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 namespace {
  24
  25 // Some functions take a {} following them, and some don't. For the ones that
  26 // don't, this is used to verify that the given block node is null and will
  27 // set the error accordingly if it's not. Returns true if the block is null.
  28 bool VerifyNoBlockForFunctionCall(const FunctionCallNode* function,
  29                                   const BlockNode* block,
  30                                   Err* err) {
  31   if (!block)
  32     return true;
  33
  34   *err = Err(block, "Unexpected '{'.",
  35       "This function call doesn't take a {} block following it, and you\n"
  36       "can't have a {} block that's not connected to something like an if\n"
  37       "statement or a target declaration.");
  38   err->AppendRange(function->function().range());
  39   return false;
  40 }
  41
  42 }  // namespace
  43
  44 bool EnsureNotProcessingImport(const ParseNode* node,
  45                                const Scope* scope,
  46                                Err* err) {
  47   if (scope->IsProcessingImport()) {
  48     *err = Err(node, "Not valid from an import.",
  49         "Imports are for defining defaults, variables, and rules. The\n"
  50         "appropriate place for this kind of thing is really in a normal\n"
  51         "BUILD file.");
  52     return false;
  53   }
  54   return true;
  55 }
  56
  57 bool EnsureNotProcessingBuildConfig(const ParseNode* node,
  58                                     const Scope* scope,
  59                                     Err* err) {
  60   if (scope->IsProcessingBuildConfig()) {
  61     *err = Err(node, "Not valid from the build config.",
  62         "You can't do this kind of thing from the build config script, "
  63         "silly!\nPut it in a regular BUILD file.");
  64     return false;
  65   }
  66   return true;
  67 }
  68
  69 bool FillTargetBlockScope(const Scope* scope,
  70                           const FunctionCallNode* function,
  71                           const std::string& target_type,
  72                           const BlockNode* block,
  73                           const std::vector<Value>& args,
  74                           Scope* block_scope,
  75                           Err* err) {
  76   if (!block) {
  77     FillNeedsBlockError(function, err);
  78     return false;
  79   }
  80
  81   // Copy the target defaults, if any, into the scope we're going to execute
  82   // the block in.
  83   const Scope* default_scope = scope->GetTargetDefaults(target_type);
  84   if (default_scope) {
  85     Scope::MergeOptions merge_options;
  86     merge_options.skip_private_vars = true;
  87     if (!default_scope->NonRecursiveMergeTo(block_scope, merge_options,
  88                                             function, "target defaults", err))
  89       return false;
  90   }
  91
  92   // The name is the single argument to the target function.
  93   if (!EnsureSingleStringArg(function, args, err))
  94     return false;
  95
  96   // Set the target name variable to the current target, and mark it used
  97   // because we don't want to issue an error if the script ignores it.
  98   const base::StringPiece target_name("target_name");
  99   block_scope->SetValue(target_name, Value(function, args[0].string_value()),
 100                         function);
 101   block_scope->MarkUsed(target_name);
 102   return true;
 103 }
 104
 105 void FillNeedsBlockError(const FunctionCallNode* function, Err* err) {
 106   *err = Err(function->function(), "This function call requires a block.",
 107       "The block's \"{\" must be on the same line as the function "
 108       "call's \")\".");
 109 }
 110
 111 bool EnsureSingleStringArg(const FunctionCallNode* function,
 112                            const std::vector<Value>& args,
 113                            Err* err) {
 114   if (args.size() != 1) {
 115     *err = Err(function->function(), "Incorrect arguments.",
 116                "This function requires a single string argument.");
 117     return false;
 118   }
 119   return args[0].VerifyTypeIs(Value::STRING, err);
 120 }
 121
 122 const Label& ToolchainLabelForScope(const Scope* scope) {
 123   return scope->settings()->toolchain_label();
