ProgressBar.hh

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#pragma once
 
#include <ostream>
#include <functional>
#include <stdexcept>
 
namespace HEJ {
 
  template<typename T>
  class ProgressBar {
  public:
 
    ProgressBar(std::ostream & out, T max) :
      out_{out}, max_{max}
    {
      if(max <= 0) {
        throw std::invalid_argument{
          "Maximum in progress bar has to be positive"
        };
      }
      print_bar();
    }
 
 
    ProgressBar & increment(T count) {
      counter_ += count;
      update_progress();
      return *this;
    }
 
 
    ProgressBar & operator++() {
      ++counter_;
      update_progress();
      return *this;
    }
 
  private:
    void update_progress() {
      counter_ = std::min(counter_, max_);
      const int ndots = (100*counter_)/max_;
      const int new_dots = ndots - ndots_;
      if(new_dots > 0) {
        for(int dot = 0; dot < new_dots; ++dot) out_.get() << '.';
        out_.get().flush();
        ndots_ = ndots;
      }
    }
 
    void print_bar() const {
      out_.get() << "0% ";
      for(int i = 10; i <= 100; i+= 10){
        out_.get() << "       " + std::to_string(i) + "%";
      }
      out_.get() << "\n|";
      for(int i = 10; i <= 100; i+= 10){
        out_.get() << "---------|";
      }
      out_.get() << '\n';
    }
 
    std::reference_wrapper<std::ostream> out_;
    T counter_ = 0;
    T ndots_ = 0;
    T max_;
  };
}