Replace more for loops in GN

tools/gn/command_help.cc

 // Copyright (c) 2013 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 <algorithm>
 #include <iostream>
 
 #include "tools/gn/args.h"
 #include "tools/gn/commands.h"
 #include "tools/gn/err.h"
 #include "tools/gn/functions.h"
 #include "tools/gn/input_conversion.h"
 #include "tools/gn/label_pattern.h"
 #include "tools/gn/setup.h"
 #include "tools/gn/standard_out.h"
 #include "tools/gn/substitution_writer.h"
 #include "tools/gn/variables.h"
 
 namespace commands {
 
 namespace {
 
 void PrintToplevelHelp() {
   OutputString("Commands (type \"gn help <command>\" for more details):\n");
-
-  const commands::CommandInfoMap& command_map = commands::GetCommands();
-  for (commands::CommandInfoMap::const_iterator i = command_map.begin();
-       i != command_map.end(); ++i)
-    PrintShortHelp(i->second.help_short);
+  for (const auto& cmd : commands::GetCommands())
+    PrintShortHelp(cmd.second.help_short);
 
   OutputString(
       "\n"
       "Common switches:\n");
   PrintShortHelp(
       "--args: Specifies build arguments overrides. "
       "See \"gn help buildargs\".");
   PrintShortHelp(
       "--[no]color: Forces colored output on or off (rather than autodetect).");
   PrintShortHelp(
       "--dotfile: Specifies an alternate .gn file. See \"gn help dotfile\".");
   PrintShortHelp(
       "--no-exec: Skips exec_script calls (for performance testing).");
   PrintShortHelp(
       "-q: Quiet mode, don't print anything on success.");
   PrintShortHelp(
       "--root: Specifies source root (overrides .gn file).");
   PrintShortHelp(
       "--time: Outputs a summary of how long everything took.");
   PrintShortHelp(
       "--tracelog: Writes a Chrome-compatible trace log to the given file.");
   PrintShortHelp(
       "-v: Verbose mode, print lots of logging.");
   PrintShortHelp(
       "--version: Print the GN binary's version and exit.");
 
   // Target declarations.
   OutputString("\nTarget declarations (type \"gn help <function>\" for more "
                "details):\n");
-  const functions::FunctionInfoMap& function_map = functions::GetFunctions();
-  for (functions::FunctionInfoMap::const_iterator i = function_map.begin();
-       i != function_map.end(); ++i) {
-    if (i->second.is_target)
-      PrintShortHelp(i->second.help_short);
+  for (const auto& func : functions::GetFunctions()) {
+    if (func.second.is_target)
+      PrintShortHelp(func.second.help_short);
   }
 
   // Functions.
   OutputString("\nBuildfile functions (type \"gn help <function>\" for more "
                "details):\n");
-  for (functions::FunctionInfoMap::const_iterator i = function_map.begin();
-       i != function_map.end(); ++i) {
-    if (!i->second.is_target)
-      PrintShortHelp(i->second.help_short);
+  for (const auto& func : functions::GetFunctions()) {
+    if (!func.second.is_target)
+      PrintShortHelp(func.second.help_short);
   }
 
   // Built-in variables.
   OutputString("\nBuilt-in predefined variables (type \"gn help <variable>\" "
                "for more details):\n");
-  const variables::VariableInfoMap& builtin_vars =
-      variables::GetBuiltinVariables();
-  for (variables::VariableInfoMap::const_iterator i = builtin_vars.begin();
-       i != builtin_vars.end(); ++i)
-    PrintShortHelp(i->second.help_short);
+  for (const auto& builtin : variables::GetBuiltinVariables())
+    PrintShortHelp(builtin.second.help_short);
 
   // Target variables.
   OutputString("\nVariables you set in targets (type \"gn help <variable>\" "
                "for more details):\n");
-  const variables::VariableInfoMap& target_vars =
-      variables::GetTargetVariables();
-  for (variables::VariableInfoMap::const_iterator i = target_vars.begin();
-       i != target_vars.end(); ++i)
-    PrintShortHelp(i->second.help_short);
+  for (const auto& target : variables::GetTargetVariables())
+    PrintShortHelp(target.second.help_short);
 
   OutputString("\nOther help topics:\n");
   PrintShortHelp("buildargs: How build arguments work.");
   PrintShortHelp("dotfile: Info about the toplevel .gn file.");
   PrintShortHelp("label_pattern: Matching more than one label.");
   PrintShortHelp(
       "input_conversion: Processing input from exec_script and read_file.");
   PrintShortHelp("source_expansion: Map sources to outputs for scripts.");
 }
 
@@ skipping 73 matching lines @@
     return 0;
   }
 
   // No help on this.
   Err(Location(), "No help on \"" + args[0] + "\".").PrintToStdout();
   RunHelp(std::vector<std::string>());
   return 1;
 }
 
 }  // namespace commands