CTextFileLinesParser.h

Go to the documentation of this file.

/* +------------------------------------------------------------------------+
   |                     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 <fstream>
#include <iosfwd>
#include <memory>
#include <string>

namespace mrpt::io
{
/** A class for parsing text files, returning each non-empty and non-comment
 * line, along its line number. Lines are strip out of leading and trailing
 * whitespaces. By default, lines starting with either "#", "//" or "%" are
 * skipped as comment lines, unless this behavior is explicitly disabled with
 * \a enableCommentFilters.
 * \ingroup mrpt_io_grp
 */
class CTextFileLinesParser
{
   public:
    /** Default constructor; should call \a open() at some moment later. */
    CTextFileLinesParser() = default;
    /** Constructor for opening a file  \exception std::exception On error
     * opening file */
    explicit CTextFileLinesParser(const std::string& filename);

    /** Constructor for reading from a generic std::istream. Note that a
     * reference to the stream is stored in the object, so it's the user
     * responsibility to make sure the stream is not destroyed before than
     * this object.
     */
    explicit CTextFileLinesParser(std::istream& in);

    /** Open a file (an alternative to the constructor with a file name) */
    void open(const std::string& fil);

    /** Opens for reading a generic std::istream. Note that a
     * reference to the stream is stored in the object, so it's the user
     * responsibility to make sure the stream is not destroyed before than
     * this object.
     */
    void open(std::istream& in);

    /** Close the file (no need to call it normally, the file is closed upon
     * destruction) */
    void close();
    /** Reset the read pointer to the beginning of the file */
    void rewind();

    /** Reads from the file and return the next (non-comment) line, as a
     * std::string
     * \return false on EOF.
     */
    bool getNextLine(std::string& out_str);

    /** Reads from the file and stores the next (non-comment) line into the
     * given stream buffer.
     * \return false on EOF.
     */
    bool getNextLine(std::istringstream& buf);

    /** Return the line number of the last line returned with \a getNextLine */
    size_t getCurrentLineNumber() const;

    /** Enable/disable filtering of lines starting with "%", "//" or "#",
     * respectively. */
    void enableCommentFilters(
        bool filter_MATLAB_comments, bool filter_C_comments,
        bool filter_SH_comments);

   private:
    std::string m_fileName;
    /** Points to either a user-owned object, or to m_my_in */
    std::istream* m_in{nullptr};
    std::shared_ptr<std::istream> m_my_in;
    size_t m_curLineNum{0};
    bool m_filter_MATLAB_comments{true};
    bool m_filter_C_comments{true};
    bool m_filter_SH_comments{true};

};  // end of CTextFileLinesParser
}  // namespace mrpt::io