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 3 // found in the LICENSE file. 4 5 // This file specifies a recursive data storage class called Value intended for 6 // storing settings and other persistable data. 7 // 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 10 // types supported by JavaScript/JSON are supported. 11 // 12 // IN PARTICULAR this means that there is no support for int64_t or unsigned 13 // numbers. Writing JSON with such types would violate the spec. If you need 14 // something like this, either use a double or make a string value containing 15 // the number you want. 16 17 #ifndef BASE_VALUES_H_ 18 #define BASE_VALUES_H_ 19 20 #include <stddef.h> 21 #include <stdint.h> 22 23 #include <iosfwd> 24 #include <map> 25 #include <string> 26 #include <utility> 27 #include <vector> 28 29 #include "base/base_export.h" 30 #include "base/compiler_specific.h" 31 #include "base/macros.h" 32 #include "base/memory/scoped_ptr.h" 33 #include "base/strings/string16.h" 34 #include "base/strings/string_piece.h" 35 36 namespace base { 37 38 class BinaryValue; 39 class DictionaryValue; 40 class FundamentalValue; 41 class ListValue; 42 class StringValue; 43 class Value; 44 45 typedef std::vector<Value*> ValueVector; 46 typedef std::map<std::string, Value*> ValueMap; 47 48 // The Value class is the base class for Values. A Value can be instantiated 49 // via the Create*Value() factory methods, or by directly creating instances of 50 // the subclasses. 51 // 52 // See the file-level comment above for more information. 53 class BASE_EXPORT Value { 54 public: 55 enum Type { 56 TYPE_NULL = 0, 57 TYPE_BOOLEAN, 58 TYPE_INTEGER, 59 TYPE_DOUBLE, 60 TYPE_STRING, 61 TYPE_BINARY, 62 TYPE_DICTIONARY, 63 TYPE_LIST 64 // Note: Do not add more types. See the file-level comment above for why. 65 }; 66 67 virtual ~Value(); 68 69 static scoped_ptr<Value> CreateNullValue(); 70 71 // 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 73 // safe to use the Type to determine whether you can cast from 74 // Value* to (Implementing Class)*. Also, a Value object never changes 75 // its type after construction. GetType()76 Type GetType() const { return type_; } 77 78 // Returns true if the current object represents a given type. IsType(Type type)79 bool IsType(Type type) const { return type == type_; } 80 81 // 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 83 // returned through the |out_value| parameter and true is returned; 84 // otherwise, false is returned and |out_value| is unchanged. 85 virtual bool GetAsBoolean(bool* out_value) const; 86 virtual bool GetAsInteger(int* out_value) const; 87 virtual bool GetAsDouble(double* out_value) const; 88 virtual bool GetAsString(std::string* out_value) const; 89 virtual bool GetAsString(string16* out_value) const; 90 virtual bool GetAsString(const StringValue** out_value) const; 91 virtual bool GetAsBinary(const BinaryValue** out_value) const; 92 virtual bool GetAsList(ListValue** out_value); 93 virtual bool GetAsList(const ListValue** out_value) const; 94 virtual bool GetAsDictionary(DictionaryValue** out_value); 95 virtual bool GetAsDictionary(const DictionaryValue** out_value) const; 96 // Note: Do not add more types. See the file-level comment above for why. 97 98 // This creates a deep copy of the entire Value tree, and returns a pointer 99 // to the copy. The caller gets ownership of the copy, of course. 100 // 101 // Subclasses return their own type directly in their overrides; 102 // this works because C++ supports covariant return types. 103 virtual Value* DeepCopy() const; 104 // Preferred version of DeepCopy. TODO(estade): remove the above. 105 scoped_ptr<Value> CreateDeepCopy() const; 106 107 // Compares if two Value objects have equal contents. 108 virtual bool Equals(const Value* other) const; 109 110 // Compares if two Value objects have equal contents. Can handle NULLs. 111 // NULLs are considered equal but different from Value::CreateNullValue(). 