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/string_piece.h" 34 35 namespace base { 36 37 class BinaryValue; 38 class DictionaryValue; 39 class FundamentalValue; 40 class ListValue; 41 class StringValue; 42 class Value; 43 44 typedef std::vector<Value*> ValueVector; 45 typedef std::map<std::string, Value*> ValueMap; 46 47 // The Value class is the base class for Values. A Value can be instantiated 48 // via the Create*Value() factory methods, or by directly creating instances of 49 // the subclasses. 50 // 51 // See the file-level comment above for more information. 52 class BASE_EXPORT Value { 53 public: 54 enum Type { 55 TYPE_NULL = 0, 56 TYPE_BOOLEAN, 57 TYPE_INTEGER, 58 TYPE_DOUBLE, 59 TYPE_STRING, 60 TYPE_BINARY, 61 TYPE_DICTIONARY, 62 TYPE_LIST 63 // Note: Do not add more types. See the file-level comment above for why. 64 }; 65 66 virtual ~Value(); 67 68 static scoped_ptr<Value> CreateNullValue(); 69 70 // Returns the type of the value stored by the current Value object. 71 // Each type will be implemented by only one subclass of Value, so it's 72 // safe to use the Type to determine whether you can cast from 73 // Value* to (Implementing Class)*. Also, a Value object never changes 74 // its type after construction. GetType()75 Type GetType() const { return type_; } 76 77 // Returns true if the current object represents a given type. IsType(Type type)78 bool IsType(Type type) const { return type == type_; } 79 80 // These methods allow the convenient retrieval of the contents of the Value. 81 // If the current object can be converted into the given type, the value is 82 // returned through the |out_value| parameter and true is returned; 83 // otherwise, false is returned and |out_value| is unchanged. 84 virtual bool GetAsBoolean(bool* out_value) const; 85 virtual bool GetAsInteger(int* out_value) const; 86 virtual bool GetAsDouble(double* out_value) const; 87 virtual bool GetAsString(std::string* out_value) const; 88 virtual bool GetAsString(const StringValue** out_value) const; 89 virtual bool GetAsBinary(const BinaryValue** out_value) const; 90 virtual bool GetAsList(ListValue** out_value); 91 virtual bool GetAsList(const ListValue** out_value) const; 92 virtual bool GetAsDictionary(DictionaryValue** out_value); 93 virtual bool GetAsDictionary(const DictionaryValue** out_value) const; 94 // Note: Do not add more types. See the file-level comment above for why. 95 96 // This creates a deep copy of the entire Value tree, and returns a pointer 97 // to the copy. The caller gets ownership of the copy, of course. 98 // 99 // Subclasses return their own type directly in their overrides; 100 // this works because C++ supports covariant return types. 101 virtual Value* DeepCopy() const; 102 // Preferred version of DeepCopy. TODO(estade): remove the above. 103 scoped_ptr<Value> CreateDeepCopy() const; 104 105 // Compares if two Value objects have equal contents. 106 virtual bool Equals(const Value* other) const; 107 108 // Compares if two Value objects have equal contents. Can handle NULLs. 109 // NULLs are considered equal but different from Value::CreateNullValue(). 110 static bool Equals(const Value* a, const Value* b); 111 112 protected: 113 // These aren't safe for end-users, but they are useful for subclasses. 114 explicit Value(Type type); 115 Value(const Value& that); 116 Value& operator=(const Value& that); 117 118 private: 119 Type type_; 120 }; 121 122 // FundamentalValue represents the simple fundamental types of values. 123 class BASE_EXPORT FundamentalValue : public Value { 124 public: 125 explicit FundamentalValue(bool in_value); 126 explicit FundamentalValue(int in_value); 127 explicit FundamentalValue(double in_value); 128 ~FundamentalValue() override; 129 130 // Overridden from Value: 131 bool GetAsBoolean(bool* out_value) const override; 132 bool GetAsInteger(int* out_value) const override; 133 // Values of both type TYPE_INTEGER and TYPE_DOUBLE can be obtained as 134 // doubles. 135 bool GetAsDouble(double* out_value) const override; 136 FundamentalValue* DeepCopy() const override; 137 bool Equals(const Value* other) const override; 138 139 private: 140 union { 141 bool boolean_value_; 142 int integer_value_; 143 double double_value_; 144 }; 145 }; 146 147 class BASE_EXPORT StringValue : public Value { 148 public: 149 // Initializes a StringValue with a UTF-8 narrow character string. 