1// Protocol Buffers - Google's data interchange format
2// Copyright 2008 Google Inc. All rights reserved.
3// https://developers.google.com/protocol-buffers/
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30
31// From: util/task/contrib/status_macros/status_macros.h
32
33#ifndef GOOGLE_PROTOBUF_STUBS_STATUS_MACROS_H_
34#define GOOGLE_PROTOBUF_STUBS_STATUS_MACROS_H_
35
36#include <google/protobuf/stubs/common.h>
37#include <google/protobuf/stubs/status.h>
38#include <google/protobuf/stubs/statusor.h>
39
40namespace google {
41namespace protobuf {
42namespace util {
43
44// Run a command that returns a util::Status. If the called code returns an
45// error status, return that status up out of this method too.
46//
47// Example:
48// RETURN_IF_ERROR(DoThings(4));
49#define RETURN_IF_ERROR(expr) \
50 do { \
51 /* Using _status below to avoid capture problems if expr is "status". */ \
52 const PROTOBUF_NAMESPACE_ID::util::Status _status = (expr); \
53 if (PROTOBUF_PREDICT_FALSE(!_status.ok())) return _status; \
54 } while (0)
55
56// Internal helper for concatenating macro values.
57#define STATUS_MACROS_CONCAT_NAME_INNER(x, y) x##y
58#define STATUS_MACROS_CONCAT_NAME(x, y) STATUS_MACROS_CONCAT_NAME_INNER(x, y)
59
60template<typename T>
61Status DoAssignOrReturn(T& lhs, StatusOr<T> result) {
62 if (result.ok()) {
63 lhs = result.value();
64 }
65 return result.status();
66}
67
68#define ASSIGN_OR_RETURN_IMPL(status, lhs, rexpr) \
69 Status status = DoAssignOrReturn(lhs, (rexpr)); \
70 if (PROTOBUF_PREDICT_FALSE(!status.ok())) return status;
71
72// Executes an expression that returns a util::StatusOr, extracting its value
73// into the variable defined by lhs (or returning on error).
74//
75// Example: Assigning to an existing value
76// ValueType value;
77// ASSIGN_OR_RETURN(value, MaybeGetValue(arg));
78//
79// WARNING: ASSIGN_OR_RETURN expands into multiple statements; it cannot be used
80// in a single statement (e.g. as the body of an if statement without {})!
81#define ASSIGN_OR_RETURN(lhs, rexpr) \
82 ASSIGN_OR_RETURN_IMPL( \
83 STATUS_MACROS_CONCAT_NAME(_status_or_value, __COUNTER__), lhs, rexpr);
84
85} // namespace util
86} // namespace protobuf
87} // namespace google
88
89#endif // GOOGLE_PROTOBUF_STUBS_STATUS_H_
90