 124 }
 125
 126 Label MakeLabelForScope(const Scope* scope,
 127                         const FunctionCallNode* function,
 128                         const std::string& name) {
 129   const Label& toolchain_label = ToolchainLabelForScope(scope);
 130   return Label(scope->GetSourceDir(), name, toolchain_label.dir(),
 131                toolchain_label.name());
 132 }
 133
 134 namespace functions {
 135
 136 // assert ----------------------------------------------------------------------
 137
 138 const char kAssert[] = "assert";
 139 const char kAssert_HelpShort[] =
 140     "assert: Assert an expression is true at generation time.";
 141 const char kAssert_Help[] =
 142     "assert: Assert an expression is true at generation time.\n"
 143     "\n"
 144     "  assert(<condition> [, <error string>])\n"
 145     "\n"
 146     "  If the condition is false, the build will fail with an error. If the\n"
 147     "  optional second argument is provided, that string will be printed\n"
 148     "  with the error message.\n"
 149     "\n"
 150     "Examples:\n"
 151     "  assert(is_win)\n"
 152     "  assert(defined(sources), \"Sources must be defined\")\n";
 153
 154 Value RunAssert(Scope* scope,
 155                 const FunctionCallNode* function,
 156                 const std::vector<Value>& args,
 157                 Err* err) {
 158   if (args.size() != 1 && args.size() != 2) {
 159     *err = Err(function->function(), "Wrong number of arguments.",
 160                "assert() takes one or two argument, "
 161                "were you expecting somethig else?");
 162   } else if (args[0].type() != Value::BOOLEAN) {
 163     *err = Err(function->function(), "Assertion value not a bool.");
 164   } else if (!args[0].boolean_value()) {
 165     if (args.size() == 2) {
 166       // Optional string message.
 167       if (args[1].type() != Value::STRING) {
 168         *err = Err(function->function(), "Assertion failed.",
 169             "<<<ERROR MESSAGE IS NOT A STRING>>>");
 170       } else {
 171         *err = Err(function->function(), "Assertion failed.",
 172             args[1].string_value());
 173       }
 174     } else {
 175       *err = Err(function->function(), "Assertion failed.");
 176     }
 177
 178     if (args[0].origin()) {
 179       // If you do "assert(foo)" we'd ideally like to show you where foo was
 180       // set, and in this case the origin of the args will tell us that.
 181       // However, if you do "assert(foo && bar)" the source of the value will
 182       // be the assert like, which isn't so helpful.
 183       //
 184       // So we try to see if the args are from the same line or not. This will
 185       // break if you do "assert(\nfoo && bar)" and we may show the second line
 186       // as the source, oh well. The way around this is to check to see if the
 187       // origin node is inside our function call block.
 188       Location origin_location = args[0].origin()->GetRange().begin();
 189       if (origin_location.file() != function->function().location().file() ||
 190           origin_location.line_number() !=
 191               function->function().location().line_number()) {
 192         err->AppendSubErr(Err(args[0].origin()->GetRange(), "",
 193                               "This is where it was set."));
 194       }
 195     }
 196   }
 197   return Value();
 198 }
 199
 200 // config ----------------------------------------------------------------------
 201
 202 const char kConfig[] = "config";
 203 const char kConfig_HelpShort[] =
 204     "config: Defines a configuration object.";
 205 const char kConfig_Help[] =
 206     "config: Defines a configuration object.\n"
 207     "\n"
 208     "  Configuration objects can be applied to targets and specify sets of\n"
 209     "  compiler flags, includes, defines, etc. They provide a way to\n"
 210     "  conveniently group sets of this configuration information.\n"
 211     "\n"
 212     "  A config is referenced by its label just like a target.\n"
 213     "\n"
 214     "  The values in a config are additive only. If you want to remove a flag\n"
 215     "  you need to remove the corresponding config that sets it. The final\n"
 216     "  set of flags, defines, etc. for a target is generated in this order:\n"
