json-validator/include/jvalidate/document_cache.h

#pragma once

#include <map>
#include <optional>

#include <jvalidate/detail/expect.h>
#include <jvalidate/forward.h>
#include <jvalidate/uri.h>

namespace jvalidate {
template <Adapter A> class DocumentCache {
public:
  using value_type = typename A::value_type;

private:
  URIResolver<A> resolve_;
  std::map<URI, value_type> cache_;

public:
  DocumentCache() = default;
  DocumentCache(URIResolver<A> const & resolve) : resolve_(resolve) {}

  operator bool() const { return resolve_; }

  std::optional<A> try_load(URI const & uri) {
    if (not resolve_) {
      return std::nullopt;
    }

    auto [it, created] = cache_.try_emplace(uri);
    if (created && not resolve_(uri, it->second)) {
      cache_.erase(it);
      return std::nullopt;
    }

    return A(it->second);
  }
};
}