OR-Tools  8.2
status_macros.h
Go to the documentation of this file.
1// Copyright 2010-2018 Google LLC
2// Licensed under the Apache License, Version 2.0 (the "License");
3// you may not use this file except in compliance with the License.
4// You may obtain a copy of the License at
5//
6// http://www.apache.org/licenses/LICENSE-2.0
7//
8// Unless required by applicable law or agreed to in writing, software
9// distributed under the License is distributed on an "AS IS" BASIS,
10// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
11// See the License for the specific language governing permissions and
12// limitations under the License.
13
14#ifndef OR_TOOLS_BASE_STATUS_MACROS_H_
15#define OR_TOOLS_BASE_STATUS_MACROS_H_
16
17#include "absl/status/status.h"
18#include "absl/status/statusor.h"
19
20namespace absl {
21
22// Run a command that returns a absl::Status. If the called code returns an
23// error status, return that status up out of this method too.
24//
25// Example:
26// RETURN_IF_ERROR(DoThings(4));
27#define RETURN_IF_ERROR(expr) \
28 do { \
29 /* Using _status below to avoid capture problems if expr is "status". */ \
30 const ::absl::Status _status = (expr); \
31 if (!_status.ok()) return _status; \
32 } while (0)
33
34// Internal helper for concatenating macro values.
35#define STATUS_MACROS_CONCAT_NAME_INNER(x, y) x##y
36#define STATUS_MACROS_CONCAT_NAME(x, y) STATUS_MACROS_CONCAT_NAME_INNER(x, y)
37
38template <typename T>
39::absl::Status DoAssignOrReturn(T& lhs, ::absl::StatusOr<T> result) { // NOLINT
40 if (result.ok()) {
41 lhs = result.value();
42 }
43 return result.status();
44}
45
46#define ASSIGN_OR_RETURN_IMPL(status, lhs, rexpr) \
47 ::absl::Status status = DoAssignOrReturn(lhs, (rexpr)); \
48 if (!status.ok()) return status;
49
50// Executes an expression that returns an absl::StatusOr, extracting its value
51// into the variable defined by lhs (or returning on error).
52//
53// Example: Assigning to an existing value
54// ValueType value;
55// ASSIGN_OR_RETURN(value, MaybeGetValue(arg));
56//
57// WARNING: ASSIGN_OR_RETURN expands into multiple statements; it cannot be used
58// in a single statement (e.g. as the body of an if statement without {})!
59#define ASSIGN_OR_RETURN(lhs, rexpr) \
60 ASSIGN_OR_RETURN_IMPL( \
61 STATUS_MACROS_CONCAT_NAME(_status_or_value, __COUNTER__), lhs, rexpr);
62
63} // namespace absl
64
65#endif // OR_TOOLS_BASE_STATUS_MACROS_H_
Definition: cleanup.h:22
::absl::Status DoAssignOrReturn(T &lhs, ::absl::StatusOr< T > result)
Definition: status_macros.h:39