Make gflags and boost::program_options play nice with each other

[folly.git] / folly / experimental / ProgramOptions.h

diff --git a/folly/experimental/ProgramOptions.h b/folly/experimental/ProgramOptions.h
new file mode 100644 (file)
index 0000000..14abe9a
--- /dev/null
+++ b/folly/experimental/ProgramOptions.h
@@ -0,0 +1,87 @@
+/*
+ * Copyright 2015 Facebook, Inc.
+ *
+ * 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
+ *
+ *   http://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.
+ */
+
+#ifndef FOLLY_PROGRAMOPTIONS_H_
+#define FOLLY_PROGRAMOPTIONS_H_
+
+#include <boost/program_options.hpp>
+#include <folly/Optional.h>
+#include <gflags/gflags.h>
+
+namespace folly {
+
+enum class ProgramOptionsStyle {
+  GFLAGS,
+  GNU
+};
+
+// Add all GFlags to the given options_description.
+// Use this *instead of* gflags::ParseCommandLineFlags().
+//
+// in GFLAGS style, the flags are named as per gflags conventions:
+//   names_with_underscores
+//   boolean flags have a "no" prefix
+//
+// in GNU style, the flags are named as per GNU conventions:
+//   names-with-dashes
+//   boolean flags have a "no-" prefix
+//
+// Consider (for example) a boolean flag:
+//   DEFINE_bool(flying_pigs, false, "...");
+//
+// In GFLAGS style, the corresponding flags are named
+//   flying_pigs
+//   noflying_pigs
+//
+// In GNU style, the corresponding flags are named
+//   flying-pigs
+//   no-flying-pigs
+//
+// You may not pass arguments to boolean flags, so you must use the
+// "no" / "no-" prefix to set them to false; "--flying_pigs false"
+// and "--flying_pigs=false" are not allowed, to prevent ambiguity.
+boost::program_options::options_description getGFlags(
+    ProgramOptionsStyle style = ProgramOptionsStyle::GNU);
+
+// Helper when parsing nested command lines:
+//
+// program [--common_options...] command [--command_options...] args
+//
+// The result has "command" set to the first positional argument, if any,
+// and "rest" set to the remaining options and arguments. Note that any
+// unrecognized flags must appear after the command name.
+//
+// You may pass "rest" to parseNestedCommandLine again, etc.
+struct NestedCommandLineParseResult {
+  NestedCommandLineParseResult() { }
+
+  boost::program_options::parsed_options options {nullptr};
+
+  Optional<std::string> command;
+  std::vector<std::string> rest;
+};
+
+NestedCommandLineParseResult parseNestedCommandLine(
+    int argc, const char* const argv[],
+    const boost::program_options::options_description& desc);
+
+NestedCommandLineParseResult parseNestedCommandLine(
+    const std::vector<std::string>& cmdline,
+    const boost::program_options::options_description& desc);
+
+}  // namespaces
+
+#endif /* FOLLY_PROGRAMOPTIONS_H_ */