Add initial prototype for the GN meta-buildsystem.

tools/gn/functions.cc

Index: tools/gn/functions.cc
diff --git a/tools/gn/functions.cc b/tools/gn/functions.cc
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--- /dev/null
+++ b/tools/gn/functions.cc
@@ -0,0 +1,443 @@
+// 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 "tools/gn/functions.h"
+
+#include <iostream>
+
+#include "base/strings/string_util.h"
+#include "tools/gn/config.h"
+#include "tools/gn/config_values_generator.h"
+#include "tools/gn/err.h"
+#include "tools/gn/input_file.h"
+#include "tools/gn/item_tree.h"
+#include "tools/gn/parse_tree.h"
+#include "tools/gn/scheduler.h"
+#include "tools/gn/scope.h"
+#include "tools/gn/settings.h"
+#include "tools/gn/target_manager.h"
+#include "tools/gn/token.h"
+#include "tools/gn/value.h"
+
+namespace {
+
+void FillNeedsBlockError(const FunctionCallNode* function, Err* err) {
+  *err = Err(function->function(), "This function call requires a block.",
+      "The block's \"{\" must be on the same line as the function "
+      "call's \")\".");
+}
+
+Value ExecuteAssert(const FunctionCallNode* function,
+                    const std::vector<Value>& args,
+                    Err* err) {
+  if (args.size() != 1) {
+    *err = Err(function->function(), "Wrong number of arguments.",
+               "assert() takes one argument, "
+               "were you expecting somethig else?");
+  } else if (args[0].InterpretAsInt() == 0) {
+    *err = Err(function->function(), "Assertion failed.");
+    if (args[0].origin()) {
+      // If you do "assert(foo)" we'd ideally like to show you where foo was
+      // set, and in this case the origin of the args will tell us that.
+      // However, if you do "assert(foo && bar)" the source of the value will
+      // be the assert like, which isn't so helpful.
+      //
+      // So we try to see if the args are from the same line or not. This will
+      // break if you do "assert(\nfoo && bar)" and we may show the second line
+      // as the source, oh well. The way around this is to check to see if the
+      // origin node is inside our function call block.
+      Location origin_location = args[0].origin()->GetRange().begin();
+      if (origin_location.file() != function->function().location().file() ||
+          origin_location.line_number() !=
+              function->function().location().line_number()) {
+        err->AppendSubErr(Err(args[0].origin()->GetRange(), "",
+                              "This is where it was set."));
+      }
+    }
+  }
+  return Value();
+}
+
+Value ExecuteConfig(Scope* scope,
+                    const FunctionCallNode* function,
+                    const std::vector<Value>& args,
+                    Err* err) {
+  if (!EnsureSingleStringArg(function, args, err) ||
+      !EnsureNotProcessingImport(function, scope, err))
+    return Value();
+
+  Label label(MakeLabelForScope(scope, function, args[0].string_value()));
+
+  if (g_scheduler->verbose_logging())
+    g_scheduler->Log("Generating config", label.GetUserVisibleName(true));
+
+  // Create the empty config object.
+  ItemTree* tree = &scope->settings()->build_settings()->item_tree();
+  Config* config = Config::GetConfig(scope->settings(), function->GetRange(),
+                                     label, NULL, err);
+  if (err->has_error())
+    return Value();
+
+  // Fill it.
+  const SourceDir input_dir = SourceDirForFunctionCall(function);
+  ConfigValuesGenerator gen(&config->config_values(), scope,
+                            function->function(), input_dir, err);
+  gen.Run();
+  if (err->has_error())
+    return Value();
+
+  // Mark as complete.
+  {
+    base::AutoLock lock(tree->lock());
+    tree->MarkItemGeneratedLocked(label);
+  }
+  return Value();
+}
+
+Value ExecuteDeclareArgs(Scope* scope,
+                         const FunctionCallNode* function,
+                         const std::vector<Value>& args,
+                         Err* err) {
+  // Only allow this to be called once. We use a variable in the current scope
+  // with a name the parser will reject if the user tried to type it.
+  const char did_declare_args_var[] = "@@declared_args";
+  if (scope->GetValue(did_declare_args_var)) {
+    *err = Err(function->function(), "Duplicate call to declared_args.");
+    err->AppendSubErr(
+        Err(scope->GetValue(did_declare_args_var)->origin()->GetRange(),
+                            "See the original call."));
+    return Value();
+  }
+
+  // Find the root scope where the values will be set.
