Take a StringPiece when looking up CommandLine switches.

base/command_line.cc

Index: base/command_line.cc
diff --git a/base/command_line.cc b/base/command_line.cc
index 61ff5c10c3813e74ffdedece08cc0bf14638716a..586c189ba35fb31ec346a2b65e4dff6bad2287ae 100644
--- a/base/command_line.cc
+++ b/base/command_line.cc
@@ -93,18 +93,6 @@ void AppendSwitchesAndArguments(CommandLine* command_line,
   }
 }
 
-// Lowercase switches for backwards compatiblity *on Windows*.
-#if defined(OS_WIN)
-std::string LowerASCIIOnWindows(const std::string& string) {
-  return StringToLowerASCII(string);
-}
-#elif defined(OS_POSIX)
-const std::string& LowerASCIIOnWindows(const std::string& string) {
-  return string;
-}
-#endif
-
-
 #if defined(OS_WIN)
 // Quote a string as necessary for CommandLineToArgvW compatiblity *on Windows*.
 string16 QuoteForCommandLineToArgvW(const string16& arg,
@@ -155,6 +143,17 @@ string16 QuoteForCommandLineToArgvW(const string16& arg,
 }
 #endif
 
+// Reconstruct |switches_by_stringpiece| to be a mirror of |switches|.
+// |switches_by_stringpiece| only contains pointers to objects owned by
+// |switches|.
+void ResetStringPieces(

[brettw, 2015/04/24 19:50:49]

Why not make this a private member function? You call it with the same arguments
each time which are just class members.

[jackhou1, 2015/05/11 13:51:42]

Done.

+    const CommandLine::SwitchMap& switches,
+    CommandLine::StringPieceSwitchMap* switches_by_stringpiece) {
+  switches_by_stringpiece->clear();
+  for (auto it = switches.begin(); it != switches.end(); ++it)

[brettw, 2015/04/24 19:50:50]

auto -> const auto&
Always use const refs when applicable (see style guide).

[jackhou1, 2015/05/11 13:51:42]

Done.

+    (*switches_by_stringpiece)[it->first] = &(it->second);
+}
+
 }  // namespace
 
 CommandLine::CommandLine(NoProgram no_program)
@@ -180,6 +179,21 @@ CommandLine::CommandLine(const StringVector& argv)
   InitFromArgv(argv);
 }
 
+CommandLine::CommandLine(const CommandLine& other)
+    : argv_(other.argv_),
+      switches_(other.switches_),
+      begin_args_(other.begin_args_) {
+  ResetStringPieces(switches_, &switches_by_stringpiece_);
+}
+
+CommandLine& CommandLine::operator=(const CommandLine& other) {
+  argv_ = other.argv_;
+  switches_ = other.switches_;
+  begin_args_ = other.begin_args_;
+  ResetStringPieces(switches_, &switches_by_stringpiece_);
+  return *this;
+}
+
 CommandLine::~CommandLine() {
 }
 
@@ -249,6 +263,7 @@ void CommandLine::InitFromArgv(int argc,
 void CommandLine::InitFromArgv(const StringVector& argv) {
   argv_ = StringVector(1);
   switches_.clear();
+  switches_by_stringpiece_.clear();
   begin_args_ = 1;
   SetProgram(argv.empty() ? FilePath() : FilePath(argv[0]));
   AppendSwitchesAndArguments(this, argv);
@@ -262,17 +277,18 @@ void CommandLine::SetProgram(const FilePath& program) {
   TrimWhitespace(program.value(), TRIM_ALL, &argv_[0]);
 }
 
-bool CommandLine::HasSwitch(const std::string& switch_string) const {
-  DCHECK_EQ(StringToLowerASCII(switch_string), switch_string);
-  return switches_.find(switch_string) != switches_.end();
+bool CommandLine::HasSwitch(const base::StringPiece& switch_string) const {
+  DCHECK_EQ(StringToLowerASCII(switch_string.as_string()), switch_string);
+  return switches_by_stringpiece_.find(switch_string) !=
+         switches_by_stringpiece_.end();
 }
 
-bool CommandLine::HasSwitch(const char string_constant[]) const {
-  return HasSwitch(std::string(string_constant));
+bool CommandLine::HasSwitch(const char switch_constant[]) const {
+  return HasSwitch(base::StringPiece(switch_constant));
 }
 
 std::string CommandLine::GetSwitchValueASCII(
-    const std::string& switch_string) const {
+    const base::StringPiece& switch_string) const {
   StringType value = GetSwitchValueNative(switch_string);
   if (!IsStringASCII(value)) {
     DLOG(WARNING) << "Value of switch (" << switch_string << ") must be ASCII.";
@@ -286,15 +302,16 @@ std::string CommandLine::GetSwitchValueASCII(
 }
 
 FilePath CommandLine::GetSwitchValuePath(
-    const std::string& switch_string) const {
+    const base::StringPiece& switch_string) const {
   return FilePath(GetSwitchValueNative(switch_string));
 }
 
 CommandLine::StringType CommandLine::GetSwitchValueNative(
-    const std::string& switch_string) const {
-  SwitchMap::const_iterator result =
-    switches_.find(LowerASCIIOnWindows(switch_string));
-  return result == switches_.end() ? StringType() : result->second;
+    const base::StringPiece& switch_string) const {
+  DCHECK_EQ(StringToLowerASCII(switch_string.as_string()), switch_string);

[brettw, 2015/04/24 19:50:49]

Shouldn't this function require that the switches are lowercase just like the
HasSwitch ones? It seems like the whole API should be consistent.

[jackhou1, 2015/05/11 13:51:42]

It has the same DCHECK as HasSwitch. AppendSwitch* ensures incoming switches are
converted to lowercase.

+  auto result = switches_by_stringpiece_.find(switch_string);
+  return result == switches_by_stringpiece_.end() ? StringType()
+                                                  : *(result->second);
 }
 
 void CommandLine::AppendSwitch(const std::string& switch_string) {
@@ -308,14 +325,19 @@ void CommandLine::AppendSwitchPath(const std::string& switch_string,
 
 void CommandLine::AppendSwitchNative(const std::string& switch_string,
                                      const CommandLine::StringType& value) {
-  std::string switch_key(LowerASCIIOnWindows(switch_string));
 #if defined(OS_WIN)
+  const std::string switch_key = StringToLowerASCII(switch_string);

[brettw, 2015/04/24 19:50:50]

Ditto for lower-case.

[jackhou1, 2015/05/11 13:51:42]

With AppendSwitch* the string may have come from an external source like argv. I
think we should keep the behavior that CommandLine converts them to lowercase to
save callers from having to.

   StringType combined_switch_string(ASCIIToUTF16(switch_key));
 #elif defined(OS_POSIX)
-  StringType combined_switch_string(switch_string);
+  const std::string& switch_key = switch_string;
+  StringType combined_switch_string(switch_key);
 #endif
   size_t prefix_length = GetSwitchPrefixLength(combined_switch_string);
-  switches_[switch_key.substr(prefix_length)] = value;
+  auto insertion =
+      switches_.insert(make_pair(switch_key.substr(prefix_length), value));
+  if (!insertion.second)
+    insertion.first->second = value;
+  switches_by_stringpiece_[insertion.first->first] = &(insertion.first->second);
   // Preserve existing switch prefixes in |argv_|; only append one if necessary.
   if (prefix_length == 0)
     combined_switch_string = kSwitchPrefixes[0] + combined_switch_string;