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1 // Copyright 2016 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 MOJO_PUBLIC_CPP_BINDINGS_WTF_ARRAY_H_ | |
6 #define MOJO_PUBLIC_CPP_BINDINGS_WTF_ARRAY_H_ | |
7 | |
8 #include <stddef.h> | |
9 #include <utility> | |
10 | |
11 #include "base/macros.h" | |
12 #include "mojo/public/cpp/bindings/lib/array_internal.h" | |
13 #include "mojo/public/cpp/bindings/lib/bindings_internal.h" | |
14 #include "mojo/public/cpp/bindings/lib/template_util.h" | |
15 #include "mojo/public/cpp/bindings/lib/wtf_clone_equals_util.h" | |
16 #include "mojo/public/cpp/bindings/type_converter.h" | |
17 #include "third_party/WebKit/Source/wtf/Vector.h" | |
18 | |
19 namespace mojo { | |
20 | |
21 // Represents an array backed by WTF::Vector. Comparing with WTF::Vector, | |
22 // mojo::WTFArray is move-only and can be null. | |
23 // It is easy to convert between WTF::Vector<T> and mojo::WTFArray<T>: | |
24 // - constructor WTFArray(WTF::Vector<T>&&) takes the contents of a | |
25 // WTF::Vector<T>; | |
26 // - method PassStorage() passes the underlying WTF::Vector. | |
27 template <typename T> | |
28 class WTFArray { | |
29 public: | |
30 // Constructs an empty array. | |
31 WTFArray() : is_null_(false) {} | |
32 // Constructs a null array. | |
33 WTFArray(std::nullptr_t null_pointer) : is_null_(true) {} | |
34 | |
35 // Constructs a new non-null array of the specified size. The elements will | |
36 // be value-initialized (meaning that they will be initialized by their | |
37 // default constructor, if any, or else zero-initialized). | |
38 explicit WTFArray(size_t size) : vec_(size), is_null_(false) {} | |
39 ~WTFArray() {} | |
40 | |
41 // Moves the contents of |other| into this array. | |
42 WTFArray(WTF::Vector<T>&& other) : vec_(std::move(other)), is_null_(false) {} | |
43 WTFArray(WTFArray&& other) : is_null_(true) { Take(&other); } | |
44 | |
45 WTFArray& operator=(WTF::Vector<T>&& other) { | |
46 vec_ = std::move(other); | |
47 is_null_ = false; | |
48 return *this; | |
49 } | |
50 WTFArray& operator=(WTFArray&& other) { | |
51 Take(&other); | |
52 return *this; | |
53 } | |
54 | |
55 WTFArray& operator=(std::nullptr_t null_pointer) { | |
56 is_null_ = true; | |
57 vec_.clear(); | |
58 return *this; | |
59 } | |
60 | |
61 // Creates a non-null array of the specified size. The elements will be | |
62 // value-initialized (meaning that they will be initialized by their default | |
63 // constructor, if any, or else zero-initialized). | |
64 static WTFArray New(size_t size) { return WTFArray(size); } | |
65 | |
66 // Creates a new array with a copy of the contents of |other|. | |
67 template <typename U> | |
68 static WTFArray From(const U& other) { | |
69 return TypeConverter<WTFArray, U>::Convert(other); | |
70 } | |
71 | |
72 // Copies the contents of this array to a new object of type |U|. | |
73 template <typename U> | |
74 U To() const { | |
75 return TypeConverter<U, WTFArray>::Convert(*this); | |
76 } | |
77 | |
78 // Indicates whether the array is null (which is distinct from empty). | |
79 bool is_null() const { | |
80 // When the array is set to null, the underlying storage |vec_| shouldn't | |
81 // contain any elements. | |
82 DCHECK(!is_null_ || vec_.isEmpty()); | |
83 return is_null_; | |
84 } | |
85 | |
86 // Indicates whether the array is empty (which is distinct from null). | |
87 bool empty() const { return vec_.isEmpty() && !is_null_; } | |
88 | |
89 // Returns a reference to the first element of the array. Calling this on a | |
90 // null or empty array causes undefined behavior. | |
91 const T& front() const { return vec_.front(); } | |
92 T& front() { return vec_.front(); } | |
93 | |
94 // Returns the size of the array, which will be zero if the array is null. | |
95 size_t size() const { return vec_.size(); } | |
96 | |
97 // Returns a reference to the element at zero-based |offset|. Calling this on | |
