1 // Copyright (c) 2013 The Chromium Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style license that can be 3 // found in the LICENSE file. 4 5 #ifndef PPAPI_CPP_EXTENSIONS_OPTIONAL_H_ 6 #define PPAPI_CPP_EXTENSIONS_OPTIONAL_H_ 7 8 namespace pp { 9 namespace ext { 10 11 template <class T> 12 class Optional { 13 public: 14 Optional() : value_(NULL) { 15 } 16 // Takes ownership of |value|. 17 explicit Optional(T* value) : value_(value) { 18 } 19 Optional(const T& value) : value_(new T(value)) { 20 } 21 Optional(const Optional<T>& other) 22 : value_(other.value_ ? new T(*other.value_) : NULL) { 23 } 24 25 ~Optional() { 26 Reset(); 27 } 28 29 Optional<T>& operator=(const T& other) { 30 if (value_ == &other) 31 return *this; 32 33 Reset(); 34 value_ = new T(other); 35 36 return *this; 37 } 38 39 Optional<T>& operator=(const Optional<T>& other) { 40 if (value_ == other.value_) 41 return *this; 42 43 Reset(); 44 if (other.value_) 45 value_ = new T(*other.value_); 46 47 return *this; 48 } 49 50 bool IsSet() const { 51 return !!value_; 52 } 53 54 T* Get() const { 55 return value_; 56 } 57 58 // Should only be used when IsSet() is true. 59 T& operator*() const { 60 return *value_; 61 } 62 63 // Should only be used when IsSet() is true. 64 T* operator->() const { 65 PP_DCHECK(value_); 66 return value_; 67 } 68 69 // Takes ownership of |value|. 70 void Set(T* value) { 71 if (value == value_) 72 return; 73 74 Reset(); 75 *value_ = value; 76 } 77 78 void Reset() { 79 T* value = value_; 80 value_ = NULL; 81 delete value; 82 } 83 84 void Swap(Optional<T>* other) { 85 T* temp = value_; 86 value_ = other->value_; 87 other->value_ = temp; 88 } 89 90 private: 91 T* value_; 92 }; 93 94 } // namespace ext 95 } // namespace pp 96 97 #endif // PPAPI_CPP_EXTENSIONS_OPTIONAL_H_ 98