112 static bool Equals(const Value* a, const Value* b); 113 114 protected: 115 // These aren't safe for end-users, but they are useful for subclasses. 116 explicit Value(Type type); 117 Value(const Value& that); 118 Value& operator=(const Value& that); 119 120 private: 121 Type type_; 122 }; 123 124 // FundamentalValue represents the simple fundamental types of values. 125 class BASE_EXPORT FundamentalValue : public Value { 126 public: 127 explicit FundamentalValue(bool in_value); 128 explicit FundamentalValue(int in_value); 129 explicit FundamentalValue(double in_value); 130 ~FundamentalValue() override; 131 132 // Overridden from Value: 133 bool GetAsBoolean(bool* out_value) const override; 134 bool GetAsInteger(int* out_value) const override; 135 // Values of both type TYPE_INTEGER and TYPE_DOUBLE can be obtained as 136 // doubles. 137 bool GetAsDouble(double* out_value) const override; 138 FundamentalValue* DeepCopy() const override; 139 bool Equals(const Value* other) const override; 140 141 private: 142 union { 143 bool boolean_value_; 144 int integer_value_; 145 double double_value_; 146 }; 147 }; 148 149 class BASE_EXPORT StringValue : public Value { 150 public: 151 // Initializes a StringValue with a UTF-8 narrow character string. 152 explicit StringValue(const std::string& in_value); 153 154 // Initializes a StringValue with a string16. 155 explicit StringValue(const string16& in_value); 156 157 ~StringValue() override; 158 159 // Returns |value_| as a pointer or reference. 160 std::string* GetString(); 161 const std::string& GetString() const; 162 163 // Overridden from Value: 164 bool GetAsString(std::string* out_value) const override; 165 bool GetAsString(string16* out_value) const override; 166 bool GetAsString(const StringValue** out_value) const override; 167 StringValue* DeepCopy() const override; 168 bool Equals(const Value* other) const override; 169 170 private: 171 std::string value_; 172 }; 173 174 class BASE_EXPORT BinaryValue: public Value { 175 public: 176 // Creates a BinaryValue with a null buffer and size of 0. 177 BinaryValue(); 178 179 // Creates a BinaryValue, taking ownership of the bytes pointed to by 180 // |buffer|. 181 BinaryValue(scoped_ptr<char[]> buffer, size_t size); 182 183 ~BinaryValue() override; 184 185 // For situations where you want to keep ownership of your buffer, this 186 // factory method creates a new BinaryValue by copying the contents of the 187 // buffer that's passed in. 188 static BinaryValue* CreateWithCopiedBuffer(const char* buffer, size_t size); 189 GetSize()190 size_t GetSize() const { return size_; } 191 192 // May return NULL. GetBuffer()193 char* GetBuffer() { return buffer_.get(); } GetBuffer()194 const char* GetBuffer() const { return buffer_.get(); } 195 196 // Overridden from Value: 197 bool GetAsBinary(const BinaryValue** out_value) const override; 198 BinaryValue* DeepCopy() const override; 199 bool Equals(const Value* other) const override; 200 201 private: 202 scoped_ptr<char[]> buffer_; 203 size_t size_; 204 205 DISALLOW_COPY_AND_ASSIGN(BinaryValue); 206 }; 207 208 // DictionaryValue provides a key-value dictionary with (optional) "path" 209 // parsing for recursive access; see the comment at the top of the file. Keys 210 // are |std::string|s and should be UTF-8 encoded. 211 class BASE_EXPORT DictionaryValue : public Value { 212 public: 213 // Returns |value| if it is a dictionary, nullptr otherwise. 214 static scoped_ptr<DictionaryValue> From(scoped_ptr<Value> value); 215 216 DictionaryValue(); 217 ~DictionaryValue() override; 218 219 // Overridden from Value: 220 bool GetAsDictionary(DictionaryValue** out_value) override; 221 bool GetAsDictionary(const DictionaryValue** out_value) const override; 222 223 // Returns true if the current dictionary has a value for the given key. 224 bool HasKey(const std::string& key) const; 225 226 // Returns the number of Values in this dictionary. size()227 size_t size() const { return dictionary_.size(); } 228 229 // Returns whether the dictionary is empty. empty()230 bool empty() const { return dictionary_.empty(); } 231 232 // Clears any current contents of this dictionary. 