 217     "\n"
 218     "   1. The values specified directly on the target (rather than using a\n"
 219     "      config.\n"
 220     "   2. The configs specified in the target's \"configs\" list, in order.\n"
 221     "   3. Public_configs from a breadth-first traversal of the dependency\n"
 222     "      tree in the order that the targets appear in \"deps\".\n"
 223     "   4. All dependent configs from a breadth-first traversal of the\n"
 224     "      dependency tree in the order that the targets appear in \"deps\".\n"
 225     "\n"
 226     "Variables valid in a config definition:\n"
 227     CONFIG_VALUES_VARS_HELP
 228     "\n"
 229     "Variables on a target used to apply configs:\n"
 230     "  all_dependent_configs, configs, public_configs,\n"
 231     "  forward_dependent_configs_from\n"
 232     "\n"
 233     "Example:\n"
 234     "  config(\"myconfig\") {\n"
 235     "    includes = [ \"include/common\" ]\n"
 236     "    defines = [ \"ENABLE_DOOM_MELON\" ]\n"
 237     "  }\n"
 238     "\n"
 239     "  executable(\"mything\") {\n"
 240     "    configs = [ \":myconfig\" ]\n"
 241     "  }\n";
 242
 243 Value RunConfig(const FunctionCallNode* function,
 244                 const std::vector<Value>& args,
 245                 Scope* scope,
 246                 Err* err) {
 247   if (!EnsureSingleStringArg(function, args, err) ||
 248       !EnsureNotProcessingImport(function, scope, err))
 249     return Value();
 250
 251   Label label(MakeLabelForScope(scope, function, args[0].string_value()));
 252
 253   if (g_scheduler->verbose_logging())
 254     g_scheduler->Log("Defining config", label.GetUserVisibleName(true));
 255
 256   // Create the new config.
 257   scoped_ptr<Config> config(new Config(scope->settings(), label));
 258   config->set_defined_from(function);
 259   if (!Visibility::FillItemVisibility(config.get(), scope, err))
 260     return Value();
 261
 262   // Fill it.
 263   const SourceDir& input_dir = scope->GetSourceDir();
 264   ConfigValuesGenerator gen(&config->config_values(), scope, input_dir, err);
 265   gen.Run();
 266   if (err->has_error())
 267     return Value();
 268
 269   // Save the generated item.
 270   Scope::ItemVector* collector = scope->GetItemCollector();
 271   if (!collector) {
 272     *err = Err(function, "Can't define a config in this context.");
 273     return Value();
 274   }
 275   collector->push_back(config.release());
 276
 277   return Value();
 278 }
 279
 280 // declare_args ----------------------------------------------------------------
 281
 282 const char kDeclareArgs[] = "declare_args";
 283 const char kDeclareArgs_HelpShort[] =
 284     "declare_args: Declare build arguments.";
 285 const char kDeclareArgs_Help[] =
 286     "declare_args: Declare build arguments.\n"
 287     "\n"
 288     "  Introduces the given arguments into the current scope. If they are\n"
 289     "  not specified on the command line or in a toolchain's arguments,\n"
 290     "  the default values given in the declare_args block will be used.\n"
 291     "  However, these defaults will not override command-line values.\n"
 292     "\n"
 293     "  See also \"gn help buildargs\" for an overview.\n"
 294     "\n"
 295     "Example:\n"
 296     "  declare_args() {\n"
 297     "    enable_teleporter = true\n"
 298     "    enable_doom_melon = false\n"
 299     "  }\n"
 300     "\n"
 301     "  If you want to override the (default disabled) Doom Melon:\n"
 302     "    gn --args=\"enable_doom_melon=true enable_teleporter=false\"\n"
 303     "  This also sets the teleporter, but it's already defaulted to on so\n"
 304     "  it will have no effect.\n";
 305
 306 Value RunDeclareArgs(Scope* scope,
 307                      const FunctionCallNode* function,
 308                      const std::vector<Value>& args,
 309                      BlockNode* block,
 310                      Err* err) {
 311   Scope block_scope(scope);
 312   block->Execute(&block_scope, err);
 313   if (err->has_error())
 314     return Value();
 315
 316   // Pass the values from our scope into the Args object for adding to the
 317   // scope with the proper values (taking into account the defaults given in
 318   // the block_scope, and arguments passed into the build).
