join.h

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#ifndef SENSESP_SRC_SENSESP_TRANSFORMS_JOIN_H_
#define SENSESP_SRC_SENSESP_TRANSFORMS_JOIN_H_
 
#include <elapsedMillis.h>
#include <tuple>
 
#include "sensesp/system/lambda_consumer.h"
#include "sensesp/system/valueproducer.h"
#include "transform.h"
 
namespace sensesp {
 
// Base class for Join. This is needed until Arduino ESP32 Core supports C++14
// and template pack indices: https://stackoverflow.com/a/55807564/2999754
 
template <int N>
class JoinBase {
 public:
  JoinBase(long max_age = 0) : max_age_{max_age} {
    for (int i = 0; i < N; i++) {
      age_[i] = max_age;
    }
  }
 
 protected:
  elapsedMillis age_[N];
  long max_age_;
 
  virtual void emit_tuple() = 0;
 
  void check_emit() {
    for (int i = 0; i < N; i++) {
      if (max_age_ != 0 && age_[i] > max_age_) {
        return;
      }
    }
    emit_tuple();
  }
};
 
template <typename T1, typename T2>
class Join : public JoinBase<2>, public ValueProducer<std::tuple<T1, T2>> {
 public:
  Join(long max_age = 0) : JoinBase<2>(max_age) {}
 
  std::tuple<LambdaConsumer<T1>, LambdaConsumer<T2>> consumers = {
      LambdaConsumer<T1>([this](T1 value) {
        std::get<0>(values) = value;
        age_[0] = 0;
        check_emit();
      }),
      LambdaConsumer<T2>([this](T2 value) {
        std::get<1>(values) = value;
        age_[1] = 0;
        check_emit();
      })};
 
 protected:
  std::tuple<T1, T2> values;
 
  void emit_tuple() override { this->emit(values); }
};
 
template <typename T1, typename T2, typename T3>
class Join3 : public JoinBase<3>, public ValueProducer<std::tuple<T1, T2, T3>> {
 public:
  Join3(long max_age = 0) : JoinBase<3>(max_age) {}
 
  std::tuple<LambdaConsumer<T1>, LambdaConsumer<T2>, LambdaConsumer<T3>>
      consumers = {LambdaConsumer<T1>([this](T1 value) {
                     std::get<0>(values) = value;
                     age_[0] = 0;
                     check_emit();
                   }),
                   LambdaConsumer<T2>([this](T2 value) {
                     std::get<1>(values) = value;
                     age_[1] = 0;
                     check_emit();
                   }),
                   LambdaConsumer<T3>([this](T3 value) {
                     std::get<2>(values) = value;
                     age_[2] = 0;
                     check_emit();
                   })};
 
 protected:
  std::tuple<T1, T2, T3> values;
 
  void emit_tuple() override { this->emit(values); }
};
 
template <typename T1, typename T2, typename T3, typename T4>
class Join4 : public JoinBase<4>,
              public ValueProducer<std::tuple<T1, T2, T3, T4>> {
 public:
  Join4(long max_age = 0) : JoinBase<4>(max_age) {}
 
  std::tuple<LambdaConsumer<T1>, LambdaConsumer<T2>, LambdaConsumer<T3>,
             LambdaConsumer<T4>>
      consumers = {LambdaConsumer<T1>([this](T1 value) {
                     std::get<0>(values) = value;
                     age_[0] = 0;
                     check_emit();
                   }),
                   LambdaConsumer<T2>([this](T2 value) {
                     std::get<1>(values) = value;
                     age_[1] = 0;
                     check_emit();
                   }),
                   LambdaConsumer<T3>([this](T3 value) {
                     std::get<2>(values) = value;
                     age_[2] = 0;
                     check_emit();
                   }),
                   LambdaConsumer<T4>([this](T4 value) {
                     std::get<3>(values) = value;
                     age_[3] = 0;
                     check_emit();
                   })};
 
 protected:
  std::tuple<T1, T2, T3, T4> values;
 
  void emit_tuple() override { this->emit(values); }
};
 
template <typename T1, typename T2, typename T3, typename T4, typename T5>
class Join5 : public JoinBase<5>,
              public ValueProducer<std::tuple<T1, T2, T3, T4, T5>> {
 public:
  Join5(long max_age = 0) : JoinBase<5>(max_age) {}
 
  std::tuple<LambdaConsumer<T1>, LambdaConsumer<T2>, LambdaConsumer<T3>,
             LambdaConsumer<T4>, LambdaConsumer<T5>>
      consumers = {LambdaConsumer<T1>([this](T1 value) {
                     std::get<0>(values) = value;
                     age_[0] = 0;
                     check_emit();
                   }),
                   LambdaConsumer<T2>([this](T2 value) {
                     std::get<1>(values) = value;
                     age_[1] = 0;
                     check_emit();
                   }),
                   LambdaConsumer<T3>([this](T3 value) {
                     std::get<2>(values) = value;
                     age_[2] = 0;
                     check_emit();
                   }),
                   LambdaConsumer<T4>([this](T4 value) {
                     std::get<3>(values) = value;
                     age_[3] = 0;
                     check_emit();
                   }),
                   LambdaConsumer<T5>([this](T5 value) {
                     std::get<4>(values) = value;
                     age_[4] = 0;
                     check_emit();
                   })};
 
 protected:
  std::tuple<T1, T2, T3, T4, T5> values;
 
  void emit_tuple() override { this->emit(values); }
};
 
}  // namespace sensesp
 
#endif