150 explicit StringValue(const std::string& in_value); 151 152 ~StringValue() override; 153 154 // Returns |value_| as a pointer or reference. 155 std::string* GetString(); 156 const std::string& GetString() const; 157 158 // Overridden from Value: 159 bool GetAsString(std::string* out_value) const override; 160 bool GetAsString(const StringValue** out_value) const override; 161 StringValue* DeepCopy() const override; 162 bool Equals(const Value* other) const override; 163 164 private: 165 std::string value_; 166 }; 167 168 class BASE_EXPORT BinaryValue : public Value { 169 public: 170 // Creates a BinaryValue with a null buffer and size of 0. 171 BinaryValue(); 172 173 // Creates a BinaryValue, taking ownership of the bytes pointed to by 174 // |buffer|. 175 BinaryValue(scoped_ptr<char[]> buffer, size_t size); 176 177 ~BinaryValue() override; 178 179 // For situations where you want to keep ownership of your buffer, this 180 // factory method creates a new BinaryValue by copying the contents of the 181 // buffer that's passed in. 182 static BinaryValue* CreateWithCopiedBuffer(const char* buffer, size_t size); 183 GetSize()184 size_t GetSize() const { return size_; } 185 186 // May return NULL. GetBuffer()187 char* GetBuffer() { return buffer_.get(); } GetBuffer()188 const char* GetBuffer() const { return buffer_.get(); } 189 190 // Overridden from Value: 191 bool GetAsBinary(const BinaryValue** out_value) const override; 192 BinaryValue* DeepCopy() const override; 193 bool Equals(const Value* other) const override; 194 195 private: 196 scoped_ptr<char[]> buffer_; 197 size_t size_; 198 199 DISALLOW_COPY_AND_ASSIGN(BinaryValue); 200 }; 201 202 // DictionaryValue provides a key-value dictionary with (optional) "path" 203 // parsing for recursive access; see the comment at the top of the file. Keys 204 // are |std::string|s and should be UTF-8 encoded. 205 class BASE_EXPORT DictionaryValue : public Value { 206 public: 207 // Returns |value| if it is a dictionary, nullptr otherwise. 208 static scoped_ptr<DictionaryValue> From(scoped_ptr<Value> value); 209 210 DictionaryValue(); 211 ~DictionaryValue() override; 212 213 // Overridden from Value: 214 bool GetAsDictionary(DictionaryValue** out_value) override; 215 bool GetAsDictionary(const DictionaryValue** out_value) const override; 216 217 // Returns true if the current dictionary has a value for the given key. 218 bool HasKey(const std::string& key) const; 219 220 // Returns the number of Values in this dictionary. size()221 size_t size() const { return dictionary_.size(); } 222 223 // Returns whether the dictionary is empty. empty()224 bool empty() const { return dictionary_.empty(); } 225 226 // Clears any current contents of this dictionary. 227 void Clear(); 228 229 // Sets the Value associated with the given path starting from this object. 230 // A path has the form "<key>" or "<key>.<key>.[...]", where "." indexes 231 // into the next DictionaryValue down. Obviously, "." can't be used 232 // within a key, but there are no other restrictions on keys. 233 // If the key at any step of the way doesn't exist, or exists but isn't 234 // a DictionaryValue, a new DictionaryValue will be created and attached 235 // to the path in that location. |in_value| must be non-null. 236 void Set(const std::string& path, scoped_ptr<Value> in_value); 237 // Deprecated version of the above. TODO(estade): remove. 238 void Set(const std::string& path, Value* in_value); 239 240 // Convenience forms of Set(). These methods will replace any existing 241 // value at that path, even if it has a different type. 242 void SetBoolean(const std::string& path, bool in_value); 243 void SetInteger(const std::string& path, int in_value); 244 void SetDouble(const std::string& path, double in_value); 245 void SetString(const std::string& path, const std::string& in_value); 246 247 // Like Set(), but without special treatment of '.'. This allows e.g. URLs to 248 // be used as paths. 249 void SetWithoutPathExpansion(const std::string& key, 250 scoped_ptr<Value> in_value); 251 // Deprecated version of the above. TODO(estade): remove. 