Simplify adding callbacks.

chrome/browser/ui/webui/chromeos/login/base_screen_handler_utils.h

+// 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 CHROME_BROWSER_UI_WEBUI_CHROMEOS_LOGIN_BASE_SCREEN_HANDLER_UTILS_H_
+#define CHROME_BROWSER_UI_WEBUI_CHROMEOS_LOGIN_BASE_SCREEN_HANDLER_UTILS_H_
+
+#include <cstddef>
+#include <string>
+
+#include "base/callback.h"
+#include "base/logging.h"
+#include "base/string16.h"
+#include "base/values.h"
+
+namespace chromeos {
+
+template<typename T>
+struct UnwrapConstRef {
+  typedef T Type;
+};
+
+template<typename T>
+struct UnwrapConstRef<const T&> {
+  typedef T Type;
+};
+
+template<typename T>
+inline bool GetArg(const base::ListValue* args, size_t index, T* out_value);
+
+template<>
+inline bool GetArg<bool>(const base::ListValue* args,
+                         size_t index,
+                         bool* out_value) {
+  return args->GetBoolean(index, out_value);
+}
+
+template<>
+inline bool GetArg<int>(const base::ListValue* args,
+                        size_t index,
+                        int* out_value) {
+  return args->GetInteger(index, out_value);
+}
+
+template<>
+inline bool GetArg<double>(const base::ListValue* args,
+                           size_t index,
+                           double* out_value) {
+  return args->GetDouble(index, out_value);
+}
+
+template<>
+inline bool GetArg<std::string>(const base::ListValue* args,
+                                size_t index,
+                                std::string* out_value) {
+  return args->GetString(index, out_value);
+}
+
+template<>
+inline bool GetArg<string16>(const base::ListValue* args,
+                             size_t index,
+                             string16* out_value) {
+  return args->GetString(index, out_value);
+}
+
+inline void CallbackWrapper0(base::Callback<void()> callback,
+                             const base::ListValue* args) {
+  DCHECK(args);
+  DCHECK(args->empty());
+  callback.Run();
+}
+
+template<typename A1>
+void CallbackWrapper1(base::Callback<void(A1)> callback,
+                      const base::ListValue* args) {
+  DCHECK(args);
+  DCHECK_EQ(1u, args->GetSize());
+  typename UnwrapConstRef<A1>::Type arg1;
+  if (!GetArg(args, 0, &arg1)) {
+    NOTREACHED();
+    return;
+  }
+  callback.Run(arg1);
+}
+
+template<typename A1, typename A2>
+void CallbackWrapper2(base::Callback<void(A1, A2)> callback,
+                      const base::ListValue* args) {
+  DCHECK(args);
+  DCHECK_EQ(2u, args->GetSize());
+  typename UnwrapConstRef<A1>::Type arg1;
+  typename UnwrapConstRef<A2>::Type arg2;
+  if (!GetArg(args, 0, &arg1) || !GetArg(args, 1, &arg2)) {
+    NOTREACHED();
+    return;
+  }
+  callback.Run(arg1, arg2);
+}
+
+template<typename A1, typename A2, typename A3>
+void CallbackWrapper3(base::Callback<void(A1, A2, A3)> callback,
+                      const base::ListValue* args) {
+  DCHECK(args);
+  DCHECK_EQ(3u, args->GetSize());
+  typename UnwrapConstRef<A1>::Type arg1;
+  typename UnwrapConstRef<A2>::Type arg2;
+  typename UnwrapConstRef<A3>::Type arg3;
+  if (!GetArg(args, 0, &arg1) ||
+      !GetArg(args, 1, &arg2) ||
+      !GetArg(args, 2, &arg3)) {
+    NOTREACHED();
+    return;
+  }
+  callback.Run(arg1, arg2, arg3);
+}
+
+template<typename A1, typename A2, typename A3, typename A4>
+void CallbackWrapper4(base::Callback<void(A1, A2, A3, A4)> callback,
+                      const base::ListValue* args) {
+  DCHECK(args);
+  DCHECK_EQ(4u, args->GetSize());
+  typename UnwrapConstRef<A1>::Type arg1;
+  typename UnwrapConstRef<A2>::Type arg2;
+  typename UnwrapConstRef<A3>::Type arg3;
+  typename UnwrapConstRef<A4>::Type arg4;
+  if (!GetArg(args, 0, &arg1) ||
+      !GetArg(args, 1, &arg2) ||
+      !GetArg(args, 2, &arg3) ||
+      !GetArg(args, 3, &arg4)) {
+    NOTREACHED();
+    return;
+  }
+  callback.Run(arg1, arg2, arg3, arg4);
+}
+
+}  // namespace chromeos
+
+#endif  // CHROME_BROWSER_UI_WEBUI_CHROMEOS_LOGIN_BASE_SCREEN_HANDLER_UTILS_H_