1 //
2 //  Copyright 2019 The Abseil Authors.
3 //
4 // Licensed under the Apache License, Version 2.0 (the "License");
5 // you may not use this file except in compliance with the License.
6 // You may obtain a copy of the License at
7 //
8 //      https://www.apache.org/licenses/LICENSE-2.0
9 //
10 // Unless required by applicable law or agreed to in writing, software
11 // distributed under the License is distributed on an "AS IS" BASIS,
12 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 // See the License for the specific language governing permissions and
14 // limitations under the License.
15 
16 #ifndef ABSL_FLAGS_INTERNAL_USAGE_H_
17 #define ABSL_FLAGS_INTERNAL_USAGE_H_
18 
19 #include <iosfwd>
20 #include <string>
21 
22 #include "absl/base/config.h"
23 #include "absl/flags/commandlineflag.h"
24 #include "absl/flags/declare.h"
25 #include "absl/strings/string_view.h"
26 
27 // --------------------------------------------------------------------
28 // Usage reporting interfaces
29 
30 namespace absl {
31 ABSL_NAMESPACE_BEGIN
32 namespace flags_internal {
33 
34 // The format to report the help messages in.
35 enum class HelpFormat {
36   kHumanReadable,
37 };
38 
39 // Streams the help message describing `flag` to `out`.
40 // The default value for `flag` is included in the output.
41 void FlagHelp(std::ostream& out, const CommandLineFlag& flag,
42               HelpFormat format = HelpFormat::kHumanReadable);
43 
44 // Produces the help messages for all flags matching the filter. A flag matches
45 // the filter if it is defined in a file with a filename which includes
46 // filter string as a substring. You can use '/' and '.' to restrict the
47 // matching to a specific file names. For example:
48 //   FlagsHelp(out, "/path/to/file.");
49 // restricts help to only flags which resides in files named like:
50 //  .../path/to/file.<ext>
51 // for any extension 'ext'. If the filter is empty this function produces help
52 // messages for all flags.
53 void FlagsHelp(std::ostream& out, absl::string_view filter,
54                HelpFormat format, absl::string_view program_usage_message);
55 
56 // --------------------------------------------------------------------
57 
58 // If any of the 'usage' related command line flags (listed on the bottom of
59 // this file) has been set this routine produces corresponding help message in
60 // the specified output stream and returns:
61 //  0 - if "version" or "only_check_flags" flags were set and handled.
62 //  1 - if some other 'usage' related flag was set and handled.
63 // -1 - if no usage flags were set on a commmand line.
64 // Non negative return values are expected to be used as an exit code for a
65 // binary.
66 int HandleUsageFlags(std::ostream& out,
67                      absl::string_view program_usage_message);
68 
69 // --------------------------------------------------------------------
70 // Globals representing usage reporting flags
71 
72 enum class HelpMode {
73   kNone,
74   kImportant,
75   kShort,
76   kFull,
77   kPackage,
78   kMatch,
79   kVersion,
80   kOnlyCheckArgs
81 };
82 
83 // Returns substring to filter help output (--help=substr argument)
84 std::string GetFlagsHelpMatchSubstr();
85 // Returns the requested help mode.
86 HelpMode GetFlagsHelpMode();
87 // Returns the requested help format.
88 HelpFormat GetFlagsHelpFormat();
89 
90 // These are corresponding setters to the attributes above.
91 void SetFlagsHelpMatchSubstr(absl::string_view);
92 void SetFlagsHelpMode(HelpMode);
93 void SetFlagsHelpFormat(HelpFormat);
94 
95 // Deduces usage flags from the input argument in a form --name=value or
96 // --name. argument is already split into name and value before we call this
97 // function.
98 bool DeduceUsageFlags(absl::string_view name, absl::string_view value);
99 
100 }  // namespace flags_internal
101 ABSL_NAMESPACE_END
102 }  // namespace absl
103 
104 #endif  // ABSL_FLAGS_INTERNAL_USAGE_H_
105