 319   Scope::KeyValueMap values;
 320   block_scope.GetCurrentScopeValues(&values);
 321   scope->settings()->build_settings()->build_args().DeclareArgs(
 322       values, scope, err);
 323   return Value();
 324 }
 325
 326 // defined ---------------------------------------------------------------------
 327
 328 const char kDefined[] = "defined";
 329 const char kDefined_HelpShort[] =
 330     "defined: Returns whether an identifier is defined.";
 331 const char kDefined_Help[] =
 332     "defined: Returns whether an identifier is defined.\n"
 333     "\n"
 334     "  Returns true if the given argument is defined. This is most useful in\n"
 335     "  templates to assert that the caller set things up properly.\n"
 336     "\n"
 337     "  You can pass an identifier:\n"
 338     "    defined(foo)\n"
 339     "  which will return true or false depending on whether foo is defined in\n"
 340     "  the current scope.\n"
 341     "\n"
 342     "  You can also check a named scope:\n"
 343     "    defined(foo.bar)\n"
 344     "  which will return true or false depending on whether bar is defined in\n"
 345     "  the named scope foo. It will throw an error if foo is not defined or\n"
 346     "  is not a scope.\n"
 347     "\n"
 348     "Example:\n"
 349     "\n"
 350     "  template(\"mytemplate\") {\n"
 351     "    # To help users call this template properly...\n"
 352     "    assert(defined(invoker.sources), \"Sources must be defined\")\n"
 353     "\n"
 354     "    # If we want to accept an optional \"values\" argument, we don't\n"
 355     "    # want to dereference something that may not be defined.\n"
 356     "    if (defined(invoker.values)) {\n"
 357     "      values = invoker.values\n"
 358     "    } else {\n"
 359     "      values = \"some default value\"\n"
 360     "    }\n"
 361     "  }\n";
 362
 363 Value RunDefined(Scope* scope,
 364                  const FunctionCallNode* function,
 365                  const ListNode* args_list,
 366                  Err* err) {
 367   const std::vector<const ParseNode*>& args_vector = args_list->contents();
 368   if (args_vector.size() != 1) {
 369     *err = Err(function, "Wrong number of arguments to defined().",
 370                "Expecting exactly one.");
 371     return Value();
 372   }
 373
 374   const IdentifierNode* identifier = args_vector[0]->AsIdentifier();
 375   if (identifier) {
 376     // Passed an identifier "defined(foo)".
 377     if (scope->GetValue(identifier->value().value()))
 378       return Value(function, true);
 379     return Value(function, false);
 380   }
 381
 382   const AccessorNode* accessor = args_vector[0]->AsAccessor();
 383   if (accessor) {
 384     // Passed an accessor "defined(foo.bar)".
 385     if (accessor->member()) {
 386       // The base of the accessor must be a scope if it's defined.
 387       const Value* base = scope->GetValue(accessor->base().value());
 388       if (!base) {
 389         *err = Err(accessor, "Undefined identifier");
 390         return Value();
 391       }
 392       if (!base->VerifyTypeIs(Value::SCOPE, err))
 393         return Value();
 394
 395       // Check the member inside the scope to see if its defined.
 396       if (base->scope_value()->GetValue(accessor->member()->value().value()))
 397         return Value(function, true);
 398       return Value(function, false);
 399     }
 400   }
 401
 402   // Argument is invalid.
 403   *err = Err(function, "Bad thing passed to defined().",
 404       "It should be of the form defined(foo) or defined(foo.bar).");
 405   return Value();
 406 }
 407
 408 // getenv ----------------------------------------------------------------------
 409
 410 const char kGetEnv[] = "getenv";
 411 const char kGetEnv_HelpShort[] =
 412     "getenv: Get an environment variable.";
 413 const char kGetEnv_Help[] =
 414     "getenv: Get an environment variable.\n"
 415     "\n"
 416     "  value = getenv(env_var_name)\n"
 417     "\n"
 418     "  Returns the value of the given enironment variable. If the value is\n"
 419     "  not found, it will try to look up the variable with the \"opposite\"\n"
 420     "  case (based on the case of the first letter of the variable), but\n"
 421     "  is otherwise case-sensitive.\n"
 422     "\n"
 423     "  If the environment variable is not found, the empty string will be\n"
 424     "  returned. Note: it might be nice to extend this if we had the concept\n"
 425     "  of \"none\" in the language to indicate lookup failure.\n"
 426     "\n"
 427     "Example:\n"
 428     "\n"
 429     "  home_dir = getenv(\"HOME\")\n";
 430
 431 Value RunGetEnv(Scope* scope,
 432                 const FunctionCallNode* function,
 433                 const std::vector<Value>& args,
 434                 Err* err) {
 435   if (!EnsureSingleStringArg(function, args, err))
 436     return Value();
 437
 438   scoped_ptr<base::Environment> env(base::Environment::Create());
 439
 440   std::string result;
 441   if (!env->GetVar(args[0].string_value().c_str(), &result))
 442     return Value(function, "");  // Not found, return empty string.
