Add initial prototype for the GN meta-buildsystem.

tools/gn/ninja_build_writer.cc

Index: tools/gn/ninja_build_writer.cc
diff --git a/tools/gn/ninja_build_writer.cc b/tools/gn/ninja_build_writer.cc
new file mode 100644
index 0000000000000000000000000000000000000000..a63765cd3aafadcb7d785d3a53db279a54456b7c
--- /dev/null
+++ b/tools/gn/ninja_build_writer.cc
@@ -0,0 +1,165 @@
+// 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/ninja_build_writer.h"
+
+#include <fstream>
+
+#include "base/command_line.h"
+#include "base/file_util.h"
+#include "base/process/process_handle.h"
+#include "base/strings/utf_string_conversions.h"
+#include "build/build_config.h"
+#include "tools/gn/build_settings.h"
+#include "tools/gn/filesystem_utils.h"
+#include "tools/gn/input_file_manager.h"
+#include "tools/gn/scheduler.h"
+#include "tools/gn/target.h"
+
+#if defined(OS_WIN)
+#include <windows.h>
+#endif
+
+namespace {
+
+std::string GetSelfInvocationCommand(const BuildSettings* build_settings) {
+#if defined(OS_WIN)
+  wchar_t module[MAX_PATH];
+  GetModuleFileName(NULL, module, MAX_PATH);
+  //result = "\"" + WideToUTF8(module) + "\"";
+  base::FilePath executable(module);
+#elif defined(OS_MACOSX)
+  // FIXME(brettw) write this on Mac!
+  base::FilePath executable("gn");
+#else
+  base::FilePath executable =
+      base::GetProcessExecutablePath(base::GetCurrentProcessHandle());
+#endif
+
+/*
+  // Append the root path.
+  CommandLine* cmdline = CommandLine::ForCurrentProcess();
+  result += " --root=\"" + FilePathToUTF8(settings->root_path()) + "\"";
+*/
+
+  CommandLine cmdline(executable);
+  cmdline.AppendSwitchPath("--root", build_settings->root_path());
+
+  // TODO(brettw) append other parameters.
+
+#if defined(OS_WIN)
+  return WideToUTF8(cmdline.GetCommandLineString());
+#else
+  return cmdline.GetCommandLineString();
+#endif
+}
+
+}  // namespace
+
+NinjaBuildWriter::NinjaBuildWriter(
+    const BuildSettings* build_settings,
+    const std::vector<const Settings*>& all_settings,
+    const std::vector<const Target*>& default_toolchain_targets,
+    std::ostream& out)
+    : build_settings_(build_settings),
+      all_settings_(all_settings),
+      default_toolchain_targets_(default_toolchain_targets),
+      out_(out),
+      path_output_(build_settings->build_dir(), ESCAPE_NINJA, true),
+      helper_(build_settings) {
+}
+
+NinjaBuildWriter::~NinjaBuildWriter() {
+}
+
+void NinjaBuildWriter::Run() {
+  WriteNinjaRules();
+  WriteSubninjas();
+  WritePhonyAndAllRules();
+}
+
+// static
+bool NinjaBuildWriter::RunAndWriteFile(
+    const BuildSettings* build_settings,
+    const std::vector<const Settings*>& all_settings,
+    const std::vector<const Target*>& default_toolchain_targets) {
+  base::FilePath ninja_file(build_settings->GetFullPath(
+      SourceFile(build_settings->build_dir().value() + "build.ninja")));
+  file_util::CreateDirectory(ninja_file.DirName());
+
+  std::ofstream file;
+  file.open(FilePathToUTF8(ninja_file).c_str(),
+            std::ios_base::out | std::ios_base::binary);
+  if (file.fail())
+    return false;
+
+  NinjaBuildWriter gen(build_settings, all_settings,
+                       default_toolchain_targets, file);
+  gen.Run();
+  return true;
+}
+
+void NinjaBuildWriter::WriteNinjaRules() {
+  out_ << "rule gn\n";
+  out_ << "  command = " << GetSelfInvocationCommand(build_settings_) << "\n";
+  out_ << "  description = GN the world\n\n";
+
+  out_ << "build build.ninja: gn";
+
+  // Input build files.
+  std::vector<SourceFile> input_files;
+  g_scheduler->input_file_manager()->GetAllInputFileNames(&input_files);
+  for (size_t i = 0; i < input_files.size(); i++) {
+    out_ << " ";
+    path_output_.WriteFile(out_, input_files[i]);
+  }
+
+  // Other files read by the build.
+  std::vector<SourceFile> other_files = g_scheduler->GetGenDependencies();
+  for (size_t i = 0; i < other_files.size(); i++) {
+    out_ << " ";
+    path_output_.WriteFile(out_, other_files[i]);
+  }
+
+  out_ << std::endl << std::endl;
+}
+
+void NinjaBuildWriter::WriteSubninjas() {
+  for (size_t i = 0; i < all_settings_.size(); i++) {
+    out_ << "subninja ";
+    path_output_.WriteFile(out_,
+                           helper_.GetNinjaFileForToolchain(all_settings_[i]));
+    out_ << std::endl;
+  }
+  out_ << std::endl;
+}
+
+void NinjaBuildWriter::WritePhonyAndAllRules() {
+  std::string all_rules;
+
+  // Write phony rules for the default toolchain (don't do other toolchains or
+  // we'll get naming conflicts).
+  for (size_t i = 0; i < default_toolchain_targets_.size(); i++) {
+    const Target* target = default_toolchain_targets_[i];
+    if (target->output_type() == Target::NONE)
+      continue;  // Nothing to generate.
+
+    OutputFile target_file = helper_.GetTargetOutputFile(target);
+    if (target_file.value() != target->label().name()) {
+      out_ << "build " << target->label().name() << ": phony ";
+      path_output_.WriteFile(out_, target_file);
+      out_ << std::endl;
+    }
+
+    if (!all_rules.empty())
+      all_rules.append(" $\n    ");
+    all_rules.append(target_file.value());
+  }
+
+  if (!all_rules.empty()) {
+    out_ << "\nbuild all: phony " << all_rules << std::endl;
+    out_ << "default all" << std::endl;
+  }
+}
+