Add initial prototype for the GN meta-buildsystem.

tools/gn/ninja_helper.cc

Index: tools/gn/ninja_helper.cc
diff --git a/tools/gn/ninja_helper.cc b/tools/gn/ninja_helper.cc
new file mode 100644
index 0000000000000000000000000000000000000000..c27c0e40c76cd91588394b967fe0c039743336d4
--- /dev/null
+++ b/tools/gn/ninja_helper.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_helper.h"
+
+#include "base/logging.h"
+#include "tools/gn/filesystem_utils.h"
+#include "tools/gn/string_utils.h"
+#include "tools/gn/target.h"
+
+namespace {
+
+const char kLibDirWithSlash[] = "lib";
+const char kObjectDirNoSlash[] = "obj";
+
+}  // namespace
+
+NinjaHelper::NinjaHelper(const BuildSettings* build_settings)
+    : build_settings_(build_settings) {
+  build_to_src_no_last_slash_ = build_settings->build_to_source_dir_string();
+  if (!build_to_src_no_last_slash_.empty() &&
+      build_to_src_no_last_slash_[build_to_src_no_last_slash_.size() - 1] ==
+          '/')
+    build_to_src_no_last_slash_.resize(build_to_src_no_last_slash_.size() - 1);
+
+  build_to_src_system_no_last_slash_ = build_to_src_no_last_slash_;
+  ConvertPathToSystem(&build_to_src_system_no_last_slash_);
+}
+
+NinjaHelper::~NinjaHelper() {
+}
+
+std::string NinjaHelper::GetTopleveOutputDir() const {
+  return kObjectDirNoSlash;
+}
+
+std::string NinjaHelper::GetTargetOutputDir(const Target* target) const {
+  return kObjectDirNoSlash + target->label().dir().SourceAbsoluteWithOneSlash();
+}
+
+OutputFile NinjaHelper::GetNinjaFileForTarget(const Target* target) const {
+  OutputFile ret(target->settings()->toolchain_output_subdir());
+  ret.value().append(kObjectDirNoSlash);
+  AppendStringPiece(&ret.value(),
+                    target->label().dir().SourceAbsoluteWithOneSlash());
+  ret.value().append(target->label().name());
+  ret.value().append(".ninja");
+  return ret;
+}
+
+OutputFile NinjaHelper::GetNinjaFileForToolchain(
+    const Settings* settings) const {
+  OutputFile ret;
+  ret.value().append(settings->toolchain_output_subdir().value());
+  ret.value().append("toolchain.ninja");
+  return ret;
+}
+
+// In Python, GypPathToUniqueOutput does the qualification. The only case where
+// the Python version doesn't qualify the name is for target outputs, which we
+// handle in a separate function.
+OutputFile NinjaHelper::GetOutputFileForSource(
+    const Target* target,
+    const SourceFile& source,
+    SourceFileType type) const {
+  // Extract the filename and remove the extension (keep the dot).
+  base::StringPiece filename = FindFilename(&source.value());
+  std::string name(filename.data(), filename.size());
+  size_t extension_offset = FindExtensionOffset(name);
+  CHECK(extension_offset != std::string::npos);
+  name.resize(extension_offset);
+
+  // Append the new extension.
+  switch (type) {
+    case SOURCE_ASM:
+    case SOURCE_C:
+    case SOURCE_CC:
+    case SOURCE_M:
+    case SOURCE_MM:
+      name.append(target->settings()->IsWin() ? "obj" : "o");
+      break;
+
+    case SOURCE_RC:
+      name.append("res");
+      break;
+
+    case SOURCE_H:
+    case SOURCE_UNKNOWN:
+      NOTREACHED();
+      return OutputFile();
+  }
+
+  // Use the scheme <path>/<target>.<name>.<extension> so that all output
+  // names are unique to different targets.
+  OutputFile ret(kObjectDirNoSlash);
+
+  // Find the directory, assume it starts with two slashes, and trim to one.
+  base::StringPiece dir = FindDir(&source.value());
+  CHECK(dir.size() >= 2 && dir[0] == '/' && dir[1] == '/')
+      << "Source file isn't in the source repo: " << dir;
+  AppendStringPiece(&ret.value(), dir.substr(1));
+
+  ret.value().append(target->label().name());
+  ret.value().append(".");
+  ret.value().append(name);
+  return ret;
+}
+
+OutputFile NinjaHelper::GetTargetOutputFile(const Target* target) const {
+  OutputFile ret;
+  if (target->output_type() == Target::NONE) {
+    NOTREACHED();
+    return ret;
+  }
+
+  const char* extension;
+  if (target->output_type() == Target::NONE ||
+      target->output_type() == Target::COPY_FILES ||
+      target->output_type() == Target::CUSTOM) {
+    extension = "stamp";
+  } else {
+    extension = GetExtensionForOutputType(target->output_type(),
+                                          target->settings()->target_os());
+  }
+
+  // Everything goes into the toolchain directory (which will be empty for the
+  // default toolchain, and will end in a slash otherwise).
+  ret.value().append(target->settings()->toolchain_output_subdir().value());
+
+  // Binaries and loadable libraries go into the toolchain root.
+  if (target->output_type() == Target::EXECUTABLE ||
+      target->output_type() == Target::LOADABLE_MODULE ||
+      (target->settings()->IsMac() &&
+          (target->output_type() == Target::SHARED_LIBRARY ||
+           target->output_type() == Target::STATIC_LIBRARY)) ||
+      (target->settings()->IsWin() &&
+       target->output_type() == Target::SHARED_LIBRARY)) {
+    // Generate a name like "<toolchain>/<name>.<extension>".
+    ret.value().append(target->label().name());
+    ret.value().push_back('.');
+    ret.value().append(extension);
+    return ret;
+  }
+
+  // Libraries go into the library subdirectory like
+  // "<toolchain>/lib/<name>.<extension>".
+  if (target->output_type() == Target::SHARED_LIBRARY) {
+    ret.value().append(kLibDirWithSlash);
+    ret.value().append(target->label().name());
+    ret.value().push_back('.');
+    ret.value().append(extension);
+    return ret;
+  }
+
+  // Everything else goes next to the target's .ninja file like
+  // "<toolchain>/obj/<path>/<name>.<extension>".
+  ret.value().append(kObjectDirNoSlash);
+  AppendStringPiece(&ret.value(),
+                    target->label().dir().SourceAbsoluteWithOneSlash());
+  ret.value().append(target->label().name());
+  ret.value().push_back('.');
+  ret.value().append(extension);
+  return ret;
+}