233 void Clear(); 234 235 // Sets the Value associated with the given path starting from this object. 236 // A path has the form "<key>" or "<key>.<key>.[...]", where "." indexes 237 // into the next DictionaryValue down. Obviously, "." can't be used 238 // within a key, but there are no other restrictions on keys. 239 // If the key at any step of the way doesn't exist, or exists but isn't 240 // a DictionaryValue, a new DictionaryValue will be created and attached 241 // to the path in that location. |in_value| must be non-null. 242 void Set(const std::string& path, scoped_ptr<Value> in_value); 243 // Deprecated version of the above. TODO(estade): remove. 244 void Set(const std::string& path, Value* in_value); 245 246 // Convenience forms of Set(). These methods will replace any existing 247 // value at that path, even if it has a different type. 248 void SetBoolean(const std::string& path, bool in_value); 249 void SetInteger(const std::string& path, int in_value); 250 void SetDouble(const std::string& path, double in_value); 251 void SetString(const std::string& path, const std::string& in_value); 252 void SetString(const std::string& path, const string16& in_value); 253 254 // Like Set(), but without special treatment of '.'. This allows e.g. URLs to 255 // be used as paths. 256 void SetWithoutPathExpansion(const std::string& key, 257 scoped_ptr<Value> in_value); 258 // Deprecated version of the above. TODO(estade): remove. 259 void SetWithoutPathExpansion(const std::string& key, Value* in_value); 260 261 // Convenience forms of SetWithoutPathExpansion(). 262 void SetBooleanWithoutPathExpansion(const std::string& path, bool in_value); 263 void SetIntegerWithoutPathExpansion(const std::string& path, int in_value); 264 void SetDoubleWithoutPathExpansion(const std::string& path, double in_value); 265 void SetStringWithoutPathExpansion(const std::string& path, 266 const std::string& in_value); 267 void SetStringWithoutPathExpansion(const std::string& path, 268 const string16& in_value); 269 270 // Gets the Value associated with the given path starting from this object. 271 // A path has the form "<key>" or "<key>.<key>.[...]", where "." indexes 272 // into the next DictionaryValue down. If the path can be resolved 273 // successfully, the value for the last key in the path will be returned 274 // through the |out_value| parameter, and the function will return true. 275 // Otherwise, it will return false and |out_value| will be untouched. 276 // Note that the dictionary always owns the value that's returned. 277 // |out_value| is optional and will only be set if non-NULL. 278 bool Get(StringPiece path, const Value** out_value) const; 279 bool Get(StringPiece path, Value** out_value); 280 281 // These are convenience forms of Get(). The value will be retrieved 282 // and the return value will be true if the path is valid and the value at 283 // the end of the path can be returned in the form specified. 284 // |out_value| is optional and will only be set if non-NULL. 285 bool GetBoolean(const std::string& path, bool* out_value) const; 286 bool GetInteger(const std::string& path, int* out_value) const; 287 // Values of both type TYPE_INTEGER and TYPE_DOUBLE can be obtained as 288 // doubles. 289 bool GetDouble(const std::string& path, double* out_value) const; 290 bool GetString(const std::string& path, std::string* out_value) const; 291 bool GetString(const std::string& path, string16* out_value) const; 292 bool GetStringASCII(const std::string& path, std::string* out_value) const; 293 bool GetBinary(const std::string& path, const BinaryValue** out_value) const; 294 bool GetBinary(const std::string& path, BinaryValue** out_value); 295 bool GetDictionary(StringPiece path, 296 const DictionaryValue** out_value) const; 297 bool GetDictionary(StringPiece path, DictionaryValue** out_value); 298 bool GetList(const std::string& path, const ListValue** out_value) const; 299 bool GetList(const std::string& path, ListValue** out_value); 300 301 // Like Get(), but without special treatment of '.'