values.h revision c2e0dbddbe15c98d52c4786dac06cb8952a8ae6d
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 setting and other persistable data. It includes the ability to 7// specify (recursive) lists and dictionaries, so it's fairly expressive. 8// However, the API is optimized for the common case, namely storing a 9// hierarchical tree of simple values. Given a DictionaryValue root, you can 10// easily do things like: 11// 12// root->SetString("global.pages.homepage", "http://goateleporter.com"); 13// std::string homepage = "http://google.com"; // default/fallback value 14// root->GetString("global.pages.homepage", &homepage); 15// 16// where "global" and "pages" are also DictionaryValues, and "homepage" is a 17// string setting. If some elements of the path didn't exist yet, the 18// SetString() method would create the missing elements and attach them to root 19// before attaching the homepage value. 20 21#ifndef BASE_VALUES_H_ 22#define BASE_VALUES_H_ 23 24#include <iterator> 25#include <map> 26#include <string> 27#include <vector> 28 29#include "base/base_export.h" 30#include "base/basictypes.h" 31#include "base/compiler_specific.h" 32#include "base/memory/scoped_ptr.h" 33#include "base/string16.h" 34 35// This file declares "using base::Value", etc. at the bottom, so that 36// current code can use these classes without the base namespace. In 37// new code, please always use base::Value, etc. or add your own 38// "using" declaration. 39// http://crbug.com/88666 40namespace base { 41 42class BinaryValue; 43class DictionaryValue; 44class FundamentalValue; 45class ListValue; 46class StringValue; 47class Value; 48 49typedef std::vector<Value*> ValueVector; 50typedef std::map<std::string, Value*> ValueMap; 51 52// The Value class is the base class for Values. A Value can be instantiated 53// via the Create*Value() factory methods, or by directly creating instances of 54// the subclasses. 55class BASE_EXPORT Value { 56 public: 57 enum Type { 58 TYPE_NULL = 0, 59 TYPE_BOOLEAN, 60 TYPE_INTEGER, 61 TYPE_DOUBLE, 62 TYPE_STRING, 63 TYPE_BINARY, 64 TYPE_DICTIONARY, 65 TYPE_LIST 66 }; 67 68 virtual ~Value(); 69 70 static Value* CreateNullValue(); 71 // DEPRECATED: Do not use the following 5 functions. Instead, use 72 // new FundamentalValue or new StringValue. 73 static FundamentalValue* CreateBooleanValue(bool in_value); 74 static FundamentalValue* CreateIntegerValue(int in_value); 75 static FundamentalValue* CreateDoubleValue(double in_value); 76 static StringValue* CreateStringValue(const std::string& in_value); 77 static StringValue* CreateStringValue(const string16& in_value); 78 79 // Returns the type of the value stored by the current Value object. 80 // Each type will be implemented by only one subclass of Value, so it's 81 // safe to use the Type to determine whether you can cast from 82 // Value* to (Implementing Class)*. Also, a Value object never changes 83 // its type after construction. 84 Type GetType() const { return type_; } 85 86 // Returns true if the current object represents a given type. 87 bool IsType(Type type) const { return type == type_; } 88 89 // These methods allow the convenient retrieval of settings. 90 // If the current setting object can be converted into the given type, 91 // the value is returned through the |out_value| parameter and true is 92 // returned; otherwise, false is returned and |out_value| is unchanged. 93 virtual bool GetAsBoolean(bool* out_value) const; 94 virtual bool GetAsInteger(int* out_value) const; 95 virtual bool GetAsDouble(double* out_value) const; 96 virtual bool GetAsString(std::string* out_value) const; 97 virtual bool GetAsString(string16* out_value) const; 98 virtual bool GetAsList(ListValue** out_value); 99 virtual bool GetAsList(const ListValue** out_value) const; 100 virtual bool GetAsDictionary(DictionaryValue** out_value); 101 virtual bool GetAsDictionary(const DictionaryValue** out_value) const; 102 103 // This creates a deep copy of the entire Value tree, and returns a pointer 104 // to the copy. The caller gets ownership of the copy, of course. 105 // 106 // Subclasses return their own type directly in their overrides; 107 // this works because C++ supports covariant return types. 108 virtual Value* DeepCopy() const; 109 110 // Compares if two Value objects have equal contents. 111 virtual bool Equals(const Value* other) const; 112 113 // Compares if two Value objects have equal contents. Can handle NULLs. 