 443   return Value(function, result);
 444 }
 445
 446 // import ----------------------------------------------------------------------
 447
 448 const char kImport[] = "import";
 449 const char kImport_HelpShort[] =
 450     "import: Import a file into the current scope.";
 451 const char kImport_Help[] =
 452     "import: Import a file into the current scope.\n"
 453     "\n"
 454     "  The import command loads the rules and variables resulting from\n"
 455     "  executing the given file into the current scope.\n"
 456     "\n"
 457     "  By convention, imported files are named with a .gni extension.\n"
 458     "\n"
 459     "  An import is different than a C++ \"include\". The imported file is\n"
 460     "  executed in a standalone environment from the caller of the import\n"
 461     "  command. The results of this execution are cached for other files that\n"
 462     "  import the same .gni file.\n"
 463     "\n"
 464     "  Note that you can not import a BUILD.gn file that's otherwise used\n"
 465     "  in the build. Files must either be imported or implicitly loaded as\n"
 466     "  a result of deps rules, but not both.\n"
 467     "\n"
 468     "  The imported file's scope will be merged with the scope at the point\n"
 469     "  import was called. If there is a conflict (both the current scope and\n"
 470     "  the imported file define some variable or rule with the same name but\n"
 471     "  different value), a runtime error will be thrown. Therefore, it's good\n"
 472     "  practice to minimize the stuff that an imported file defines.\n"
 473     "\n"
 474     "  Variables and templates beginning with an underscore '_' are\n"
 475     "  considered private and will not be imported. Imported files can use\n"
 476     "  such variables for internal computation without affecting other files.\n"
 477     "\n"
 478     "Examples:\n"
 479     "\n"
 480     "  import(\"//build/rules/idl_compilation_rule.gni\")\n"
 481     "\n"
 482     "  # Looks in the current directory.\n"
 483     "  import(\"my_vars.gni\")\n";
 484
 485 Value RunImport(Scope* scope,
 486                 const FunctionCallNode* function,
 487                 const std::vector<Value>& args,
 488                 Err* err) {
 489   if (!EnsureSingleStringArg(function, args, err))
 490     return Value();
 491
 492   const SourceDir& input_dir = scope->GetSourceDir();
 493   SourceFile import_file =
 494       input_dir.ResolveRelativeFile(args[0].string_value(),
 495           scope->settings()->build_settings()->root_path_utf8());
 496   scope->settings()->import_manager().DoImport(import_file, function,
 497                                                scope, err);
 498   return Value();
 499 }
 500
 501 // set_sources_assignment_filter -----------------------------------------------
 502
 503 const char kSetSourcesAssignmentFilter[] = "set_sources_assignment_filter";
 504 const char kSetSourcesAssignmentFilter_HelpShort[] =
 505     "set_sources_assignment_filter: Set a pattern to filter source files.";
 506 const char kSetSourcesAssignmentFilter_Help[] =
 507     "set_sources_assignment_filter: Set a pattern to filter source files.\n"
 508     "\n"
 509     "  The sources assignment filter is a list of patterns that remove files\n"
 510     "  from the list implicitly whenever the \"sources\" variable is\n"
 511     "  assigned to. This is intended to be used to globally filter out files\n"
 512     "  with platform-specific naming schemes when they don't apply, for\n"
 513     "  example, you may want to filter out all \"*_win.cc\" files on non-\n"
