chromium/third_party/abseil-cpp/absl/flags/parse.cc

//
// 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/parse.h"

#include <stdlib.h>

#include <algorithm>
#include <cstdint>
#include <cstdlib>
#include <fstream>
#include <iostream>
#include <ostream>
#include <string>
#include <tuple>
#include <utility>
#include <vector>

#ifdef _WIN32
#include <windows.h>
#endif

#include "absl/algorithm/container.h"
#include "absl/base/attributes.h"
#include "absl/base/config.h"
#include "absl/base/const_init.h"
#include "absl/base/thread_annotations.h"
#include "absl/flags/commandlineflag.h"
#include "absl/flags/config.h"
#include "absl/flags/flag.h"
#include "absl/flags/internal/commandlineflag.h"
#include "absl/flags/internal/flag.h"
#include "absl/flags/internal/parse.h"
#include "absl/flags/internal/private_handle_accessor.h"
#include "absl/flags/internal/program_name.h"
#include "absl/flags/internal/usage.h"
#include "absl/flags/reflection.h"
#include "absl/flags/usage.h"
#include "absl/flags/usage_config.h"
#include "absl/strings/ascii.h"
#include "absl/strings/internal/damerau_levenshtein_distance.h"
#include "absl/strings/str_cat.h"
#include "absl/strings/str_join.h"
#include "absl/strings/string_view.h"
#include "absl/strings/strip.h"
#include "absl/synchronization/mutex.h"

// --------------------------------------------------------------------

namespace absl {
ABSL_NAMESPACE_BEGIN
namespace flags_internal {
namespace {

ABSL_CONST_INIT absl::Mutex processing_checks_guard(absl::kConstInit);

ABSL_CONST_INIT bool flagfile_needs_processing
    ABSL_GUARDED_BY(processing_checks_guard) = …;
ABSL_CONST_INIT bool fromenv_needs_processing
    ABSL_GUARDED_BY(processing_checks_guard) = …;
ABSL_CONST_INIT bool tryfromenv_needs_processing
    ABSL_GUARDED_BY(processing_checks_guard) = …;

ABSL_CONST_INIT absl::Mutex specified_flags_guard(absl::kConstInit);
ABSL_CONST_INIT std::vector<const CommandLineFlag*>* specified_flags
    ABSL_GUARDED_BY(specified_flags_guard) = …;

// Suggesting at most kMaxHints flags in case of misspellings.
ABSL_CONST_INIT const size_t kMaxHints = …;
// Suggesting only flags which have a smaller distance than kMaxDistance.
ABSL_CONST_INIT const size_t kMaxDistance = …;

struct SpecifiedFlagsCompare { … };

}  // namespace
}  // namespace flags_internal
ABSL_NAMESPACE_END
}  // namespace absl

// These flags influence how command line flags are parsed and are only intended
// to be set on the command line.  Avoid reading or setting them from C++ code.
ABSL_FLAG(…);
ABSL_FLAG(…);
ABSL_FLAG(…);

// Rather than reading or setting --undefok from C++ code, please consider using
// ABSL_RETIRED_FLAG instead.
ABSL_FLAG(…);

namespace absl {
ABSL_NAMESPACE_BEGIN
namespace flags_internal {

namespace {

class ArgsList { … };

bool ArgsList::ReadFromFlagfile(const std::string& flag_file_name) { … }

// --------------------------------------------------------------------

// Reads the environment variable with name `name` and stores results in
// `value`. If variable is not present in environment returns false, otherwise
// returns true.
bool GetEnvVar(const char* var_name, std::string& var_value) { … }

// --------------------------------------------------------------------

// Returns:
//  Flag name or empty if arg= --
//  Flag value after = in --flag=value (empty if --foo)
//  "Is empty value" status. True if arg= --foo=, false otherwise. This is
//  required to separate --foo from --foo=.
// For example:
//      arg           return values
//   "--foo=bar" -> {"foo", "bar", false}.
//   "--foo"     -> {"foo", "", false}.
//   "--foo="    -> {"foo", "", true}.
std::tuple<absl::string_view, absl::string_view, bool> SplitNameAndValue(
    absl::string_view arg) { … }

// --------------------------------------------------------------------

// Returns:
//  found flag or nullptr
//  is negative in case of --nofoo
std::tuple<CommandLineFlag*, bool> LocateFlag(absl::string_view flag_name) { … }

