micro optimize CommandLine.GetSwitchPrefixLength

base/command_line.cc

 // 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.
 
 #include "base/command_line.h"
 
 #include <algorithm>
 #include <ostream>
 
 #include "base/basictypes.h"
@@ skipping 19 matching lines @@
 #if defined(OS_WIN)
 const CommandLine::CharType* const kSwitchPrefixes[] = {L"--", L"-", L"/"};
 #elif defined(OS_POSIX)
 // Unixes don't use slash as a switch.
 const CommandLine::CharType* const kSwitchPrefixes[] = {"--", "-"};
 #endif
 
 size_t GetSwitchPrefixLength(const CommandLine::StringType& string) {
   for (size_t i = 0; i < arraysize(kSwitchPrefixes); ++i) {
     CommandLine::StringType prefix(kSwitchPrefixes[i]);
-    if (string.find(prefix) == 0)
+    if (string.compare(0, prefix.length(), prefix) == 0)
       return prefix.length();
   }
   return 0;
 }
 
 // Fills in |switch_string| and |switch_value| if |string| is a switch.
 // This will preserve the input switch prefix in the output |switch_string|.
 bool IsSwitch(const CommandLine::StringType& string,
               CommandLine::StringType* switch_string,
               CommandLine::StringType* switch_value) {
@@ skipping 342 matching lines @@
   int num_args = 0;
   wchar_t** args = NULL;
   args = ::CommandLineToArgvW(command_line_string.c_str(), &num_args);
 
   PLOG_IF(FATAL, !args) << "CommandLineToArgvW failed on command line: " <<
                            command_line;
   InitFromArgv(num_args, args);
   LocalFree(args);
 }
 #endif