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Side by Side Diff: sky/engine/bindings-dart/common/Nullable.h

Issue 918273002: Remove bindings-dart (Closed) Base URL: git@github.com:domokit/mojo.git@master
Patch Set: Created 5 years, 10 months ago
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1 // Copyright 2014 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 Nullable_h
6 #define Nullable_h
7
8 #include "platform/heap/Handle.h"
9 #include "wtf/Assertions.h"
10
11 namespace blink {
12
13 template <typename T>
14 class Nullable {
15 DISALLOW_ALLOCATION();
16 public:
17 Nullable()
18 : m_value()
19 , m_isNull(true) { }
20
21 Nullable(const T& value)
22 : m_value(value)
23 , m_isNull(false) { }
24
25 Nullable(const Nullable& other)
26 : m_value(other.m_value)
27 , m_isNull(other.m_isNull) { }
28
29 Nullable& operator=(const Nullable& other)
30 {
31 m_value = other.m_value;
32 m_isNull = other.m_isNull;
33 return *this;
34 }
35
36 void set(const T& value)
37 {
38 m_value = value;
39 m_isNull = false;
40 }
41 const T& get() const { ASSERT(!m_isNull); return m_value; }
42 T& get() { ASSERT(!m_isNull); return m_value; }
43 bool isNull() const { return m_isNull; }
44
45 // See comment in RefPtr.h about what UnspecifiedBoolType is.
46 typedef const T* UnspecifiedBoolType;
47 operator UnspecifiedBoolType() const { return m_isNull ? 0 : &m_value; }
48
49 bool operator==(const Nullable& other) const
50 {
51 return (m_isNull && other.m_isNull) || (!m_isNull && !other.m_isNull && m_value == other.m_value);
52 }
53
54 void trace(Visitor* visitor)
55 {
56 TraceIfNeeded<T>::trace(visitor, &m_value);
57 }
58
59 private:
60 T m_value;
61 bool m_isNull;
62 };
63
64 } // namespace blink
65
66 #endif // Nullable_h
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