CTextFileLinesParser.h

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/* +------------------------------------------------------------------------+
   |                     Mobile Robot Programming Toolkit (MRPT)            |
   |                          http://www.mrpt.org/                          |
   |                                                                        |
   | Copyright (c) 2005-2018, Individual contributors, see AUTHORS file     |
   | See: http://www.mrpt.org/Authors - All rights reserved.                |
   | Released under BSD License. See details in http://www.mrpt.org/License |
   +------------------------------------------------------------------------+ */
#pragma once

#include <fstream>
#include <string>
#include <iosfwd>

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() {}
    /** 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;
    std::istream *m_in{ nullptr };
    bool m_in_ownership{ true };
    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
}