Suggest similar flags in case of undefined flags.
Using Damerau-Levenshtein distance to calculate potential candidates to suggest.
PiperOrigin-RevId: 499449034
Change-Id: I805aafefcd0f4f85585ac33a041c15360619c96a
diff --git a/absl/flags/internal/parse.h b/absl/flags/internal/parse.h
index de706c8..0a7012f 100644
--- a/absl/flags/internal/parse.h
+++ b/absl/flags/internal/parse.h
@@ -52,6 +52,10 @@
// command line or specified in flag file present on the original command line.
bool WasPresentOnCommandLine(absl::string_view flag_name);
+// Return existing flags similar to the parameter, in order to help in case of
+// misspellings.
+std::vector<std::string> GetMisspellingHints(absl::string_view flag);
+
} // namespace flags_internal
ABSL_NAMESPACE_END
} // namespace absl
diff --git a/absl/flags/parse.cc b/absl/flags/parse.cc
index 2851c0f..cd61e80 100644
--- a/absl/flags/parse.cc
+++ b/absl/flags/parse.cc
@@ -18,6 +18,7 @@
#include <stdlib.h>
#include <algorithm>
+#include <cstdint>
#include <fstream>
#include <iostream>
#include <iterator>
@@ -47,7 +48,9 @@
#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"
@@ -72,6 +75,11 @@
ABSL_CONST_INIT std::vector<const CommandLineFlag*>* specified_flags
ABSL_GUARDED_BY(specified_flags_guard) = nullptr;
+// Suggesting at most kMaxHints flags in case of misspellings.
+ABSL_CONST_INIT const size_t kMaxHints = 100;
+// Suggesting only flags which have a smaller distance than kMaxDistance.
+ABSL_CONST_INIT const size_t kMaxDistance = 3;
+
struct SpecifiedFlagsCompare {
bool operator()(const CommandLineFlag* a, const CommandLineFlag* b) const {
return a->Name() < b->Name();
@@ -605,6 +613,55 @@
// --------------------------------------------------------------------
+struct BestHints {
+ explicit BestHints(uint8_t _max) : best_distance(_max + 1) {}
+ bool AddHint(absl::string_view hint, uint8_t distance) {
+ if (hints.size() >= kMaxHints) return false;
+ if (distance == best_distance) {
+ hints.emplace_back(hint);
+ }
+ if (distance < best_distance) {
+ best_distance = distance;
+ hints = std::vector<std::string>{std::string(hint)};
+ }
+ return true;
+ }
+
+ uint8_t best_distance;
+ std::vector<std::string> hints;
+};
+
+// 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) {
+ const size_t maxCutoff = std::min(flag.size() / 2 + 1, kMaxDistance);
+ auto undefok = absl::GetFlag(FLAGS_undefok);
+ BestHints best_hints(static_cast<uint8_t>(maxCutoff));
+ absl::flags_internal::ForEachFlag([&](const CommandLineFlag& f) {
+ if (best_hints.hints.size() >= kMaxHints) return;
+ uint8_t distance = strings_internal::CappedDamerauLevenshteinDistance(
+ flag, f.Name(), best_hints.best_distance);
+ best_hints.AddHint(f.Name(), distance);
+ // For boolean flags, also calculate distance to the negated form.
+ if (f.IsOfType<bool>()) {
+ const std::string negated_flag = absl::StrCat("no", f.Name());
+ distance = strings_internal::CappedDamerauLevenshteinDistance(
+ flag, negated_flag, best_hints.best_distance);
+ best_hints.AddHint(negated_flag, distance);
+ }
+ });
+ // Finally calculate distance to flags in "undefok".