114 // NULLs are considered equal but different from Value::CreateNullValue(). 115 static bool Equals(const Value* a, const Value* b); 116 117 protected: 118 // These aren't safe for end-users, but they are useful for subclasses. 119 explicit Value(Type type); 120 Value(const Value& that); 121 Value& operator=(const Value& that); 122 123 private: 124 Type type_; 125}; 126 127// FundamentalValue represents the simple fundamental types of values. 128class 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 virtual ~FundamentalValue(); 134 135 // Overridden from Value: 136 virtual bool GetAsBoolean(bool* out_value) const OVERRIDE; 137 virtual bool GetAsInteger(int* out_value) const OVERRIDE; 138 virtual bool GetAsDouble(double* out_value) const OVERRIDE; 139 virtual FundamentalValue* DeepCopy() const OVERRIDE; 140 virtual bool Equals(const Value* other) const OVERRIDE; 141 142 private: 143 union { 144 bool boolean_value_; 145 int integer_value_; 146 double double_value_; 147 }; 148}; 149 150class BASE_EXPORT StringValue : public Value { 151 public: 152 // Initializes a StringValue with a UTF-8 narrow character string. 153 explicit StringValue(const std::string& in_value); 154 155 // Initializes a StringValue with a string16. 156 explicit StringValue(const string16& in_value); 157 158 virtual ~StringValue(); 159 160 // Overridden from Value: 161 virtual bool GetAsString(std::string* out_value) const OVERRIDE; 162 virtual bool GetAsString(string16* out_value) const OVERRIDE; 163 virtual StringValue* DeepCopy() const OVERRIDE; 164 virtual bool Equals(const Value* other) const OVERRIDE; 165 166 private: 167 std::string value_; 168}; 169 170class BASE_EXPORT BinaryValue: public Value { 171 public: 172 // Creates a BinaryValue with a null buffer and size of 0. 173 BinaryValue(); 174 175 // Creates a BinaryValue, taking ownership of the bytes pointed to by 176 // |buffer|. 177 BinaryValue(scoped_ptr<char[]> buffer, size_t size); 178 179 virtual ~BinaryValue(); 180 181 // For situations where you want to keep ownership of your buffer, this 182 // factory method creates a new BinaryValue by copying the contents of the 183 // buffer that's passed in. 184 static BinaryValue* CreateWithCopiedBuffer(const char* buffer, size_t size); 185 186 size_t GetSize() const { return size_; } 187 188 // May return NULL. 189 char* GetBuffer() { return buffer_.get(); } 190 const char* GetBuffer() const { return buffer_.get(); } 191 192 // Overridden from Value: 193 virtual BinaryValue* DeepCopy() const OVERRIDE; 194 virtual bool Equals(const Value* other) const OVERRIDE; 195 196 private: 197 scoped_ptr<char[]> buffer_; 198 size_t size_; 199 200 DISALLOW_COPY_AND_ASSIGN(BinaryValue); 201}; 202 203// DictionaryValue provides a key-value dictionary with (optional) "path" 204// parsing for recursive access; see the comment at the top of the file. Keys 205// are |std::string|s and should be UTF-8 encoded. 206class BASE_EXPORT DictionaryValue : public Value { 207 public: 208 DictionaryValue(); 209 virtual ~DictionaryValue(); 210 211 // Overridden from Value: 212 virtual bool GetAsDictionary(DictionaryValue** out_value) OVERRIDE; 213 virtual bool GetAsDictionary( 214 const DictionaryValue** out_value) const OVERRIDE; 215 216 // Returns true if the current dictionary has a value for the given key. 217 bool HasKey(const std::string& key) const; 218 219 // Returns the number of Values in this dictionary. 220 size_t size() const { return dictionary_.size(); } 221 222 // Returns whether the dictionary is empty. 223 bool empty() const { return dictionary_.empty(); } 224 225 // Clears any current contents of this dictionary. 226 void Clear(); 227 228 // Sets the Value associated with the given path starting from this object. 229 // A path has the form "<key>" or "<key>.<key>.[...]", where "." indexes 230 // into the next DictionaryValue down. Obviously, "." can't be used 231 // within a key, but there are no other restrictions on keys. 232 // If the key at any step of the way doesn't exist, or exists but isn't 233 // a DictionaryValue, a new DictionaryValue will be created and attached 234 // to the path in that location. 