src/google/protobuf/stubs/status_macros.h

// Protocol Buffers - Google's data interchange format
// Copyright 2008 Google Inc.  All rights reserved.
//
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file or at
// https://developers.google.com/open-source/licenses/bsd

// From: util/task/contrib/status_macros/status_macros.h

#ifndef GOOGLE_PROTOBUF_STUBS_STATUS_MACROS_H_
#define GOOGLE_PROTOBUF_STUBS_STATUS_MACROS_H_

#include "absl/status/status.h"
#include "absl/status/statusor.h"
#include "google/protobuf/stubs/common.h"

// Needs to be last.
#include "google/protobuf/port_def.inc"  // NOLINT

namespace google {
namespace protobuf {
namespace util {

// Run a command that returns a util::Status.  If the called code returns an
// error status, return that status up out of this method too.
//
// Example:
//   RETURN_IF_ERROR(DoThings(4));
#define RETURN_IF_ERROR(expr)                                                \
  do {                                                                       \
    /* Using _status below to avoid capture problems if expr is "status". */ \
    const absl::Status _status = (expr);                                     \
    if (PROTOBUF_PREDICT_FALSE(!_status.ok())) return _status;               \
  } while (0)

// Internal helper for concatenating macro values.
#define STATUS_MACROS_CONCAT_NAME_INNER(x, y) x##y
#define STATUS_MACROS_CONCAT_NAME(x, y) STATUS_MACROS_CONCAT_NAME_INNER(x, y)

template <typename T>
absl::Status DoAssignOrReturn(T& lhs, absl::StatusOr<T> result) {
  if (result.ok()) {
    lhs = result.value();
  }
  return result.status();
}

#define ASSIGN_OR_RETURN_IMPL(status, lhs, rexpr)       \
  absl::Status status = DoAssignOrReturn(lhs, (rexpr)); \
  if (PROTOBUF_PREDICT_FALSE(!status.ok())) return status;

// Executes an expression that returns a util::StatusOr, extracting its value
// into the variable defined by lhs (or returning on error).
//
// Example: Assigning to an existing value
//   ValueType value;
//   ASSIGN_OR_RETURN(value, MaybeGetValue(arg));
//
// WARNING: ASSIGN_OR_RETURN expands into multiple statements; it cannot be used
//  in a single statement (e.g. as the body of an if statement without {})!
#define ASSIGN_OR_RETURN(lhs, rexpr) \
  ASSIGN_OR_RETURN_IMPL(             \
      STATUS_MACROS_CONCAT_NAME(_status_or_value, __COUNTER__), lhs, rexpr);

}  // namespace util
}  // namespace protobuf
}  // namespace google

#include "google/protobuf/port_undef.inc"  // NOLINT

#endif  // GOOGLE_PROTOBUF_STUBS_STATUS_H_