1 // Protocol Buffers - Google's data interchange format
2 // Copyright 2008 Google Inc. All rights reserved.
3 // https://developers.google.com/protocol-buffers/
4 //
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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
40 namespace google {
41 namespace protobuf {
42 namespace 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
60 template<typename T>
DoAssignOrReturn(T & lhs,StatusOr<T> result)61 Status DoAssignOrReturn(T& lhs, StatusOr<T> result) {
62 if (result.ok()) {
63 lhs = result.ValueOrDie();
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