235 // Note that the dictionary takes ownership of the value referenced by 236 // |in_value|, and therefore |in_value| must be non-NULL. 237 void Set(const std::string& path, Value* in_value); 238 239 // Convenience forms of Set(). These methods will replace any existing 240 // value at that path, even if it has a different type. 241 void SetBoolean(const std::string& path, bool in_value); 242 void SetInteger(const std::string& path, int in_value); 243 void SetDouble(const std::string& path, double in_value); 244 void SetString(const std::string& path, const std::string& in_value); 245 void SetString(const std::string& path, const string16& 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, Value* in_value); 250 251 // Convenience forms of SetWithoutPathExpansion(). 252 void SetBooleanWithoutPathExpansion(const std::string& path, bool in_value); 253 void SetIntegerWithoutPathExpansion(const std::string& path, int in_value); 254 void SetDoubleWithoutPathExpansion(const std::string& path, double in_value); 255 void SetStringWithoutPathExpansion(const std::string& path, 256 const std::string& in_value); 257 void SetStringWithoutPathExpansion(const std::string& path, 258 const string16& in_value); 259 260 // Gets the Value associated with the given path starting from this object. 261 // A path has the form "<key>" or "<key>.<key>.[...]", where "." indexes 262 // into the next DictionaryValue down. If the path can be resolved 263 // successfully, the value for the last key in the path will be returned 264 // through the |out_value| parameter, and the function will return true. 265 // Otherwise, it will return false and |out_value| will be untouched. 266 // Note that the dictionary always owns the value that's returned. 267 bool Get(const std::string& path, const Value** out_value) const; 268 bool Get(const std::string& path, Value** out_value); 269 270 // These are convenience forms of Get(). The value will be retrieved 271 // and the return value will be true if the path is valid and the value at 272 // the end of the path can be returned in the form specified. 273 bool GetBoolean(const std::string& path, bool* out_value) const; 274 bool GetInteger(const std::string& path, int* out_value) const; 275 bool GetDouble(const std::string& path, double* out_value) const; 276 bool GetString(const std::string& path, std::string* out_value) const; 277 bool GetString(const std::string& path, string16* out_value) const; 278 bool GetStringASCII(const std::string& path, std::string* out_value) const; 279 bool GetBinary(const std::string& path, const BinaryValue** out_value) const; 280 bool GetBinary(const std::string& path, BinaryValue** out_value); 281 bool GetDictionary(const std::string& path, 282 const DictionaryValue** out_value) const; 283 bool GetDictionary(const std::string& path, DictionaryValue** out_value); 284 bool GetList(const std::string& path, const ListValue** out_value) const; 285 bool GetList(const std::string& path, ListValue** out_value); 286 287 // Like Get(), but without special treatment of '.'. This allows e.g. URLs to 288 // be used as paths. 289 bool GetWithoutPathExpansion(const std::string& key, 290 const Value** out_value) const; 291 bool GetWithoutPathExpansion(const std::string& key, Value** out_value); 292 bool GetBooleanWithoutPathExpansion(const std::string& key, 293 bool* out_value) const; 294 bool GetIntegerWithoutPathExpansion(const std::string& key, 295 int* out_value) const; 296 bool GetDoubleWithoutPathExpansion(const std::string& key, 297 double* out_value) const; 298 bool GetStringWithoutPathExpansion(const std::string& key, 299 std::string* out_value) const; 300 bool GetStringWithoutPathExpansion(const std::string& key, 301 string16* out_value) const; 302 bool GetDictionaryWithoutPathExpansion( 303 const std::string& key, 304 const DictionaryValue** out_value) const; 305 bool GetDictionaryWithoutPathExpansion(const std::string& key, 306 DictionaryValue** out_value); 307 bool GetListWithoutPathExpansion(const std::string& key, 308 const ListValue** out_value) const; 309 bool GetListWithoutPathExpansion(const std::string& key, 310 ListValue** out_value); 311 312 // Removes the Value with the specified path from this dictionary (or one 313 // of its child dictionaries, if the path is more than just a local key). 314 // If |out_value| is non-NULL, the removed Value AND ITS OWNERSHIP will be 315 // passed out via out_value. If |out_value| is NULL, the removed value will 316 // be deleted. This method returns true if |path| is a valid path; otherwise 317 // it will return false and the DictionaryValue object will be unchanged. 