| /* |
| * Copyright 2021 Google LLC. |
| * |
| * Use of this source code is governed by a BSD-style license that can be |
| * found in the LICENSE file. |
| */ |
| |
| #ifndef SkTOptional_DEFINED |
| #define SkTOptional_DEFINED |
| |
| #include "include/core/SkTypes.h" |
| |
| #include <utility> |
| |
| namespace skstd { |
| |
| /** |
| * Simple drop-in replacement for std::optional until we move to C++17. This does not have all of |
| * std::optional's capabilities, but it covers our needs for the time being. |
| */ |
| template<typename T> |
| class optional { |
| public: |
| optional(const T& value) |
| : fHasValue(true) { |
| new(&fPayload.fValue) T(value); |
| } |
| |
| optional(T&& value) |
| : fHasValue(true) { |
| new(&fPayload.fValue) T(std::move(value)); |
| } |
| |
| optional() {} |
| |
| optional(const optional& other) { |
| *this = other; |
| } |
| |
| // We need a non-const copy constructor because otherwise optional(nonConstSrc) isn't an exact |
| // match for the copy constructor, and we'd end up invoking the Args&&... template by mistake. |
| optional(optional& other) { |
| *this = other; |
| } |
| |
| optional(optional&& other) { |
| *this = std::move(other); |
| } |
| |
| template<typename... Args> |
| optional(Args&&... args) { |
| fHasValue = true; |
| new(&fPayload.fValue) T(std::forward<Args...>(args...)); |
| } |
| |
| ~optional() { |
| this->reset(); |
| } |
| |
| optional& operator=(const optional& other) { |
| if (this != &other) { |
| if (fHasValue) { |
| if (other.fHasValue) { |
| fPayload.fValue = other.fPayload.fValue; |
| } else { |
| this->reset(); |
| } |
| } else { |
| if (other.fHasValue) { |
| fHasValue = true; |
| new (&fPayload.fValue) T(other.fPayload.fValue); |
| } else { |
| // do nothing, no value on either side |
| } |
| } |
| } |
| return *this; |
| } |
| |
| optional& operator=(optional&& other) { |
| if (this != &other) { |
| if (fHasValue) { |
| if (other.fHasValue) { |
| fPayload.fValue = std::move(other.fPayload.fValue); |
| } else { |
| this->reset(); |
| } |
| } else { |
| if (other.fHasValue) { |
| fHasValue = true; |
| new (&fPayload.fValue) T(std::move(other.fPayload.fValue)); |
| } else { |
| // do nothing, no value on either side |
| } |
| } |
| } |
| return *this; |
| } |
| |
| const T& value() const { |
| SkASSERT(fHasValue); |
| return fPayload.fValue; |
| } |
| |
| T& value() { |
| return fPayload.fValue; |
| } |
| |
| T& operator*() { |
| SkASSERT(fHasValue); |
| return this->value(); |
| } |
| |
| T* operator->() { |
| SkASSERT(fHasValue); |
| return &this->value(); |
| } |
| |
| const T& operator*() const { |
| return this->value(); |
| } |
| |
| const T* operator->() const { |
| SkASSERT(fHasValue); |
| return &this->value(); |
| } |
| |
| bool has_value() const { |
| return fHasValue; |
| } |
| |
| explicit operator bool() const { |
| return this->has_value(); |
| } |
| |
| void reset() { |
| if (fHasValue) { |
| fPayload.fValue.~T(); |
| fHasValue = false; |
| } |
| } |
| |
| private: |
| union Payload { |
| T fValue; |
| |
| Payload() {} |
| |
| ~Payload() {} |
| } fPayload; |
| |
| bool fHasValue = false; |
| }; |
| |
| } // namespace skstd |
| |
| #endif |