Add initial prototype for the GN meta-buildsystem.

tools/gn/source_file.cc

Index: tools/gn/source_file.cc
diff --git a/tools/gn/source_file.cc b/tools/gn/source_file.cc
new file mode 100644
index 0000000000000000000000000000000000000000..de07de1171b0883e3584e87f1b865ce1bd949def
--- /dev/null
+++ b/tools/gn/source_file.cc
@@ -0,0 +1,67 @@
+// 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/source_file.h"
+
+#include "base/logging.h"
+#include "build/build_config.h"
+#include "tools/gn/filesystem_utils.h"
+#include "tools/gn/source_dir.h"
+
+SourceFile::SourceFile() {
+}
+
+SourceFile::SourceFile(const base::StringPiece& p)
+    : value_(p.data(), p.size()) {
+  DCHECK(!value_.empty());
+  DCHECK(value_[0] == '/');
+  DCHECK(!EndsWithSlash(value_));
+}
+
+SourceFile::~SourceFile() {
+}
+
+std::string SourceFile::GetName() const {
+  if (is_null())
+    return std::string();
+
+  DCHECK(value_.find('/') != std::string::npos);
+  size_t last_slash = value_.rfind('/');
+  return std::string(&value_[last_slash + 1],
+                     value_.size() - last_slash - 1);
+}
+
+SourceDir SourceFile::GetDir() const {
+  if (is_null())
+    return SourceDir();
+
+  DCHECK(value_.find('/') != std::string::npos);
+  size_t last_slash = value_.rfind('/');
+  return SourceDir(base::StringPiece(&value_[0], last_slash + 1));
+}
+
+base::FilePath SourceFile::Resolve(const base::FilePath& source_root) const {
+  if (is_null())
+    return base::FilePath();
+
+  std::string converted;
+#if defined(OS_WIN)
+  if (is_system_absolute()) {
+    converted.assign(&value_[1], value_.size() - 1);
+    DCHECK(converted.size() > 2 && converted[1] == ':')
+        << "Expecting Windows absolute file path with a drive letter: "
+        << value_;
+    return base::FilePath(UTF8ToFilePath(converted));
+  }
+
+  converted.assign(&value_[2], value_.size() - 2);
+  ConvertPathToSystem(&converted);
+  return root_path_.Append(UTF8ToFilePath(converted));
+#else
+  if (is_system_absolute())
+    return base::FilePath(value_);
+  converted.assign(&value_[2], value_.size() - 2);
+  return source_root.Append(converted);
+#endif
+}