tools/gn/functions.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 "tools/gn/functions.h"
   6
   7 #include <iostream>
   8
   9 #include "base/environment.h"
  10 #include "base/strings/string_util.h"
  11 #include "tools/gn/config.h"
  12 #include "tools/gn/config_values_generator.h"
  13 #include "tools/gn/err.h"
  14 #include "tools/gn/input_file.h"
  15 #include "tools/gn/parse_tree.h"
  16 #include "tools/gn/scheduler.h"
  17 #include "tools/gn/scope.h"
  18 #include "tools/gn/settings.h"
  19 #include "tools/gn/template.h"
  20 #include "tools/gn/token.h"
  21 #include "tools/gn/value.h"
  22
  23 bool EnsureNotProcessingImport(const ParseNode* node,
  24                                const Scope* scope,
  25                                Err* err) {
  26   if (scope->IsProcessingImport()) {
  27     *err = Err(node, "Not valid from an import.",
  28         "Imports are for defining defaults, variables, and rules. The\n"
  29         "appropriate place for this kind of thing is really in a normal\n"
  30         "BUILD file.");
  31     return false;
  32   }
  33   return true;
  34 }
  35
  36 bool EnsureNotProcessingBuildConfig(const ParseNode* node,
  37                                     const Scope* scope,
  38                                     Err* err) {
  39   if (scope->IsProcessingBuildConfig()) {
  40     *err = Err(node, "Not valid from the build config.",
  41         "You can't do this kind of thing from the build config script, "
  42         "silly!\nPut it in a regular BUILD file.");
  43     return false;
  44   }
  45   return true;
  46 }
  47
  48 bool FillTargetBlockScope(const Scope* scope,
  49                           const FunctionCallNode* function,
  50                           const std::string& target_type,
  51                           const BlockNode* block,
  52                           const std::vector<Value>& args,
  53                           Scope* block_scope,
  54                           Err* err) {
  55   if (!block) {
  56     FillNeedsBlockError(function, err);
  57     return false;
  58   }
  59
  60   // Copy the target defaults, if any, into the scope we're going to execute
  61   // the block in.
  62   const Scope* default_scope = scope->GetTargetDefaults(target_type);
  63   if (default_scope) {
  64     Scope::MergeOptions merge_options;
  65     merge_options.skip_private_vars = true;
  66     if (!default_scope->NonRecursiveMergeTo(block_scope, merge_options,
  67                                             function, "target defaults", err))
  68       return false;
  69   }
  70
  71   // The name is the single argument to the target function.
  72   if (!EnsureSingleStringArg(function, args, err))
  73     return false;
  74
  75   // Set the target name variable to the current target, and mark it used
  76   // because we don't want to issue an error if the script ignores it.
  77   const base::StringPiece target_name("target_name");
  78   block_scope->SetValue(target_name, Value(function, args[0].string_value()),
  79                         function);
  80   block_scope->MarkUsed(target_name);
  81   return true;
  82 }
  83
  84 void FillNeedsBlockError(const FunctionCallNode* function, Err* err) {
  85   *err = Err(function->function(), "This function call requires a block.",
  86       "The block's \"{\" must be on the same line as the function "
  87       "call's \")\".");
  88 }
  89
  90 bool EnsureSingleStringArg(const FunctionCallNode* function,
  91                            const std::vector<Value>& args,
  92                            Err* err) {
  93   if (args.size() != 1) {
  94     *err = Err(function->function(), "Incorrect arguments.",
  95                "This function requires a single string argument.");
  96     return false;
  97   }
  98   return args[0].VerifyTypeIs(Value::STRING, err);
  99 }
 100
 101 const Label& ToolchainLabelForScope(const Scope* scope) {
 102   return scope->settings()->toolchain_label();
 103 }
 104
 105 Label MakeLabelForScope(const Scope* scope,
 106                         const FunctionCallNode* function,
 107                         const std::string& name) {
