Qt: CSV row parsing (Excel style)

example.cpp

// example usage:

QFile csv(filename);
csv.open(QFile::ReadOnly | QFile::Text);

QTextStream in(&csv);
QStringList row;

while (readCSVRow(in, &row))
    qDebug() << row;

readCSVRow.cpp

/*
This is free and unencumbered software released into the public domain.

Anyone is free to copy, modify, publish, use, compile, sell, or
distribute this software, either in source code form or as a compiled
binary, for any purpose, commercial or non-commercial, and by any
means.

In jurisdictions that recognize copyright laws, the author or authors
of this software dedicate any and all copyright interest in the
software to the public domain. We make this dedication for the benefit
of the public at large and to the detriment of our heirs and
successors. We intend this dedication to be an overt act of
relinquishment in perpetuity of all present and future rights to this
software under copyright law.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR
OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
OTHER DEALINGS IN THE SOFTWARE.

For more information, please refer to <http://unlicense.org/>
*/

/**
 * Parses Excel style CSV's, handling quotes and double-quotes appropriately, and 
 * allows newlines in fields. Handles Windows and Unix line endings properly as 
 * long as your file is opened with QFile::Text. Doesn't support binary-mode 
 * untranslated line-endings.
 *
 *    @param   in   A valid QTextStream.
 *    @param   row  Receives columns. Cleared first. Do not pass nullptr.
 *    @return  True on success, false on EOF.
 *    @throws  std::runtime_error on parse error.
 */

bool readCSVRow (QTextStream &in, QStringList *row) {

    static const int delta[][5] = {
        //  ,    "   \n    ?  eof
        {   1,   2,  -1,   0,  -1  }, // 0: parsing (store char)
        {   1,   2,  -1,   0,  -1  }, // 1: parsing (store column)
        {   3,   4,   3,   3,  -2  }, // 2: quote entered (no-op)
        {   3,   4,   3,   3,  -2  }, // 3: parsing inside quotes (store char)
        {   1,   3,  -1,   0,  -1  }, // 4: quote exited (no-op)
        // -1: end of row, store column, success
        // -2: eof inside quotes
    };

    row->clear();

    if (in.atEnd())
        return false;

    int state = 0, t;
    char ch;
    QString cell;

    while (state >= 0) {

        if (in.atEnd())
            t = 4;
        else {
            in >> ch;
            if (ch == ',') t = 0;
            else if (ch == '\"') t = 1;
            else if (ch == '\n') t = 2;
            else t = 3;
        }

        state = delta[state][t];

        if (state == 0 || state == 3) {
            cell += ch;
        } else if (state == -1 || state == 1) {
            row->append(cell);
            cell = "";
        }

    }

    if (state == -2)
        throw runtime_error("End-of-file found while inside quotes.");

    return true;

}

Info at this SO post.