. This allows e.g. URLs to 302 // be used as paths. 303 bool GetWithoutPathExpansion(const std::string& key, 304 const Value** out_value) const; 305 bool GetWithoutPathExpansion(const std::string& key, Value** out_value); 306 bool GetBooleanWithoutPathExpansion(const std::string& key, 307 bool* out_value) const; 308 bool GetIntegerWithoutPathExpansion(const std::string& key, 309 int* out_value) const; 310 bool GetDoubleWithoutPathExpansion(const std::string& key, 311 double* out_value) const; 312 bool GetStringWithoutPathExpansion(const std::string& key, 313 std::string* out_value) const; 314 bool GetStringWithoutPathExpansion(const std::string& key, 315 string16* out_value) const; 316 bool GetDictionaryWithoutPathExpansion( 317 const std::string& key, 318 const DictionaryValue** out_value) const; 319 bool GetDictionaryWithoutPathExpansion(const std::string& key, 320 DictionaryValue** out_value); 321 bool GetListWithoutPathExpansion(const std::string& key, 322 const ListValue** out_value) const; 323 bool GetListWithoutPathExpansion(const std::string& key, 324 ListValue** out_value); 325 326 // Removes the Value with the specified path from this dictionary (or one 327 // of its child dictionaries, if the path is more than just a local key). 328 // If |out_value| is non-NULL, the removed Value will be passed out via 329 // |out_value|. If |out_value| is NULL, the removed value will be deleted. 330 // This method returns true if |path| is a valid path; otherwise it will 331 // return false and the DictionaryValue object will be unchanged. 332 virtual bool Remove(const std::string& path, scoped_ptr<Value>* out_value); 333 334 // Like Remove(), but without special treatment of '.'. This allows e.g. URLs 335 // to be used as paths. 336 virtual bool RemoveWithoutPathExpansion(const std::string& key, 337 scoped_ptr<Value>* out_value); 338 339 // Removes a path, clearing out all dictionaries on |path| that remain empty 340 // after removing the value at |path|. 341 virtual bool RemovePath(const std::string& path, 342 scoped_ptr<Value>* out_value); 343 344 // Makes a copy of |this| but doesn't include empty dictionaries and lists in 345 // the copy. This never returns NULL, even if |this| itself is empty. 346 scoped_ptr<DictionaryValue> DeepCopyWithoutEmptyChildren() const; 347 348 // Merge |dictionary| into this dictionary. This is done recursively, i.e. any 349 // sub-dictionaries will be merged as well. In case of key collisions, the 350 // passed in dictionary takes precedence and data already present will be 351 // replaced. Values within |dictionary| are deep-copied, so |dictionary| may 352 // be freed any time after this call. 353 void MergeDictionary(const DictionaryValue* dictionary); 354 355 // Swaps contents with the |other| dictionary. 356 virtual void Swap(DictionaryValue* other); 357 358 // This class provides an iterator over both keys and values in the 359 // dictionary. It can't be used to modify the dictionary. 360 class BASE_EXPORT Iterator { 361 public: 362 explicit Iterator(const DictionaryValue& target); 363 ~Iterator(); 364 IsAtEnd()365 bool IsAtEnd() const { return it_ == target_.dictionary_.end(); } Advance()366 void Advance() { ++it_; } 367 key()368 const std::string& key() const { return it_->first; } value()369 const Value& value() const { return *it_->second; } 370 371 private: 372 const DictionaryValue& target_; 373 ValueMap::const_iterator it_; 374 }; 375 376 // Overridden from Value: 377 DictionaryValue* DeepCopy() const override; 378 // Preferred version of DeepCopy. TODO(estade): remove the above. 