status_with_size.h

// Copyright 2024 The Pigweed Authors
//
// Licensed under the Apache License, Version 2.0 (the "License"); you may not
// use this file except in compliance with the License. You may obtain a copy of
// the License at
//
//     https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
// License for the specific language governing permissions and limitations under
// the License.
#pragma once
 
#include <cstddef>
#include <type_traits>
 
#include "pw_status/status.h"
 
namespace pw {
 
class _PW_STATUS_NO_DISCARD StatusWithSize {
 public:
  static constexpr StatusWithSize Cancelled(size_t size = 0) {
    return StatusWithSize(Status::Cancelled(), size);
  }
  static constexpr StatusWithSize Unknown(size_t size = 0) {
    return StatusWithSize(Status::Unknown(), size);
  }
  static constexpr StatusWithSize InvalidArgument(size_t size = 0) {
    return StatusWithSize(Status::InvalidArgument(), size);
  }
  static constexpr StatusWithSize DeadlineExceeded(size_t size = 0) {
    return StatusWithSize(Status::DeadlineExceeded(), size);
  }
  static constexpr StatusWithSize NotFound(size_t size = 0) {
    return StatusWithSize(Status::NotFound(), size);
  }
  static constexpr StatusWithSize AlreadyExists(size_t size = 0) {
    return StatusWithSize(Status::AlreadyExists(), size);
  }
  static constexpr StatusWithSize PermissionDenied(size_t size = 0) {
    return StatusWithSize(Status::PermissionDenied(), size);
  }
  static constexpr StatusWithSize Unauthenticated(size_t size = 0) {
    return StatusWithSize(Status::Unauthenticated(), size);
  }
  static constexpr StatusWithSize ResourceExhausted(size_t size = 0) {
    return StatusWithSize(Status::ResourceExhausted(), size);
  }
  static constexpr StatusWithSize FailedPrecondition(size_t size = 0) {
    return StatusWithSize(Status::FailedPrecondition(), size);
  }
  static constexpr StatusWithSize Aborted(size_t size = 0) {
    return StatusWithSize(Status::Aborted(), size);
  }
  static constexpr StatusWithSize OutOfRange(size_t size = 0) {
    return StatusWithSize(Status::OutOfRange(), size);
  }
  static constexpr StatusWithSize Unimplemented(size_t size = 0) {
    return StatusWithSize(Status::Unimplemented(), size);
  }
  static constexpr StatusWithSize Internal(size_t size = 0) {
    return StatusWithSize(Status::Internal(), size);
  }
  static constexpr StatusWithSize Unavailable(size_t size = 0) {
    return StatusWithSize(Status::Unavailable(), size);
  }
  static constexpr StatusWithSize DataLoss(size_t size = 0) {
    return StatusWithSize(Status::DataLoss(), size);
  }
 
  explicit constexpr StatusWithSize() : size_(0) {}
 
  template <typename T, typename = std::enable_if_t<std::is_integral<T>::value>>
  explicit constexpr StatusWithSize(T size) : size_(static_cast<size_t>(size)) {
    // TODO(hepler): Add debug-only assert that size <= max_size().
  }
 
  explicit constexpr StatusWithSize(Status status, size_t size)
      : StatusWithSize((static_cast<size_t>(status.code()) << kStatusShift) |
                       size) {}
 
  constexpr StatusWithSize(const StatusWithSize&) = default;
  constexpr StatusWithSize& operator=(const StatusWithSize&) = default;
 
  constexpr void UpdateAndAdd(StatusWithSize new_status_with_size) {
    Status new_status;
    if (ok()) {
      new_status = new_status_with_size.status();
    } else {
      new_status = status();
    }
    size_t new_size = size() + new_status_with_size.size();
    *this = StatusWithSize(new_status, new_size);
  }
 
  constexpr void ZeroIfNotOk() {
    if (!ok()) {
      *this = StatusWithSize(status(), 0);
    }
  }
 
  [[nodiscard]] constexpr size_t size() const { return size_ & kSizeMask; }
 
  [[nodiscard]] static constexpr size_t max_size() { return kSizeMask; }
 
  [[nodiscard]] constexpr bool ok() const {
    return (size_ & kStatusMask) == 0u;
  }
 
  constexpr void IgnoreError() const {}
 
  [[nodiscard]] constexpr Status status() const {
    return static_cast<Status::Code>((size_ & kStatusMask) >> kStatusShift);
  }
 
  // Functions for checking which status the StatusWithSize contains.
  [[nodiscard]] constexpr bool IsCancelled() const {
    return status().IsCancelled();
  }
  [[nodiscard]] constexpr bool IsUnknown() const {
    return status().IsUnknown();
  }
  [[nodiscard]] constexpr bool IsInvalidArgument() const {
    return status().IsInvalidArgument();
  }
  [[nodiscard]] constexpr bool IsDeadlineExceeded() const {
    return status().IsDeadlineExceeded();
  }
  [[nodiscard]] constexpr bool IsNotFound() const {
    return status().IsNotFound();
  }
  [[nodiscard]] constexpr bool IsAlreadyExists() const {
    return status().IsAlreadyExists();
  }
  [[nodiscard]] constexpr bool IsPermissionDenied() const {
    return status().IsPermissionDenied();
  }
  [[nodiscard]] constexpr bool IsResourceExhausted() const {
    return status().IsResourceExhausted();
  }
  [[nodiscard]] constexpr bool IsFailedPrecondition() const {
    return status().IsFailedPrecondition();
  }
  [[nodiscard]] constexpr bool IsAborted() const {
    return status().IsAborted();
  }
  [[nodiscard]] constexpr bool IsOutOfRange() const {
    return status().IsOutOfRange();
  }
  [[nodiscard]] constexpr bool IsUnimplemented() const {
    return status().IsUnimplemented();
  }
  [[nodiscard]] constexpr bool IsInternal() const {
    return status().IsInternal();
  }
  [[nodiscard]] constexpr bool IsUnavailable() const {
    return status().IsUnavailable();
  }
  [[nodiscard]] constexpr bool IsDataLoss() const {
    return status().IsDataLoss();
  }
  [[nodiscard]] constexpr bool IsUnauthenticated() const {
    return status().IsUnauthenticated();
  }
 
 private:
  static constexpr size_t kStatusBits = 5;
  static constexpr size_t kSizeMask = ~static_cast<size_t>(0) >> kStatusBits;
  static constexpr size_t kStatusMask = ~kSizeMask;
  static constexpr size_t kStatusShift = sizeof(size_t) * 8 - kStatusBits;
 
  size_t size_;
};
 
namespace internal {
 
constexpr Status ConvertToStatus(StatusWithSize status_with_size) {
  return status_with_size.status();
}
 
constexpr size_t ConvertToValue(StatusWithSize status_with_size) {
  return status_with_size.size();
}
 
constexpr StatusWithSize ConvertToStatusWithSize(Status status) {
  return StatusWithSize(status, 0);
}
 
constexpr StatusWithSize ConvertToStatusWithSize(
    StatusWithSize status_with_size) {
  return status_with_size;
}
 
}  // namespace internal
}  // namespace pw