ClickHouse/base/poco/Foundation/include/Poco/URIStreamOpener.h

//
// URIStreamOpener.h
//
// Library: Foundation
// Package: URI
// Module:  URIStreamOpener
//
// Definition of the URIStreamOpener class.
//
// Copyright (c) 2004-2006, Applied Informatics Software Engineering GmbH.
// and Contributors.
//
// SPDX-License-Identifier:	BSL-1.0
//


#ifndef Foundation_URIStreamOpener_INCLUDED
#define Foundation_URIStreamOpener_INCLUDED


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


namespace Poco
{


class URI;
class URIStreamFactory;
class Path;


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