//
// 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 <stdint.h>
#include <functional>
#include <map>
#include <ostream>
#include <string>
#include <utility>
#include <vector>
#include "absl/base/config.h"
#include "absl/flags/commandlineflag.h"
#include "absl/flags/flag.h"
#include "absl/flags/internal/flag.h"
#include "absl/flags/internal/path_util.h"
#include "absl/flags/internal/private_handle_accessor.h"
#include "absl/flags/internal/program_name.h"
#include "absl/flags/internal/registry.h"
#include "absl/flags/usage_config.h"
#include "absl/strings/str_cat.h"
#include "absl/strings/str_split.h"
#include "absl/strings/string_view.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 {
ABSL_NAMESPACE_BEGIN
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 string - do nothing.
if (str.empty()) return;
std::vector<absl::string_view> tokens;
if (wrap_line) {
for (auto line : absl::StrSplit(str, absl::ByAnyChar("\n\r"))) {
if (!tokens.empty()) {
// Keep line separators in the input string.
tokens.push_back("\n");
}
for (auto token :
absl::StrSplit(line, absl::ByAnyChar(" \t"), absl::SkipEmpty())) {
tokens.push_back(token);
}
}
} else {
tokens.push_back(str);
}
for (auto token : tokens) {
bool new_line = (line_len_ == 0);
// Respect line separators in the input string.
if (token == "\n") {
EndLine();
continue;
}
// Write the token, ending the 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 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);
// 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();
std::string curr_val = flag.CurrentValue();
bool is_modified = curr_val != dflt_val;
if (flag.IsOfType<std::string>()) {
dflt_val = absl::StrCat("\"", dflt_val, "\"");
}
printer.Write(absl::StrCat("default: ", dflt_val, ";"));
if (is_modified) {
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, absl::string_view program_usage_message) {
if (format == HelpFormat::kHumanReadable) {
out << flags_internal::ShortProgramInvocationName() << ": "
<< program_usage_message << "\n\n";
} else {
// XML schema is not a part of our public API for now.
out << "<?xml version=\"1.0\"?>\n"
<< "<!-- This output should be used with care. We do not report type "
"names for flags with user defined types -->\n"
<< "<!-- Prefer flag only_check_args for validating flag inputs -->\n"
// The document.
<< "<AllFlags>\n"
// The program name and usage.
<< XMLElement("program", flags_internal::ShortProgramInvocationName())
<< '\n'
<< XMLElement("usage", program_usage_message) << '\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 absl::CommandLineFlag*>>>
matching_flags;
flags_internal::ForEachFlag([&](absl::CommandLineFlag& 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";
}
}
} // namespace
// --------------------------------------------------------------------
// Produces the help message describing specific flag.
void FlagHelp(std::ostream& out, const 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,
absl::string_view program_usage_message) {
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, program_usage_message);
}
// --------------------------------------------------------------------
// Checks all the 'usage' command line flags to see if any have been set.
// If so, handles them appropriately.
int HandleUsageFlags(std::ostream& out,
absl::string_view program_usage_message) {
if (absl::GetFlag(FLAGS_helpshort)) {
flags_internal::FlagsHelpImpl(
out, flags_internal::GetUsageConfig().contains_helpshort_flags,
HelpFormat::kHumanReadable, program_usage_message);
return 1;
}
if (absl::GetFlag(FLAGS_helpfull)) {
// show all options
flags_internal::FlagsHelp(out, "", HelpFormat::kHumanReadable,
program_usage_message);
return 1;
}
if (!absl::GetFlag(FLAGS_helpon).empty()) {
flags_internal::FlagsHelp(
out, absl::StrCat("/", absl::GetFlag(FLAGS_helpon), "."),
HelpFormat::kHumanReadable, program_usage_message);
return 1;
}
if (!absl::GetFlag(FLAGS_helpmatch).empty()) {
flags_internal::FlagsHelp(out, absl::GetFlag(FLAGS_helpmatch),
HelpFormat::kHumanReadable,
program_usage_message);
return 1;
}
if (absl::GetFlag(FLAGS_help)) {
flags_internal::FlagsHelpImpl(
out, flags_internal::GetUsageConfig().contains_help_flags,
HelpFormat::kHumanReadable, program_usage_message);
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,
HelpFormat::kHumanReadable, program_usage_message);
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
ABSL_NAMESPACE_END
} // namespace absl
