CommandLine refactoring and cleanup.

base/command_line.h

 // Copyright (c) 2011 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.
+// Arguments with prefixes ('--', '-', and on Windows, '/') are switches.
+// Switches will precede all other arguments without switch prefixes.
+// Switches can optionally have values, delimited by '=', e.g., "-switch=value".
+// An argument of "--" will terminate switch parsing during initialization,
+// interpreting subsequent tokens as non-switch arguments, regardless of prefix.
 
 // 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().
 
 #ifndef BASE_COMMAND_LINE_H_
 #define BASE_COMMAND_LINE_H_
 #pragma once
 
 #include <stddef.h>
 #include <map>
 #include <string>
 #include <vector>
 
 #include "base/base_api.h"
 #include "build/build_config.h"
 
 class FilePath;
 
 class BASE_API CommandLine {
  public:
 #if defined(OS_WIN)
   // The native command line string type.
   typedef std::wstring StringType;
 #elif defined(OS_POSIX)
   typedef std::string StringType;
 #endif
 
+  typedef StringType::value_type CharType;
   typedef std::vector<StringType> StringVector;
-  // The type of map for parsed-out switch key and values.
   typedef std::map<std::string, StringType> SwitchMap;
 
   // A constructor for CommandLines that only carry switches and arguments.
   enum NoProgram { NO_PROGRAM };
   explicit CommandLine(NoProgram no_program);
 
   // Construct a new command line with |program| as argv[0].
   explicit CommandLine(const FilePath& program);
 
-#if defined(OS_POSIX)
-  CommandLine(int argc, const char* const* argv);
+  // Construct a new command line from an argument list.
+  CommandLine(int argc, const CharType* const* argv);
   explicit CommandLine(const StringVector& argv);
-#endif
 
   ~CommandLine();
 
   // 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);
 
   // 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, as in main(), 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();
 
 #if defined(OS_WIN)
   static CommandLine FromString(const std::wstring& command_line);
 #endif
 
-#if defined(OS_POSIX)
   // Initialize from an argv vector.
-  void InitFromArgv(int argc, const char* const* argv);
+  void InitFromArgv(int argc, const CharType* const* argv);
   void InitFromArgv(const StringVector& argv);
-#endif
 
-  // Returns the represented command line string.
+  // Constructs and returns the represented command line string.
   // CAUTION! This should be avoided because quoting behavior is unclear.
+  // TODO(msw): Rename GetCommandLineString.
   StringType command_line_string() const;
 
-#if defined(OS_POSIX)
   // Returns the original command line string as a vector of strings.
   const StringVector& argv() const { return argv_; }
-#endif
 
-  // Returns the program part of the command line string (the first item).
+  // Get and Set the program part of the command line string (the first item).
   FilePath GetProgram() const;
+  void SetProgram(const FilePath& program);
 
   // 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.
   // TODO(msw): Remove unnecessary API.
   size_t GetSwitchCount() const;
 
   // Get a copy of all switches, along with their values.
   const SwitchMap& GetSwitches() const { return switches_; }
 
   // Append a switch [with optional value] to the command line.
-  // CAUTION! Appending a switch after the "--" switch terminator is futile!
+  // Note: Switches will precede arguments regardless of appending order.
   void AppendSwitch(const std::string& switch_string);
   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);
-  void AppendSwitches(const CommandLine& other);
 
   // Copy a set of switches (and any values) from another command line.
   // Commonly used when launching a subprocess.
-  void CopySwitchesFrom(const CommandLine& source, const char* const switches[],
+  void CopySwitchesFrom(const CommandLine& source,
+                        const char* const switches[],
                         size_t count);
 
   // Get the remaining arguments to the command.
-  const StringVector& args() const { return args_; }
+  // TODO(msw): Rename GetArgs.
+  StringVector args() const;
 
   // Append an argument to the command line. Note that the argument is quoted
   // properly such that it is interpreted as one argument to the target command.
   // AppendArg is primarily for ASCII; non-ASCII input is interpreted as UTF-8.
+  // Note: Switches will precede arguments regardless of appending order.
   void AppendArg(const std::string& value);
   void AppendArgPath(const FilePath& value);
   void AppendArgNative(const StringType& value);
-  void AppendArgs(const CommandLine& other);
 
-  // Append the arguments from another command line to this one.
+  // Append the switches and 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);
+  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);
 
 #if defined(OS_WIN)
   // 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);
 #endif
 
  private:
-  // Disallow public default construction; a program name must be specified.
+  // Disallow default constructor; a program name must be explicitly specified.
   CommandLine();
+  // Allow the copy constructor. A common pattern is to copy of the current
+  // process's command line and then add some flags to it. For example:
+  //   CommandLine cl(*CommandLine::ForCurrentProcess());
+  //   cl.AppendSwitch(...);
 
   // The singleton CommandLine 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.
-  StringType command_line_string_;
-  // The name of the program.
-  StringType program_;
-#elif defined(OS_POSIX)
-  // The argv array, with the program name in argv_[0].
+  // The argv array: { program, [(--|-|/)switch[=value]]*, [--], [argument]* }
   StringVector argv_;
-#endif
 
   // Parsed-out switch keys and values.
   SwitchMap switches_;
 
-  // Non-switch command line arguments.
-  StringVector args_;
-
-  // Allow the copy constructor. A common pattern is to copy the current
-  // process's command line and then add some flags to it. For example:
-  //   CommandLine cl(*CommandLine::ForCurrentProcess());
-  //   cl.AppendSwitch(...);
+  // The index after the program and switches, any arguments start here.
+  size_t begin_args_;
 };
 
 #endif  // BASE_COMMAND_LINE_H_