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
24namespace absl {
25ABSL_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// Example:
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// `DFATAL` and `kLogDebugFatal` are similarly accepted.
68//
69// Unparsing a flag produces the same result as `absl::LogSeverityName()` for
70// the standard levels and a base-ten integer otherwise.
71enum class LogSeverity : int {
72 kInfo = 0,
73 kWarning = 1,
74 kError = 2,
75 kFatal = 3,
76};
77
78// LogSeverities()
79//
80// Returns an iterable of all standard `absl::LogSeverity` values, ordered from
81// least to most severe.
82constexpr std::array<absl::LogSeverity, 4> LogSeverities() {
83 return {._M_elems: {absl::LogSeverity::kInfo, absl::LogSeverity::kWarning,
84 absl::LogSeverity::kError, absl::LogSeverity::kFatal}};
85}
86
87// `absl::kLogDebugFatal` equals `absl::LogSeverity::kFatal` in debug builds
88// (i.e. when `NDEBUG` is not defined) and `absl::LogSeverity::kError`
89// otherwise. Avoid ODR-using this variable as it has internal linkage and thus
90// distinct storage in different TUs.
91#ifdef NDEBUG
92static constexpr absl::LogSeverity kLogDebugFatal = absl::LogSeverity::kError;
93#else
94static constexpr absl::LogSeverity kLogDebugFatal = absl::LogSeverity::kFatal;
95#endif
96
97// LogSeverityName()
98//
99// Returns the all-caps string representation (e.g. "INFO") of the specified
100// severity level if it is one of the standard levels and "UNKNOWN" otherwise.
101constexpr const char* LogSeverityName(absl::LogSeverity s) {
102 switch (s) {
103 case absl::LogSeverity::kInfo: return "INFO";
104 case absl::LogSeverity::kWarning: return "WARNING";
105 case absl::LogSeverity::kError: return "ERROR";
106 case absl::LogSeverity::kFatal: return "FATAL";
107 }
108 return "UNKNOWN";
109}
110
111// NormalizeLogSeverity()
112//
113// Values less than `kInfo` normalize to `kInfo`; values greater than `kFatal`
114// normalize to `kError` (**NOT** `kFatal`).
115constexpr absl::LogSeverity NormalizeLogSeverity(absl::LogSeverity s) {
116 absl::LogSeverity n = s;
117 if (n < absl::LogSeverity::kInfo) n = absl::LogSeverity::kInfo;
118 if (n > absl::LogSeverity::kFatal) n = absl::LogSeverity::kError;
119 return n;
120}
121constexpr absl::LogSeverity NormalizeLogSeverity(int s) {
122 return absl::NormalizeLogSeverity(s: static_cast<absl::LogSeverity>(s));
123}
124
125// operator<<
126//
127// The exact representation of a streamed `absl::LogSeverity` is deliberately
128// unspecified; do not rely on it.
129std::ostream& operator<<(std::ostream& os, absl::LogSeverity s);
130
131// Enums representing a lower bound for LogSeverity. APIs that only operate on
132// messages of at least a certain level (for example, `SetMinLogLevel()`) use
133// this type to specify that level. absl::LogSeverityAtLeast::kInfinity is
134// a level above all threshold levels and therefore no log message will
135// ever meet this threshold.
136enum class LogSeverityAtLeast : int {
137 kInfo = static_cast<int>(absl::LogSeverity::kInfo),
138 kWarning = static_cast<int>(absl::LogSeverity::kWarning),
139 kError = static_cast<int>(absl::LogSeverity::kError),
140 kFatal = static_cast<int>(absl::LogSeverity::kFatal),
141 kInfinity = 1000,
142};
143
144std::ostream& operator<<(std::ostream& os, absl::LogSeverityAtLeast s);
145
146// Enums representing an upper bound for LogSeverity. APIs that only operate on
147// messages of at most a certain level (for example, buffer all messages at or
148// below a certain level) use this type to specify that level.
149// absl::LogSeverityAtMost::kNegativeInfinity is a level below all threshold
150// levels and therefore will exclude all log messages.
151enum class LogSeverityAtMost : int {
152 kNegativeInfinity = -1000,
153 kInfo = static_cast<int>(absl::LogSeverity::kInfo),
154 kWarning = static_cast<int>(absl::LogSeverity::kWarning),
155 kError = static_cast<int>(absl::LogSeverity::kError),
156 kFatal = static_cast<int>(absl::LogSeverity::kFatal),
157};
158
159std::ostream& operator<<(std::ostream& os, absl::LogSeverityAtMost s);
160
161#define COMPOP(op1, op2, T) \
162 constexpr bool operator op1(absl::T lhs, absl::LogSeverity rhs) { \
163 return static_cast<absl::LogSeverity>(lhs) op1 rhs; \
164 } \
165 constexpr bool operator op2(absl::LogSeverity lhs, absl::T rhs) { \
166 return lhs op2 static_cast<absl::LogSeverity>(rhs); \
167 }
168
169// Comparisons between `LogSeverity` and `LogSeverityAtLeast`/
170// `LogSeverityAtMost` are only supported in one direction.
171// Valid checks are:
172// LogSeverity >= LogSeverityAtLeast
173// LogSeverity < LogSeverityAtLeast
174// LogSeverity <= LogSeverityAtMost
175// LogSeverity > LogSeverityAtMost
176COMPOP(>, <, LogSeverityAtLeast)
177COMPOP(<=, >=, LogSeverityAtLeast)
178COMPOP(<, >, LogSeverityAtMost)
179COMPOP(>=, <=, LogSeverityAtMost)
180#undef COMPOP
181
182ABSL_NAMESPACE_END
183} // namespace absl
184
185#endif // ABSL_BASE_LOG_SEVERITY_H_
186