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1 // Copyright (c) 2012 The Chromium Authors. All rights reserved. | 1 // Copyright (c) 2012 The Chromium Authors. All rights reserved. |
2 // Use of this source code is governed by a BSD-style license that can be | 2 // Use of this source code is governed by a BSD-style license that can be |
3 // found in the LICENSE file. | 3 // found in the LICENSE file. |
4 | 4 |
5 // This file specifies a recursive data storage class called Value intended for | 5 // This file specifies a recursive data storage class called Value intended for |
6 // storing settings and other persistable data. | 6 // storing settings and other persistable data. |
7 // | 7 // |
8 // A Value represents something that can be stored in JSON or passed to/from | 8 // A Value represents something that can be stored in JSON or passed to/from |
9 // JavaScript. As such, it is NOT a generalized variant type, since only the | 9 // JavaScript. As such, it is NOT a generalized variant type, since only the |
10 // types supported by JavaScript/JSON are supported. | 10 // types supported by JavaScript/JSON are supported. |
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30 #include "base/base_export.h" | 30 #include "base/base_export.h" |
31 #include "base/compiler_specific.h" | 31 #include "base/compiler_specific.h" |
32 #include "base/macros.h" | 32 #include "base/macros.h" |
33 #include "base/strings/string16.h" | 33 #include "base/strings/string16.h" |
34 #include "base/strings/string_piece.h" | 34 #include "base/strings/string_piece.h" |
35 | 35 |
36 namespace base { | 36 namespace base { |
37 | 37 |
38 class BinaryValue; | 38 class BinaryValue; |
39 class DictionaryValue; | 39 class DictionaryValue; |
40 class FundamentalValue; | |
41 class ListValue; | 40 class ListValue; |
42 class StringValue; | 41 class StringValue; |
43 class Value; | 42 class Value; |
| 43 using FundamentalValue = Value; |
44 | 44 |
45 // The Value class is the base class for Values. A Value can be instantiated | 45 // The Value class is the base class for Values. A Value can be instantiated |
46 // via the Create*Value() factory methods, or by directly creating instances of | 46 // via the Create*Value() factory methods, or by directly creating instances of |
47 // the subclasses. | 47 // the subclasses. |
48 // | 48 // |
49 // See the file-level comment above for more information. | 49 // See the file-level comment above for more information. |
50 class BASE_EXPORT Value { | 50 class BASE_EXPORT Value { |
51 public: | 51 public: |
52 enum class Type { | 52 enum class Type { |
53 NONE = 0, | 53 NONE = 0, |
54 BOOLEAN, | 54 BOOLEAN, |
55 INTEGER, | 55 INTEGER, |
56 DOUBLE, | 56 DOUBLE, |
57 STRING, | 57 STRING, |
58 BINARY, | 58 BINARY, |
59 DICTIONARY, | 59 DICTIONARY, |
60 LIST | 60 LIST |
61 // Note: Do not add more types. See the file-level comment above for why. | 61 // Note: Do not add more types. See the file-level comment above for why. |
62 }; | 62 }; |
63 | 63 |
| 64 static std::unique_ptr<Value> CreateNullValue(); |
| 65 |
| 66 Value(const Value& that); |
| 67 Value(Value&& that); |
| 68 Value(); // A null value. |
| 69 explicit Value(Type type); |
| 70 explicit Value(bool in_bool); |
| 71 explicit Value(int in_int); |
| 72 explicit Value(double in_double); |
| 73 |
| 74 Value& operator=(const Value& that); |
| 75 Value& operator=(Value&& that); |
| 76 |
64 virtual ~Value(); | 77 virtual ~Value(); |
65 | 78 |
66 static std::unique_ptr<Value> CreateNullValue(); | |
67 | |
68 // Returns the name for a given |type|. | 79 // Returns the name for a given |type|. |
69 static const char* GetTypeName(Type type); | 80 static const char* GetTypeName(Type type); |
70 | 81 |
71 // Returns the type of the value stored by the current Value object. | 82 // Returns the type of the value stored by the current Value object. |
72 // Each type will be implemented by only one subclass of Value, so it's | 83 // Each type will be implemented by only one subclass of Value, so it's |
73 // safe to use the Type to determine whether you can cast from | 84 // safe to use the Type to determine whether you can cast from |
74 // Value* to (Implementing Class)*. Also, a Value object never changes | 85 // Value* to (Implementing Class)*. Also, a Value object never changes |
75 // its type after construction. | 86 // its type after construction. |
76 Type GetType() const { return type_; } | 87 Type GetType() const { return type_; } // DEPRECATED, use type(). |
| 88 Type type() const { return type_; } |
77 | 89 |
78 // Returns true if the current object represents a given type. | 90 // Returns true if the current object represents a given type. |