+  Scope* root = scope->mutable_containing();
+  if (!root || root->containing() || !scope->IsProcessingBuildConfig()) {
+    *err = Err(function->function(), "declare_args called incorrectly."
+        "It must be called only from the build config script and in the "
+        "root scope.");
+    return Value();
+  }
+
+  // Take all variables set in the current scope as default values and put
+  // them in the parent scope. The values in the current scope are the defaults,
+  // then we apply the external args to this list.
+  Scope::KeyValueVector values;
+  scope->GetCurrentScopeValues(&values);
+  for (size_t i = 0; i < values.size(); i++) {
+    // TODO(brettw) actually import the arguments from the command line rather
+    // than only using the defaults.
+    root->SetValue(values[i].first, values[i].second,
+                   values[i].second.origin());
+  }
+
+  scope->SetValue(did_declare_args_var, Value(function, 1), NULL);
+  return Value();
+}
+
+Value ExecuteImport(Scope* scope,
+                    const FunctionCallNode* function,
+                    const std::vector<Value>& args,
+                    Err* err) {
+  if (!EnsureSingleStringArg(function, args, err) ||
+      !EnsureNotProcessingImport(function, scope, err))
+    return Value();
+
+  const SourceDir input_dir = SourceDirForFunctionCall(function);
+  SourceFile import_file =
+      input_dir.ResolveRelativeFile(args[0].string_value());
+  scope->settings()->import_manager().DoImport(import_file, function,
+                                               scope, err);
+  return Value();
+}
+
+Value ExecuteTemplate(Scope* scope,
+                      const FunctionCallNode* invocation,
+                      const std::vector<Value>& args,
+                      BlockNode* block,
+                      const FunctionCallNode* rule,
+                      Err* err) {
+  if (!EnsureNotProcessingImport(invocation, scope, err))
+    return Value();
+  Scope block_scope(scope);
+  if (!FillTargetBlockScope(scope, invocation,
+                            invocation->function().value().data(),
+                            block, args, &block_scope, err))
+    return Value();
+
+  // Run the block for the rule invocation.
+  block->ExecuteBlockInScope(&block_scope, err);
+  if (err->has_error())
+    return Value();
+
+  // Now run the rule itself with that block as the current scope.
+  rule->block()->ExecuteBlockInScope(&block_scope, err);
+  if (err->has_error())
+    return Value();
+
+  return Value();
+}
+
+Value ExecuteSetDefaults(Scope* scope,
+                         const FunctionCallNode* function,
+                         const std::vector<Value>& args,
+                         BlockNode* block,
+                         Err* err) {
+  if (!EnsureSingleStringArg(function, args, err))
+    return Value();
+  const std::string& target_type(args[0].string_value());
+
+  // Ensure there aren't defaults already set.
+  if (scope->GetTargetDefaults(target_type)) {
+    *err = Err(function->function(),
+               "This target type defaults were already set.");
+    return Value();
+  }
+
+  // Execute the block in a new scope that has a parent of the containing
+  // scope.
+  Scope block_scope(scope);
+  if (!FillTargetBlockScope(scope, function,
+                            function->function().value().data(),
+                            block, args, &block_scope, err))
+    return Value();
+
+  // Run the block for the rule invocation.
+  block->ExecuteBlockInScope(&block_scope, err);
+  if (err->has_error())
+    return Value();
+
+  // Now copy the values set on the scope we made into the free-floating one
+  // (with no containing scope) used to hold the target defaults.
+  Scope* dest = scope->MakeTargetDefaults(target_type);
+  block_scope.NonRecursiveMergeTo(dest, function, "<SHOULD NOT FAIL>", err);
+  return Value();
+}
+
+Value ExecuteSetSourcesAssignmentFilter(Scope* scope,
+                                        const FunctionCallNode* function,
+                                        const std::vector<Value>& args,
+                                        Err* err) {
+  if (args.size() != 1) {
+    *err = Err(function, "set_sources_assignment_filter takes one argument.");
+  } else {
+    scoped_ptr<PatternList> f(new PatternList);
+    f->SetFromValue(args[0], err);
+    if (!err->has_error())
+      scope->set_sources_assignment_filter(f.Pass());
+  }
+  return Value();
+}
+
+// void print(...)
+// prints all arguments to the console separated by spaces.