 108   const Label& toolchain_label = ToolchainLabelForScope(scope);
 109   return Label(scope->GetSourceDir(), name, toolchain_label.dir(),
 110                toolchain_label.name());
 111 }
 112
 113 namespace functions {
 114
 115 // assert ----------------------------------------------------------------------
 116
 117 const char kAssert[] = "assert";
 118 const char kAssert_HelpShort[] =
 119     "assert: Assert an expression is true at generation time.";
 120 const char kAssert_Help[] =
 121     "assert: Assert an expression is true at generation time.\n"
 122     "\n"
 123     "  assert(<condition> [, <error string>])\n"
 124     "\n"
 125     "  If the condition is false, the build will fail with an error. If the\n"
 126     "  optional second argument is provided, that string will be printed\n"
 127     "  with the error message.\n"
 128     "\n"
 129     "Examples:\n"
 130     "  assert(is_win)\n"
 131     "  assert(defined(sources), \"Sources must be defined\")\n";
 132
 133 Value RunAssert(Scope* scope,
 134                 const FunctionCallNode* function,
 135                 const std::vector<Value>& args,
 136                 Err* err) {
 137   if (args.size() != 1 && args.size() != 2) {
 138     *err = Err(function->function(), "Wrong number of arguments.",
 139                "assert() takes one or two argument, "
 140                "were you expecting somethig else?");
 141   } else if (args[0].type() != Value::BOOLEAN) {
 142     *err = Err(function->function(), "Assertion value not a bool.");
 143   } else if (!args[0].boolean_value()) {
 144     if (args.size() == 2) {
 145       // Optional string message.
 146       if (args[1].type() != Value::STRING) {
 147         *err = Err(function->function(), "Assertion failed.",
 148             "<<<ERROR MESSAGE IS NOT A STRING>>>");
 149       } else {
 150         *err = Err(function->function(), "Assertion failed.",
 151             args[1].string_value());
 152       }
 153     } else {
 154       *err = Err(function->function(), "Assertion failed.");
 155     }
 156
 157     if (args[0].origin()) {
 158       // If you do "assert(foo)" we'd ideally like to show you where foo was
 159       // set, and in this case the origin of the args will tell us that.
 160       // However, if you do "assert(foo && bar)" the source of the value will
 161       // be the assert like, which isn't so helpful.
 162       //
 163       // So we try to see if the args are from the same line or not. This will
 164       // break if you do "assert(\nfoo && bar)" and we may show the second line
 165       // as the source, oh well. The way around this is to check to see if the
 166       // origin node is inside our function call block.
 167       Location origin_location = args[0].origin()->GetRange().begin();
 168       if (origin_location.file() != function->function().location().file() ||
 169           origin_location.line_number() !=
 170               function->function().location().line_number()) {
 171         err->AppendSubErr(Err(args[0].origin()->GetRange(), "",
 172                               "This is where it was set."));
 173       }
 174     }
 175   }
 176   return Value();
 177 }
 178
 179 // config ----------------------------------------------------------------------
 180
 181 const char kConfig[] = "config";
 182 const char kConfig_HelpShort[] =
 183     "config: Defines a configuration object.";
 184 const char kConfig_Help[] =
 185     "config: Defines a configuration object.\n"
 186     "\n"
 187     "  Configuration objects can be applied to targets and specify sets of\n"
 188     "  compiler flags, includes, defines, etc. They provide a way to\n"
 189     "  conveniently group sets of this configuration information.\n"
 190     "\n"
 191     "  A config is referenced by its label just like a target.\n"
 192     "\n"
 193     "  The values in a config are additive only. If you want to remove a flag\n"
 194     "  you need to remove the corresponding config that sets it. The final\n"
 195     "  set of flags, defines, etc. for a target is generated in this order:\n"
 196     "\n"
 197     "   1. The values specified directly on the target (rather than using a\n"
