simple_lru_example.cpp

#include <boxes/cache.hpp>
 
#include <functional>
#include <iostream>
 
uint64_t fib(uint64_t n) {
  if (n <= 1) {
    return n;
  }
  return fib(n - 1) + fib(n - 2);
}
 
int main() {
  auto make_fib_cache = [](std::size_t cacheSize) {
    return [cacheSize](uint64_t n) -> uint64_t {
      auto cache = boxes::cache::makeLRU<uint64_t, uint64_t>(cacheSize);
      auto impl = [cache = std::move(cache)](auto &self,
                                             uint64_t n) mutable -> uint64_t {
        if (cache.contains(n)) {
          return cache.at(n);
        }
 
        uint64_t result = 0;
        if (n <= 1) {
          result = n;
        } else {
          result = self(self, n - 1) + self(self, n - 2);
        }
 
        cache.insert(n, result);
        return result;
      };
 
      return impl(impl, n);
    };
  };
 
  auto fib_cache = make_fib_cache(32);
 
  std::cout << "Fibonacci with cache of 50: " << fib_cache(50) << std::endl;
 
  // This will take a long time... and memory
  // std::cout << "Fibonacci of 50: " << fib(50) << std::endl;
  return 0;
}