upload android base code part6

android/system/extras/simpleperf/cmd_help.cpp

@@ -0,0 +1,87 @@
+/*
+ * Copyright (C) 2015 The Android Open Source Project
+ *
+ * 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.
+ */
+
+#include <stdio.h>
+#include <string>
+#include <vector>
+
+#include <android-base/logging.h>
+
+#include "command.h"
+
+class HelpCommand : public Command {
+ public:
+  HelpCommand()
+      : Command("help", "print help information for simpleperf",
+                // clang-format off
+"Usage: simpleperf help [subcommand]\n"
+"    Without subcommand, print short help string for every subcommand.\n"
+"    With subcommand, print long help string for the subcommand.\n\n"
+                // clang-format on
+                ) {}
+
+  bool Run(const std::vector<std::string>& args) override;
+
+ private:
+  void PrintShortHelp();
+  void PrintLongHelpForOneCommand(const Command& cmd);
+};
+
+bool HelpCommand::Run(const std::vector<std::string>& args) {
+  if (args.empty()) {
+    PrintShortHelp();
+  } else {
+    std::unique_ptr<Command> cmd = CreateCommandInstance(args[0]);
+    if (cmd == nullptr) {
+      LOG(ERROR) << "malformed command line: can't find help string for "
+                    "unknown command "
+                 << args[0];
+      LOG(ERROR) << "try using \"--help\"";
+      return false;
+    } else {
+      PrintLongHelpForOneCommand(*cmd);
+    }
+  }
+  return true;
+}
+
+void HelpCommand::PrintShortHelp() {
+  printf(
+      // clang-format off
+"Usage: simpleperf [common options] subcommand [args_for_subcommand]\n"
+"common options:\n"
+"    -h/--help     Print this help information.\n"
+"    --log <severity> Set the minimum severity of logging. Possible severities\n"
+"                     include verbose, debug, warning, info, error, fatal.\n"
+"                     Default is info.\n"
+"    --version     Print version of simpleperf.\n"
+      "subcommands:\n"
+      // clang-format on
+      );
+  for (auto& cmd_name : GetAllCommandNames()) {
+    std::unique_ptr<Command> cmd = CreateCommandInstance(cmd_name);
+    printf("    %-20s%s\n", cmd_name.c_str(), cmd->ShortHelpString().c_str());
+  }
+}
+
+void HelpCommand::PrintLongHelpForOneCommand(const Command& command) {
+  printf("%s\n", command.LongHelpString().c_str());
+}
+
+void RegisterHelpCommand() {
+  RegisterCommand("help",
+                  [] { return std::unique_ptr<Command>(new HelpCommand); });
+}