ConstantNumber.h

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//
// Created by Nico on 24/05/2019.
//
 
#ifndef JODA_CONSTANTNUMBER_H
#define JODA_CONSTANTNUMBER_H
#include "AtomProvider.h"
#include "IValueProvider.h"
 
namespace joda::query {
template <class Calc>
class ConstantNumber : public AtomProvider<typename Calc::AtomType> {
 public:
  explicit ConstantNumber(
      std::vector<std::unique_ptr<IValueProvider>> &&parameters)
      : AtomProvider<typename Calc::AtomType>(Calc::value()) {
        if (parameters.size() != 0) {
          throw WrongParameterCountException(parameters.size(), 0, getName());
        }
      }
 
  explicit ConstantNumber()
      : AtomProvider<typename Calc::AtomType>(Calc::value()) {}
 
  std::string getName() const override { return std::string(Calc::name); }
 
  std::string toString() const override { return getName() + "()"; }
 
  CREATE_FACTORY(ConstantNumber<Calc>)
};
 
struct PiConstantFunction {
  typedef double AtomType;
  static constexpr auto name = "PI";
 
  static constexpr auto value() { return M_PI; }
};
 
typedef ConstantNumber<PiConstantFunction> PiProvider;
 
struct NowConstantFunction {
  typedef uint64_t AtomType;
  static constexpr auto name = "NOW";
 
  static auto value() {
    auto ms = std::chrono::duration_cast<std::chrono::milliseconds>(
        std::chrono::system_clock::now().time_since_epoch());
    return ms.count();
  }
};
 
typedef ConstantNumber<NowConstantFunction> NowProvider;
 
template class ConstantNumber<joda::query::PiConstantFunction>;
 
template class ConstantNumber<joda::query::NowConstantFunction>;
}  // namespace joda::query
#endif  // JODA_CONSTANTNUMBER_H