+Value ExecutePrint(const std::vector<Value>& args, Err* err) {
+  for (size_t i = 0; i < args.size(); i++) {
+    if (i != 0)
+      std::cout << " ";
+    std::cout << args[i].ToString();
+  }
+  std::cout << std::endl;
+  return Value();
+}
+
+}  // namespace
+
+// ----------------------------------------------------------------------------
+
+namespace functions {
+
+const char kAssert[] = "assert";
+const char kComponent[] = "component";
+const char kConfig[] = "config";
+const char kCopy[] = "copy";
+const char kCustom[] = "custom";
+const char kDeclareArgs[] = "declare_args";
+const char kExecScript[] = "exec_script";
+const char kExecutable[] = "executable";
+const char kGroup[] = "group";
+const char kImport[] = "import";
+const char kPrint[] = "print";
+const char kProcessFileTemplate[] = "process_file_template";
+const char kReadFile[] = "read_file";
+const char kSetDefaults[] = "set_defaults";
+const char kSetDefaultToolchain[] = "set_default_toolchain";
+const char kSetSourcesAssignmentFilter[] = "set_sources_assignment_filter";
+const char kSharedLibrary[] = "shared_library";
+const char kStaticLibrary[] = "static_library";
+const char kTemplate[] = "template";
+const char kTool[] = "tool";
+const char kToolchain[] = "toolchain";
+const char kTest[] = "test";
+const char kWriteFile[] = "write_file";
+
+}  // namespace functions
+
+// ----------------------------------------------------------------------------
+
+bool EnsureNotProcessingImport(const ParseNode* node,
+                               const Scope* scope,
+                               Err* err) {
+  if (scope->IsProcessingImport()) {
+    *err = Err(node, "Not valid from an import.",
+        "We need to talk about this thing you are doing here. Doing this\n"
+        "kind of thing from an imported file makes me feel like you are\n"
+        "abusing me. Imports are for defining defaults, variables, and rules.\n"
+        "The appropriate place for this kind of thing is really in a normal\n"
+        "BUILD file.");
+    return false;
+  }
+  return true;
+}
+
+bool EnsureNotProcessingBuildConfig(const ParseNode* node,
+                                    const Scope* scope,
+                                    Err* err) {
+  if (scope->IsProcessingBuildConfig()) {
+    *err = Err(node, "Not valid from the build config.",
+        "You can't do this kind of thing from the build config script, "
+        "silly!\nPut it in a regular BUILD file.");
+    return false;
+  }
+  return true;
+}
+
+bool FillTargetBlockScope(const Scope* scope,
+                          const FunctionCallNode* function,
+                          const char* target_type,
+                          const BlockNode* block,
+                          const std::vector<Value>& args,
+                          Scope* block_scope,
+                          Err* err) {
+  if (!block) {
+    FillNeedsBlockError(function, err);
+    return false;
+  }
+
+  // Copy the target defaults, if any, into the scope we're going to execute
+  // the block in.
+  const Scope* default_scope = scope->GetTargetDefaults(target_type);
+  if (default_scope) {
+    if (!default_scope->NonRecursiveMergeTo(block_scope, function,
+                                            "target defaults", err))
+      return false;
+  }
+
+  // The name is the single argument to the target function.
+  if (!EnsureSingleStringArg(function, args, err))
+    return false;
+
+  // Set the target name variable to the current target, and mark it used
+  // because we don't want to issue an error if the script ignores it.
+  const base::StringPiece target_name("target_name");
+  block_scope->SetValue(target_name, Value(function, args[0].string_value()),
+                        function);
+  block_scope->MarkUsed(target_name);
+  return true;
+}
+
+bool EnsureSingleStringArg(const FunctionCallNode* function,
+                           const std::vector<Value>& args,
+                           Err* err) {
+  if (args.size() != 1) {
+    *err = Err(function->function(), "Incorrect arguments.",
+               "This function requires a single string argument.");
+    return false;
+  }
+  return args[0].VerifyTypeIs(Value::STRING, err);
+}
+
+const SourceDir& SourceDirForFunctionCall(const FunctionCallNode* function) {
+  return function->function().location().file()->dir();
+}
+
+const Label& ToolchainLabelForScope(const Scope* scope) {
+  return scope->settings()->toolchain()->label();
+}
+
+Label MakeLabelForScope(const Scope* scope,
+                        const FunctionCallNode* function,
+                        const std::string& name) {
+  const SourceDir& input_dir = SourceDirForFunctionCall(function);
+  const Label& toolchain_label = ToolchainLabelForScope(scope);
+  return Label(input_dir, name, toolchain_label.dir(), toolchain_label.name());
+}
+
+Value ExecuteFunction(Scope* scope,
+                      const FunctionCallNode* function,
+                      const std::vector<Value>& args,
+                      BlockNode* block,
+                      Err* err) {
+  const Token& name = function->function();
+  if (block) {
+    // These target generators need to execute the block themselves.