+ absl::c_for_each(undefok, [&](const absl::string_view f) {
+ if (best_hints.hints.size() >= kMaxHints) return;
+ uint8_t distance = strings_internal::CappedDamerauLevenshteinDistance(
+ flag, f, best_hints.best_distance);
+ best_hints.AddHint(absl::StrCat(f, " (undefok)"), distance);
+ });
+ return best_hints.hints;
+}
+
+// --------------------------------------------------------------------
+
std::vector<char*> ParseCommandLineImpl(int argc, char* argv[],
ArgvListAction arg_list_act,
UsageFlagsAction usage_flag_act,
@@ -755,10 +812,19 @@
for (const auto& flag_name : undefined_flag_names) {
if (CanIgnoreUndefinedFlag(flag_name.second)) continue;
-
- flags_internal::ReportUsageError(
- absl::StrCat("Unknown command line flag '", flag_name.second, "'"),
- true);
+ // Verify if flag_name has the "no" already removed
+ std::vector<std::string> flags;
+ if (flag_name.first) flags = GetMisspellingHints(flag_name.second);
+ if (flags.empty()) {
+ flags_internal::ReportUsageError(
+ absl::StrCat("Unknown command line flag '", flag_name.second, "'"),
+ true);
+ } else {
+ flags_internal::ReportUsageError(
+ absl::StrCat("Unknown command line flag '", flag_name.second,
+ "'. Did you mean: ", absl::StrJoin(flags, ", "), " ?"),
+ true);
+ }
success = false;
}
diff --git a/absl/flags/parse_test.cc b/absl/flags/parse_test.cc
index 8dc91db..418b0e5 100644
--- a/absl/flags/parse_test.cc
+++ b/absl/flags/parse_test.cc
@@ -17,6 +17,7 @@
#include <stdlib.h>
+#include <cstddef>
#include <fstream>
#include <string>
#include <vector>
@@ -39,6 +40,36 @@
#include <windows.h>
#endif
+// Define 125 similar flags to test kMaxHints for flag suggestions.
+#define FLAG_MULT(x) F3(x)
+#define TEST_FLAG_HEADER FLAG_HEADER_
+
+#define F(name) ABSL_FLAG(int, name, 0, "");
+
+#define F1(name) \
+ F(name##1); \
+ F(name##2); \
+ F(name##3); \
+ F(name##4); \
+ F(name##5);
+/**/
+#define F2(name) \
+ F1(name##1); \
+ F1(name##2); \
+ F1(name##3); \
+ F1(name##4); \
+ F1(name##5);
+/**/
+#define F3(name) \
+ F2(name##1); \
+ F2(name##2); \
+ F2(name##3); \
+ F2(name##4); \
+ F2(name##5);
+/**/
+
+FLAG_MULT(TEST_FLAG_HEADER)
+
namespace {
using absl::base_internal::ScopedSetEnv;
@@ -565,6 +596,49 @@
// --------------------------------------------------------------------
+TEST_F(ParseDeathTest, TestFlagSuggestions) {
+ const char* in_args1[] = {
+ "testbin",
+ "--legacy_boo",
+ };
+ EXPECT_DEATH_IF_SUPPORTED(
+ InvokeParse(in_args1),
+ "Unknown command line flag 'legacy_boo'. Did you mean: legacy_bool ?");
+
+ const char* in_args2[] = {"testbin", "--foo", "--undefok=foo1"};
+ EXPECT_DEATH_IF_SUPPORTED(
+ InvokeParse(in_args2),
+ "Unknown command line flag 'foo'. Did you mean: foo1 \\(undefok\\)?");
+
+ const char* in_args3[] = {
+ "testbin",
+ "--nolegacy_ino",
+ };
+ EXPECT_DEATH_IF_SUPPORTED(InvokeParse(in_args3),
+ "Unknown command line flag 'nolegacy_ino'. Did "
+ "you mean: nolegacy_bool, legacy_int ?");
+}
+
+// --------------------------------------------------------------------
+
+TEST_F(ParseTest, GetHints) {
+ EXPECT_THAT(absl::flags_internal::GetMisspellingHints("legacy_boo"),
+ testing::ContainerEq(std::vector<std::string>{"legacy_bool"}));
+ EXPECT_THAT(absl::flags_internal::GetMisspellingHints("nolegacy_itn"),
+ testing::ContainerEq(std::vector<std::string>{"legacy_int"}));
+ EXPECT_THAT(absl::flags_internal::GetMisspellingHints("nolegacy_int1"),
+ testing::ContainerEq(std::vector<std::string>{"legacy_int"}));
+ EXPECT_THAT(absl::flags_internal::GetMisspellingHints("nolegacy_int"),
+ testing::ContainerEq(std::vector<std::string>{"legacy_int"}));
+ EXPECT_THAT(absl::flags_internal::GetMisspellingHints("nolegacy_ino"),
+ testing::ContainerEq(
+ std::vector<std::string>{"nolegacy_bool", "legacy_int"}));
+ EXPECT_THAT(
+ absl::flags_internal::GetMisspellingHints("FLAG_HEADER_000").size(), 100);
+}
+
+// --------------------------------------------------------------------
+
TEST_F(ParseTest, TestLegacyFlags) {
const char* in_args1[] = {
"testbin",