252 void SetWithoutPathExpansion(const std::string& key, Value* in_value); 253 254 // Convenience forms of SetWithoutPathExpansion(). 255 void SetBooleanWithoutPathExpansion(const std::string& path, bool in_value); 256 void SetIntegerWithoutPathExpansion(const std::string& path, int in_value); 257 void SetDoubleWithoutPathExpansion(const std::string& path, double in_value); 258 void SetStringWithoutPathExpansion(const std::string& path, 259 const std::string& in_value); 260 261 // Gets the Value associated with the given path starting from this object. 262 // A path has the form "<key>" or "<key>.<key>.[...]", where "." indexes 263 // into the next DictionaryValue down. If the path can be resolved 264 // successfully, the value for the last key in the path will be returned 265 // through the |out_value| parameter, and the function will return true. 266 // Otherwise, it will return false and |out_value| will be untouched. 267 // Note that the dictionary always owns the value that's returned. 268 // |out_value| is optional and will only be set if non-NULL. 269 bool Get(StringPiece path, const Value** out_value) const; 270 bool Get(StringPiece path, Value** out_value); 271 272 // These are convenience forms of Get(). The value will be retrieved 273 // and the return value will be true if the path is valid and the value at 274 // the end of the path can be returned in the form specified. 275 // |out_value| is optional and will only be set if non-NULL. 276 bool GetBoolean(const std::string& path, bool* out_value) const; 277 bool GetInteger(const std::string& path, int* out_value) const; 278 // Values of both type TYPE_INTEGER and TYPE_DOUBLE can be obtained as 279 // doubles. 280 bool GetDouble(const std::string& path, double* out_value) const; 281 bool GetString(const std::string& path, std::string* out_value) const; 282 bool GetStringASCII(const std::string& path, std::string* out_value) const; 283 bool GetBinary(const std::string& path, const BinaryValue** out_value) const; 284 bool GetBinary(const std::string& path, BinaryValue** out_value); 285 bool GetDictionary(StringPiece path, 286 const DictionaryValue** out_value) const; 287 bool GetDictionary(StringPiece path, DictionaryValue** out_value); 288 bool GetList(const std::string& path, const ListValue** out_value) const; 289 bool GetList(const std::string& path, ListValue** out_value); 290 291 // Like Get(), but without special treatment of '.'. This allows e.g. URLs to 292 // be used as paths. 293 bool GetWithoutPathExpansion(const std::string& key, 294 const Value** out_value) const; 295 bool GetWithoutPathExpansion(const std::string& key, Value** out_value); 296 bool GetBooleanWithoutPathExpansion(const std::string& key, 297 bool* out_value) const; 298 bool GetIntegerWithoutPathExpansion(const std::string& key, 299 int* out_value) const; 300 bool GetDoubleWithoutPathExpansion(const std::string& key, 301 double* out_value) const; 302 bool GetStringWithoutPathExpansion(const std::string& key, 303 std::string* out_value) const; 304 bool GetDictionaryWithoutPathExpansion( 305 const std::string& key, 306 const DictionaryValue** out_value) const; 307 bool GetDictionaryWithoutPathExpansion(const std::string& key, 308 DictionaryValue** out_value); 309 bool GetListWithoutPathExpansion(const std::string& key, 310 const ListValue** out_value) const; 311 bool GetListWithoutPathExpansion(const std::string& key, 312 ListValue** out_value); 313 314 // Removes the Value with the specified path from this dictionary (or one 315 // of its child dictionaries, if the path is more than just a local key). 316 // If |out_value| is non-NULL, the removed Value will be passed out via 317 // |out_value|. If |out_value| is NULL, the removed value will be deleted. 318 // This method returns true if |path| is a valid path; otherwise it will 319 // return false and the DictionaryValue object will be unchanged. 320 virtual bool Remove(const std::string& path, scoped_ptr<Value>* out_value); 321 322 // Like Remove(), but without special treatment of '.'. This allows e.g. URLs 323 // to be used as paths. 324 virtual bool RemoveWithoutPathExpansion(const std::string& key, 325 scoped_ptr<Value>* out_value); 326 327 // Removes a path, clearing out all dictionaries on |path| that remain empty 328 // after removing the value at |path|. 