[ui/base;css] adding string template expression replacement

ui/base/template_expressions.h

+// Copyright 2015 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.
+
+// This file defines utility functions for replacing template expressions.
+// For example "Hello ${name}" could have ${name} replaced by the user's name.
+
+#ifndef UI_BASE_TEMPLATE_EXPRESSIONS_H_
+#define UI_BASE_TEMPLATE_EXPRESSIONS_H_
+
+#include <map>
+#include <string>
+
+#include "base/strings/utf_string_conversions.h"
+#include "ui/base/ui_base_export.h"
+
+namespace ui {
+
+// Replace ${foo} in the format string with the value for the foo key in
+// |subst|. Additionally, any number of consecutive '$' characters is replaced
+// by that number less one. Eg $$ becomes $, $$$ becomes $$, etc.
+UI_BASE_EXPORT std::string ReplaceTemplateExpressions(
+    base::StringPiece format_string,
+    const std::map<base::StringPiece, std::string>& substitutions);
+UI_BASE_EXPORT base::string16 ReplaceTemplateExpressions(
+    const base::string16& format_string,
+    const std::map<base::string16, base::string16>& substitutions);
+UI_BASE_EXPORT std::string ReplaceTemplateExpressions(
+    const std::string& format_string,
+    const std::map<std::string, std::string>& substitutions);
+
+}  // namespace ui
+
+#endif  // UI_BASE_TEMPLATE_EXPRESSIONS_H_