Add initial prototype for the GN meta-buildsystem.

tools/gn/ninja_toolchain_writer.cc

Index: tools/gn/ninja_toolchain_writer.cc
diff --git a/tools/gn/ninja_toolchain_writer.cc b/tools/gn/ninja_toolchain_writer.cc
new file mode 100644
index 0000000000000000000000000000000000000000..0e38b8c3fc94cd62303e5eb6beb5475d7796898f
--- /dev/null
+++ b/tools/gn/ninja_toolchain_writer.cc
@@ -0,0 +1,94 @@
+// 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_toolchain_writer.h"
+
+#include <fstream>
+
+#include "base/file_util.h"
+#include "base/strings/stringize_macros.h"
+#include "tools/gn/build_settings.h"
+#include "tools/gn/settings.h"
+#include "tools/gn/target.h"
+#include "tools/gn/toolchain.h"
+
+NinjaToolchainWriter::NinjaToolchainWriter(
+    const Settings* settings,
+    const std::vector<const Target*>& targets,
+    std::ostream& out)
+    : settings_(settings),
+      targets_(targets),
+      out_(out),
+      path_output_(settings_->build_settings()->build_dir(),
+                   ESCAPE_NINJA, true),
+      helper_(settings->build_settings()) {
+}
+
+NinjaToolchainWriter::~NinjaToolchainWriter() {
+}
+
+void NinjaToolchainWriter::Run() {
+  WriteRules();
+  WriteSubninjas();
+}
+
+// static
+bool NinjaToolchainWriter::RunAndWriteFile(
+    const Settings* settings,
+    const std::vector<const Target*>& targets) {
+  NinjaHelper helper(settings->build_settings());
+  base::FilePath ninja_file(settings->build_settings()->GetFullPath(
+      helper.GetNinjaFileForToolchain(settings).GetSourceFile(
+          settings->build_settings())));
+  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;
+
+  NinjaToolchainWriter gen(settings, targets, file);
+  gen.Run();
+  return true;
+}
+
+void NinjaToolchainWriter::WriteRules() {
+  const Toolchain* tc = settings_->toolchain();
+  std::string indent("  ");
+
+  for (int i = Toolchain::TYPE_NONE + 1; i < Toolchain::TYPE_NUMTYPES; i++) {
+    Toolchain::ToolType tool_type = static_cast<Toolchain::ToolType>(i);
+    const Toolchain::Tool& tool = tc->GetTool(tool_type);
+    if (tool.empty())
+      continue;
+
+    out_ << "rule " << Toolchain::ToolTypeToName(tool_type) << std::endl;
+
+    #define WRITE_ARG(name) \
+      if (!tool.name.empty()) \
+        out_ << indent << "  " STRINGIZE(name) " = " << tool.name << std::endl;
+    WRITE_ARG(command);
+    WRITE_ARG(depfile);
+    WRITE_ARG(deps);
+    WRITE_ARG(description);
+    WRITE_ARG(pool);
+    WRITE_ARG(restat);
+    WRITE_ARG(rspfile);
+    WRITE_ARG(rspfile_content);
+    #undef WRITE_ARG
+  }
+  out_ << std::endl;
+}
+
+void NinjaToolchainWriter::WriteSubninjas() {
+  for (size_t i = 0; i < targets_.size(); i++) {
+    if (targets_[i]->output_type() != Target::NONE) {
+      out_ << "subninja ";
+      path_output_.WriteFile(out_, helper_.GetNinjaFileForTarget(targets_[i]));
+      out_ << std::endl;
+    }
+  }
+  out_ << std::endl;
+}