 514     "  Windows platforms.\n"
 515     "\n"
 516     "  Typically this will be called once in the master build config script\n"
 517     "  to set up the filter for the current platform. Subsequent calls will\n"
 518     "  overwrite the previous values.\n"
 519     "\n"
 520     "  If you want to bypass the filter and add a file even if it might\n"
 521     "  be filtered out, call set_sources_assignment_filter([]) to clear the\n"
 522     "  list of filters. This will apply until the current scope exits\n"
 523     "\n"
 524     "How to use patterns\n"
 525     "\n"
 526     "  File patterns are VERY limited regular expressions. They must match\n"
 527     "  the entire input string to be counted as a match. In regular\n"
 528     "  expression parlance, there is an implicit \"^...$\" surrounding your\n"
 529     "  input. If you want to match a substring, you need to use wildcards at\n"
 530     "  the beginning and end.\n"
 531     "\n"
 532     "  There are only two special tokens understood by the pattern matcher.\n"
 533     "  Everything else is a literal.\n"
 534     "\n"
 535     "   * Matches zero or more of any character. It does not depend on the\n"
 536     "     preceding character (in regular expression parlance it is\n"
 537     "     equivalent to \".*\").\n"
 538     "\n"
 539     "  \\b Matches a path boundary. This will match the beginning or end of\n"
 540     "     a string, or a slash.\n"
 541     "\n"
 542     "Pattern examples\n"
 543     "\n"
 544     "  \"*asdf*\"\n"
 545     "      Matches a string containing \"asdf\" anywhere.\n"
 546     "\n"
 547     "  \"asdf\"\n"
 548     "      Matches only the exact string \"asdf\".\n"
 549     "\n"
 550     "  \"*.cc\"\n"
 551     "      Matches strings ending in the literal \".cc\".\n"
 552     "\n"
 553     "  \"\\bwin/*\"\n"
 554     "      Matches \"win/foo\" and \"foo/win/bar.cc\" but not \"iwin/foo\".\n"
 555     "\n"
 556     "Sources assignment example\n"
 557     "\n"
 558     "  # Filter out all _win files.\n"
 559     "  set_sources_assignment_filter([ \"*_win.cc\", \"*_win.h\" ])\n"
 560     "  sources = [ \"a.cc\", \"b_win.cc\" ]\n"
 561     "  print(sources)\n"
 562     "  # Will print [ \"a.cc\" ]. b_win one was filtered out.\n";
 563
 564 Value RunSetSourcesAssignmentFilter(Scope* scope,
 565                                     const FunctionCallNode* function,
 566                                     const std::vector<Value>& args,
 567                                     Err* err) {
 568   if (args.size() != 1) {
 569     *err = Err(function, "set_sources_assignment_filter takes one argument.");
 570   } else {
 571     scoped_ptr<PatternList> f(new PatternList);
 572     f->SetFromValue(args[0], err);
 573     if (!err->has_error())
 574       scope->set_sources_assignment_filter(f.Pass());
 575   }
 576   return Value();
 577 }
 578
 579 // print -----------------------------------------------------------------------
 580
 581 const char kPrint[] = "print";
 582 const char kPrint_HelpShort[] =
 583     "print: Prints to the console.";
 584 const char kPrint_Help[] =
 585     "print: Prints to the console.\n"
 586     "\n"
 587     "  Prints all arguments to the console separated by spaces. A newline is\n"
 588     "  automatically appended to the end.\n"
 589     "\n"
 590     "  This function is intended for debugging. Note that build files are run\n"
 591     "  in parallel so you may get interleaved prints. A buildfile may also\n"
 592     "  be executed more than once in parallel in the context of different\n"