379 scoped_ptr<DictionaryValue> CreateDeepCopy() const; 380 bool Equals(const Value* other) const override; 381 382 private: 383 ValueMap dictionary_; 384 385 DISALLOW_COPY_AND_ASSIGN(DictionaryValue); 386 }; 387 388 // This type of Value represents a list of other Value values. 389 class BASE_EXPORT ListValue : public Value { 390 public: 391 typedef ValueVector::iterator iterator; 392 typedef ValueVector::const_iterator const_iterator; 393 394 // Returns |value| if it is a list, nullptr otherwise. 395 static scoped_ptr<ListValue> From(scoped_ptr<Value> value); 396 397 ListValue(); 398 ~ListValue() override; 399 400 // Clears the contents of this ListValue 401 void Clear(); 402 403 // Returns the number of Values in this list. GetSize()404 size_t GetSize() const { return list_.size(); } 405 406 // Returns whether the list is empty. empty()407 bool empty() const { return list_.empty(); } 408 409 // Sets the list item at the given index to be the Value specified by 410 // the value given. If the index beyond the current end of the list, null 411 // Values will be used to pad out the list. 412 // Returns true if successful, or false if the index was negative or 413 // the value is a null pointer. 414 bool Set(size_t index, Value* in_value); 415 // Preferred version of the above. TODO(estade): remove the above. 416 bool Set(size_t index, scoped_ptr<Value> in_value); 417 418 // Gets the Value at the given index. Modifies |out_value| (and returns true) 419 // only if the index falls within the current list range. 420 // Note that the list always owns the Value passed out via |out_value|. 421 // |out_value| is optional and will only be set if non-NULL. 422 bool Get(size_t index, const Value** out_value) const; 423 bool Get(size_t index, Value** out_value); 424 425 // Convenience forms of Get(). Modifies |out_value| (and returns true) 426 // only if the index is valid and the Value at that index can be returned 427 // in the specified form. 428 // |out_value| is optional and will only be set if non-NULL. 429 bool GetBoolean(size_t index, bool* out_value) const; 430 bool GetInteger(size_t index, int* out_value) const; 431 // Values of both type TYPE_INTEGER and TYPE_DOUBLE can be obtained as 432 // doubles. 433 bool GetDouble(size_t index, double* out_value) const; 434 bool GetString(size_t index, std::string* out_value) const; 435 bool GetString(size_t index, string16* out_value) const; 436 bool GetBinary(size_t index, const BinaryValue** out_value) const; 437 bool GetBinary(size_t index, BinaryValue** out_value); 438 bool GetDictionary(size_t index, const DictionaryValue** out_value) const; 439 bool GetDictionary(size_t index, DictionaryValue** out_value); 440 bool GetList(size_t index, const ListValue** out_value) const; 441 bool GetList(size_t index, ListValue** out_value); 442 443 // Removes the Value with the specified index from this list. 444 // If |out_value| is non-NULL, the removed Value AND ITS OWNERSHIP will be 445 // passed out via |out_value|. If |out_value| is NULL, the removed value will 446 // be deleted. This method returns true if |index| is valid; otherwise 447 // it will return false and the ListValue object will be unchanged. 448 virtual bool Remove(size_t index, scoped_ptr<Value>* out_value); 449 450 // Removes the first instance of |value| found in the list, if any, and 451 // deletes it. |index| is the location where |value| was found. Returns false 452 // if not found. 453 bool Remove(const Value& value, size_t* index); 454 455 // Removes the element at |iter|. If |out_value| is NULL, the value will be 456 // deleted, otherwise ownership of the value is passed back to the caller. 457 // Returns an iterator pointing to the location of the element that 458 // followed the erased element. 459 iterator Erase(iterator iter, scoped_ptr<Value>* out_value); 460 461 // Appends a Value to the end of the list. 462 void Append(scoped_ptr<Value> in_value); 463 // Deprecated version of the above. TODO(estade): remove. 