gnc-tokenizer-csv.cpp

/********************************************************************\
 * gnc-tokenizer-csv.cpp - takes a csv file and converts it into a  *
 *                         two-dimensional vector of strings (table)*
 *                                                                  *
 *  Copyright (C) 2015 Geert Janssens <geert@kobaltwit.be>          *
 *                                                                  *
 * This program is free software; you can redistribute it and/or    *
 * modify it under the terms of the GNU General Public License as   *
 * published by the Free Software Foundation; either version 2 of   *
 * the License, or (at your option) any later version.              *
 *                                                                  *
 * This program is distributed in the hope that it will be useful,  *
 * but WITHOUT ANY WARRANTY; without even the implied warranty of   *
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the    *
 * GNU General Public License for more details.                     *
 *                                                                  *
 * You should have received a copy of the GNU General Public License*
 * along with this program; if not, contact:                        *
 *                                                                  *
 * Free Software Foundation           Voice:  +1-617-542-5942       *
 * 51 Franklin Street, Fifth Floor    Fax:    +1-617-542-2652       *
 * Boston, MA  02110-1301,  USA       gnu@gnu.org                   *
\********************************************************************/

#include "gnc-tokenizer-csv.hpp"

#include <iostream>
#include <fstream>      // fstream
#include <vector>
#include <string>
#include <algorithm>    // copy
#include <iterator>     // ostream_operator

#include <boost/tokenizer.hpp>
#include <boost/locale.hpp>
#include <boost/algorithm/string.hpp>

#include <glib/gi18n.h>

void
GncCsvTokenizer::set_separators(const std::string& separators)
{
    m_sep_str = separators;
}

void
GncCsvTokenizer::set_enable_escape(const bool enable)
{
    m_enable_escape = enable;
}


int GncCsvTokenizer::tokenize()
{
    using Tokenizer = boost::tokenizer< boost::escaped_list_separator<char>>;

    boost::escaped_list_separator<char> sep("\\", m_sep_str, "\"");

    StrVec vec;
    std::string line;
    std::string buffer;

    bool inside_quotes(false);
    size_t last_quote(0);

    m_tokenized_contents.clear();
    std::istringstream in_stream(m_utf8_contents);

    try
    {
        while (std::getline (in_stream, buffer))
        {
            // --- deal with line breaks in quoted strings
            buffer = boost::trim_copy (buffer); // Removes trailing newline and spaces
            last_quote = buffer.find_first_of('"');
            while (last_quote != std::string::npos)
            {
                if (last_quote == 0) // Test separately because last_quote - 1 would be out of range
                    inside_quotes = !inside_quotes;
                else if (!m_enable_escape || buffer[ last_quote - 1 ] != '\\')
                    inside_quotes = !inside_quotes;

                last_quote = buffer.find_first_of('"',last_quote+1);
            }

            line.append(buffer);
            if (inside_quotes)
            {
                line.append(" ");
                continue;
            }
            // ---

            // Deal with backslashes that are not meant to be escapes
            // The boost::tokenizer with escaped_list_separator as we use
            // it would choke on this.
            auto bs_pos = line.find ('\\');
            while (bs_pos != std::string::npos)
            {
                if (! m_enable_escape)
                {
                    // Put an escape before this escape and look for the next
                    line.insert (bs_pos, 1, '\\');
                    bs_pos += 2;
                }
                else
                {
                    // Process as before
                    if ((bs_pos == line.size()) ||                                 // got trailing single backslash
                        (line.find_first_of ("\"\\n", bs_pos + 1) != bs_pos + 1))  // backslash is not part of known escapes \\, \" or \n
                        line = line.substr(0, bs_pos) + "\\\\" + line.substr(bs_pos + 1);
                    bs_pos += 2;
                }

                bs_pos = line.find ('\\', bs_pos);
            }

            // Deal with repeated " ("") in strings.
            // This is commonly used as escape mechanism for double quotes in csv files.
            // However boost just eats them.
            bs_pos = line.find ("\"\"");
            while (bs_pos != std::string::npos)
            {
                // Only make changes in case the double quotes are part of a larger field
                // In other words a field which only contains two double quotes represent an
                // empty field. We don't need to touch those.
                // The way to determine whether the double quotes represent an empty string
                // is by checking whether the character in front or after are either
                // a field separator or the beginning or end of of the string.
                if (!(((bs_pos == 0) ||                                          // quotes are at start of line
                       (m_sep_str.find (line[bs_pos-1]) != std::string::npos))    // quotes preceded by field separator
                      &&
                      ((bs_pos + 2 >= line.length()) ||                          // quotes are at end of line
                       (m_sep_str.find (line[bs_pos+2]) != std::string::npos))))   // quotes followed by field separator
                    // Only make changes in case the double quotes are not an empty field
                    line.replace (bs_pos, 2, "\\\"");
                bs_pos = line.find ("\"\"", bs_pos + 2);
            }

            Tokenizer tok(line, sep);
            vec.assign(tok.begin(),tok.end());
            m_tokenized_contents.push_back(vec);
            line.clear();
        }
    }
    catch (boost::escaped_list_error &e)
    {
        throw (std::range_error N_("There was an error parsing the file."));
    }

    return 0;
}