 198     "      config.\n"
 199     "   2. The configs specified in the target's \"configs\" list, in order.\n"
 200     "   3. Public_configs from a breadth-first traversal of the dependency\n"
 201     "      tree in the order that the targets appear in \"deps\".\n"
 202     "   4. All dependent configs from a breadth-first traversal of the\n"
 203     "      dependency tree in the order that the targets appear in \"deps\".\n"
 204     "\n"
 205     "Variables valid in a config definition:\n"
 206     CONFIG_VALUES_VARS_HELP
 207     "\n"
 208     "Variables on a target used to apply configs:\n"
 209     "  all_dependent_configs, configs, public_configs,\n"
 210     "  forward_dependent_configs_from\n"
 211     "\n"
 212     "Example:\n"
 213     "  config(\"myconfig\") {\n"
 214     "    includes = [ \"include/common\" ]\n"
 215     "    defines = [ \"ENABLE_DOOM_MELON\" ]\n"
 216     "  }\n"
 217     "\n"
 218     "  executable(\"mything\") {\n"
 219     "    configs = [ \":myconfig\" ]\n"
 220     "  }\n";
 221
 222 Value RunConfig(const FunctionCallNode* function,
 223                 const std::vector<Value>& args,
 224                 Scope* scope,
 225                 Err* err) {
 226   if (!EnsureSingleStringArg(function, args, err) ||
 227       !EnsureNotProcessingImport(function, scope, err))
 228     return Value();
 229
 230   Label label(MakeLabelForScope(scope, function, args[0].string_value()));
 231
 232   if (g_scheduler->verbose_logging())
 233     g_scheduler->Log("Defining config", label.GetUserVisibleName(true));
 234
 235   // Create the new config.
 236   scoped_ptr<Config> config(new Config(scope->settings(), label));
 237   config->set_defined_from(function);
 238   if (!Visibility::FillItemVisibility(config.get(), scope, err))
 239     return Value();
 240
 241   // Fill it.
 242   const SourceDir& input_dir = scope->GetSourceDir();
 243   ConfigValuesGenerator gen(&config->config_values(), scope, input_dir, err);
 244   gen.Run();
 245   if (err->has_error())
 246     return Value();
 247
 248   // Save the generated item.
 249   Scope::ItemVector* collector = scope->GetItemCollector();
 250   if (!collector) {
 251     *err = Err(function, "Can't define a config in this context.");
 252     return Value();
 253   }
 254   collector->push_back(config.release());
 255
 256   return Value();
 257 }
 258
 259 // declare_args ----------------------------------------------------------------
 260
 261 const char kDeclareArgs[] = "declare_args";
 262 const char kDeclareArgs_HelpShort[] =
 263     "declare_args: Declare build arguments.";
 264 const char kDeclareArgs_Help[] =
 265     "declare_args: Declare build arguments.\n"
 266     "\n"
 267     "  Introduces the given arguments into the current scope. If they are\n"
 268     "  not specified on the command line or in a toolchain's arguments,\n"
 269     "  the default values given in the declare_args block will be used.\n"
 270     "  However, these defaults will not override command-line values.\n"
 271     "\n"
 272     "  See also \"gn help buildargs\" for an overview.\n"
 273     "\n"
 274     "Example:\n"
 275     "  declare_args() {\n"
 276     "    enable_teleporter = true\n"
 277     "    enable_doom_melon = false\n"
 278     "  }\n"
 279     "\n"
 280     "  If you want to override the (default disabled) Doom Melon:\n"
 281     "    gn --args=\"enable_doom_melon=true enable_teleporter=false\"\n"
 282     "  This also sets the teleporter, but it's already defaulted to on so\n"
 283     "  it will have no effect.\n";
 284
 285 Value RunDeclareArgs(Scope* scope,
 286                      const FunctionCallNode* function,
 287                      const std::vector<Value>& args,
 288                      BlockNode* block,
 289                      Err* err) {
 290   Scope block_scope(scope);
 291   block->ExecuteBlockInScope(&block_scope, err);
 292   if (err->has_error())
 293     return Value();
 294
 295   // Pass the values from our scope into the Args object for adding to the
 296   // scope with the proper values (taking into account the defaults given in
 297   // the block_scope, and arguments passed into the build).
