11using ParentMap = std::map<const nix::Expr *, const nix::Expr *>;
Describe how to traverse upon nix::Expr * nodes.
Access EvalCache in nix::EvalState.
std::map< const nix::Expr *, const nix::Expr * > ParentMap
The parent map. The key is "child", the value is "parent".
ParentMap parentMap(const nix::Expr *Root)
Construct child -> parent relations of nix::Expr nodes.