io/CFileGZInputStream.h

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/* +------------------------------------------------------------------------+
   |                     Mobile Robot Programming Toolkit (MRPT)            |
   |                          https://www.mrpt.org/                         |
   |                                                                        |
   | Copyright (c) 2005-2020, Individual contributors, see AUTHORS file     |
   | See: https://www.mrpt.org/Authors - All rights reserved.               |
   | Released under BSD License. See: https://www.mrpt.org/License          |
   +------------------------------------------------------------------------+ */
#pragma once

#include <mrpt/core/optional_ref.h>
#include <mrpt/core/pimpl.h>
#include <mrpt/io/CStream.h>

namespace mrpt::io
{
/** Transparently opens a compressed "gz" file and reads uncompressed data from
 * it.
 *   If the file is not a .gz file, it silently reads data from the file.
 *  This class requires compiling MRPT with wxWidgets. If wxWidgets is not
 * available then the class is actually mapped to the standard CFileInputStream
 *
 * \sa CFileInputStream
 * \ingroup mrpt_io_grp
 */
class CFileGZInputStream : public CStream
{
   private:
    struct Impl;
    mrpt::pimpl<Impl> m_f;
    /** Compressed file size */
    uint64_t m_file_size{0};

   public:
    /** Constructor without open */
    CFileGZInputStream();

    /** Constructor and open
     * \param fileName The file to be open in this stream
     * \exception std::exception If there's an error opening the file.
     */
    CFileGZInputStream(const std::string& fileName);

    CFileGZInputStream(const CFileGZInputStream&) = delete;
    CFileGZInputStream& operator=(const CFileGZInputStream&) = delete;

    /** Dtor */
    ~CFileGZInputStream() override;

    /** Opens the file for read.
     * \param fileName The file to be open in this stream
     * \return false if there's an error opening the file, true otherwise
     */
    bool open(
        const std::string& fileName,
        mrpt::optional_ref<std::string> error_msg = std::nullopt);
    /** Closes the file */
    void close();
    /** Returns true if the file was open without errors. */
    bool fileOpenCorrectly() const;
    /** Returns true if the file was open without errors. */
    bool is_open() { return fileOpenCorrectly(); }
    /** Will be true if EOF has been already reached. */
    bool checkEOF();

    /** Method for getting the total number of <b>compressed</b> bytes of in the
     * file (the physical size of the compressed file). */
    uint64_t getTotalBytesCount() const override;
    /** Method for getting the current cursor position in the <b>compressed</b>,
     * where 0 is the first byte and TotalBytesCount-1 the last one. */
    uint64_t getPosition() const override;

    /** This method is not implemented in this class */
    uint64_t Seek(int64_t, CStream::TSeekOrigin = sFromBeginning) override;
    size_t Read(void* Buffer, size_t Count) override;
    size_t Write(const void* Buffer, size_t Count) override;
};  // End of class def.
}  // namespace mrpt::io