 298   Scope::KeyValueMap values;
 299   block_scope.GetCurrentScopeValues(&values);
 300   scope->settings()->build_settings()->build_args().DeclareArgs(
 301       values, scope, err);
 302   return Value();
 303 }
 304
 305 // defined ---------------------------------------------------------------------
 306
 307 const char kDefined[] = "defined";
 308 const char kDefined_HelpShort[] =
 309     "defined: Returns whether an identifier is defined.";
 310 const char kDefined_Help[] =
 311     "defined: Returns whether an identifier is defined.\n"
 312     "\n"
 313     "  Returns true if the given argument is defined. This is most useful in\n"
 314     "  templates to assert that the caller set things up properly.\n"
 315     "\n"
 316     "  You can pass an identifier:\n"
 317     "    defined(foo)\n"
 318     "  which will return true or false depending on whether foo is defined in\n"
 319     "  the current scope.\n"
 320     "\n"
 321     "  You can also check a named scope:\n"
 322     "    defined(foo.bar)\n"
 323     "  which returns true if both foo is defined and bar is defined on the\n"
 324     "  named scope foo. It will throw an error if foo is defined but is not\n"
 325     "  a scope.\n"
 326     "\n"
 327     "Example:\n"
 328     "\n"
 329     "  template(\"mytemplate\") {\n"
 330     "    # To help users call this template properly...\n"
 331     "    assert(defined(invoker.sources), \"Sources must be defined\")\n"
 332     "\n"
 333     "    # If we want to accept an optional \"values\" argument, we don't\n"
 334     "    # want to dereference something that may not be defined.\n"
 335     "    if (defined(invoker.values)) {\n"
 336     "      values = invoker.values\n"
 337     "    } else {\n"
 338     "      values = \"some default value\"\n"
 339     "    }\n"
 340     "  }\n";
 341
 342 Value RunDefined(Scope* scope,
 343                  const FunctionCallNode* function,
 344                  const ListNode* args_list,
 345                  Err* err) {
 346   const std::vector<const ParseNode*>& args_vector = args_list->contents();
 347   if (args_vector.size() != 1) {
 348     *err = Err(function, "Wrong number of arguments to defined().",
 349                "Expecting exactly one.");
 350     return Value();
 351   }
 352
 353   const IdentifierNode* identifier = args_vector[0]->AsIdentifier();
 354   if (identifier) {
 355     // Passed an identifier "defined(foo)".
 356     if (scope->GetValue(identifier->value().value()))
 357       return Value(function, true);
 358     return Value(function, false);
 359   }
 360
 361   const AccessorNode* accessor = args_vector[0]->AsAccessor();
 362   if (accessor) {
 363     // Passed an accessor "defined(foo.bar)".
 364     if (accessor->member()) {
 365       // The base of the accessor must be a scope if it's defined.
 366       const Value* base = scope->GetValue(accessor->base().value());
 367       if (!base)
 368         return Value(function, false);
 369       if (!base->VerifyTypeIs(Value::SCOPE, err))
 370         return Value();
 371
 372       // Check the member inside the scope to see if its defined.
 373       if (base->scope_value()->GetValue(accessor->member()->value().value()))
 374         return Value(function, true);
 375       return Value(function, false);
 376     }
 377   }
 378
 379   // Argument is invalid.
 380   *err = Err(function, "Bad thing passed to defined().",
 381       "It should be of the form defined(foo) or defined(foo.bar).");
 382   return Value();
 383 }
 384
 385 // getenv ----------------------------------------------------------------------
 386
 387 const char kGetEnv[] = "getenv";
 388 const char kGetEnv_HelpShort[] =
 389     "getenv: Get an environment variable.";
 390 const char kGetEnv_Help[] =
 391     "getenv: Get an environment variable.\n"
 392     "\n"
 393     "  value = getenv(env_var_name)\n"
 394     "\n"
 395     "  Returns the value of the given enironment variable. If the value is\n"
 396     "  not found, it will try to look up the variable with the \"opposite\"\n"
 397     "  case (based on the case of the first letter of the variable), but\n"
 398     "  is otherwise case-sensitive.\n"
 399     "\n"
 400     "  If the environment variable is not found, the empty string will be\n"
 401     "  returned. Note: it might be nice to extend this if we had the concept\n"
 402     "  of \"none\" in the language to indicate lookup failure.\n"
 403     "\n"
 404     "Example:\n"
 405     "\n"
 406     "  home_dir = getenv(\"HOME\")\n";
 407
 408 Value RunGetEnv(Scope* scope,
 409                 const FunctionCallNode* function,
 410                 const std::vector<Value>& args,
 411                 Err* err) {
 412   if (!EnsureSingleStringArg(function, args, err))
 413     return Value();
 414
 415   scoped_ptr<base::Environment> env(base::Environment::Create());
 416
 417   std::string result;
 418   if (!env->GetVar(args[0].string_value().c_str(), &result))
 419     return Value(function, "");  // Not found, return empty string.
