status_macros.h

Go to the documentation of this file.

// Protocol Buffers - Google's data interchange format
// Copyright 2008 Google Inc.  All rights reserved.
// https://developers.google.com/protocol-buffers/
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
//     * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
//     * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
//     * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

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

#ifndef GOOGLE_PROTOBUF_STUBS_STATUS_MACROS_H_
#define GOOGLE_PROTOBUF_STUBS_STATUS_MACROS_H_

#include <google/protobuf/stubs/common.h>
#include <google/protobuf/stubs/status.h>
#include <google/protobuf/stubs/statusor.h>

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 ::google::protobuf::util::Status _status = (expr); \
    if (GOOGLE_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>
Status DoAssignOrReturn(T& lhs, StatusOr<T> result) {
  if (result.ok()) {
    lhs = result.ValueOrDie();
  }
  return result.status();
}

#define ASSIGN_OR_RETURN_IMPL(status, lhs, rexpr) \
  Status status = DoAssignOrReturn(lhs, (rexpr)); \
  if (GOOGLE_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

#endif  // GOOGLE_PROTOBUF_STUBS_STATUS_H_