#pragma once

#include <optional>
#include <string>
#include <unordered_map>
#include <vector>

namespace xlang {

template <typename T>
class Scope {
  std::vector<std::unordered_map<std::string, T>> stack;

 public:
  void enter() {
    stack.emplace_back();
  }

  void leave() {
    stack.pop_back();
  }

  void add(const std::string &name, T v) {
    stack.back().emplace(name, v);
  }

  std::optional<T> get(const std::string &name) {
    for (auto scope = stack.end() - 1;; scope--) {
      auto it = scope->find(name);

      if (it != scope->end()) {
        return it->second;
      }
      if (scope == stack.begin()) {
        break;
      }
    }
    return {};
  }
};

}  // namespace xlang