| // 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. |
| |
| #ifndef SKY_ENGINE_BINDINGS_NULLABLE_H_ |
| #define SKY_ENGINE_BINDINGS_NULLABLE_H_ |
| |
| #include "base/logging.h" |
| |
| namespace blink { |
| |
| template <typename T> |
| class Nullable { |
| public: |
| Nullable() : value_(), is_null_(true) {} |
| Nullable(const T& value) : value_(value), is_null_(false) {} |
| Nullable(const Nullable& other) |
| : value_(other.value_), is_null_(other.is_null_) {} |
| |
| Nullable& operator=(const Nullable& other) = default; |
| |
| void set(const T& value) { |
| value_ = value; |
| is_null_ = false; |
| } |
| |
| const T& get() const { |
| DCHECK(!is_null_); |
| return value_; |
| } |
| T& get() { |
| DCHECK(!is_null_); |
| return value_; |
| } |
| |
| bool is_null() const { return is_null_; } |
| |
| // See comment in RefPtr.h about what UnspecifiedBoolType is. |
| typedef const T* UnspecifiedBoolType; |
| operator UnspecifiedBoolType() const { return is_null_ ? 0 : &value_; } |
| |
| bool operator==(const Nullable& other) const { |
| return (is_null_ && other.is_null_) || |
| (!is_null_ && !other.is_null_ && value_ == other.value_); |
| } |
| |
| private: |
| T value_; |
| bool is_null_; |
| }; |
| |
| } // namespace blink |
| |
| #endif // SKY_ENGINE_BINDINGS_NULLABLE_H_ |