json-validator/include/jvalidate/detail/relative_pointer.h

#pragma once

#include <string>
#include <string_view>

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

namespace jvalidate::detail {
class RelativePointer {
public:
  RelativePointer(std::string_view path) {
    if (auto pos = path.find('/'); pos != path.npos) {
      pointer_ = Pointer(path.substr(pos));
      path.remove_suffix(path.size() - pos);
    } else {
      EXPECT_M(not path.empty() && path.back() == '#',
               "RelativePointer must end in a pointer, or a '#'")
      path.remove_suffix(1);
    }
    parent_steps_ = std::stoull(std::string(path));
  }

  template <Adapter A>
  std::variant<std::string, A> inspect(Pointer const & where, A const & root) const {
    if (pointer_) {
      return pointer_->walk(where.parent(parent_steps_).walk(root));
    }
    return where.parent(parent_steps_).back();
  }

private:
  size_t parent_steps_;
  std::optional<Pointer> pointer_;
};
}