1 // Copyright 2017 The Abseil Authors.
2 //
3 // Licensed under the Apache License, Version 2.0 (the "License");
4 // you may not use this file except in compliance with the License.
5 // You may obtain a copy of the License at
6 //
7 // https://www.apache.org/licenses/LICENSE-2.0
8 //
9 // Unless required by applicable law or agreed to in writing, software
10 // distributed under the License is distributed on an "AS IS" BASIS,
11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12 // See the License for the specific language governing permissions and
13 // limitations under the License.
14
15 #ifndef ABSL_BASE_LOG_SEVERITY_H_
16 #define ABSL_BASE_LOG_SEVERITY_H_
17
18 #include <array>
19 #include <ostream>
20
21 #include "absl/base/attributes.h"
22 #include "absl/base/config.h"
23
24 namespace absl {
25 ABSL_NAMESPACE_BEGIN
26
27 // absl::LogSeverity
28 //
29 // Four severity levels are defined. Logging APIs should terminate the program
30 // when a message is logged at severity `kFatal`; the other levels have no
31 // special semantics.
32 //
33 // Values other than the four defined levels (e.g. produced by `static_cast`)
34 // are valid, but their semantics when passed to a function, macro, or flag
35 // depend on the function, macro, or flag. The usual behavior is to normalize
36 // such values to a defined severity level, however in some cases values other
37 // than the defined levels are useful for comparison.
38 //
39 // Exmaple:
40 //
41 // // Effectively disables all logging:
42 // SetMinLogLevel(static_cast<absl::LogSeverity>(100));
43 //
44 // Abseil flags may be defined with type `LogSeverity`. Dependency layering
45 // constraints require that the `AbslParseFlag()` overload be declared and
46 // defined in the flags library itself rather than here. The `AbslUnparseFlag()`
47 // overload is defined there as well for consistency.
48 //
49 // absl::LogSeverity Flag String Representation
50 //
51 // An `absl::LogSeverity` has a string representation used for parsing
52 // command-line flags based on the enumerator name (e.g. `kFatal`) or
53 // its unprefixed name (without the `k`) in any case-insensitive form. (E.g.
54 // "FATAL", "fatal" or "Fatal" are all valid.) Unparsing such flags produces an
55 // unprefixed string representation in all caps (e.g. "FATAL") or an integer.
56 //
57 // Additionally, the parser accepts arbitrary integers (as if the type were
58 // `int`).
59 //
60 // Examples:
61 //
62 // --my_log_level=kInfo
63 // --my_log_level=INFO
64 // --my_log_level=info
65 // --my_log_level=0
66 //
67 // Unparsing a flag produces the same result as `absl::LogSeverityName()` for
68 // the standard levels and a base-ten integer otherwise.
69 enum class LogSeverity : int {
70 kInfo = 0,
71 kWarning = 1,
72 kError = 2,
73 kFatal = 3,
74 };
75
76 // LogSeverities()
77 //
78 // Returns an iterable of all standard `absl::LogSeverity` values, ordered from
79 // least to most severe.
LogSeverities()80 constexpr std::array<absl::LogSeverity, 4> LogSeverities() {
81 return {{absl::LogSeverity::kInfo, absl::LogSeverity::kWarning,
82 absl::LogSeverity::kError, absl::LogSeverity::kFatal}};
83 }
84
85 // LogSeverityName()
86 //
87 // Returns the all-caps string representation (e.g. "INFO") of the specified
88 // severity level if it is one of the standard levels and "UNKNOWN" otherwise.
LogSeverityName(absl::LogSeverity s)89 constexpr const char* LogSeverityName(absl::LogSeverity s) {
90 return s == absl::LogSeverity::kInfo
91 ? "INFO"
92 : s == absl::LogSeverity::kWarning
93 ? "WARNING"
94 : s == absl::LogSeverity::kError
95 ? "ERROR"
96 : s == absl::LogSeverity::kFatal ? "FATAL" : "UNKNOWN";
97 }
98
99 // NormalizeLogSeverity()
100 //
101 // Values less than `kInfo` normalize to `kInfo`; values greater than `kFatal`
102 // normalize to `kError` (**NOT** `kFatal`).
NormalizeLogSeverity(absl::LogSeverity s)103 constexpr absl::LogSeverity NormalizeLogSeverity(absl::LogSeverity s) {
104 return s < absl::LogSeverity::kInfo
105 ? absl::LogSeverity::kInfo
106 : s > absl::LogSeverity::kFatal ? absl::LogSeverity::kError : s;
107 }
NormalizeLogSeverity(int s)108 constexpr absl::LogSeverity NormalizeLogSeverity(int s) {
109 return absl::NormalizeLogSeverity(static_cast<absl::LogSeverity>(s));
110 }
111
112 // operator<<
113 //
114 // The exact representation of a streamed `absl::LogSeverity` is deliberately
115 // unspecified; do not rely on it.
116 std::ostream& operator<<(std::ostream& os, absl::LogSeverity s);
117
118 ABSL_NAMESPACE_END
119 } // namespace absl
120
121 #endif // ABSL_BASE_LOG_SEVERITY_H_
122