79 bool IsType(Type type) const { return type == type_; } | 91 bool IsType(Type type) const { return type == type_; } |
| 92 bool is_bool() const { return type() == Type::BOOLEAN; } |
| 93 bool is_int() const { return type() == Type::INTEGER; } |
| 94 bool is_double() const { return type() == Type::DOUBLE; } |
| 95 bool is_string() const { return type() == Type::STRING; } |
| 96 bool is_blob() const { return type() == Type::BINARY; } |
| 97 bool is_dict() const { return type() == Type::DICTIONARY; } |
| 98 bool is_list() const { return type() == Type::LIST; } |
| 99 |
| 100 // These will all fatally assert if the type doesn't match. |
| 101 bool GetBool() const; |
| 102 int GetInt() const; |
| 103 double GetDouble() const; // Implicitly converts from int if necessary. |
80 | 104 |
81 // These methods allow the convenient retrieval of the contents of the Value. | 105 // These methods allow the convenient retrieval of the contents of the Value. |
82 // If the current object can be converted into the given type, the value is | 106 // If the current object can be converted into the given type, the value is |
83 // returned through the |out_value| parameter and true is returned; | 107 // returned through the |out_value| parameter and true is returned; |
84 // otherwise, false is returned and |out_value| is unchanged. | 108 // otherwise, false is returned and |out_value| is unchanged. |
85 virtual bool GetAsBoolean(bool* out_value) const; | 109 virtual bool GetAsBoolean(bool* out_value) const; |
86 virtual bool GetAsInteger(int* out_value) const; | 110 virtual bool GetAsInteger(int* out_value) const; |
87 virtual bool GetAsDouble(double* out_value) const; | 111 virtual bool GetAsDouble(double* out_value) const; |
88 virtual bool GetAsString(std::string* out_value) const; | 112 virtual bool GetAsString(std::string* out_value) const; |
89 virtual bool GetAsString(string16* out_value) const; | 113 virtual bool GetAsString(string16* out_value) const; |
90 virtual bool GetAsString(const StringValue** out_value) const; | 114 virtual bool GetAsString(const StringValue** out_value) const; |
91 virtual bool GetAsString(StringPiece* out_value) const; | 115 virtual bool GetAsString(StringPiece* out_value) const; |
92 virtual bool GetAsBinary(const BinaryValue** out_value) const; | 116 virtual bool GetAsBinary(const BinaryValue** out_value) const; |
93 // ListValue::From is the equivalent for std::unique_ptr conversions. | 117 // ListValue::From is the equivalent for std::unique_ptr conversions. |
94 virtual bool GetAsList(ListValue** out_value); | 118 virtual bool GetAsList(ListValue** out_value); |
95 virtual bool GetAsList(const ListValue** out_value) const; | 119 virtual bool GetAsList(const ListValue** out_value) const; |
96 // DictionaryValue::From is the equivalent for std::unique_ptr conversions. | 120 // DictionaryValue::From is the equivalent for std::unique_ptr conversions. |
97 virtual bool GetAsDictionary(DictionaryValue** out_value); | 121 virtual bool GetAsDictionary(DictionaryValue** out_value); |
98 virtual bool GetAsDictionary(const DictionaryValue** out_value) const; | 122 virtual bool GetAsDictionary(const DictionaryValue** out_value) const; |
99 // Note: Do not add more types. See the file-level comment above for why. | 123 // Note: Do not add more types. See the file-level comment above for why. |
100 | 124 |
101 // This creates a deep copy of the entire Value tree, and returns a pointer | 125 // This creates a deep copy of the entire Value tree, and returns a pointer |
102 // to the copy. The caller gets ownership of the copy, of course. | 126 // to the copy. The caller gets ownership of the copy, of course. |
103 // | |
104 // Subclasses return their own type directly in their overrides; | 127 // Subclasses return their own type directly in their overrides; |
105 // this works because C++ supports covariant return types. | 128 // this works because C++ supports covariant return types. |
106 virtual Value* DeepCopy() const; | 129 virtual Value* DeepCopy() const; |
107 // Preferred version of DeepCopy. TODO(estade): remove the above. | 130 // Preferred version of DeepCopy. TODO(estade): remove the above. |
108 std::unique_ptr<Value> CreateDeepCopy() const; | 131 std::unique_ptr<Value> CreateDeepCopy() const; |
109 | 132 |
110 // Compares if two Value objects have equal contents. | 133 // Compares if two Value objects have equal contents. |
111 virtual bool Equals(const Value* other) const; | 134 virtual bool Equals(const Value* other) const; |
112 | 135 |
113 // Compares if two Value objects have equal contents. Can handle NULLs. | 136 // Compares if two Value objects have equal contents. Can handle NULLs. |
114 // NULLs are considered equal but different from Value::CreateNullValue(). | 137 // NULLs are considered equal but different from Value::CreateNullValue(). |
