json-validator/include/jvalidate/detail/scoped_state.h

#pragma once

#include <functional>
#include <type_traits>

#define CONCAT2(A, B) A##B
#define CONCAT(A, B) CONCAT2(A, B)
#define scoped_state(prop, value)                                                                  \
  auto CONCAT(scoped_state_, __LINE__) = detail::ScopedState(prop, value)

namespace jvalidate::detail {
class ScopedState {
private:
  std::function<void()> reset_;

public:
  template <typename T, typename S>
  requires(std::is_constructible_v<T, S>) ScopedState(T & prop, S value)
      : reset_([reset = prop, &prop]() { prop = reset; }) {
    prop = std::move(value);
  }

  ~ScopedState() { reset_(); }

  explicit operator bool() const { return true; }
};
}