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

//
// FileStream.h
//
// Library: Foundation
// Package: Streams
// Module:  FileStream
//
// Definition of the FileStreamBuf, FileInputStream and FileOutputStream classes.
//
// Copyright (c) 2007, Applied Informatics Software Engineering GmbH.
// and Contributors.
//
// SPDX-License-Identifier:	BSL-1.0
//


#ifndef Foundation_FileStream_INCLUDED
#define Foundation_FileStream_INCLUDED


#include "Poco/Foundation.h"
#if defined(POCO_OS_FAMILY_WINDOWS)
#    include "Poco/FileStream_WIN32.h"
#else
#    include "Poco/FileStream_POSIX.h"
#endif
#include <istream>
#include <ostream>


namespace Poco
{


class Foundation_API FileIOS : public virtual std::ios
/// The base class for FileInputStream and FileOutputStream.
///
/// This class is needed to ensure the correct initialization
/// order of the stream buffer and base classes.
///
/// Files are always opened in binary mode, a text mode
/// with CR-LF translation is not supported. Thus, the
/// file is always opened as if the std::ios::binary flag
/// was specified.
/// Use an InputLineEndingConverter or OutputLineEndingConverter
/// if you require CR-LF translation.
///
/// On Windows platforms, if POCO_WIN32_UTF8 is #define'd,
/// UTF-8 encoded Unicode paths are correctly handled.
{
public:
    FileIOS(std::ios::openmode defaultMode);
    /// Creates the basic stream.

    ~FileIOS();
    /// Destroys the stream.

    void open(const std::string & path, std::ios::openmode mode);
    /// Opens the file specified by path, using the given mode.
    ///
    /// Throws a FileException (or a similar exception) if the file
    /// does not exist or is not accessible for other reasons and
    /// a new file cannot be created.

    void close();
    /// Closes the file stream.
    ///
    /// If, for an output stream, the close operation fails (because
    /// the contents of the stream buffer cannot synced back to
    /// the filesystem), the bad bit is set in the stream state.

    FileStreamBuf * rdbuf();
    /// Returns a pointer to the underlying streambuf.

protected:
    FileStreamBuf _buf;
    std::ios::openmode _defaultMode;
};


class Foundation_API FileInputStream : public FileIOS, public std::istream
/// An input stream for reading from a file.
///
/// Files are always opened in binary mode, a text mode
/// with CR-LF translation is not supported. Thus, the
/// file is always opened as if the std::ios::binary flag
/// was specified.
/// Use an InputLineEndingConverter if you require CR-LF translation.
///
/// On Windows platforms, if POCO_WIN32_UTF8 is #define'd,
/// UTF-8 encoded Unicode paths are correctly handled.
{
public:
    FileInputStream();
    /// Creates an unopened FileInputStream.

    FileInputStream(const std::string & path, std::ios::openmode mode = std::ios::in);
    /// Creates the FileInputStream for the file given by path, using
    /// the given mode.
    ///
    /// The std::ios::in flag is always set, regardless of the actual
    /// value specified for mode.
    ///
    /// Throws a FileNotFoundException (or a similar exception) if the file
    /// does not exist or is not accessible for other reasons.

    ~FileInputStream();
    /// Destroys the stream.
};


class Foundation_API FileOutputStream : public FileIOS, public std::ostream
/// An output stream for writing to a file.
///
/// Files are always opened in binary mode, a text mode
/// with CR-LF translation is not supported. Thus, the
/// file is always opened as if the std::ios::binary flag
/// was specified.
/// Use an OutputLineEndingConverter if you require CR-LF translation.
///
/// On Windows platforms, if POCO_WIN32_UTF8 is #define'd,
/// UTF-8 encoded Unicode paths are correctly handled.
{
public:
    FileOutputStream();
    /// Creates an unopened FileOutputStream.

    FileOutputStream(const std::string & path, std::ios::openmode mode = std::ios::out | std::ios::trunc);
    /// Creates the FileOutputStream for the file given by path, using
    /// the given mode.
    ///
    /// The std::ios::out is always set, regardless of the actual
    /// value specified for mode.
    ///
    /// Throws a FileException (or a similar exception) if the file
    /// does not exist or is not accessible for other reasons and
    /// a new file cannot be created.

    ~FileOutputStream();
    /// Destroys the FileOutputStream.
};


class Foundation_API FileStream : public FileIOS, public std::iostream
/// A stream for reading from and writing to a file.
///
/// Files are always opened in binary mode, a text mode
/// with CR-LF translation is not supported. Thus, the
/// file is always opened as if the std::ios::binary flag
/// was specified.
/// Use an InputLineEndingConverter or OutputLineEndingConverter
/// if you require CR-LF translation.
///
/// A seek (seekg() or seekp()) operation will always set the
/// read position and the write position simultaneously to the
/// same value.
///
/// On Windows platforms, if POCO_WIN32_UTF8 is #define'd,
/// UTF-8 encoded Unicode paths are correctly handled.
{
public:
    FileStream();
    /// Creates an unopened FileStream.

    FileStream(const std::string & path, std::ios::openmode mode = std::ios::out | std::ios::in);
    /// Creates the FileStream for the file given by path, using
    /// the given mode.

    ~FileStream();
    /// Destroys the FileOutputStream.
};


} // namespace Poco


#endif // Foundation_FileStream_INCLUDED