text: // Copyright 2010-2018 Google LLC
  // 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
  //
  //     http://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.
  
  #ifndef OR_TOOLS_BASE_STATUS_MACROS_H_
  #define OR_TOOLS_BASE_STATUS_MACROS_H_
  
  #include "absl/status/status.h"
  #include "ortools/base/statusor.h"
  
  namespace absl {
  
  // Run a command that returns a absl::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 (!_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) {  // NOLINT
    if (result.ok()) {
      lhs = result.value();
    }
    return result.status();
  }
  
  #define ASSIGN_OR_RETURN_IMPL(status, lhs, rexpr)         \
    ::absl::Status status = DoAssignOrReturn(lhs, (rexpr)); \
    if (!status.ok()) return status;
  
  // Executes an expression that returns a absl::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 absl
  
  #endif  // OR_TOOLS_BASE_STATUS_MACROS_H_
  