329 virtual bool RemovePath(const std::string& path, 330 scoped_ptr<Value>* out_value); 331 332 // Makes a copy of |this| but doesn't include empty dictionaries and lists in 333 // the copy. This never returns NULL, even if |this| itself is empty. 334 scoped_ptr<DictionaryValue> DeepCopyWithoutEmptyChildren() const; 335 336 // Merge |dictionary| into this dictionary. This is done recursively, i.e. any 337 // sub-dictionaries will be merged as well. In case of key collisions, the 338 // passed in dictionary takes precedence and data already present will be 339 // replaced. Values within |dictionary| are deep-copied, so |dictionary| may 340 // be freed any time after this call. 341 void MergeDictionary(const DictionaryValue* dictionary); 342 343 // Swaps contents with the |other| dictionary. 344 virtual void Swap(DictionaryValue* other); 345 346 // This class provides an iterator over both keys and values in the 347 // dictionary. It can't be used to modify the dictionary. 348 class BASE_EXPORT Iterator { 349 public: 350 explicit Iterator(const DictionaryValue& target); 351 ~Iterator(); 352 IsAtEnd()353 bool IsAtEnd() const { return it_ == target_.dictionary_.end(); } Advance()354 void Advance() { ++it_; } 355 key()356 const std::string& key() const { return it_->first; } value()357 const Value& value() const { return *it_->second; } 358 359 private: 360 const DictionaryValue& target_; 361 ValueMap::const_iterator it_; 362 }; 363 364 // Overridden from Value: 365 DictionaryValue* DeepCopy() const override; 366 // Preferred version of DeepCopy. TODO(estade): remove the above. 367 scoped_ptr<DictionaryValue> CreateDeepCopy() const; 368 bool Equals(const Value* other) const override; 369 370 private: 371 ValueMap dictionary_; 372 373 DISALLOW_COPY_AND_ASSIGN(DictionaryValue); 374 }; 375 376 // This type of Value represents a list of other Value values. 377 class BASE_EXPORT ListValue : public Value { 378 public: 379 typedef ValueVector::iterator iterator; 380 typedef ValueVector::const_iterator const_iterator; 381 382 // Returns |value| if it is a list, nullptr otherwise. 383 static scoped_ptr<ListValue> From(scoped_ptr<Value> value); 384 385 ListValue(); 386 ~ListValue() override; 387 388 // Clears the contents of this ListValue 389 void Clear(); 390 391 // Returns the number of Values in this list. GetSize()392 size_t GetSize() const { return list_.size(); } 393 394 // Returns whether the list is empty. empty()395 bool empty() const { return list_.empty(); } 396 397 // Sets the list item at the given index to be the Value specified by 398 // the value given. If the index beyond the current end of the list, null 399 // Values will be used to pad out the list. 400 // Returns true if successful, or false if the index was negative or 401 // the value is a null pointer. 402 bool Set(size_t index, Value* in_value); 403 // Preferred version of the above. TODO(estade): remove the above. 404 bool Set(size_t index, scoped_ptr<Value> in_value); 405 406 // Gets the Value at the given index. Modifies |out_value| (and returns true) 407 // only if the index falls within the current list range. 408 // Note that the list always owns the Value passed out via |out_value|. 409 // |out_value| is optional and will only be set if non-NULL. 410 bool Get(size_t index, const Value** out_value) const; 411 bool Get(size_t index, Value** out_value); 412 413 // Convenience forms of Get(). Modifies |out_value| (and returns true) 414 // only if the index is valid and the Value at that index can be returned 415 // in the specified form. 416 // |out_value| is optional and will only be set if non-NULL. 417 bool GetBoolean(size_t index, bool* out_value) const; 418 bool GetInteger(size_t index, int* out_value) const; 419 // Values of both type TYPE_INTEGER and TYPE_DOUBLE can be obtained as 420 // doubles. 