Revert 214325 "Revert 214254 "Add initial prototype for the GN m..."

The issue was already fixed :)

> Revert 214254 "Add initial prototype for the GN meta-buildsystem."
>
> It broke the check_licenses step on Android (see http://build.chromium.org/p/chromium.linux/builders/Android%20Builder%20%28dbg%29/builds/39904/steps/check_licenses/logs/stdio):
>
> @@@BUILD_STEP check_licenses@@@
> > /b/build/slave/Android_Builder__dbg_/build/src/android_webview/tools/webview_licenses.py scan
> Got LicenseError "missing README.chromium or licenses.py SPECIAL_CASES entry" while scanning tools/gn/secondary/base/third_party/dynamic_annotations
> Got LicenseError "missing README.chromium or licenses.py SPECIAL_CASES entry" while scanning tools/gn/secondary/third_party/modp_b64
> < /b/build/slave/Android_Builder__dbg_/build/src/android_webview/tools/webview_licenses.py scan
> ERROR: process exited with code 2
> @@@STEP_FAILURE@@@
>
>
> > Add initial prototype for the GN meta-buildsystem.
> >
> > This is currently not hooked into the build. To build, add a reference to the
> > gn.gyp file to build/all.gyp
> >
> > R=darin@chromium.org, scottmg@chromium.org
> >
> > Review URL: https://codereview.chromium.org/21114002
>
> TBR=brettw@chromium.org
>
> Review URL: https://codereview.chromium.org/21084010

TBR=bauerb@chromium.org

Review URL: https://codereview.chromium.org/21204003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@214333 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 57 insertions, 0 deletions

diff --git a/tools/gn/value_extractors.h b/tools/gn/value_extractors.h
new file mode 100644
index 0000000..556f44f
--- /dev/null
+++ b/tools/gn/value_extractors.h
@@ -0,0 +1,57 @@
+// 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.
+
+#ifndef TOOLS_GN_VALUE_EXTRACTORS_H_
+#define TOOLS_GN_VALUE_EXTRACTORS_H_
+
+#include <string>
+#include <vector>
+
+#include "tools/gn/value.h"
+
+class Err;
+class Label;
+class SourceDir;
+class SourceFile;
+
+// Sets the error and returns false on failure.
+template<typename T, class Converter>
+bool ListValueExtractor(const Value& value, std::vector<T>* dest,
+                        Err* err,
+                        const Converter& converter) {
+  if (!value.VerifyTypeIs(Value::LIST, err))
+    return false;
+  const std::vector<Value>& input_list = value.list_value();
+  dest->resize(input_list.size());
+  for (size_t i = 0; i < input_list.size(); i++) {
+    if (!converter(input_list[i], &(*dest)[i], err))
+      return false;
+  }
+  return true;
+}
+
+// On failure, returns false and sets the error.
+bool ExtractListOfStringValues(const Value& value,
+                               std::vector<std::string>* dest,
+                               Err* err);
+
+// Looks for a list of source files relative to a given current dir.
+bool ExtractListOfRelativeFiles(const Value& value,
+                                const SourceDir& current_dir,
+                                std::vector<SourceFile>* files,
+                                Err* err);
+
+// Looks for a list of source directories relative to a given current dir.
+bool ExtractListOfRelativeDirs(const Value& value,
+                               const SourceDir& current_dir,
+                               std::vector<SourceDir>* dest,
+                               Err* err);
+
+bool ExtractListOfLabels(const Value& value,
+                         const SourceDir& current_dir,
+                         const Label& current_toolchain,
+                         std::vector<Label>* dest,
+                         Err* err);
+
+#endif  // TOOLS_GN_VALUE_EXTRACTORS_H_