 420   return Value(function, result);
 421 }
 422
 423 // import ----------------------------------------------------------------------
 424
 425 const char kImport[] = "import";
 426 const char kImport_HelpShort[] =
 427     "import: Import a file into the current scope.";
 428 const char kImport_Help[] =
 429     "import: Import a file into the current scope.\n"
 430     "\n"
 431     "  The import command loads the rules and variables resulting from\n"
 432     "  executing the given file into the current scope.\n"
 433     "\n"
 434     "  By convention, imported files are named with a .gni extension.\n"
 435     "\n"
 436     "  An import is different than a C++ \"include\". The imported file is\n"
 437     "  executed in a standalone environment from the caller of the import\n"
 438     "  command. The results of this execution are cached for other files that\n"
 439     "  import the same .gni file.\n"
 440     "\n"
 441     "  Note that you can not import a BUILD.gn file that's otherwise used\n"
 442     "  in the build. Files must either be imported or implicitly loaded as\n"
 443     "  a result of deps rules, but not both.\n"
 444     "\n"
 445     "  The imported file's scope will be merged with the scope at the point\n"
 446     "  import was called. If there is a conflict (both the current scope and\n"
 447     "  the imported file define some variable or rule with the same name but\n"
 448     "  different value), a runtime error will be thrown. Therefore, it's good\n"
 449     "  practice to minimize the stuff that an imported file defines.\n"
 450     "\n"
 451     "  Variables and templates beginning with an underscore '_' are\n"
 452     "  considered private and will not be imported. Imported files can use\n"
 453     "  such variables for internal computation without affecting other files.\n"
 454     "\n"
 455     "Examples:\n"
 456     "\n"
 457     "  import(\"//build/rules/idl_compilation_rule.gni\")\n"
 458     "\n"
 459     "  # Looks in the current directory.\n"
 460     "  import(\"my_vars.gni\")\n";
 461
 462 Value RunImport(Scope* scope,
 463                 const FunctionCallNode* function,
 464                 const std::vector<Value>& args,
 465                 Err* err) {
 466   if (!EnsureSingleStringArg(function, args, err))
 467     return Value();
 468
 469   const SourceDir& input_dir = scope->GetSourceDir();
 470   SourceFile import_file =
 471       input_dir.ResolveRelativeFile(args[0].string_value(),
 472           scope->settings()->build_settings()->root_path_utf8());
 473   scope->settings()->import_manager().DoImport(import_file, function,
 474                                                scope, err);
 475   return Value();
 476 }
 477
 478 // set_sources_assignment_filter -----------------------------------------------
 479
 480 const char kSetSourcesAssignmentFilter[] = "set_sources_assignment_filter";
 481 const char kSetSourcesAssignmentFilter_HelpShort[] =
 482     "set_sources_assignment_filter: Set a pattern to filter source files.";
 483 const char kSetSourcesAssignmentFilter_Help[] =
 484     "set_sources_assignment_filter: Set a pattern to filter source files.\n"
 485     "\n"
 486     "  The sources assignment filter is a list of patterns that remove files\n"
 487     "  from the list implicitly whenever the \"sources\" variable is\n"
 488     "  assigned to. This is intended to be used to globally filter out files\n"
 489     "  with platform-specific naming schemes when they don't apply, for\n"
 490     "  example, you may want to filter out all \"*_win.cc\" files on non-\n"
