command_line.h

// Copyright (c) 2006-2008 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

// This class works with command lines: building and parsing.
// Switches can optionally have a value attached using an equals sign,
// as in "-switch=value".  Arguments that aren't prefixed with a
// switch prefix are saved as extra arguments.  An argument of "--"
// will terminate switch parsing, causing everything after to be
// considered as extra arguments.

// There is a singleton read-only CommandLine that represents the command
// line that the current process was started with.  It must be initialized
// in main() (or whatever the platform's equivalent function is).

#ifndef BASE_COMMAND_LINE_H_
#define BASE_COMMAND_LINE_H_
#pragma once

#include "build/build_config.h"

#include <map>
#include <string>
#include <vector>

#include "base/basictypes.h"

class FilePath;
class InProcessBrowserTest;

class CommandLine {
 public:
  // A constructor for CommandLines that are used only to carry switches and
  // arguments.
  enum NoProgram { NO_PROGRAM };
  explicit CommandLine(NoProgram no_program);
  ~CommandLine();

#if defined(OS_WIN)
  // The type of native command line arguments.
  typedef std::wstring StringType;

  // Initialize by parsing the given command-line string.
  // The program name is assumed to be the first item in the string.
  void ParseFromString(const std::wstring& command_line);
  static CommandLine FromString(const std::wstring& command_line);
#elif defined(OS_POSIX)
  // The type of native command line arguments.
  typedef std::string StringType;

  // Initialize from an argv vector.
  void InitFromArgv(int argc, const char* const* argv);
  void InitFromArgv(const std::vector<std::string>& argv);

  CommandLine(int argc, const char* const* argv);
  explicit CommandLine(const std::vector<std::string>& argv);
#endif

  // Construct a new, empty command line.
  // |program| is the name of the program to run (aka argv[0]).
  explicit CommandLine(const FilePath& program);

  // Initialize the current process CommandLine singleton.  On Windows,
  // ignores its arguments (we instead parse GetCommandLineW()
  // directly) because we don't trust the CRT's parsing of the command
  // line, but it still must be called to set up the command line.
  static void Init(int argc, const char* const* argv);

#if defined(OS_POSIX) && !defined(OS_MACOSX)
  // Sets the current process' arguments that show in "ps" etc. to those
  // in |current_process_commandline_|. Used by the zygote host so that
  // renderers show up with --type=renderer.
  static void SetProcTitle();
#endif

  // Destroys the current process CommandLine singleton. This is necessary if
  // you want to reset the base library to its initial state (for example in an
  // outer library that needs to be able to terminate, and be re-initialized).
  // If Init is called only once, e.g. in main(), calling Reset() is not
  // necessary.
  static void Reset();

  // Get the singleton CommandLine representing the current process's
  // command line.  Note: returned value is mutable, but not thread safe;
  // only mutate if you know what you're doing!
  static CommandLine* ForCurrentProcess();

  // Returns true if this command line contains the given switch.
  // (Switch names are case-insensitive.)
  bool HasSwitch(const std::string& switch_string) const;

  // Returns the value associated with the given switch.  If the
  // switch has no value or isn't present, this method returns
  // the empty string.
  std::string GetSwitchValueASCII(const std::string& switch_string) const;
  FilePath GetSwitchValuePath(const std::string& switch_string) const;
  StringType GetSwitchValueNative(const std::string& switch_string) const;

  // Get the number of switches in this process.
  size_t GetSwitchCount() const { return switches_.size(); }

  // The type of map for parsed-out switch key and values.
  typedef std::map<std::string, StringType> SwitchMap;

  // Get a copy of all switches, along with their values
  const SwitchMap& GetSwitches() const {
    return switches_;
  }

  // Get the remaining arguments to the command.
  const std::vector<StringType>& args() const { return args_; }

#if defined(OS_WIN)
  // Returns the original command line string.
  const std::wstring& command_line_string() const {
    return command_line_string_;
  }
#elif defined(OS_POSIX)
  // Returns the original command line string as a vector of strings.
  const std::vector<std::string>& argv() const {
    return argv_;
  }
  // Try to match the same result as command_line_string() would get you
  // on windows.
  std::string command_line_string() const;
#endif

  // Returns the program part of the command line string (the first item).
  FilePath GetProgram() const;

  // Append a switch to the command line.
  void AppendSwitch(const std::string& switch_string);

  // Append a switch and value to the command line.
  void AppendSwitchPath(const std::string& switch_string, const FilePath& path);
  void AppendSwitchNative(const std::string& switch_string,
                          const StringType& value);
  void AppendSwitchASCII(const std::string& switch_string,
                         const std::string& value);

  // Append an argument to the command line.
  // Note on quoting: the argument will be quoted properly such that it is
  // interpreted as one argument to the target command.
  // AppendArg is primarily for ASCII; non-ASCII input will be
  // interpreted as UTF-8.
  void AppendArg(const std::string& value);
  void AppendArgPath(const FilePath& value);
  void AppendArgNative(const StringType& value);

  // Append the arguments from another command line to this one.
  // If |include_program| is true, include |other|'s program as well.
  void AppendArguments(const CommandLine& other,
                       bool include_program);

  // Insert a command before the current command.  Common for debuggers,
  // like "valgrind" or "gdb --args".
  void PrependWrapper(const StringType& wrapper);

  // Copy a set of switches (and their values, if any) from another command
  // line.  Commonly used when launching a subprocess.
  void CopySwitchesFrom(const CommandLine& source, const char* const switches[],
                        size_t count);

 private:
  friend class InProcessBrowserTest;

  CommandLine();

  // Used by InProcessBrowserTest.
  static CommandLine* ForCurrentProcessMutable();

  // The singleton CommandLine instance representing the current process's
  // command line.
  static CommandLine* current_process_commandline_;

  // We store a platform-native version of the command line, used when building
  // up a new command line to be executed.  This ifdef delimits that code.

#if defined(OS_WIN)
  // The quoted, space-separated command-line string.
  std::wstring command_line_string_;
  // The name of the program.
  std::wstring program_;
#elif defined(OS_POSIX)
  // The argv array, with the program name in argv_[0].
  std::vector<std::string> argv_;
#endif

  // Returns true and fills in |switch_string| and |switch_value|
  // if |parameter_string| represents a switch.
  static bool IsSwitch(const StringType& parameter_string,
                       std::string* switch_string,
                       StringType* switch_value);

  // Parsed-out values.
  SwitchMap switches_;

  // Non-switch command-line arguments.
  std::vector<StringType> args_;

  // We allow copy constructors, because a common pattern is to grab a
  // copy of the current process's command line and then add some
  // flags to it.  E.g.:
  //   CommandLine cl(*CommandLine::ForCurrentProcess());
  //   cl.AppendSwitch(...);
};

#endif  // BASE_COMMAND_LINE_H_