sdk/lib/driver/devicetree/visitors/multivisitor.h

// Copyright 2023 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef LIB_DRIVER_DEVICETREE_VISITORS_MULTIVISITOR_H_
#define LIB_DRIVER_DEVICETREE_VISITORS_MULTIVISITOR_H_

#include <lib/driver/devicetree/manager/visitor.h>

namespace fdf_devicetree {

// A collection of visitors.
// Each visitor's Visit() is invoked during device tree Walk().
template <typename... Visitors>
class MultiVisitor : public Visitor {
 public:
  explicit MultiVisitor() : Visitor() { Init<0, Visitors...>(); }
  ~MultiVisitor() override = default;

  // Allow move construction and assignment.
  MultiVisitor(MultiVisitor&& other) = default;
  MultiVisitor& operator=(MultiVisitor&& other) = default;

  template <int I, typename T, typename... Other>
  constexpr void Init() {
    visitors_[I] = std::unique_ptr<Visitor>(new T());
    if constexpr (sizeof...(Other) > 1) {
      Init<I + 1, Other...>();
    } else if constexpr (sizeof...(Other) == 1) {
      // We use make_unique here so that it deals with the parameter unpacking.
      visitors_[I + 1] = std::unique_ptr<Visitor>(std::make_unique<Other...>().release());
    }
  }

  zx::result<> Visit(Node& node, const devicetree::PropertyDecoder& decoder) override {
    zx::result<> final_status = zx::ok();
    for (const auto& visitor : visitors_) {
      auto status = visitor->Visit(node, decoder);
      if (status.is_error()) {
        final_status = zx::error(ZX_ERR_INTERNAL);
      }
    }
    return final_status;
  }

  zx::result<> FinalizeNode(Node& node) override {
    zx::result<> final_status = zx::ok();
    for (const auto& visitor : visitors_) {
      auto status = visitor->FinalizeNode(node);
      if (status.is_error()) {
        final_status = zx::error(ZX_ERR_INTERNAL);
      }
    }
    return final_status;
  }

 private:
  std::array<std::unique_ptr<Visitor>, sizeof...(Visitors)> visitors_;
};

}  // namespace fdf_devicetree

#endif  // LIB_DRIVER_DEVICETREE_VISITORS_MULTIVISITOR_H_