 491     "  Windows platforms.\n"
 492     "\n"
 493     "  Typically this will be called once in the master build config script\n"
 494     "  to set up the filter for the current platform. Subsequent calls will\n"
 495     "  overwrite the previous values.\n"
 496     "\n"
 497     "  If you want to bypass the filter and add a file even if it might\n"
 498     "  be filtered out, call set_sources_assignment_filter([]) to clear the\n"
 499     "  list of filters. This will apply until the current scope exits\n"
 500     "\n"
 501     "How to use patterns\n"
 502     "\n"
 503     "  File patterns are VERY limited regular expressions. They must match\n"
 504     "  the entire input string to be counted as a match. In regular\n"
 505     "  expression parlance, there is an implicit \"^...$\" surrounding your\n"
 506     "  input. If you want to match a substring, you need to use wildcards at\n"
 507     "  the beginning and end.\n"
 508     "\n"
 509     "  There are only two special tokens understood by the pattern matcher.\n"
 510     "  Everything else is a literal.\n"
 511     "\n"
 512     "   * Matches zero or more of any character. It does not depend on the\n"
 513     "     preceding character (in regular expression parlance it is\n"
 514     "     equivalent to \".*\").\n"
 515     "\n"
 516     "  \\b Matches a path boundary. This will match the beginning or end of\n"
 517     "     a string, or a slash.\n"
 518     "\n"
 519     "Pattern examples\n"
 520     "\n"
 521     "  \"*asdf*\"\n"
 522     "      Matches a string containing \"asdf\" anywhere.\n"
 523     "\n"
 524     "  \"asdf\"\n"
 525     "      Matches only the exact string \"asdf\".\n"
 526     "\n"
 527     "  \"*.cc\"\n"
 528     "      Matches strings ending in the literal \".cc\".\n"
 529     "\n"
 530     "  \"\\bwin/*\"\n"
 531     "      Matches \"win/foo\" and \"foo/win/bar.cc\" but not \"iwin/foo\".\n"
 532     "\n"
 533     "Sources assignment example\n"
 534     "\n"
 535     "  # Filter out all _win files.\n"
 536     "  set_sources_assignment_filter([ \"*_win.cc\", \"*_win.h\" ])\n"
 537     "  sources = [ \"a.cc\", \"b_win.cc\" ]\n"
 538     "  print(sources)\n"
 539     "  # Will print [ \"a.cc\" ]. b_win one was filtered out.\n";
 540
 541 Value RunSetSourcesAssignmentFilter(Scope* scope,
 542                                     const FunctionCallNode* function,
 543                                     const std::vector<Value>& args,
 544                                     Err* err) {
 545   if (args.size() != 1) {
 546     *err = Err(function, "set_sources_assignment_filter takes one argument.");
 547   } else {
 548     scoped_ptr<PatternList> f(new PatternList);
 549     f->SetFromValue(args[0], err);
 550     if (!err->has_error())
 551       scope->set_sources_assignment_filter(f.Pass());
 552   }
 553   return Value();
 554 }
 555
 556 // print -----------------------------------------------------------------------
 557
 558 const char kPrint[] = "print";
 559 const char kPrint_HelpShort[] =
 560     "print: Prints to the console.";
 561 const char kPrint_Help[] =
 562     "print: Prints to the console.\n"
 563     "\n"
 564     "  Prints all arguments to the console separated by spaces. A newline is\n"
 565     "  automatically appended to the end.\n"
 566     "\n"
 567     "  This function is intended for debugging. Note that build files are run\n"
 568     "  in parallel so you may get interleaved prints. A buildfile may also\n"
 569     "  be executed more than once in parallel in the context of different\n"