98 // an array with size less than |offset|+1 causes undefined behavior. | |
99 const T& at(size_t offset) const { return vec_.at(offset); } | |
100 const T& operator[](size_t offset) const { return at(offset); } | |
101 T& at(size_t offset) { return vec_.at(offset); } | |
102 T& operator[](size_t offset) { return at(offset); } | |
103 | |
104 // Resizes the array to |size| and makes it non-null. Otherwise, works just | |
105 // like the resize method of |WTF::Vector|. | |
106 void resize(size_t size) { | |
107 is_null_ = false; | |
108 vec_.resize(size); | |
109 } | |
110 | |
111 // Sets the array to empty (even if previously it was null.) | |
112 void SetToEmpty() { resize(0); } | |
113 | |
114 // Returns a const reference to the |WTF::Vector| managed by this class. If | |
115 // the array is null, this will be an empty vector. | |
116 const WTF::Vector<T>& storage() const { return vec_; } | |
117 | |
118 // Passes the underlying storage and resets this array to null. | |
119 // | |
120 // TODO(yzshen): Consider changing this to a rvalue-ref-qualified conversion | |
121 // to WTF::Vector<T> after we move to MSVC 2015. | |
122 WTF::Vector<T> PassStorage() { | |
123 is_null_ = true; | |
124 return std::move(vec_); | |
125 } | |
126 | |
127 void Swap(WTFArray* other) { | |
128 std::swap(is_null_, other->is_null_); | |
129 vec_.swap(other->vec_); | |
130 } | |
131 | |
132 // Swaps the contents of this array with the specified vector, making this | |
133 // array non-null. Since the vector cannot represent null, it will just be | |
134 // made empty if this array is null. | |
135 void Swap(WTF::Vector<T>* other) { | |
136 is_null_ = false; | |
137 vec_.swap(*other); | |
138 } | |
139 | |
140 // Returns a copy of the array where each value of the new array has been | |
141 // "cloned" from the corresponding value of this array. If the element type | |
142 // defines a Clone() method, it will be used; otherwise copy | |
143 // constructor/assignment will be used. | |
144 // | |
145 // Please note that calling this method will fail compilation if the element | |
146 // type cannot be cloned (which usually means that it is a Mojo handle type or | |
147 // a type containing Mojo handles). | |
148 WTFArray Clone() const { | |
149 WTFArray result; | |
150 result.is_null_ = is_null_; | |
151 result.vec_ = internal::Clone(vec_); | |
152 return result; | |
153 } | |
154 | |
155 // Indicates whether the contents of this array are equal to |other|. A null | |
156 // array is only equal to another null array. If the element type defines an | |
157 // Equals() method, it will be used; otherwise == operator will be used. | |
158 bool Equals(const WTFArray& other) const { | |
159 if (is_null() != other.is_null()) | |
160 return false; | |
161 return internal::Equals(vec_, other.vec_); | |
162 } | |
163 | |
164 private: | |
165 // TODO(dcheng): Use an explicit conversion operator. | |
166 typedef WTF::Vector<T> WTFArray::*Testable; | |
167 | |
168 public: | |
169 operator Testable() const { | |
170 // When the array is set to null, the underlying storage |vec_| shouldn't | |
171 // contain any elements. | |
172 DCHECK(!is_null_ || vec_.isEmpty()); | |
173 return is_null_ ? 0 : &WTFArray::vec_; | |
174 } | |
175 | |
176 private: | |
177 // Forbid the == and != operators explicitly, otherwise WTFArray will be | |
178 // converted to Testable to do == or != comparison. | |
179 template <typename U> | |
180 bool operator==(const WTFArray<U>& other) const = delete; | |
181 template <typename U> | |
182 bool operator!=(const WTFArray<U>& other) const = delete; | |
183 | |
184 void Take(WTFArray* other) { | |
185 operator=(nullptr); | |
186 Swap(other); | |
187 } | |
188 | |
189 WTF::Vector<T> vec_; | |
190 bool is_null_; | |
191 | |
192 DISALLOW_COPY_AND_ASSIGN(WTFArray); | |
193 }; | |
194 | |
195 } // namespace mojo | |
196 | |
197 #endif // MOJO_PUBLIC_CPP_BINDINGS_WTF_ARRAY_H_ | |
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