421 bool GetDouble(size_t index, double* out_value) const; 422 bool GetString(size_t index, std::string* out_value) const; 423 bool GetBinary(size_t index, const BinaryValue** out_value) const; 424 bool GetBinary(size_t index, BinaryValue** out_value); 425 bool GetDictionary(size_t index, const DictionaryValue** out_value) const; 426 bool GetDictionary(size_t index, DictionaryValue** out_value); 427 bool GetList(size_t index, const ListValue** out_value) const; 428 bool GetList(size_t index, ListValue** out_value); 429 430 // Removes the Value with the specified index from this list. 431 // If |out_value| is non-NULL, the removed Value AND ITS OWNERSHIP will be 432 // passed out via |out_value|. If |out_value| is NULL, the removed value will 433 // be deleted. This method returns true if |index| is valid; otherwise 434 // it will return false and the ListValue object will be unchanged. 435 virtual bool Remove(size_t index, scoped_ptr<Value>* out_value); 436 437 // Removes the first instance of |value| found in the list, if any, and 438 // deletes it. |index| is the location where |value| was found. Returns false 439 // if not found. 440 bool Remove(const Value& value, size_t* index); 441 442 // Removes the element at |iter|. If |out_value| is NULL, the value will be 443 // deleted, otherwise ownership of the value is passed back to the caller. 444 // Returns an iterator pointing to the location of the element that 445 // followed the erased element. 446 iterator Erase(iterator iter, scoped_ptr<Value>* out_value); 447 448 // Appends a Value to the end of the list. 449 void Append(scoped_ptr<Value> in_value); 450 // Deprecated version of the above. TODO(estade): remove. 451 void Append(Value* in_value); 452 453 // Convenience forms of Append. 454 void AppendBoolean(bool in_value); 455 void AppendInteger(int in_value); 456 void AppendDouble(double in_value); 457 void AppendString(const std::string& in_value); 458 void AppendStrings(const std::vector<std::string>& in_values); 459 460 // Appends a Value if it's not already present. Takes ownership of the 461 // |in_value|. Returns true if successful, or false if the value was already 462 // present. If the value was already present the |in_value| is deleted. 463 bool AppendIfNotPresent(Value* in_value); 464 465 // Insert a Value at index. 466 // Returns true if successful, or false if the index was out of range. 467 bool Insert(size_t index, Value* in_value); 468 469 // Searches for the first instance of |value| in the list using the Equals 470 // method of the Value type. 471 // Returns a const_iterator to the found item or to end() if none exists. 472 const_iterator Find(const Value& value) const; 473 474 // Swaps contents with the |other| list. 475 virtual void Swap(ListValue* other); 476 477 // Iteration. begin()478 iterator begin() { return list_.begin(); } end()479 iterator end() { return list_.end(); } 480 begin()481 const_iterator begin() const { return list_.begin(); } end()482 const_iterator end() const { return list_.end(); } 483 484 // Overridden from Value: 485 bool GetAsList(ListValue** out_value) override; 486 bool GetAsList(const ListValue** out_value) const override; 487 ListValue* DeepCopy() const override; 488 bool Equals(const Value* other) const override; 489 490 // Preferred version of DeepCopy. TODO(estade): remove DeepCopy. 491 scoped_ptr<ListValue> CreateDeepCopy() const; 492 493 private: 494 ValueVector list_; 495 496 DISALLOW_COPY_AND_ASSIGN(ListValue); 497 }; 498 499 // Stream operator so Values can be used in assertion statements. In order that 500 // gtest uses this operator to print readable output on test failures, we must 501 // override each specific type. Otherwise, the default template implementation 502 // is preferred over an upcast. 503 BASE_EXPORT std::ostream& operator<<(std::ostream& out, const Value& value); 504 505 BASE_EXPORT inline std::ostream& operator<<(std::ostream& out, 506 const FundamentalValue& value) { 507 return out << static_cast<const Value&>(value); 508 } 509 510 BASE_EXPORT inline std::ostream& operator<<(std::ostream& out, 511 const StringValue& value) { 512 return out << static_cast<const Value&>(value); 513 } 514 515 BASE_EXPORT inline std::ostream& operator<<(std::ostream& out, 516 const DictionaryValue& value) { 517 return out << static_cast<const Value&>(value); 518 } 519 520 BASE_EXPORT inline std::ostream& operator<<(std::ostream& out, 521 const ListValue& value) { 522 return out << static_cast<const Value&>(value); 523 } 524 525 } // namespace base 526 527 #endif // BASE_VALUES_H_ 528