Refactor chromedriver's script execution to reduce amount of custom Value parsing.

chrome/test/automation/value_conversion_traits.h

+// Copyright (c) 2011 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 CHROME_TEST_AUTOMATION_VALUE_CONVERSION_TRAITS_H_
+#define CHROME_TEST_AUTOMATION_VALUE_CONVERSION_TRAITS_H_
+#pragma once
+
+#include <string>
+
+namespace base {
+class DictionaryValue;
+class ListValue;
+class Value;
+}
+
+// ValueConversionTraits contains functions for converting between a base::Value
+// and a particular type. See particular function descriptions below.
+template <typename T>
+struct ValueConversionTraits {
+  // Create a value from |t|. Will not return NULL.
+  // static base::Value* CreateValueFrom(const T& t);
+
+  // Attempts to set |t| from the given value. Returns true on success.
+  // |t| will not be modified unless successful.
+  // static bool SetFromValue(const base::Value* value, T* t);
+
+  // Returns whether |value| can be converted to type |T|.
+  // If true, |SetFromValue| will succeed.
+  // static bool CanConvert(const base::Value* value);
+};
+
+template <>
+struct ValueConversionTraits<int> {
+  static base::Value* CreateValueFrom(int t);
+  static bool SetFromValue(const base::Value* value, int* t);
+  static bool CanConvert(const base::Value* value);
+};
+
+template <>
+struct ValueConversionTraits<bool> {
+  static base::Value* CreateValueFrom(bool t);
+  static bool SetFromValue(const base::Value* value, bool* t);
+  static bool CanConvert(const base::Value* value);
+};
+
+template <>
+struct ValueConversionTraits<std::string> {
+  static base::Value* CreateValueFrom(const std::string& t);
+  static bool SetFromValue(const base::Value* value, std::string* t);
+  static bool CanConvert(const base::Value* value);
+};
+
+// The conversion will involve deep copying, not just casting.
+template <>
+struct ValueConversionTraits<base::Value*> {
+  static base::Value* CreateValueFrom(const base::Value* t);
+  static bool SetFromValue(const base::Value* value, base::Value** t);
+  static bool CanConvert(const base::Value* value);
+};
+
+// The conversion will involve deep copying, not just casting.
+template <>
+struct ValueConversionTraits<base::ListValue*> {
+  static base::Value* CreateValueFrom(const base::ListValue* t);
+  static bool SetFromValue(const base::Value* value, base::ListValue** t);
+  static bool CanConvert(const base::Value* value);
+};
+
+// The conversion will involve deep copying, not just casting.
+template <>
+struct ValueConversionTraits<base::DictionaryValue*> {
+  static base::Value* CreateValueFrom(const base::DictionaryValue* t);
+  static bool SetFromValue(const base::Value* value, base::DictionaryValue** t);
+  static bool CanConvert(const base::Value* value);
+};
+
+#endif  // CHROME_TEST_AUTOMATION_VALUE_CONVERSION_TRAITS_H_