Add initial prototype for the GN meta-buildsystem.

tools/gn/function_write_file.cc

Index: tools/gn/function_write_file.cc
diff --git a/tools/gn/function_write_file.cc b/tools/gn/function_write_file.cc
new file mode 100644
index 0000000000000000000000000000000000000000..9356feb0495bac3bd76b04b7218e730a60431970
--- /dev/null
+++ b/tools/gn/function_write_file.cc
@@ -0,0 +1,84 @@
+// 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 <iostream>
+#include <sstream>
+
+#include "base/file_util.h"
+#include "base/strings/string_split.h"
+#include "base/strings/string_util.h"
+#include "tools/gn/err.h"
+#include "tools/gn/filesystem_utils.h"
+#include "tools/gn/functions.h"
+#include "tools/gn/input_file.h"
+#include "tools/gn/parse_tree.h"
+#include "tools/gn/scheduler.h"
+
+/*
+write_file: Read a file into a variable.
+
+  write_file(filename, data)
+
+  If data is a list, the list will be written one-item-per-line with no
+  quoting or brackets.
+
+  TODO(brettw) we probably need an optional third argument to control list
+  formatting.
+
+Arguments:
+
+  filename:
+      Filename to write. This must be within the output directory.
+
+  data:
+      The list or string to write.
+*/
+Value ExecuteWriteFile(Scope* scope,
+                       const FunctionCallNode* function,
+                       const std::vector<Value>& args,
+                       Err* err) {
+  if (args.size() != 2) {
+    *err = Err(function->function(), "Wrong number of args to write_file",
+               "I expected two arguments.");
+    return Value();
+  }
+
+  // Compute the file name and make sure it's in the output dir.
+  if (!args[0].VerifyTypeIs(Value::STRING, err))
+    return Value();
+  const SourceDir& cur_dir = SourceDirForFunctionCall(function);
+  SourceFile source_file = cur_dir.ResolveRelativeFile(args[0].string_value());
+  if (!EnsureStringIsInOutputDir(
+          scope->settings()->build_settings()->build_dir(),
+          source_file.value(), args[0], err))
+    return Value();
+
+  // Compute output.
+  std::ostringstream contents;
+  if (args[1].type() == Value::LIST) {
+    const std::vector<Value>& list = args[1].list_value();
+    for (size_t i = 0; i < list.size(); i++)
+      contents << list[i].ToString() << std::endl;
+  } else {
+    contents << args[1].ToString();
+  }
+
+  // Write file, creating the directory if necessary.
+  base::FilePath file_path =
+      scope->settings()->build_settings()->GetFullPath(source_file);
+  const std::string& contents_string = contents.str();
+  if (!file_util::CreateDirectory(file_path.DirName())) {
+    *err = Err(function->function(), "Unable to create directory.",
+               "I was using \"" + FilePathToUTF8(file_path.DirName()) + "\".");
+    return Value();
+  }
+  if (file_util::WriteFile(file_path,
+                           contents_string.c_str(), contents_string.size())
+      != static_cast<int>(contents_string.size())) {
+    *err = Err(function->function(), "Unable to write file.",
+               "I was writing \"" + FilePathToUTF8(file_path) + "\".");
+    return Value();
+  }
+  return Value();
+}