HackCache.h

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/// Access EvalCache in \p nix::EvalState
 
#pragma once
 
#include <nix/eval.hh>
 
namespace nixt {
 
#if HAVE_BOEHMGC
using FileEvalCache =
    std::map<nix::SourcePath, nix::Value, std::less<nix::SourcePath>,
             traceable_allocator<std::pair<const nix::SourcePath, nix::Value>>>;
#else
using FileEvalCache = std::map<nix::SourcePath, nix::Expr *>;
#endif
 
namespace detail {
 
template <typename Tag> struct R {
  using type = typename Tag::type;
  static type P;
};
 
template <typename Tag> typename R<Tag>::type R<Tag>::P;
 
template <typename Tag, typename Tag::type p> struct RB : R<Tag> {
  struct F {
    F() { R<Tag>::P = p; }
  };
  static F FO;
};
 
template <typename Tag, typename Tag::type p>
typename RB<Tag, p>::F RB<Tag, p>::FO;
 
// Impl
 
struct EvalCacheF {
  using type = FileEvalCache nix::EvalState::*;
};
 
template struct RB<EvalCacheF, &nix::EvalState::fileEvalCache>;
 
} // namespace detail
 
inline FileEvalCache &getFileEvalCache(nix::EvalState &S) {
  return S.*detail::R<detail::EvalCacheF>::P;
}
 
} // namespace nixt