115 static bool Equals(const Value* a, const Value* b); | 138 static bool Equals(const Value* a, const Value* b); |
116 | 139 |
117 protected: | 140 private: |
118 // These aren't safe for end-users, but they are useful for subclasses. | 141 void InternalCopyFrom(const Value& that); |
119 explicit Value(Type type); | |
120 Value(const Value& that); | |
121 Value& operator=(const Value& that); | |
122 | 142 |
123 private: | |
124 Type type_; | 143 Type type_; |
125 }; | |
126 | 144 |
127 // FundamentalValue represents the simple fundamental types of values. | |
128 class BASE_EXPORT FundamentalValue : public Value { | |
129 public: | |
130 explicit FundamentalValue(bool in_value); | |
131 explicit FundamentalValue(int in_value); | |
132 explicit FundamentalValue(double in_value); | |
133 ~FundamentalValue() override; | |
134 | |
135 // Overridden from Value: | |
136 bool GetAsBoolean(bool* out_value) const override; | |
137 bool GetAsInteger(int* out_value) const override; | |
138 // Values of both type Type::INTEGER and Type::DOUBLE can be obtained as | |
139 // doubles. | |
140 bool GetAsDouble(double* out_value) const override; | |
141 FundamentalValue* DeepCopy() const override; | |
142 bool Equals(const Value* other) const override; | |
143 | |
144 private: | |
145 union { | 145 union { |
146 bool boolean_value_; | 146 bool bool_value_; |
147 int integer_value_; | 147 int int_value_; |
148 double double_value_; | 148 double double_value_; |
149 }; | 149 }; |
150 }; | 150 }; |
151 | 151 |
152 class BASE_EXPORT StringValue : public Value { | 152 class BASE_EXPORT StringValue : public Value { |
153 public: | 153 public: |
154 // Initializes a StringValue with a UTF-8 narrow character string. | 154 // Initializes a StringValue with a UTF-8 narrow character string. |
155 explicit StringValue(StringPiece in_value); | 155 explicit StringValue(StringPiece in_value); |
156 | 156 |
157 // Initializes a StringValue with a string16. | 157 // Initializes a StringValue with a string16. |
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538 std::string* error_str) = 0; | 538 std::string* error_str) = 0; |
539 }; | 539 }; |
540 | 540 |
541 // Stream operator so Values can be used in assertion statements. In order that | 541 // Stream operator so Values can be used in assertion statements. In order that |
542 // gtest uses this operator to print readable output on test failures, we must | 542 // gtest uses this operator to print readable output on test failures, we must |
543 // override each specific type. Otherwise, the default template implementation | 543 // override each specific type. Otherwise, the default template implementation |
544 // is preferred over an upcast. | 544 // is preferred over an upcast. |
545 BASE_EXPORT std::ostream& operator<<(std::ostream& out, const Value& value); | 545 BASE_EXPORT std::ostream& operator<<(std::ostream& out, const Value& value); |
546 | 546 |
547 BASE_EXPORT inline std::ostream& operator<<(std::ostream& out, | 547 BASE_EXPORT inline std::ostream& operator<<(std::ostream& out, |
548 const FundamentalValue& value) { | |
549 return out << static_cast<const Value&>(value); | |
550 } | |
551 | |
552 BASE_EXPORT inline std::ostream& operator<<(std::ostream& out, | |
553 const StringValue& value) { | 548 const StringValue& value) { |
554 return out << static_cast<const Value&>(value); | 549 return out << static_cast<const Value&>(value); |
555 } | 550 } |
556 | 551 |
557 BASE_EXPORT inline std::ostream& operator<<(std::ostream& out, | 552 BASE_EXPORT inline std::ostream& operator<<(std::ostream& out, |
558 const DictionaryValue& value) { | 553 const DictionaryValue& value) { |
559 return out << static_cast<const Value&>(value); | 554 return out << static_cast<const Value&>(value); |
560 } | 555 } |
561 | 556 |
562 BASE_EXPORT inline std::ostream& operator<<(std::ostream& out, | 557 BASE_EXPORT inline std::ostream& operator<<(std::ostream& out, |
563 const ListValue& value) { | 558 const ListValue& value) { |
564 return out << static_cast<const Value&>(value); | 559 return out << static_cast<const Value&>(value); |
565 } | 560 } |
566 | 561 |
567 // Stream operator so that enum class Types can be used in log statements. | 562 // Stream operator so that enum class Types can be used in log statements. |
568 BASE_EXPORT std::ostream& operator<<(std::ostream& out, | 563 BASE_EXPORT std::ostream& operator<<(std::ostream& out, |
569 const Value::Type& type); | 564 const Value::Type& type); |
570 | 565 |
571 } // namespace base | 566 } // namespace base |
572 | 567 |
573 #endif // BASE_VALUES_H_ | 568 #endif // BASE_VALUES_H_ |
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