme);
            /// Returns true iff a URIStreamFactory for the given scheme
            /// has been registered.

      static URIStreamOpener& defaultOpener();
            /// Returns a reference to the default URIStreamOpener.

protected:
      std::istream* openFile(const Path& path) const;
      std::istream* openURI(const std::string& scheme, const URI& uri) const;

private:
      URIStreamOpener(const URIStreamOpener&);
      URIStreamOpener& operator = (const URIStreamOpener&);

      typedef std::map<std::string, URIStreamFactory*> FactoryMap;
      
      FactoryMap        _map;
      mutable FastMutex _mutex;
};


} // namespace Poco


#endif // Foundation_URIStreamOpener_INCLUDED

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