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Diffstat (limited to 'absl/flags/internal/usage.cc')
| -rw-r--r-- | absl/flags/internal/usage.cc | 392 |
1 files changed, 392 insertions, 0 deletions
diff --git a/absl/flags/internal/usage.cc b/absl/flags/internal/usage.cc new file mode 100644 index 00000000..f17cc6c5 --- /dev/null +++ b/absl/flags/internal/usage.cc @@ -0,0 +1,392 @@ +// +// Copyright 2019 The Abseil Authors. +// +// Licensed under the Apache License, Version 2.0 (the "License"); +// you may not use this file except in compliance with the License. +// You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software +// distributed under the License is distributed on an "AS IS" BASIS, +// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +// See the License for the specific language governing permissions and +// limitations under the License. + +#include "absl/flags/internal/usage.h" + +#include <map> +#include <string> + +#include "absl/flags/flag.h" +#include "absl/flags/internal/path_util.h" +#include "absl/flags/internal/program_name.h" +#include "absl/flags/usage_config.h" +#include "absl/strings/ascii.h" +#include "absl/strings/str_cat.h" +#include "absl/strings/str_split.h" +#include "absl/synchronization/mutex.h" + +ABSL_FLAG(bool, help, false, + "show help on important flags for this binary [tip: all flags can " + "have two dashes]"); +ABSL_FLAG(bool, helpfull, false, "show help on all flags"); +ABSL_FLAG(bool, helpshort, false, + "show help on only the main module for this program"); +ABSL_FLAG(bool, helppackage, false, + "show help on all modules in the main package"); +ABSL_FLAG(bool, version, false, "show version and build info and exit"); +ABSL_FLAG(bool, only_check_args, false, "exit after checking all flags"); +ABSL_FLAG(std::string, helpon, "", + "show help on the modules named by this flag value"); +ABSL_FLAG(std::string, helpmatch, "", + "show help on modules whose name contains the specified substr"); + +namespace absl { +namespace flags_internal { +namespace { + +// This class is used to emit an XML element with `tag` and `text`. +// It adds opening and closing tags and escapes special characters in the text. +// For example: +// std::cout << XMLElement("title", "Milk & Cookies"); +// prints "<title>Milk & Cookies</title>" +class XMLElement { + public: + XMLElement(absl::string_view tag, absl::string_view txt) + : tag_(tag), txt_(txt) {} + + friend std::ostream& operator<<(std::ostream& out, + const XMLElement& xml_elem) { + out << "<" << xml_elem.tag_ << ">"; + + for (auto c : xml_elem.txt_) { + switch (c) { + case '"': + out << """; + break; + case '\'': + out << "'"; + break; + case '&': + out << "&"; + break; + case '<': + out << "<"; + break; + case '>': + out << ">"; + break; + default: + out << c; + break; + } + } + + return out << "</" << xml_elem.tag_ << ">"; + } + + private: + absl::string_view tag_; + absl::string_view txt_; +}; + +// -------------------------------------------------------------------- +// Helper class to pretty-print info about a flag. + +class FlagHelpPrettyPrinter { + public: + // Pretty printer holds on to the std::ostream& reference to direct an output + // to that stream. + FlagHelpPrettyPrinter(int max_line_len, std::ostream* out) + : out_(*out), + max_line_len_(max_line_len), + line_len_(0), + first_line_(true) {} + + void Write(absl::string_view str, bool wrap_line = false) { + // Empty std::string - do nothing. + if (str.empty()) return; + + std::vector<absl::string_view> tokens; + if (wrap_line) { + tokens = absl::StrSplit(str, absl::ByAnyChar(" \f\n\r\t\v"), + absl::SkipEmpty()); + } else { + tokens.push_back(str); + } + + for (auto token : tokens) { + bool new_line = (line_len_ == 0); + + // Write the token, ending the std::string first if necessary/possible. + if (!new_line && (line_len_ + token.size() >= max_line_len_)) { + EndLine(); + new_line = true; + } + + if (new_line) { + StartLine(); + } else { + out_ << ' '; + ++line_len_; + } + + out_ << token; + line_len_ += token.size(); + } + } + + void StartLine() { + if (first_line_) { + out_ << " "; + line_len_ = 4; + first_line_ = false; + } else { + out_ << " "; + line_len_ = 6; + } + } + void EndLine() { + out_ << '\n'; + line_len_ = 0; + } + + private: + std::ostream& out_; + const int max_line_len_; + int line_len_; + bool first_line_; +}; + +void FlagHelpHumanReadable(const flags_internal::CommandLineFlag& flag, + std::ostream* out) { + FlagHelpPrettyPrinter printer(80, out); // Max line length is 80. + + // Flag name. + printer.Write(absl::StrCat("-", flag.Name())); + + // Flag help. + printer.Write(absl::StrCat("(", flag.Help(), ");"), /*wrap_line=*/true); + + // Flag data type (for V1 flags only). + if (!flag.IsAbseilFlag() && !flag.IsRetired()) { + printer.Write(absl::StrCat("type: ", flag.Typename(), ";")); + } + + // The listed default value will be the actual default from the flag + // definition in the originating source file, unless the value has + // subsequently been modified using SetCommandLineOption() with mode + // SET_FLAGS_DEFAULT. + std::string dflt_val = flag.DefaultValue(); + if (flag.IsOfType<std::string>()) { + dflt_val = absl::StrCat("\"", dflt_val, "\""); + } + printer.Write(absl::StrCat("default: ", dflt_val, ";")); + + if (flag.modified) { + std::string curr_val = flag.CurrentValue(); + if (flag.IsOfType<std::string>()) { + curr_val = absl::StrCat("\"", curr_val, "\""); + } + printer.Write(absl::StrCat("currently: ", curr_val, ";")); + } + + printer.EndLine(); +} + +// Shows help for every filename which matches any of the filters +// If filters are empty, shows help for every file. +// If a flag's help message has been stripped (e.g. by adding '#define +// STRIP_FLAG_HELP 1' then this flag will not be displayed by '--help' +// and its variants. +void FlagsHelpImpl(std::ostream& out, flags_internal::FlagKindFilter filter_cb, + HelpFormat format = HelpFormat::kHumanReadable) { + if (format == HelpFormat::kHumanReadable) { + out << flags_internal::ShortProgramInvocationName() << ": " + << flags_internal::ProgramUsageMessage() << "\n\n"; + } else { + // XML schema is not a part of our public API for now. + out << "<?xml version=\"1.0\"?>\n" + // The document. + << "<AllFlags>\n" + // The program name and usage. + << XMLElement("program", flags_internal::ShortProgramInvocationName()) + << '\n' + << XMLElement("usage", flags_internal::ProgramUsageMessage()) << '\n'; + } + + // Map of package name to + // map of file name to + // vector of flags in the file. + // This map is used to output matching flags grouped by package and file + // name. + std::map<std::string, + std::map<std::string, + std::vector<const flags_internal::CommandLineFlag*>>> + matching_flags; + + flags_internal::ForEachFlag([&](flags_internal::CommandLineFlag* flag) { + absl::MutexLock l(InitFlagIfNecessary(flag)); + + std::string flag_filename = flag->Filename(); + + // Ignore retired flags. + if (flag->IsRetired()) return; + + // If the flag has been stripped, pretend that it doesn't exist. + if (flag->Help() == flags_internal::kStrippedFlagHelp) return; + + // Make sure flag satisfies the filter + if (!filter_cb || !filter_cb(flag_filename)) return; + + matching_flags[std::string(flags_internal::Package(flag_filename))] + [flag_filename] + .push_back(flag); + }); + + absl::string_view + package_separator; // controls blank lines between packages. + absl::string_view file_separator; // controls blank lines between files. + for (const auto& package : matching_flags) { + if (format == HelpFormat::kHumanReadable) { + out << package_separator; + package_separator = "\n\n"; + } + + file_separator = ""; + for (const auto& flags_in_file : package.second) { + if (format == HelpFormat::kHumanReadable) { + out << file_separator << " Flags from " << flags_in_file.first + << ":\n"; + file_separator = "\n"; + } + + for (const auto* flag : flags_in_file.second) { + flags_internal::FlagHelp(out, *flag, format); + } + } + } + + if (format == HelpFormat::kHumanReadable) { + if (filter_cb && matching_flags.empty()) { + out << " No modules matched: use -helpfull\n"; + } + } else { + // The end of the document. + out << "</AllFlags>\n"; + } +} + +ABSL_CONST_INIT absl::Mutex usage_message_guard(absl::kConstInit); +ABSL_CONST_INIT std::string* program_usage_message + GUARDED_BY(usage_message_guard) = nullptr; + +} // namespace + +// -------------------------------------------------------------------- +// Sets the "usage" message to be used by help reporting routines. + +void SetProgramUsageMessage(absl::string_view new_usage_message) { + absl::MutexLock l(&usage_message_guard); + + if (flags_internal::program_usage_message != nullptr) { + ABSL_INTERNAL_LOG(FATAL, "SetProgramUsageMessage() called twice."); + std::exit(1); + } + + program_usage_message = new std::string(new_usage_message); +} + +// -------------------------------------------------------------------- +// Returns the usage message set by SetProgramUsageMessage(). +// Note: We able to return string_view here only because calling +// SetProgramUsageMessage twice is prohibited. +absl::string_view ProgramUsageMessage() { + absl::MutexLock l(&usage_message_guard); + + return program_usage_message != nullptr + ? absl::string_view(*program_usage_message) + : "Warning: SetProgramUsageMessage() never called"; +} + +// -------------------------------------------------------------------- +// Produces the help message describing specific flag. +void FlagHelp(std::ostream& out, const flags_internal::CommandLineFlag& flag, + HelpFormat format) { + if (format == HelpFormat::kHumanReadable) + flags_internal::FlagHelpHumanReadable(flag, &out); +} + +// -------------------------------------------------------------------- +// Produces the help messages for all flags matching the filter. +// If filter is empty produces help messages for all flags. +void FlagsHelp(std::ostream& out, absl::string_view filter, HelpFormat format) { + flags_internal::FlagKindFilter filter_cb = [&](absl::string_view filename) { + return filter.empty() || filename.find(filter) != absl::string_view::npos; + }; + flags_internal::FlagsHelpImpl(out, filter_cb, format); +} + +// -------------------------------------------------------------------- +// Checks all the 'usage' command line flags to see if any have been set. +// If so, handles them appropriately. +int HandleUsageFlags(std::ostream& out) { + if (absl::GetFlag(FLAGS_helpshort)) { + flags_internal::FlagsHelpImpl( + out, flags_internal::GetUsageConfig().contains_helpshort_flags, + HelpFormat::kHumanReadable); + return 1; + } + + if (absl::GetFlag(FLAGS_helpfull)) { + // show all options + flags_internal::FlagsHelp(out); + return 1; + } + + if (!absl::GetFlag(FLAGS_helpon).empty()) { + flags_internal::FlagsHelp( + out, absl::StrCat("/", absl::GetFlag(FLAGS_helpon), ".")); + return 1; + } + + if (!absl::GetFlag(FLAGS_helpmatch).empty()) { + flags_internal::FlagsHelp(out, absl::GetFlag(FLAGS_helpmatch)); + return 1; + } + + if (absl::GetFlag(FLAGS_help)) { + flags_internal::FlagsHelpImpl( + out, flags_internal::GetUsageConfig().contains_help_flags); + + out << "\nTry --helpfull to get a list of all flags.\n"; + + return 1; + } + + if (absl::GetFlag(FLAGS_helppackage)) { + flags_internal::FlagsHelpImpl( + out, flags_internal::GetUsageConfig().contains_helppackage_flags); + + out << "\nTry --helpfull to get a list of all flags.\n"; + + return 1; + } + + if (absl::GetFlag(FLAGS_version)) { + if (flags_internal::GetUsageConfig().version_string) + out << flags_internal::GetUsageConfig().version_string(); + // Unlike help, we may be asking for version in a script, so return 0 + return 0; + } + + if (absl::GetFlag(FLAGS_only_check_args)) { + return 0; + } + + return -1; +} + +} // namespace flags_internal +} // namespace absl |