Remove a number of unnecessary copies made while parsing the command …

…line PiperOrigin-RevId: 240222700
bazelbuild · Mar 25, 2019 · 9cda2ec · 9cda2ec
1 parent 70e3c33
commit 9cda2ec
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Showing 2 changed files with 29 additions and 25 deletions.
diff --git a/src/main/cpp/option_processor.cc b/src/main/cpp/option_processor.cc
@@ -20,6 +20,7 @@
 #include <string.h>
 #include <algorithm>
 #include <cassert>
+#include <iterator>
 #include <set>
 #include <sstream>
 #include <utility>
@@ -65,7 +66,7 @@ OptionProcessor::OptionProcessor(
       system_bazelrc_path_(system_bazelrc_path) {}
 
 std::unique_ptr<CommandLine> OptionProcessor::SplitCommandLine(
-    const vector<string>& args, string* error) const {
+    vector<string> args, string* error) const {
   const string lowercase_product_name =
       parsed_startup_options_->GetLowercaseProductName();
 
@@ -75,13 +76,13 @@ std::unique_ptr<CommandLine> OptionProcessor::SplitCommandLine(
     return nullptr;
   }
 
-  const string path_to_binary(args[0]);
+  string& path_to_binary = args[0];
 
   // Process the startup options.
   vector<string> startup_args;
   vector<string>::size_type i = 1;
   while (i < args.size() && IsArg(args[i])) {
-    const string current_arg(args[i]);
+    string& current_arg = args[i];
     // If the current argument is a valid nullary startup option such as
     // --master_bazelrc or --nomaster_bazelrc proceed to examine the next
     // argument.
@@ -95,7 +96,7 @@ std::unique_ptr<CommandLine> OptionProcessor::SplitCommandLine(
       // The option is of the form '--bazelrc=value', hence proceed to
       // examine the next argument.
       if (current_arg.find("=") != string::npos) {
-        startup_args.push_back(current_arg);
+        startup_args.push_back(std::move(current_arg));
         i++;
       } else {
         // Otherwise, the option is of the form '--bazelrc value', hence
@@ -112,7 +113,8 @@ std::unique_ptr<CommandLine> OptionProcessor::SplitCommandLine(
           return nullptr;
         }
         // In this case we transform it to the form '--bazelrc=value'.
-        startup_args.push_back(current_arg + string("=") + args[i + 1]);
+        startup_args.push_back(std::move(current_arg) + "=" +
+                               std::move(args[i + 1]));
         i += 2;
       }
     } else {
@@ -129,16 +131,18 @@ std::unique_ptr<CommandLine> OptionProcessor::SplitCommandLine(
 
   // The command is the arg right after the startup options.
   if (i == args.size()) {
-    return std::unique_ptr<CommandLine>(
-        new CommandLine(path_to_binary, startup_args, "", {}));
+    return std::unique_ptr<CommandLine>(new CommandLine(
+        std::move(path_to_binary), std::move(startup_args), "", {}));
   }
-  const string command(args[i]);
+  string& command = args[i];
 
   // The rest are the command arguments.
-  const vector<string> command_args(args.begin() + i + 1, args.end());
+  vector<string> command_args(std::make_move_iterator(args.begin() + i + 1),
+                              std::make_move_iterator(args.end()));
 
   return std::unique_ptr<CommandLine>(
-      new CommandLine(path_to_binary, startup_args, command, command_args));
+      new CommandLine(std::move(path_to_binary), std::move(startup_args),
+                      std::move(command), std::move(command_args)));
 }
 
 namespace internal {

diff --git a/src/main/cpp/option_processor.h b/src/main/cpp/option_processor.h
@@ -18,6 +18,7 @@
 #include <list>
 #include <memory>
 #include <string>
+#include <utility>
 #include <vector>
 
 #include "src/main/cpp/rc_file.h"
@@ -33,19 +34,19 @@ class WorkspaceLayout;
 // breakdown should suffice to access the parts of the command line that the
 // client cares about, notably the binary and startup startup options.
 struct CommandLine {
-  const std::string path_to_binary;
-  const std::vector<std::string> startup_args;
-  const std::string command;
-  const std::vector<std::string> command_args;
-
-  CommandLine(const std::string& path_to_binary_arg,
-              const std::vector<std::string>& startup_args_arg,
-              const std::string& command_arg,
-              const std::vector<std::string>& command_args_arg)
-      : path_to_binary(path_to_binary_arg),
-        startup_args(startup_args_arg),
-        command(command_arg),
-        command_args(command_args_arg) {}
+  std::string path_to_binary;
+  std::vector<std::string> startup_args;
+  std::string command;
+  std::vector<std::string> command_args;
+
+  CommandLine(std::string path_to_binary_arg,
+              std::vector<std::string> startup_args_arg,
+              std::string command_arg,
+              std::vector<std::string> command_args_arg)
+      : path_to_binary(std::move(path_to_binary_arg)),
+        startup_args(std::move(startup_args_arg)),
+        command(std::move(command_arg)),
+        command_args(std::move(command_args_arg)) {}
 };
 
 // This class is responsible for parsing the command line of the Blaze binary,
@@ -82,8 +83,7 @@ class OptionProcessor {
   // If the method fails then error will contain the cause, otherwise error
   // remains untouched.
   virtual std::unique_ptr<CommandLine> SplitCommandLine(
-      const std::vector<std::string>& args,
-      std::string* error) const;
+      std::vector<std::string> args, std::string* error) const;
 
   // Parse a command line and the appropriate blazerc files and stores the
   // results. This should be invoked only once per OptionProcessor object.