+    if (name.IsIdentifierEqualTo(functions::kComponent))
+      return ExecuteComponent(scope, function, args, block, err);
+    if (name.IsIdentifierEqualTo(functions::kCustom))
+      return ExecuteCustom(scope, function, args, block, err);
+    if (name.IsIdentifierEqualTo(functions::kExecutable))
+      return ExecuteExecutable(scope, function, args, block, err);
+    if (name.IsIdentifierEqualTo(functions::kSetDefaults))
+      return ExecuteSetDefaults(scope, function, args, block, err);
+    if (name.IsIdentifierEqualTo(functions::kSharedLibrary))
+      return ExecuteSharedLibrary(scope, function, args, block, err);
+    if (name.IsIdentifierEqualTo(functions::kStaticLibrary))
+      return ExecuteStaticLibrary(scope, function, args, block, err);
+    if (name.IsIdentifierEqualTo(functions::kGroup))
+      return ExecuteGroup(scope, function, args, block, err);
+    if (name.IsIdentifierEqualTo(functions::kTest))
+      return ExecuteExecutable(scope, function, args, block, err);
+    if (name.IsIdentifierEqualTo(functions::kTemplate))
+      return ExecuteTemplate(scope, function, args, block, err);
+    if (name.IsIdentifierEqualTo(functions::kTool))
+      return ExecuteTool(scope, function, args, block, err);
+    if (name.IsIdentifierEqualTo(functions::kToolchain))
+      return ExecuteToolchain(scope, function, args, block, err);
+
+    const FunctionCallNode* rule =
+        scope->GetTemplate(function->function().value().as_string());
+    if (rule)
+      return ExecuteTemplate(scope, function, args, block, rule, err);
+
+    // FIXME(brettw) This is not right, what if you specify a function that
+    // doesn't take a block but specify one?!?!?
+
+    // The rest of the functions can take a pre-executed block for simplicity.
+    Scope block_scope(scope);
+    block->ExecuteBlockInScope(&block_scope, err);
+    if (err->has_error())
+      return Value();
+
+    if (name.IsIdentifierEqualTo(functions::kConfig))
+      return ExecuteConfig(&block_scope, function, args, err);
+    if (name.IsIdentifierEqualTo(functions::kCopy))
+      return ExecuteCopy(&block_scope, function, args, err);
+    if (name.IsIdentifierEqualTo(functions::kDeclareArgs))
+      return ExecuteDeclareArgs(&block_scope, function, args, err);
+
+    *err = Err(name, "Unknown function.");
+    return Value();
+  }
+
+  if (name.IsIdentifierEqualTo(functions::kAssert))
+    return ExecuteAssert(function, args, err);
+  if (name.IsIdentifierEqualTo(functions::kExecScript))
+    return ExecuteExecScript(scope, function, args, err);
+  if (name.IsIdentifierEqualTo(functions::kImport))
+    return ExecuteImport(scope, function, args, err);
+  if (name.IsIdentifierEqualTo(functions::kPrint))
+    return ExecutePrint(args, err);
+  if (name.IsIdentifierEqualTo(functions::kProcessFileTemplate))
+    return ExecuteProcessFileTemplate(scope, function, args, err);
+  if (name.IsIdentifierEqualTo(functions::kReadFile))
+    return ExecuteReadFile(scope, function, args, err);
+  if (name.IsIdentifierEqualTo(functions::kSetDefaultToolchain))
+    return ExecuteSetDefaultToolchain(scope, function, args, err);
+  if (name.IsIdentifierEqualTo(functions::kSetSourcesAssignmentFilter))
+    return ExecuteSetSourcesAssignmentFilter(scope, function, args, err);
+  if (name.IsIdentifierEqualTo(functions::kWriteFile))
+    return ExecuteWriteFile(scope, function, args, err);
+
+  *err = Err(function, "Unknown function.");
+  return Value();
+}