Scala parser

SclParser.cpp

#include <iostream>
#include <string>
#include <math.h>
#include <array>

class ScalaDigester
{
  public:
    ScalaDigester(std::string input)
    {
      scala_string = input;
      current_pos = 0;
    }

    std::string getNextLine()
    {
      bool is_comment = false;
      std::string line;
      if (current_pos < scala_string.length())
        do
        {
          line = scala_string.substr(current_pos,
              scala_string.find("\n", current_pos) - current_pos);
          current_pos += line.length() + 1;
          // lines in a scala file beginning with ! are comments
          if (line.at(0) == '!')
            is_comment = true;
          else
            is_comment = false;
        }
        while (is_comment == true);
      return line;
    }
  private:
    std::string scala_string;
    int current_pos;
};

class Scale
{
  public:

  Scale(std::string input)
  {
    ScalaDigester digester(input);
    name = digester.getNextLine();
    degrees = std::stoi(digester.getNextLine());

    int count = 0;
    while (count < degrees)
      intervals[count++] = digester.getNextLine();
  }

  std::string getName()
  {
    return name;
  }

  int getDegrees()
  {
    return degrees;
  }

  void getFrequencies(float frequencies[128], float root)
  {
    frequencies[0] = root;
    int key_note = 1;
    while (key_note < 128)
    {
      int current_degree = 0;
      while (current_degree < degrees)
      {
        float interval = parseInterval(intervals[current_degree]);
        frequencies[key_note] = root * interval;
        current_degree++;
        if (current_degree == degrees)
          root = frequencies[key_note];
        key_note++;
        if (key_note > 128)
          return;
      }
    }
  }

  private:

  float parseInterval(std::string interval)
  {
    if (interval.find(".") < interval.length())
      return pow(2.0, std::stof(interval) / 1200.0);
    else
    {
      int slash_pos = interval.find("/");
      float numerator;
      float denominator;
      if (slash_pos > -1) {
        numerator = std::stof(interval.substr(0,slash_pos));
        denominator = std::stof(interval.substr(slash_pos + 1));
      }
      else
      {
        numerator = std::stof(interval);
        denominator = 1.f;
      }
      return numerator / denominator;
    }
  }

  std::string name;
  int degrees;
  std::string intervals[128];
};

int main()
{
  // taken from http://www.huygens-fokker.org/scala/scl_format.html
  std::string sample_input = "! meanquar.scl\n!\n1/4-comma meantone scale. Pietro Aaron's temperament (1523)\n 12\n!\n 76.04900\n 193.15686\n 310.26471\n 5/4\n 503.42157\n 579.47057\n 696.57843\n 25/16\n 889.73529\n 1006.84314\n 1082.89214\n 2/1";

  // after you instantiate the object you can get the name and # scale degrees
  Scale scale(sample_input);
  std::cout << scale.getName() << "\n";
  std::cout << scale.getDegrees() << "\n";

  // given a root_frequency, it will populate a frequencies array with the scale
  float root_frequency = 1.0;
  float frequencies[128];
  scale.getFrequencies(frequencies, root_frequency);

  // print them out for testing purposes
  int i = 0;
  while (i < 128)
    std::cout << frequencies[i++] << "\n";

  return 0;
}