1 files changed, 152 insertions, 0 deletions
diff --git a/absl/flags/usage_config.cc b/absl/flags/usage_config.cc
new file mode 100644
index 000000000000..d34ecfc82c7b
--- /dev/null
+++ b/absl/flags/usage_config.cc
@@ -0,0 +1,152 @@
+//
+//  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/usage_config.h"
+
+#include <iostream>
+#include <memory>
+
+#include "absl/base/attributes.h"
+#include "absl/flags/internal/path_util.h"
+#include "absl/flags/internal/program_name.h"
+#include "absl/strings/str_cat.h"
+#include "absl/strings/strip.h"
+#include "absl/synchronization/mutex.h"
+
+extern "C" {
+
+// Additional report of fatal usage error message before we std::exit. Error is
+// fatal if is_fatal argument to ReportUsageError is true.
+ABSL_ATTRIBUTE_WEAK void AbslInternalReportFatalUsageError(absl::string_view) {}
+
+}  // extern "C"
+
+namespace absl {
+namespace flags_internal {
+
+namespace {
+
+// --------------------------------------------------------------------
+// Returns true if flags defined in the filename should be reported with
+// -helpshort flag.
+
+bool ContainsHelpshortFlags(absl::string_view filename) {
+  // By default we only want flags in binary's main. We expect the main
+  // routine to reside in <program>.cc or <program>-main.cc or
+  // <program>_main.cc, where the <program> is the name of the binary.
+  auto suffix = flags_internal::Basename(filename);
+  if (!absl::ConsumePrefix(&suffix,
+                           flags_internal::ShortProgramInvocationName()))
+    return false;
+  return absl::StartsWith(suffix, ".") || absl::StartsWith(suffix, "-main.") ||
+         absl::StartsWith(suffix, "_main.");
+}
+
+// --------------------------------------------------------------------
+// Returns true if flags defined in the filename should be reported with
+// -helppackage flag.
+
+bool ContainsHelppackageFlags(absl::string_view filename) {
+  // TODO(rogeeff): implement properly when registry is available.
+  return ContainsHelpshortFlags(filename);
+}
+
+// --------------------------------------------------------------------
+// Generates program version information into supplied output.
+
+std::string VersionString() {
+  std::string version_str(flags_internal::ShortProgramInvocationName());
+
+  version_str += "\n";
+
+#if !defined(NDEBUG)
+  version_str += "Debug build (NDEBUG not #defined)\n";
+#endif
+
+  return version_str;
+}
+
+// --------------------------------------------------------------------
+// Normalizes the filename specific to the build system/filesystem used.
+
+std::string NormalizeFilename(absl::string_view filename) {
+  // Skip any leading slashes
+  auto pos = filename.find_first_not_of("\\/");
+  if (pos == absl::string_view::npos) return "";
+
+  filename.remove_prefix(pos);
+  return std::string(filename);
+}
+
+// --------------------------------------------------------------------
+
+ABSL_CONST_INIT absl::Mutex custom_usage_config_guard(absl::kConstInit);
+ABSL_CONST_INIT FlagsUsageConfig* custom_usage_config
+    GUARDED_BY(custom_usage_config_guard) = nullptr;
+
+}  // namespace
+
+FlagsUsageConfig GetUsageConfig() {
+  absl::MutexLock l(&custom_usage_config_guard);
+
+  if (custom_usage_config) return *custom_usage_config;
+
+  FlagsUsageConfig default_config;
+  default_config.contains_helpshort_flags = &ContainsHelpshortFlags;
+  default_config.contains_help_flags = &ContainsHelppackageFlags;
+  default_config.contains_helppackage_flags = &ContainsHelppackageFlags;
+  default_config.version_string = &VersionString;
+  default_config.normalize_filename = &NormalizeFilename;
+
+  return default_config;
+}
+
+void ReportUsageError(absl::string_view msg, bool is_fatal) {
+  std::cerr << "ERROR: " << msg << std::endl;
+
+  if (is_fatal) {
+    AbslInternalReportFatalUsageError(msg);
+  }
+}
+
+}  // namespace flags_internal
+
+void SetFlagsUsageConfig(FlagsUsageConfig usage_config) {
+  absl::MutexLock l(&flags_internal::custom_usage_config_guard);
+
+  if (!usage_config.contains_helpshort_flags)
+    usage_config.contains_helpshort_flags =
+        flags_internal::ContainsHelpshortFlags;
+
+  if (!usage_config.contains_help_flags)
+    usage_config.contains_help_flags = flags_internal::ContainsHelppackageFlags;
+
+  if (!usage_config.contains_helppackage_flags)
+    usage_config.contains_helppackage_flags =
+        flags_internal::ContainsHelppackageFlags;
+
+  if (!usage_config.version_string)
+    usage_config.version_string = flags_internal::VersionString;
+
+  if (!usage_config.normalize_filename)
+    usage_config.normalize_filename = flags_internal::NormalizeFilename;
+
+  if (flags_internal::custom_usage_config)
+    *flags_internal::custom_usage_config = usage_config;
+  else
+    flags_internal::custom_usage_config = new FlagsUsageConfig(usage_config);
+}
+
+}  // namespace absl