CsvUtil.C

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#include <fstream>
 
#include <boost/tokenizer.hpp>
 
#include <Wt/WAbstractItemModel.h>
#include <Wt/WStandardItemModel.h>
#include <Wt/WStandardItem.h>
#include <Wt/WString.h>
 
#include "CsvUtil.h"
 
/*
 * A standard item which converts text edits to numbers
 */
class NumericItem : public WStandardItem {
public:
  virtual std::unique_ptr<WStandardItem> clone() const {
    return std::unique_ptr<NumericItem>(std::make_unique<NumericItem>());
  }
 
  virtual void setData(const cpp17::any &data, ItemDataRole role = ItemDataRole::User) {
    cpp17::any dt;
 
    if (role == ItemDataRole::Edit) {
      std::string s = asString(data).toUTF8();
 
      char *end;
      double d = std::strtod(s.c_str(), &end);
      if (*end == 0)
        dt = cpp17::any(d);
      else
        dt = data;
    } else
      dt = data;
 
    WStandardItem::setData(dt, role);
  }
};
 
std::shared_ptr<WStandardItemModel> csvToModel(const std::string& csvFile,
                                   bool firstLineIsHeaders)
{
  std::ifstream f(csvFile.c_str());
 
  if (f) {
    std::shared_ptr<WStandardItemModel> result = std::make_shared<WStandardItemModel>(0, 0);
    result->setItemPrototype(std::make_unique<NumericItem>());
    readFromCsv(f, result, -1, firstLineIsHeaders);
    return result;
  } else
    return nullptr;
}
 
void readFromCsv(std::istream& f, std::shared_ptr<WAbstractItemModel> model,
                 int numRows, bool firstLineIsHeaders)
{
  int csvRow = 0;
 
  while (f) {
    std::string line;
    getline(f, line);
 
    if (f) {
      typedef boost::tokenizer<boost::escaped_list_separator<char> >
        CsvTokenizer;
      CsvTokenizer tok(line);
 
      int col = 0;
      for (CsvTokenizer::iterator i = tok.begin();
           i != tok.end(); ++i, ++col) {
 
        if (col >= model->columnCount())
          model->insertColumns(model->columnCount(),
                               col + 1 - model->columnCount());
 
        if (firstLineIsHeaders && csvRow == 0)
          model->setHeaderData(col, cpp17::any{WString{*i}});
        else {
          int dataRow = firstLineIsHeaders ? csvRow - 1 : csvRow;
 
          if (numRows != -1 && dataRow >= numRows)
            return;
 
          if (dataRow >= model->rowCount())
            model->insertRows(model->rowCount(),
                              dataRow + 1 - model->rowCount());
 
          cpp17::any data{WString{*i}};
          model->setData(dataRow, col, data);
        }
      }
    }
 
    ++csvRow;
  }
}