 570     "  toolchains so the prints from one file may be duplicated or\n"
 571     "  interleaved with itself.\n"
 572     "\n"
 573     "Examples:\n"
 574     "  print(\"Hello world\")\n"
 575     "\n"
 576     "  print(sources, deps)\n";
 577
 578 Value RunPrint(Scope* scope,
 579                const FunctionCallNode* function,
 580                const std::vector<Value>& args,
 581                Err* err) {
 582   std::string output;
 583   for (size_t i = 0; i < args.size(); i++) {
 584     if (i != 0)
 585       output.push_back(' ');
 586     output.append(args[i].ToString(false));
 587   }
 588   output.push_back('\n');
 589
 590   const BuildSettings::PrintCallback& cb =
 591       scope->settings()->build_settings()->print_callback();
 592   if (cb.is_null())
 593     printf("%s", output.c_str());
 594   else
 595     cb.Run(output);
 596
 597   return Value();
 598 }
 599
 600 // -----------------------------------------------------------------------------
 601
 602 FunctionInfo::FunctionInfo()
 603     : self_evaluating_args_runner(nullptr),
 604       generic_block_runner(nullptr),
 605       executed_block_runner(nullptr),
 606       no_block_runner(nullptr),
 607       help_short(nullptr),
 608       help(nullptr),
 609       is_target(false) {
 610 }
 611
 612 FunctionInfo::FunctionInfo(SelfEvaluatingArgsFunction seaf,
 613                            const char* in_help_short,
 614                            const char* in_help,
 615                            bool in_is_target)
 616     : self_evaluating_args_runner(seaf),
 617       generic_block_runner(nullptr),
 618       executed_block_runner(nullptr),
 619       no_block_runner(nullptr),
 620       help_short(in_help_short),
 621       help(in_help),
 622       is_target(in_is_target) {
 623 }
 624
 625 FunctionInfo::FunctionInfo(GenericBlockFunction gbf,
 626                            const char* in_help_short,
 627                            const char* in_help,
 628                            bool in_is_target)
 629     : self_evaluating_args_runner(nullptr),
 630       generic_block_runner(gbf),
 631       executed_block_runner(nullptr),
 632       no_block_runner(nullptr),
 633       help_short(in_help_short),
 634       help(in_help),
 635       is_target(in_is_target) {
 636 }
 637
 638 FunctionInfo::FunctionInfo(ExecutedBlockFunction ebf,
 639                            const char* in_help_short,
 640                            const char* in_help,
 641                            bool in_is_target)
 642     : self_evaluating_args_runner(nullptr),
 643       generic_block_runner(nullptr),
 644       executed_block_runner(ebf),
 645       no_block_runner(nullptr),
 646       help_short(in_help_short),
 647       help(in_help),
 648       is_target(in_is_target) {
 649 }
 650
 651 FunctionInfo::FunctionInfo(NoBlockFunction nbf,
 652                            const char* in_help_short,
 653                            const char* in_help,
 654                            bool in_is_target)
 655     : self_evaluating_args_runner(nullptr),
 656       generic_block_runner(nullptr),
 657       executed_block_runner(nullptr),
 658       no_block_runner(nbf),
 659       help_short(in_help_short),
 660       help(in_help),
 661       is_target(in_is_target) {
 662 }
 663
 664 // Setup the function map via a static initializer. We use this because it
 665 // avoids race conditions without having to do some global setup function or
 666 // locking-heavy singleton checks at runtime. In practice, we always need this
 667 // before we can do anything interesting, so it's OK to wait for the
 668 // initializer.
