tools/gn/command_help.cc

   1 // Copyright (c) 2013 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include <algorithm>
   6 #include <iostream>
   7
   8 #include "base/command_line.h"
   9 #include "tools/gn/args.h"
  10 #include "tools/gn/commands.h"
  11 #include "tools/gn/err.h"
  12 #include "tools/gn/functions.h"
  13 #include "tools/gn/input_conversion.h"
  14 #include "tools/gn/label_pattern.h"
  15 #include "tools/gn/setup.h"
  16 #include "tools/gn/standard_out.h"
  17 #include "tools/gn/substitution_writer.h"
  18 #include "tools/gn/switches.h"
  19 #include "tools/gn/variables.h"
  20
  21 namespace commands {
  22
  23 namespace {
  24
  25 void PrintToplevelHelp() {
  26   OutputString("Commands (type \"gn help <command>\" for more details):\n");
  27   for (const auto& cmd : commands::GetCommands())
  28     PrintShortHelp(cmd.second.help_short);
  29
  30   // Target declarations.
  31   OutputString("\nTarget declarations (type \"gn help <function>\" for more "
  32                "details):\n");
  33   for (const auto& func : functions::GetFunctions()) {
  34     if (func.second.is_target)
  35       PrintShortHelp(func.second.help_short);
  36   }
  37
  38   // Functions.
  39   OutputString("\nBuildfile functions (type \"gn help <function>\" for more "
  40                "details):\n");
  41   for (const auto& func : functions::GetFunctions()) {
  42     if (!func.second.is_target)
  43       PrintShortHelp(func.second.help_short);
  44   }
  45
  46   // Built-in variables.
  47   OutputString("\nBuilt-in predefined variables (type \"gn help <variable>\" "
  48                "for more details):\n");
  49   for (const auto& builtin : variables::GetBuiltinVariables())
  50     PrintShortHelp(builtin.second.help_short);
  51
  52   // Target variables.
  53   OutputString("\nVariables you set in targets (type \"gn help <variable>\" "
  54                "for more details):\n");
  55   for (const auto& target : variables::GetTargetVariables())
  56     PrintShortHelp(target.second.help_short);
  57
  58   OutputString("\nOther help topics:\n");
  59   PrintShortHelp("buildargs: How build arguments work.");
  60   PrintShortHelp("dotfile: Info about the toplevel .gn file.");
  61   PrintShortHelp("label_pattern: Matching more than one label.");
  62   PrintShortHelp(
  63       "input_conversion: Processing input from exec_script and read_file.");
  64   PrintShortHelp("source_expansion: Map sources to outputs for scripts.");
  65   PrintShortHelp("switches: Show available command-line switches.");
  66 }
  67
  68 void PrintSwitchHelp() {
  69   OutputString("Available global switches\n", DECORATION_YELLOW);
  70   OutputString(
  71       "  Do \"gn help --the_switch_you_want_help_on\" for more. Individual\n"
  72       "  commands may take command-specific switches not listed here. See the\n"
  73       "  help on your specific command for more.\n\n");
  74
  75   for (const auto& s : switches::GetSwitches())
  76     PrintShortHelp(s.second.short_help);
  77 }
  78
  79 // Prints help on the given switch. There should be no leading hyphens. Returns
  80 // true if the switch was found and help was printed. False means the switch is
  81 // unknown.
  82 bool PrintHelpOnSwitch(const std::string& what) {
  83   const switches::SwitchInfoMap& all = switches::GetSwitches();
  84   switches::SwitchInfoMap::const_iterator found =
  85       all.find(base::StringPiece(what));
  86   if (found == all.end())
  87     return false;
  88   PrintLongHelp(found->second.long_help);
  89   return true;
  90 }
  91
  92 }  // namespace
  93
  94 const char kHelp[] = "help";
  95 const char kHelp_HelpShort[] =
  96     "help: Does what you think.";
  97 const char kHelp_Help[] =
  98     "gn help <anything>\n"
  99     "  Yo dawg, I heard you like help on your help so I put help on the help\n"
 100     "  in the help.\n";
 101
 102 int RunHelp(const std::vector<std::string>& args) {
 103   std::string what;
 104   if (args.size() == 0) {
 105     // If no argument is specified, check for switches to allow things like
 106     // "gn help --args" for help on the args switch.
 107     const base::CommandLine::SwitchMap& switches =
 108         CommandLine::ForCurrentProcess()->GetSwitches();
 109     if (switches.empty()) {
 110       // Still nothing, show help overview.
 111       PrintToplevelHelp();
 112       return 0;
 113     }
 114
 115     // Switch help needs to be done separately. The CommandLine will strip the
 116     // switch separators so --args will come out as "args" which is then
 117     // ambiguous with the variable named "args".
 118     if (!PrintHelpOnSwitch(switches.begin()->first))
 119       PrintToplevelHelp();
 120     return 0;
 121   } else {
 122     what = args[0];
 123   }
 124
 125   // Check commands.
 126   const commands::CommandInfoMap& command_map = commands::GetCommands();
 127   commands::CommandInfoMap::const_iterator found_command =
 128       command_map.find(what);
 129   if (found_command != command_map.end()) {
 130     PrintLongHelp(found_command->second.help);
 131     return 0;
 132   }
 133
 134   // Check functions.
 135   const functions::FunctionInfoMap& function_map = functions::GetFunctions();
 136   functions::FunctionInfoMap::const_iterator found_function =
 137       function_map.find(what);
 138   if (found_function != function_map.end()) {
 139     PrintLongHelp(found_function->second.help);
 140     return 0;
 141   }
 142
 143   // Builtin variables.
 144   const variables::VariableInfoMap& builtin_vars =
 145       variables::GetBuiltinVariables();
 146   variables::VariableInfoMap::const_iterator found_builtin_var =
 147       builtin_vars.find(what);
 148   if (found_builtin_var != builtin_vars.end()) {
 149     PrintLongHelp(found_builtin_var->second.help);
 150     return 0;
 151   }
 152
 153   // Target variables.
 154   const variables::VariableInfoMap& target_vars =
 155       variables::GetTargetVariables();
 156   variables::VariableInfoMap::const_iterator found_target_var =
 157       target_vars.find(what);
 158   if (found_target_var != target_vars.end()) {
 159     PrintLongHelp(found_target_var->second.help);
 160     return 0;
 161   }
 162
 163   // Random other topics.
 164   if (what == "buildargs") {
 165     PrintLongHelp(kBuildArgs_Help);
 166     return 0;
 167   }
 168   if (what == "dotfile") {
 169     PrintLongHelp(kDotfile_Help);
 170     return 0;
 171   }
 172   if (what == "input_conversion") {
 173     PrintLongHelp(kInputConversion_Help);
 174     return 0;
 175   }
 176   if (what == "label_pattern") {
 177     PrintLongHelp(kLabelPattern_Help);
 178     return 0;
 179   }
 180   if (what == "source_expansion") {
 181     PrintLongHelp(kSourceExpansion_Help);
 182     return 0;
 183   }
 184   if (what == "switches") {
 185     PrintSwitchHelp();
 186     return 0;
 187   }
 188
 189   // No help on this.
 190   Err(Location(), "No help on \"" + what + "\".").PrintToStdout();
 191   RunHelp(std::vector<std::string>());
 192   return 1;
 193 }
 194
 195 }  // namespace commands