lua_custom_function.cpp

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#include "lua_custom_function.h"
#include <QTextStream>

LuaCustomFunction::LuaCustomFunction(SnippetData snippet) : CustomFunction(snippet)
{
  initEngine();
  {
    QTextStream in(&snippet.global_vars);
    while (!in.atEnd())
    {
      in.readLine();
      global_lines_++;
    }
  }
  {
    QTextStream in(&snippet.function);
    while (!in.atEnd())
    {
      in.readLine();
      function_lines_++;
    }
  }
}

void LuaCustomFunction::initEngine()
{
  std::unique_lock<std::mutex> lk(mutex_);

  _lua_function = {};
  _lua_engine = {};
  _lua_engine.open_libraries();
  auto result = _lua_engine.safe_script(_snippet.global_vars.toStdString());
  if (!result.valid())
  {
    sol::error err = result;
    throw std::runtime_error(getError(err));
  }

  auto calcMethodStr = QString("function calc(time, value");
  for (int index = 1; index <= _snippet.additional_sources.size(); index++)
  {
    calcMethodStr += QString(", v%1").arg(index);
  }
  calcMethodStr += QString(")\n%1\nend").arg(snippet().function);

  result = _lua_engine.safe_script(calcMethodStr.toStdString());
  if (!result.valid())
  {
    sol::error err = result;
    throw std::runtime_error(getError(err));
  }
  _lua_function = _lua_engine["calc"];
}

void LuaCustomFunction::calculatePoints(const std::vector<const PlotData*>& src_data,
                                        size_t point_index,
                                        std::vector<PlotData::Point>& points)
{
  std::unique_lock<std::mutex> lk(mutex_);

  _chan_values.resize(src_data.size());

  const PlotData::Point& old_point = src_data.front()->at(point_index);

  for (size_t chan_index = 0; chan_index < src_data.size(); chan_index++)
  {
    double value;
    const PlotData* chan_data = src_data[chan_index];
    int index = chan_data->getIndexFromX(old_point.x);
    if (index != -1)
    {
      value = chan_data->at(index).y;
    }
    else
    {
      value = std::numeric_limits<double>::quiet_NaN();
    }
    _chan_values[chan_index] = value;
  }

  sol::safe_function_result result;
  const auto& v = _chan_values;
  // ugly code, sorry
  switch (_snippet.additional_sources.size())
  {
    case 0:
      result = _lua_function(old_point.x, v[0]);
      break;
    case 1:
      result = _lua_function(old_point.x, v[0], v[1]);
      break;
    case 2:
      result = _lua_function(old_point.x, v[0], v[1], v[2]);
      break;
    case 3:
      result = _lua_function(old_point.x, v[0], v[1], v[2], v[3]);
      break;
    case 4:
      result = _lua_function(old_point.x, v[0], v[1], v[2], v[3], v[4]);
      break;
    case 5:
      result = _lua_function(old_point.x, v[0], v[1], v[2], v[3], v[4], v[5]);
      break;
    case 6:
      result = _lua_function(old_point.x, v[0], v[1], v[2], v[3], v[4], v[5], v[6]);
      break;
    case 7:
      result = _lua_function(old_point.x, v[0], v[1], v[2], v[3], v[4], v[5], v[6], v[7]);
      break;
    case 8:
      result = _lua_function(old_point.x, v[0], v[1], v[2], v[3], v[4], v[5], v[6], v[7],
                             v[8]);
      break;
    default:
      throw std::runtime_error("Lua Engine: maximum number of additional data sources is "
                               "8");
  }

  if (!result.valid())
  {
    sol::error err = result;
    throw std::runtime_error(getError(err));
  }

  if (result.return_count() == 2)
  {
    PlotData::Point new_point;
    new_point.x = result.get<double>(0);
    new_point.y = result.get<double>(1);
    points.push_back(new_point);
  }
  else if (result.return_count() == 1 && result.get_type(0) == sol::type::number)
  {
    PlotData::Point new_point;
    new_point.x = old_point.x;
    new_point.y = result.get<double>(0);
    points.push_back(new_point);
  }
  else if (result.return_count() == 1 && result.get_type(0) == sol::type::table)
  {
    static std::vector<std::array<double, 2>> multi_samples;
    multi_samples.clear();

    multi_samples = result.get<std::vector<std::array<double, 2>>>(0);

    for (std::array<double, 2> sample : multi_samples)
    {
      PlotData::Point point;
      point.x = sample[0];
      point.y = sample[1];
      points.push_back(point);
    }
  }
  else
  {
    throw std::runtime_error("Wrong return object: expecting either a single value, "
                             "two values (time, value) "
                             "or an array of two-sized arrays (time, value)");
  }
}

bool LuaCustomFunction::xmlLoadState(const QDomElement& parent_element)
{
  bool ret = CustomFunction::xmlLoadState(parent_element);
  initEngine();
  return ret;
}

std::string LuaCustomFunction::getError(sol::error err)
{
  std::string out;
  auto parts = QString(err.what()).split(":");

  if (parts.size() < 3)
  {
    return err.what();
  }

  bool is_function = parts[0].contains("[string \"function calc(time,");
  out = is_function ? "[Function]: line " : "[Global]: line ";

  int line_num = parts[1].toInt();
  if (is_function)
  {
    line_num -= 1;
  }
  out += std::to_string(line_num) + ": ";
  out += parts[2].toStdString();
  return out;
}