 669 struct FunctionInfoInitializer {
 670   FunctionInfoMap map;
 671
 672   FunctionInfoInitializer() {
 673     #define INSERT_FUNCTION(command, is_target) \
 674         map[k##command] = FunctionInfo(&Run##command, \
 675                                        k##command##_HelpShort, \
 676                                        k##command##_Help, \
 677                                        is_target);
 678
 679     INSERT_FUNCTION(Action, true)
 680     INSERT_FUNCTION(ActionForEach, true)
 681     INSERT_FUNCTION(Copy, true)
 682     INSERT_FUNCTION(Executable, true)
 683     INSERT_FUNCTION(Group, true)
 684     INSERT_FUNCTION(SharedLibrary, true)
 685     INSERT_FUNCTION(SourceSet, true)
 686     INSERT_FUNCTION(StaticLibrary, true)
 687
 688     INSERT_FUNCTION(Assert, false)
 689     INSERT_FUNCTION(Config, false)
 690     INSERT_FUNCTION(DeclareArgs, false)
 691     INSERT_FUNCTION(Defined, false)
 692     INSERT_FUNCTION(ExecScript, false)
 693     INSERT_FUNCTION(ForEach, false)
 694     INSERT_FUNCTION(GetEnv, false)
 695     INSERT_FUNCTION(GetLabelInfo, false)
 696     INSERT_FUNCTION(GetPathInfo, false)
 697     INSERT_FUNCTION(GetTargetOutputs, false)
 698     INSERT_FUNCTION(Import, false)
 699     INSERT_FUNCTION(Print, false)
 700     INSERT_FUNCTION(ProcessFileTemplate, false)
 701     INSERT_FUNCTION(ReadFile, false)
 702     INSERT_FUNCTION(RebasePath, false)
 703     INSERT_FUNCTION(SetDefaults, false)
 704     INSERT_FUNCTION(SetDefaultToolchain, false)
 705     INSERT_FUNCTION(SetSourcesAssignmentFilter, false)
 706     INSERT_FUNCTION(Template, false)
 707     INSERT_FUNCTION(Tool, false)
 708     INSERT_FUNCTION(Toolchain, false)
 709     INSERT_FUNCTION(ToolchainArgs, false)
 710     INSERT_FUNCTION(WriteFile, false)
 711
 712     #undef INSERT_FUNCTION
 713   }
 714 };
 715 const FunctionInfoInitializer function_info;
 716
 717 const FunctionInfoMap& GetFunctions() {
 718   return function_info.map;
 719 }
 720
 721 Value RunFunction(Scope* scope,
 722                   const FunctionCallNode* function,
 723                   const ListNode* args_list,
 724                   BlockNode* block,
 725                   Err* err) {
 726   const Token& name = function->function();
 727
 728   const FunctionInfoMap& function_map = GetFunctions();
 729   FunctionInfoMap::const_iterator found_function =
 730       function_map.find(name.value());
 731   if (found_function == function_map.end()) {
 732     // No built-in function matching this, check for a template.
 733     const Template* templ =
 734         scope->GetTemplate(function->function().value().as_string());
 735     if (templ) {
 736       Value args = args_list->Execute(scope, err);
 737       if (err->has_error())
 738         return Value();
 739       return templ->Invoke(scope, function, args.list_value(), block, err);
 740     }
 741
 742     *err = Err(name, "Unknown function.");
 743     return Value();
 744   }
 745
 746   if (found_function->second.self_evaluating_args_runner) {
 747     return found_function->second.self_evaluating_args_runner(
 748         scope, function, args_list, err);
 749   }
 750
 751   // All other function types take a pre-executed set of args.
 752   Value args = args_list->Execute(scope, err);
 753   if (err->has_error())
 754     return Value();
 755
 756   if (found_function->second.generic_block_runner) {
 757     if (!block) {
 758       FillNeedsBlockError(function, err);
 759       return Value();
 760     }
 761     return found_function->second.generic_block_runner(
 762         scope, function, args.list_value(), block, err);
 763   }
 764
 765   if (found_function->second.executed_block_runner) {
 766     if (!block) {
 767       FillNeedsBlockError(function, err);
 768       return Value();
 769     }
 770
 771     Scope block_scope(scope);
 772     block->ExecuteBlockInScope(&block_scope, err);
 773     if (err->has_error())
 774       return Value();
 775
 776     Value result = found_function->second.executed_block_runner(
 777         function, args.list_value(), &block_scope, err);
 778     if (err->has_error())
 779       return Value();
 780
 781     if (!block_scope.CheckForUnusedVars(err))
 782       return Value();
 783     return result;
 784   }
 785
 786   // Otherwise it's a no-block function.
 787   return found_function->second.no_block_runner(scope, function,
 788                                                 args.list_value(), err);
 789 }
 790
 791 }  // namespace functions