 593     "  toolchains so the prints from one file may be duplicated or\n"
 594     "  interleaved with itself.\n"
 595     "\n"
 596     "Examples:\n"
 597     "  print(\"Hello world\")\n"
 598     "\n"
 599     "  print(sources, deps)\n";
 600
 601 Value RunPrint(Scope* scope,
 602                const FunctionCallNode* function,
 603                const std::vector<Value>& args,
 604                Err* err) {
 605   std::string output;
 606   for (size_t i = 0; i < args.size(); i++) {
 607     if (i != 0)
 608       output.push_back(' ');
 609     output.append(args[i].ToString(false));
 610   }
 611   output.push_back('\n');
 612
 613   const BuildSettings::PrintCallback& cb =
 614       scope->settings()->build_settings()->print_callback();
 615   if (cb.is_null())
 616     printf("%s", output.c_str());
 617   else
 618     cb.Run(output);
 619
 620   return Value();
 621 }
 622
 623 // -----------------------------------------------------------------------------
 624
 625 FunctionInfo::FunctionInfo()
 626     : self_evaluating_args_runner(nullptr),
 627       generic_block_runner(nullptr),
 628       executed_block_runner(nullptr),
 629       no_block_runner(nullptr),
 630       help_short(nullptr),
 631       help(nullptr),
 632       is_target(false) {
 633 }
 634
 635 FunctionInfo::FunctionInfo(SelfEvaluatingArgsFunction seaf,
 636                            const char* in_help_short,
 637                            const char* in_help,
 638                            bool in_is_target)
 639     : self_evaluating_args_runner(seaf),
 640       generic_block_runner(nullptr),
 641       executed_block_runner(nullptr),
 642       no_block_runner(nullptr),
 643       help_short(in_help_short),
 644       help(in_help),
 645       is_target(in_is_target) {
 646 }
 647
 648 FunctionInfo::FunctionInfo(GenericBlockFunction gbf,
 649                            const char* in_help_short,
 650                            const char* in_help,
 651                            bool in_is_target)
 652     : self_evaluating_args_runner(nullptr),
 653       generic_block_runner(gbf),
 654       executed_block_runner(nullptr),
 655       no_block_runner(nullptr),
 656       help_short(in_help_short),
 657       help(in_help),
 658       is_target(in_is_target) {
 659 }
 660
 661 FunctionInfo::FunctionInfo(ExecutedBlockFunction ebf,
 662                            const char* in_help_short,
 663                            const char* in_help,
 664                            bool in_is_target)
 665     : self_evaluating_args_runner(nullptr),
 666       generic_block_runner(nullptr),
 667       executed_block_runner(ebf),
 668       no_block_runner(nullptr),
 669       help_short(in_help_short),
 670       help(in_help),
 671       is_target(in_is_target) {
 672 }
 673
 674 FunctionInfo::FunctionInfo(NoBlockFunction nbf,
 675                            const char* in_help_short,
 676                            const char* in_help,
 677                            bool in_is_target)
 678     : self_evaluating_args_runner(nullptr),
 679       generic_block_runner(nullptr),
 680       executed_block_runner(nullptr),
 681       no_block_runner(nbf),
 682       help_short(in_help_short),
 683       help(in_help),
 684       is_target(in_is_target) {
 685 }
 686
 687 // Setup the function map via a static initializer. We use this because it
 688 // avoids race conditions without having to do some global setup function or
 689 // locking-heavy singleton checks at runtime. In practice, we always need this
 690 // before we can do anything interesting, so it's OK to wait for the
 691 // initializer.
