Refactorise the policy_path_parser framework

chrome/browser/policy/policy_path_parser.cc

+// Copyright 2014 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 "chrome/browser/policy/policy_path_parser.h"
+
+#include "base/bind.h"
+#include "base/files/file_path.h"
+
+namespace {
+
+void TrimQuotes(base::FilePath::StringType* path) {
+  if (path->length() > 1 &&
+      (((*path)[0] == FILE_PATH_LITERAL('"') &&
+        (*path)[path->length() - 1] == FILE_PATH_LITERAL('"')) ||
+       ((*path)[0] == FILE_PATH_LITERAL('\'') &&
+        (*path)[path->length() - 1] == FILE_PATH_LITERAL('\'')))) {
+    // Strip first and last char which should be matching quotes now.
+    *path = path->substr(1, path->length() - 2);
+  }
+}
+
+}  // namespace
+
+namespace policy {
+
+namespace path_parser {
+
+// This function performs a lazy call to the GetValueCallback, that is the
+// callback is invoked only if the variable is found in the path. This is done
+// to reduce the overhead during initialization.
+void ReplaceVariableInPathWithValue(
+    const base::FilePath::StringType& variable,
+    const policy::path_parser::internal::GetValueFuncPtr& value_func_ptr,
+    base::FilePath::StringType* path) {
+  size_t position = path->find(variable);
+  base::FilePath::StringType value;
+  if (position != base::FilePath::StringType::npos && value_func_ptr(&value))
+    path->replace(position, variable.length(), value);
+}
+
+// Replaces all variable occurrences in the policy string with the respective
+// system settings values.
+base::FilePath::StringType ExpandPathVariables(
+    const base::FilePath::StringType& untranslated_string) {
+  base::FilePath::StringType result(untranslated_string);
+
+  if (result.length() == 0)
+    return result;
+
+  // Sanitize quotes in case of any around the whole string.
+  TrimQuotes(&result);
+
+  base::FilePath::StringType variable;
+  internal::GetValueFuncPtr val_func_ptr;
+  for (int i = 0; i < internal::kNoOfVariables; ++i) {
+    variable = internal::kVariableNameAndValueCallbacks[i].name;
+    val_func_ptr = internal::kVariableNameAndValueCallbacks[i].value_func_ptr;
+    ReplaceVariableInPathWithValue(variable, val_func_ptr, &result);
+  }
+
+  return result;
+}
+
+}  // namespace path_parser
+
+}  // namespace policy