318 virtual bool Remove(const std::string& path, Value** out_value); 319 320 // Like Remove(), but without special treatment of '.'. This allows e.g. URLs 321 // to be used as paths. 322 virtual bool RemoveWithoutPathExpansion(const std::string& key, 323 Value** out_value); 324 325 // Makes a copy of |this| but doesn't include empty dictionaries and lists in 326 // the copy. This never returns NULL, even if |this| itself is empty. 327 DictionaryValue* DeepCopyWithoutEmptyChildren(); 328 329 // Merge |dictionary| into this dictionary. This is done recursively, i.e. any 330 // sub-dictionaries will be merged as well. In case of key collisions, the 331 // passed in dictionary takes precedence and data already present will be 332 // replaced. Values within |dictionary| are deep-copied, so |dictionary| may 333 // be freed any time after this call. 334 void MergeDictionary(const DictionaryValue* dictionary); 335 336 // Swaps contents with the |other| dictionary. 337 virtual void Swap(DictionaryValue* other); 338 339 // This class provides an iterator over both keys and values in the 340 // dictionary. It can't be used to modify the dictionary. 341 class BASE_EXPORT Iterator { 342 public: 343 explicit Iterator(const DictionaryValue& target); 344 345 bool IsAtEnd() const { return it_ == target_.dictionary_.end(); } 346 void Advance() { ++it_; } 347 348 const std::string& key() const { return it_->first; } 349 const Value& value() const { return *it_->second; } 350 351 private: 352 const DictionaryValue& target_; 353 ValueMap::const_iterator it_; 354 }; 355 356 // Overridden from Value: 357 virtual DictionaryValue* DeepCopy() const OVERRIDE; 358 virtual bool Equals(const Value* other) const OVERRIDE; 359 360 private: 361 ValueMap dictionary_; 362 363 DISALLOW_COPY_AND_ASSIGN(DictionaryValue); 364}; 365 366// This type of Value represents a list of other Value values. 367class BASE_EXPORT ListValue : public Value { 368 public: 369 typedef ValueVector::iterator iterator; 370 typedef ValueVector::const_iterator const_iterator; 371 372 ListValue(); 373 virtual ~ListValue(); 374 375 // Clears the contents of this ListValue 376 void Clear(); 377 378 // Returns the number of Values in this list. 379 size_t GetSize() const { return list_.size(); } 380 381 // Returns whether the list is empty. 382 bool empty() const { return list_.empty(); } 383 384 // Sets the list item at the given index to be the Value specified by 385 // the value given. If the index beyond the current end of the list, null 386 // Values will be used to pad out the list. 387 // Returns true if successful, or false if the index was negative or 388 // the value is a null pointer. 389 bool Set(size_t index, Value* in_value); 390 391 // Gets the Value at the given index. Modifies |out_value| (and returns true) 392 // only if the index falls within the current list range. 393 // Note that the list always owns the Value passed out via |out_value|. 394 bool Get(size_t index, const Value** out_value) const; 395 bool Get(size_t index, Value** out_value); 396 397 // Convenience forms of Get(). Modifies |out_value| (and returns true) 398 // only if the index is valid and the Value at that index can be returned 399 // in the specified form. 400 bool GetBoolean(size_t index, bool* out_value) const; 401 bool GetInteger(size_t index, int* out_value) const; 402 bool GetDouble(size_t index, double* out_value) const; 403 bool GetString(size_t index, std::string* out_value) const; 404 bool GetString(size_t index, string16* out_value) const; 405 bool GetBinary(size_t index, const BinaryValue** out_value) const; 406 bool GetBinary(size_t index, BinaryValue** out_value); 407 bool GetDictionary(size_t index, const DictionaryValue** out_value) const; 408 bool GetDictionary(size_t index, DictionaryValue** out_value); 409 bool GetList(size_t index, const ListValue** out_value) const; 410 bool GetList(size_t index, ListValue** out_value); 411 412 // Removes the Value with the specified index from this list. 413 // If |out_value| is non-NULL, the removed Value AND ITS OWNERSHIP will be 414 // passed out via |out_value|. If |out_value| is NULL, the removed value will 415 // be deleted. This method returns true if |index| is valid; otherwise 416 // it will return false and the ListValue object will be unchanged. 