RangeTokenizer.h

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// Copyright 2019-2020 CERN and copyright holders of ALICE O2.
// See https://alice-o2.web.cern.ch/copyright for details of the copyright holders.
// All rights not expressly granted are reserved.
//
// This software is distributed under the terms of the GNU General Public
// License v3 (GPL Version 3), copied verbatim in the file "COPYING".
//
// In applying this license CERN does not waive the privileges and immunities
// granted to it by virtue of its status as an Intergovernmental Organization
// or submit itself to any jurisdiction.
#ifndef RANGE_TOKENIZER_H
#define RANGE_TOKENIZER_H
 
 
#include <vector>
#include <string>
#include <sstream>
#include <utility>    // std::move
#include <functional> // std::function
 
namespace o2
{
 
struct RangeTokenizer {
  template <typename T>
  static std::vector<T> tokenize(
    std::string input, std::function<T(std::string const&)> convert = [](std::string const& token) {T value; std::istringstream(token) >> value; return value; })
  {
    std::istringstream stream(input);
    std::string token;
    std::vector<T> res;
    while (std::getline(stream, token, ',')) {
      if (std::is_integral<T>::value && token.find('-') != token.npos) {
        // extract range
        if constexpr (std::is_integral<T>::value) { // c++17 compile time
          insertRange(res, token, convert);
        }
      } else {
        res.emplace_back(convert(token));
      }
    }
    return std::move(res);
  }
 
  template <typename T, typename std::enable_if_t<std::is_integral<T>::value == true, int> = 0>
  static void insertRange(std::vector<T>& res, std::string token, std::function<T(std::string const&)> convert)
  {
    std::istringstream tokenstream(token);
    std::string bound;
    T lowerBound, upperBound;
    if (std::getline(tokenstream, bound, '-')) {
      lowerBound = convert(bound);
      if (std::getline(tokenstream, bound, '-')) {
        upperBound = convert(bound);
        for (T index = lowerBound; index <= upperBound; index++) {
          res.emplace_back(index);
        }
      }
    }
  }
};
}; // namespace o2
 
#endif