// --------------------------------------------------------------------

// Verify that default values of typed flags must be convertible to string and
// back.
void CheckDefaultValuesParsingRoundtrip() { … }

// --------------------------------------------------------------------

// Returns success status, which is true if we successfully read all flag files,
// in which case new ArgLists are appended to the input_args in a reverse order
// of file names in the input flagfiles list. This order ensures that flags from
// the first flagfile in the input list are processed before the second flagfile
// etc.
bool ReadFlagfiles(const std::vector<std::string>& flagfiles,
                   std::vector<ArgsList>& input_args) { … }

// Returns success status, which is true if were able to locate all environment
// variables correctly or if fail_on_absent_in_env is false. The environment
// variable names are expected to be of the form `FLAGS_<flag_name>`, where
// `flag_name` is a string from the input flag_names list. If successful we
// append a single ArgList at the end of the input_args.
bool ReadFlagsFromEnv(const std::vector<std::string>& flag_names,
                      std::vector<ArgsList>& input_args,
                      bool fail_on_absent_in_env) { … }

// --------------------------------------------------------------------

// Returns success status, which is true if were able to handle all generator
// flags (flagfile, fromenv, tryfromemv) successfully.
bool HandleGeneratorFlags(std::vector<ArgsList>& input_args,
                          std::vector<std::string>& flagfile_value) { … }

// --------------------------------------------------------------------

void ResetGeneratorFlags(const std::vector<std::string>& flagfile_value) { … }

// --------------------------------------------------------------------

// Returns:
//  success status
//  deduced value
// We are also mutating curr_list in case if we need to get a hold of next
// argument in the input.
std::tuple<bool, absl::string_view> DeduceFlagValue(const CommandLineFlag& flag,
                                                    absl::string_view value,
                                                    bool is_negative,
                                                    bool is_empty_value,
                                                    ArgsList* curr_list) { … }

// --------------------------------------------------------------------

bool CanIgnoreUndefinedFlag(absl::string_view flag_name) { … }

// --------------------------------------------------------------------

void ReportUnrecognizedFlags(
    const std::vector<UnrecognizedFlag>& unrecognized_flags,
    bool report_as_fatal_error) { … }

}  // namespace

// --------------------------------------------------------------------

bool WasPresentOnCommandLine(absl::string_view flag_name) { … }

// --------------------------------------------------------------------

struct BestHints { … };

// Return the list of flags with the smallest Damerau-Levenshtein distance to
// the given flag.
std::vector<std::string> GetMisspellingHints(const absl::string_view flag) { … }

// --------------------------------------------------------------------

std::vector<char*> ParseCommandLineImpl(int argc, char* argv[],
                                        UsageFlagsAction usage_flag_action,
                                        OnUndefinedFlag undef_flag_action,
                                        std::ostream& error_help_output) { … }

// --------------------------------------------------------------------

// This function handles all Abseil Flags and built-in usage flags and, if any
// help mode was handled, it returns that help mode. The caller of this function
// can decide to exit based on the returned help mode.
// The caller may decide to handle unrecognized positional arguments and
// unrecognized flags first before exiting.
//
// Returns:
// * HelpMode::kFull if parsing errors were detected in recognized arguments
// * The HelpMode that was handled in case when `usage_flag_action` is
//   UsageFlagsAction::kHandleUsage and a usage flag was specified on the
//   commandline
// * Otherwise it returns HelpMode::kNone
HelpMode ParseAbseilFlagsOnlyImpl(
    int argc, char* argv[], std::vector<char*>& positional_args,
    std::vector<UnrecognizedFlag>& unrecognized_flags,
    UsageFlagsAction usage_flag_action) { … }

}  // namespace flags_internal

void ParseAbseilFlagsOnly(int argc, char* argv[],
                          std::vector<char*>& positional_args,
                          std::vector<UnrecognizedFlag>& unrecognized_flags) { … }

// --------------------------------------------------------------------

void ReportUnrecognizedFlags(
    const std::vector<UnrecognizedFlag>& unrecognized_flags) { … }

// --------------------------------------------------------------------

std::vector<char*> ParseCommandLine(int argc, char* argv[]) { … }

ABSL_NAMESPACE_END
}  // namespace absl