Add initial prototype for the GN meta-buildsystem.

tools/gn/setup.cc

Index: tools/gn/setup.cc
diff --git a/tools/gn/setup.cc b/tools/gn/setup.cc
new file mode 100644
index 0000000000000000000000000000000000000000..f93cd4d31a1ced58ad526b62249ec91e97777db4
--- /dev/null
+++ b/tools/gn/setup.cc
@@ -0,0 +1,195 @@
+// 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/setup.h"
+
+#include "base/command_line.h"
+#include "base/file_util.h"
+#include "base/files/file_path.h"
+#include "tools/gn/filesystem_utils.h"
+#include "tools/gn/input_file.h"
+#include "tools/gn/parse_tree.h"
+#include "tools/gn/parser.h"
+#include "tools/gn/source_dir.h"
+#include "tools/gn/source_file.h"
+#include "tools/gn/tokenizer.h"
+#include "tools/gn/value.h"
+
+namespace {
+
+// More logging.
+const char kSwitchVerbose[] = "v";
+
+const char kSwitchRoot[] = "root";
+const char kSecondarySource[] = "secondary";
+
+const base::FilePath::CharType kGnFile[] = FILE_PATH_LITERAL(".gn");
+
+base::FilePath FindDotFile(const base::FilePath& current_dir) {
+  base::FilePath try_this_file = current_dir.Append(kGnFile);
+  if (base::PathExists(try_this_file))
+    return try_this_file;
+
+  base::FilePath with_no_slash = current_dir.StripTrailingSeparators();
+  base::FilePath up_one_dir = with_no_slash.DirName();
+  if (up_one_dir == current_dir)
+    return base::FilePath();  // Got to the top.
+
+  return FindDotFile(up_one_dir);
+}
+
+}  // namespace
+
+Setup::Setup()
+    : dotfile_toolchain_(Label()),
+      dotfile_settings_(&dotfile_build_settings_, &dotfile_toolchain_,
+                        std::string()),
+      dotfile_scope_(&dotfile_settings_) {
+}
+
+Setup::~Setup() {
+}
+
+bool Setup::DoSetup() {
+  CommandLine* cmdline = CommandLine::ForCurrentProcess();
+
+  scheduler_.set_verbose_logging(cmdline->HasSwitch(kSwitchVerbose));
+
+  if (!FillSourceDir(*cmdline))
+    return false;
+  if (!RunConfigFile())
+    return false;
+  if (!FillOtherConfig(*cmdline))
+    return false;
+
+  // FIXME(brettw) get python path!
+/*#if defined(OS_WIN)
+  build_settings_.set_python_path(base::FilePath(
+      //L"P:\\depot_tools\\python_bin\\python.exe"));
+      L"C:\\apps\\depot_tools\\python_bin\\python.exe"));
+#else*/
+  build_settings_.set_python_path(base::FilePath("python"));
+//#endif
+
+  build_settings_.SetBuildDir(SourceDir("//out/gn/"));
+
+  return true;
+}
+
+bool Setup::Run() {
+  // Load the root build file and start runnung.
+  build_settings_.toolchain_manager().StartLoadingUnlocked(
+      SourceFile("//BUILD.gn"));
+  if (!scheduler_.Run())
+    return false;
+
+  Err err = build_settings_.item_tree().CheckForBadItems();
+  if (err.has_error()) {
+    err.PrintToStdout();
+    return false;
+  }
+  return true;
+}
+
+bool Setup::FillSourceDir(const CommandLine& cmdline) {
+  // Find the .gn file.
+  base::FilePath root_path;
+
+  // Prefer the command line args to the config file.
+  base::FilePath relative_root_path = cmdline.GetSwitchValuePath(kSwitchRoot);
+  if (!relative_root_path.empty()) {
+    root_path = base::MakeAbsoluteFilePath(relative_root_path);
+    dotfile_name_ = root_path.Append(kGnFile);
+  } else {
+    base::FilePath cur_dir;
+    file_util::GetCurrentDirectory(&cur_dir);
+    dotfile_name_ = FindDotFile(cur_dir);
+    if (dotfile_name_.empty()) {
+      Err(Location(), "Can't find source root.",
+          "I could not find a \".gn\" file in the current directory or any "
+          "parent,\nand the --root command-line argument was not specified.")
+          .PrintToStdout();
+      return false;
+    }
+    root_path = dotfile_name_.DirName();
+  }
+
+  if (scheduler_.verbose_logging())
+    scheduler_.Log("Using source root", FilePathToUTF8(root_path));
+  build_settings_.set_root_path(root_path);
+
+  return true;
+}
+
+bool Setup::RunConfigFile() {
+  if (scheduler_.verbose_logging())
+    scheduler_.Log("Got dotfile", FilePathToUTF8(dotfile_name_));
+
+  dotfile_input_file_.reset(new InputFile(SourceFile("//.gn")));
+  if (!dotfile_input_file_->Load(dotfile_name_)) {
+    Err(Location(), "Could not load dotfile.",
+        "The file \"" + FilePathToUTF8(dotfile_name_) + "\" cound't be loaded")
+        .PrintToStdout();
+    return false;
+  }
+
+  Err err;
+  dotfile_tokens_ = Tokenizer::Tokenize(dotfile_input_file_.get(), &err);
+  if (err.has_error()) {
+    err.PrintToStdout();
+    return false;
+  }
+
+  dotfile_root_ = Parser::Parse(dotfile_tokens_, &err);
+  if (err.has_error()) {
+    err.PrintToStdout();
+    return false;
+  }
+
+  dotfile_root_->AsBlock()->ExecuteBlockInScope(&dotfile_scope_, &err);
+  if (err.has_error()) {
+    err.PrintToStdout();
+    return false;
+  }
+
+  return true;
+}
+
+bool Setup::FillOtherConfig(const CommandLine& cmdline) {
+  Err err;
+
+  // Secondary source path.
+  SourceDir secondary_source;
+  if (cmdline.HasSwitch(kSecondarySource)) {
+    // Prefer the command line over the config file.
+    secondary_source =
+        SourceDir(cmdline.GetSwitchValueASCII(kSecondarySource));
+  } else {
+    // Read from the config file if present.
+    const Value* secondary_value =
+        dotfile_scope_.GetValue("secondary_source", true);
+    if (secondary_value) {
+      if (!secondary_value->VerifyTypeIs(Value::STRING, &err)) {
+        err.PrintToStdout();
+        return false;
+      }
+      build_settings_.SetSecondarySourcePath(
+          SourceDir(secondary_value->string_value()));
+    }
+  }
+
+  // Build config dir.
+  const Value* build_config_value =
+      dotfile_scope_.GetValue("buildconfig", true);
+  if (!build_config_value) {
+    Err(Location(), "No build config file.",
+        "Your .gn file (\"" + FilePathToUTF8(dotfile_name_) + "\")\n"
+        "didn't specify a \"buildconfig\" value.").PrintToStdout();
+    return false;
+  }
+  build_settings_.set_build_config_file(
+      SourceFile("//build/config/BUILDCONFIG.gn"));
+
+  return true;
+}