json-validator/include/jvalidate/document_cache.h

#pragma once

#include <map>
#include <optional>

#include <jvalidate/detail/expect.h>
#include <jvalidate/detail/pointer.h>
#include <jvalidate/detail/reference.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, A> references_;
  std::map<URI, value_type> cache_;

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

  void cache_reference(URI const & where, A const & handle) {
    EXPECT(references_.emplace(where, handle).second);
  }

  operator bool() const { return resolve_; }

  std::optional<A> try_load(detail::Reference const & ref) {
    if (auto it = references_.find(ref.uri()); it != references_.end()) {
      return ref.pointer().walk(it->second);
    }

    if (not resolve_) {
      return std::nullopt;
    }

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

    return ref.pointer().walk(A(it->second));
  }
};
}