 692 struct FunctionInfoInitializer {
 693   FunctionInfoMap map;
 694
 695   FunctionInfoInitializer() {
 696     #define INSERT_FUNCTION(command, is_target) \
 697         map[k##command] = FunctionInfo(&Run##command, \
 698                                        k##command##_HelpShort, \
 699                                        k##command##_Help, \
 700                                        is_target);
 701
 702     INSERT_FUNCTION(Action, true)
 703     INSERT_FUNCTION(ActionForEach, true)
 704     INSERT_FUNCTION(Copy, true)
 705     INSERT_FUNCTION(Executable, true)
 706     INSERT_FUNCTION(Group, true)
 707     INSERT_FUNCTION(SharedLibrary, true)
 708     INSERT_FUNCTION(SourceSet, true)
 709     INSERT_FUNCTION(StaticLibrary, true)
 710
 711     INSERT_FUNCTION(Assert, false)
 712     INSERT_FUNCTION(Config, false)
 713     INSERT_FUNCTION(DeclareArgs, false)
 714     INSERT_FUNCTION(Defined, false)
 715     INSERT_FUNCTION(ExecScript, false)
 716     INSERT_FUNCTION(ForEach, false)
 717     INSERT_FUNCTION(GetEnv, false)
 718     INSERT_FUNCTION(GetLabelInfo, false)
 719     INSERT_FUNCTION(GetPathInfo, false)
 720     INSERT_FUNCTION(GetTargetOutputs, false)
 721     INSERT_FUNCTION(Import, false)
 722     INSERT_FUNCTION(Print, false)
 723     INSERT_FUNCTION(ProcessFileTemplate, false)
 724     INSERT_FUNCTION(ReadFile, false)
 725     INSERT_FUNCTION(RebasePath, false)
 726     INSERT_FUNCTION(SetDefaults, false)
 727     INSERT_FUNCTION(SetDefaultToolchain, false)
 728     INSERT_FUNCTION(SetSourcesAssignmentFilter, false)
 729     INSERT_FUNCTION(Template, false)
 730     INSERT_FUNCTION(Tool, false)
 731     INSERT_FUNCTION(Toolchain, false)
 732     INSERT_FUNCTION(ToolchainArgs, false)
 733     INSERT_FUNCTION(WriteFile, false)
 734
 735     #undef INSERT_FUNCTION
 736   }
 737 };
 738 const FunctionInfoInitializer function_info;
 739
 740 const FunctionInfoMap& GetFunctions() {
 741   return function_info.map;
 742 }
 743
 744 Value RunFunction(Scope* scope,
 745                   const FunctionCallNode* function,
 746                   const ListNode* args_list,
 747                   BlockNode* block,
 748                   Err* err) {
 749   const Token& name = function->function();
 750
 751   const FunctionInfoMap& function_map = GetFunctions();
 752   FunctionInfoMap::const_iterator found_function =
 753       function_map.find(name.value());
 754   if (found_function == function_map.end()) {
 755     // No built-in function matching this, check for a template.
 756     const Template* templ =
 757         scope->GetTemplate(function->function().value().as_string());
 758     if (templ) {
 759       Value args = args_list->Execute(scope, err);
 760       if (err->has_error())
 761         return Value();
 762       return templ->Invoke(scope, function, args.list_value(), block, err);
 763     }
 764
 765     *err = Err(name, "Unknown function.");
 766     return Value();
 767   }
 768
 769   if (found_function->second.self_evaluating_args_runner) {
 770     // Self evaluating args functions are special weird built-ins. Currently,
 771     // only foreach() takes a block following it. Rather than force them all to
 772     // check that they have a block or no block and risk bugs for new additions,
 773     // check a whitelist here.
 774     if (found_function->second.self_evaluating_args_runner != &RunForEach) {
 775       if (!VerifyNoBlockForFunctionCall(function, block, err))
 776         return Value();
 777     }
 778     return found_function->second.self_evaluating_args_runner(
 779         scope, function, args_list, err);
 780   }
 781
 782   // All other function types take a pre-executed set of args.
 783   Value args = args_list->Execute(scope, err);
 784   if (err->has_error())
 785     return Value();
 786
 787   if (found_function->second.generic_block_runner) {
 788     if (!block) {
 789       FillNeedsBlockError(function, err);
 790       return Value();
 791     }
 792     return found_function->second.generic_block_runner(
 793         scope, function, args.list_value(), block, err);
 794   }
 795
 796   if (found_function->second.executed_block_runner) {
 797     if (!block) {
 798       FillNeedsBlockError(function, err);
 799       return Value();
 800     }
 801
 802     Scope block_scope(scope);
 803     block->Execute(&block_scope, err);
 804     if (err->has_error())
 805       return Value();
 806
 807     Value result = found_function->second.executed_block_runner(
 808         function, args.list_value(), &block_scope, err);
 809     if (err->has_error())
 810       return Value();
 811
 812     if (!block_scope.CheckForUnusedVars(err))
 813       return Value();
 814     return result;
 815   }
 816
 817   // Otherwise it's a no-block function.
 818   if (!VerifyNoBlockForFunctionCall(function, block, err))
 819     return Value();
 820   return found_function->second.no_block_runner(scope, function,
 821                                                 args.list_value(), err);
 822 }
 823
 824 }  // namespace functions