464 void Append(Value* in_value); 465 466 // Convenience forms of Append. 467 void AppendBoolean(bool in_value); 468 void AppendInteger(int in_value); 469 void AppendDouble(double in_value); 470 void AppendString(const std::string& in_value); 471 void AppendString(const string16& in_value); 472 void AppendStrings(const std::vector<std::string>& in_values); 473 void AppendStrings(const std::vector<string16>& in_values); 474 475 // Appends a Value if it's not already present. Takes ownership of the 476 // |in_value|. Returns true if successful, or false if the value was already 477 // present. If the value was already present the |in_value| is deleted. 478 bool AppendIfNotPresent(Value* in_value); 479 480 // Insert a Value at index. 481 // Returns true if successful, or false if the index was out of range. 482 bool Insert(size_t index, Value* in_value); 483 484 // Searches for the first instance of |value| in the list using the Equals 485 // method of the Value type. 486 // Returns a const_iterator to the found item or to end() if none exists. 487 const_iterator Find(const Value& value) const; 488 489 // Swaps contents with the |other| list. 490 virtual void Swap(ListValue* other); 491 492 // Iteration. begin()493 iterator begin() { return list_.begin(); } end()494 iterator end() { return list_.end(); } 495 begin()496 const_iterator begin() const { return list_.begin(); } end()497 const_iterator end() const { return list_.end(); } 498 499 // Overridden from Value: 500 bool GetAsList(ListValue** out_value) override; 501 bool GetAsList(const ListValue** out_value) const override; 502 ListValue* DeepCopy() const override; 503 bool Equals(const Value* other) const override; 504 505 // Preferred version of DeepCopy. TODO(estade): remove DeepCopy. 506 scoped_ptr<ListValue> CreateDeepCopy() const; 507 508 private: 509 ValueVector list_; 510 511 DISALLOW_COPY_AND_ASSIGN(ListValue); 512 }; 513 514 // This interface is implemented by classes that know how to serialize 515 // Value objects. 516 class BASE_EXPORT ValueSerializer { 517 public: 518 virtual ~ValueSerializer(); 519 520 virtual bool Serialize(const Value& root) = 0; 521 }; 522 523 // This interface is implemented by classes that know how to deserialize Value 524 // objects. 525 class BASE_EXPORT ValueDeserializer { 526 public: 527 virtual ~ValueDeserializer(); 528 529 // This method deserializes the subclass-specific format into a Value object. 530 // If the return value is non-NULL, the caller takes ownership of returned 531 // Value. If the return value is NULL, and if error_code is non-NULL, 532 // error_code will be set with the underlying error. 533 // If |error_message| is non-null, it will be filled in with a formatted 534 // error message including the location of the error if appropriate. 535 virtual scoped_ptr<Value> Deserialize(int* error_code, 536 std::string* error_str) = 0; 537 }; 538 539 // Stream operator so Values can be used in assertion statements. In order that 540 // gtest uses this operator to print readable output on test failures, we must 541 // override each specific type. Otherwise, the default template implementation 542 // is preferred over an upcast. 543 BASE_EXPORT std::ostream& operator<<(std::ostream& out, const Value& value); 544 545 BASE_EXPORT inline std::ostream& operator<<(std::ostream& out, 546 const FundamentalValue& value) { 547 return out << static_cast<const Value&>(value); 548 } 549 550 BASE_EXPORT inline std::ostream& operator<<(std::ostream& out, 551 const StringValue& value) { 552 return out << static_cast<const Value&>(value); 553 } 554 555 BASE_EXPORT inline std::ostream& operator<<(std::ostream& out, 556 const DictionaryValue& value) { 557 return out << static_cast<const Value&>(value); 558 } 559 560 BASE_EXPORT inline std::ostream& operator<<(std::ostream& out, 561 const ListValue& value) { 562 return out << static_cast<const Value&>(value); 563 } 564 565 } // namespace base 566 567 #endif // BASE_VALUES_H_ 568