CommandLine API rework

base/command_line.h

Index: base/command_line.h
diff --git a/base/command_line.h b/base/command_line.h
index 56aa2fc8f5808f9f28d78bdbac5611bb373b4830..f1a2005c86afef9e01815dfdc2f0c420b464eb11 100644
--- a/base/command_line.h
+++ b/base/command_line.h
@@ -2,46 +2,60 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// This file contains a class that can be used to extract the salient
-// elements of a command line in a relatively lightweight manner.
+// 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 considered "loose parameters".  Switch names
-// are case-insensitive.  An argument of "--" will terminate switch parsing,
-// causing everything after to be considered as loose parameters.
+// switch prefix are considered "loose parameters".  Switch names are
+// case-insensitive.  An argument of "--" will terminate switch
+// parsing, causing everything after to be considered as loose
+// parameters.
+
+// 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_
 
+#include "build/build_config.h"
+
 #include <map>
 #include <string>
 #include <vector>
 
 #include "base/basictypes.h"
+#include "base/logging.h"
 #include "base/scoped_ptr.h"
 
 class CommandLine {
  public:
-  // Creates a parsed version of the command line used to launch
-  // the current process.
-  CommandLine();
-
 #if defined(OS_WIN)
   // Creates a parsed version of the given command-line string.
-  // The program name is assumed to be the first item in the string.  
-  CommandLine(const std::wstring& command_line);
+  // The program name is assumed to be the first item in the string.
+  void ParseFromString(const std::wstring& command_line);
 #elif defined(OS_POSIX)
+  // Initialize from an argv vector (or directly from main()'s argv).
   CommandLine(int argc, const char* const* argv);
-  CommandLine(const std::vector<std::string>& argv);
+  explicit CommandLine(const std::vector<std::string>& argv);
 #endif
 
-  ~CommandLine();
+  // Construct a new, empty command line.
+  // |program| is the name of the program to run (aka argv[0]).
+  // TODO(port): should be a FilePath.
+  explicit CommandLine(const std::wstring& 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);
 
-  // On non-Windows platforms, main() must call SetArgcArgv() before accessing
-  // any members of this class.
-  // On Windows, this call is a no-op (we instead parse GetCommandLineW()
-  // directly) because we don't trust the CRT's parsing of the command line.
-  static void SetArgcArgv(int argc, const char* const* argv);
+  // Get the singleton CommandLine representing the current process's
+  // command line.
+  static const CommandLine* ForCurrentProcess() {
+    DCHECK(current_process_commandline_);
+    return current_process_commandline_;
+  }
 
   // Returns true if this command line contains the given switch.
   // (Switch names are case-insensitive.)
@@ -52,40 +66,25 @@ class CommandLine {
   // the empty string.
   std::wstring GetSwitchValue(const std::wstring& switch_string) const;
 
-  // Returns the number of "loose values" found in the command line.
-  // Loose values are arguments that aren't switches.
-  // (The program name is also excluded from the set of loose values.)
-  size_t GetLooseValueCount() const;
-
-  typedef std::vector<std::wstring>::const_iterator LooseValueIterator;
-
-  // Returns a const_iterator to the list of loose values.
-  LooseValueIterator GetLooseValuesBegin() const;
-
-  // Returns the end const_iterator for the list of loose values.
-  LooseValueIterator GetLooseValuesEnd() const;
+  // Get the remaining arguments to the command.
+  // WARNING: this is incorrect on POSIX; we must do string conversions.
+  std::vector<std::wstring> GetLooseValues() const;
 
-  // Simply returns the original command line string.
-  std::wstring command_line_string() const;
-
-#if defined(OS_POSIX)
+#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;
+  const std::vector<std::string>& argv() const {
+    return argv_;
+  }
 #endif
 
   // Returns the program part of the command line string (the first item).
   std::wstring program() const;
 
-  // An array containing the prefixes that identify an argument as
-  // a switch.
-  static const wchar_t* const kSwitchPrefixes[];
-
-  // The string that's used to separate switches from their values.
-  static const wchar_t kSwitchValueSeparator[];
-
-  // Treat everything after this argument as loose parameters.
-  static const wchar_t kSwitchTerminator[];
-
   // Return a copy of the string prefixed with a switch prefix.
   // Used internally.
   static std::wstring PrefixedSwitchString(const std::wstring& switch_string);
@@ -98,27 +97,69 @@ class CommandLine {
 
   // Appends the given switch string (preceded by a space and a switch
   // prefix) to the given string.
-  static void AppendSwitch(std::wstring* command_line_string,
-                           const std::wstring& switch_string);
+  void AppendSwitch(const std::wstring& switch_string);
 
   // Appends the given switch string (preceded by a space and a switch
   // prefix) to the given string, with the given value attached.
-  static void AppendSwitchWithValue(std::wstring* command_line_string,
-                                    const std::wstring& switch_string,
-                                    const std::wstring& value_string);
+  void AppendSwitchWithValue(const std::wstring& switch_string,
+                             const std::wstring& value_string);
+
+  // Append a loose value to the command line.
+  void AppendLooseValue(const std::wstring& 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);
 
  private:
-  class Data;
+  CommandLine() {}
+
+  // 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_;
+
+  // The type of native command line arguments.
+  typedef std::wstring StringType;
+
+#elif defined(OS_POSIX)
+  // The argv array, with the program name in argv_[0].
+  std::vector<std::string> argv_;
+
+  // The type of native command line arguments.
+  typedef std::string StringType;
+
+  // Shared by the two POSIX constructor forms.  Initalize from argv_.
+  void InitFromArgv();
+#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.
+  std::map<std::string, StringType> switches_;
 
-  // True if we are responsible for deleting our |data_| pointer.  In some cases
-  // we cache the result of parsing the command line and |data_|'s lifetime is
-  // managed by someone else (e.g., the |Singleton| class).
-  bool we_own_data_;
+  // Non-switch command-line arguments.
+  std::vector<StringType> loose_values_;
 
-  // A pointer to the parsed version of the command line.
-  Data* data_;
-  
-  DISALLOW_EVIL_CONSTRUCTORS(CommandLine);
+  // 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_