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comparison: dom/bindings/Nullable.h
dom/bindings/Nullable.h
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- TOR_BUG_9701
- changeset 8
- 97036ab72558
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| -1:000000000000 | 0:b1550ef6e800 |
|---|---|
| 1 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-*/ | |
| 2 /* vim: set ts=2 sw=2 et tw=79: */ | |
| 3 /* This Source Code Form is subject to the terms of the Mozilla Public | |
| 4 * License, v. 2.0. If a copy of the MPL was not distributed with this file, | |
| 5 * You can obtain one at http://mozilla.org/MPL/2.0/. */ | |
| 6 | |
| 7 #ifndef mozilla_dom_Nullable_h | |
| 8 #define mozilla_dom_Nullable_h | |
| 9 | |
| 10 #include "mozilla/Assertions.h" | |
| 11 #include "nsTArrayForwardDeclare.h" | |
| 12 #include "mozilla/Move.h" | |
| 13 | |
| 14 namespace mozilla { | |
| 15 namespace dom { | |
| 16 | |
| 17 // Support for nullable types | |
| 18 template <typename T> | |
| 19 struct Nullable | |
| 20 { | |
| 21 private: | |
| 22 // mIsNull MUST COME FIRST because otherwise the casting in our array | |
| 23 // conversion operators would shift where it is found in the struct. | |
| 24 bool mIsNull; | |
| 25 T mValue; | |
| 26 | |
| 27 public: | |
| 28 Nullable() | |
| 29 : mIsNull(true) | |
| 30 {} | |
| 31 | |
| 32 explicit Nullable(T aValue) | |
| 33 : mIsNull(false) | |
| 34 , mValue(aValue) | |
| 35 {} | |
| 36 | |
| 37 explicit Nullable(Nullable<T>&& aOther) | |
| 38 : mIsNull(aOther.mIsNull) | |
| 39 , mValue(mozilla::Move(aOther.mValue)) | |
| 40 {} | |
| 41 | |
| 42 Nullable(const Nullable<T>& aOther) | |
| 43 : mIsNull(aOther.mIsNull) | |
| 44 , mValue(aOther.mValue) | |
| 45 {} | |
| 46 | |
| 47 void operator=(const Nullable<T>& aOther) | |
| 48 { | |
| 49 mIsNull = aOther.mIsNull; | |
| 50 mValue = aOther.mValue; | |
| 51 } | |
| 52 | |
| 53 void SetValue(T aValue) { | |
| 54 mValue = aValue; | |
| 55 mIsNull = false; | |
| 56 } | |
| 57 | |
| 58 // For cases when |T| is some type with nontrivial copy behavior, we may want | |
| 59 // to get a reference to our internal copy of T and work with it directly | |
| 60 // instead of relying on the copying version of SetValue(). | |
| 61 T& SetValue() { | |
| 62 mIsNull = false; | |
| 63 return mValue; | |
| 64 } | |
| 65 | |
| 66 void SetNull() { | |
| 67 mIsNull = true; | |
| 68 } | |
| 69 | |
| 70 const T& Value() const { | |
| 71 MOZ_ASSERT(!mIsNull); | |
| 72 return mValue; | |
| 73 } | |
| 74 | |
| 75 T& Value() { | |
| 76 MOZ_ASSERT(!mIsNull); | |
| 77 return mValue; | |
| 78 } | |
| 79 | |
| 80 bool IsNull() const { | |
| 81 return mIsNull; | |
| 82 } | |
| 83 | |
| 84 bool Equals(const Nullable<T>& aOtherNullable) const | |
| 85 { | |
| 86 return (mIsNull && aOtherNullable.mIsNull) || | |
| 87 (!mIsNull && !aOtherNullable.mIsNull && | |
| 88 mValue == aOtherNullable.mValue); | |
| 89 } | |
| 90 | |
| 91 bool operator==(const Nullable<T>& aOtherNullable) const | |
| 92 { | |
| 93 return Equals(aOtherNullable); | |
| 94 } | |
| 95 | |
| 96 bool operator!=(const Nullable<T>& aOtherNullable) const | |
| 97 { | |
| 98 return !Equals(aOtherNullable); | |
| 99 } | |
| 100 | |
| 101 // Make it possible to use a const Nullable of an array type with other | |
| 102 // array types. | |
| 103 template<typename U> | |
| 104 operator const Nullable< nsTArray<U> >&() const { | |
| 105 // Make sure that T is ok to reinterpret to nsTArray<U> | |
| 106 const nsTArray<U>& arr = mValue; | |
| 107 (void)arr; | |
| 108 return *reinterpret_cast<const Nullable< nsTArray<U> >*>(this); | |
| 109 } | |
| 110 template<typename U> | |
| 111 operator const Nullable< FallibleTArray<U> >&() const { | |
| 112 // Make sure that T is ok to reinterpret to FallibleTArray<U> | |
| 113 const FallibleTArray<U>& arr = mValue; | |
| 114 (void)arr; | |
| 115 return *reinterpret_cast<const Nullable< FallibleTArray<U> >*>(this); | |
| 116 } | |
| 117 }; | |
| 118 | |
| 119 } // namespace dom | |
| 120 } // namespace mozilla | |
| 121 | |
| 122 #endif /* mozilla_dom_Nullable_h */ |