417 virtual bool Remove(size_t index, Value** out_value); 418 419 // Removes the first instance of |value| found in the list, if any, and 420 // deletes it. |index| is the location where |value| was found. Returns false 421 // if not found. 422 bool Remove(const Value& value, size_t* index); 423 424 // Removes the element at |iter|. If |out_value| is NULL, the value will be 425 // deleted, otherwise ownership of the value is passed back to the caller. 426 // Returns an iterator pointing to the location of the element that 427 // followed the erased element. 428 iterator Erase(iterator iter, Value** out_value); 429 430 // Appends a Value to the end of the list. 431 void Append(Value* in_value); 432 433 // Convenience forms of Append. 434 void AppendBoolean(bool in_value); 435 void AppendInteger(int in_value); 436 void AppendDouble(double in_value); 437 void AppendString(const std::string& in_value); 438 void AppendString(const string16& in_value); 439 void AppendStrings(const std::vector<std::string>& in_values); 440 void AppendStrings(const std::vector<string16>& in_values); 441 442 // Appends a Value if it's not already present. Takes ownership of the 443 // |in_value|. Returns true if successful, or false if the value was already 444 // present. If the value was already present the |in_value| is deleted. 445 bool AppendIfNotPresent(Value* in_value); 446 447 // Insert a Value at index. 448 // Returns true if successful, or false if the index was out of range. 449 bool Insert(size_t index, Value* in_value); 450 451 // Searches for the first instance of |value| in the list using the Equals 452 // method of the Value type. 453 // Returns a const_iterator to the found item or to end() if none exists. 454 const_iterator Find(const Value& value) const; 455 456 // Swaps contents with the |other| list. 457 virtual void Swap(ListValue* other); 458 459 // Iteration. 460 iterator begin() { return list_.begin(); } 461 iterator end() { return list_.end(); } 462 463 const_iterator begin() const { return list_.begin(); } 464 const_iterator end() const { return list_.end(); } 465 466 // Overridden from Value: 467 virtual bool GetAsList(ListValue** out_value) OVERRIDE; 468 virtual bool GetAsList(const ListValue** out_value) const OVERRIDE; 469 virtual ListValue* DeepCopy() const OVERRIDE; 470 virtual bool Equals(const Value* other) const OVERRIDE; 471 472 private: 473 ValueVector list_; 474 475 DISALLOW_COPY_AND_ASSIGN(ListValue); 476}; 477 478// This interface is implemented by classes that know how to serialize and 479// deserialize Value objects. 480class BASE_EXPORT ValueSerializer { 481 public: 482 virtual ~ValueSerializer(); 483 484 virtual bool Serialize(const Value& root) = 0; 485 486 // This method deserializes the subclass-specific format into a Value object. 487 // If the return value is non-NULL, the caller takes ownership of returned 488 // Value. If the return value is NULL, and if error_code is non-NULL, 489 // error_code will be set with the underlying error. 490 // If |error_message| is non-null, it will be filled in with a formatted 491 // error message including the location of the error if appropriate. 492 virtual Value* Deserialize(int* error_code, std::string* error_str) = 0; 493}; 494 495// Stream operator so Values can be used in assertion statements. In order that 496// gtest uses this operator to print readable output on test failures, we must 497// override each specific type. Otherwise, the default template implementation 498// is preferred over an upcast. 499BASE_EXPORT std::ostream& operator<<(std::ostream& out, const Value& value); 500 501BASE_EXPORT inline std::ostream& operator<<(std::ostream& out, 502 const FundamentalValue& value) { 503 return out << static_cast<const Value&>(value); 504} 505 506BASE_EXPORT inline std::ostream& operator<<(std::ostream& out, 507 const StringValue& value) { 508 return out << static_cast<const Value&>(value); 509} 510 511BASE_EXPORT inline std::ostream& operator<<(std::ostream& out, 512 const DictionaryValue& value) { 513 return out << static_cast<const Value&>(value); 514} 515 516BASE_EXPORT inline std::ostream& operator<<(std::ostream& out, 517 const ListValue& value) { 518 return out << static_cast<const Value&>(value); 519} 520 521} // namespace base 522 523// http://crbug.com/88666 524using base::DictionaryValue; 525using base::ListValue; 526using base::StringValue; 527using base::Value; 528 529#endif // BASE_VALUES_H_ 530