values.h revision 731df977c0511bca2206b5f333555b1205ff1f43
1// Copyright (c) 2010 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#pragma once 24 25#include <iterator> 26#include <map> 27#include <string> 28#include <vector> 29 30#include "base/basictypes.h" 31#include "base/string16.h" 32#include "build/build_config.h" 33 34class Value; 35class FundamentalValue; 36class StringValue; 37class BinaryValue; 38class DictionaryValue; 39class ListValue; 40 41typedef std::vector<Value*> ValueVector; 42typedef std::map<std::string, Value*> ValueMap; 43 44// The Value class is the base class for Values. A Value can be 45// instantiated via the Create*Value() factory methods, or by directly 46// creating instances of the subclasses. 47class Value { 48 public: 49 virtual ~Value(); 50 51 // Convenience methods for creating Value objects for various 52 // kinds of values without thinking about which class implements them. 53 // These can always be expected to return a valid Value*. 54 static Value* CreateNullValue(); 55 static Value* CreateBooleanValue(bool in_value); 56 static Value* CreateIntegerValue(int in_value); 57 static Value* CreateRealValue(double in_value); 58 static Value* CreateStringValue(const std::string& in_value); 59 static Value* CreateStringValue(const string16& in_value); 60 61 // This one can return NULL if the input isn't valid. If the return value 62 // is non-null, the new object has taken ownership of the buffer pointer. 63 static BinaryValue* CreateBinaryValue(char* buffer, size_t size); 64 65 typedef enum { 66 TYPE_NULL = 0, 67 TYPE_BOOLEAN, 68 TYPE_INTEGER, 69 TYPE_REAL, 70 TYPE_STRING, 71 TYPE_BINARY, 72 TYPE_DICTIONARY, 73 TYPE_LIST 74 } ValueType; 75 76 // Returns the type of the value stored by the current Value object. 77 // Each type will be implemented by only one subclass of Value, so it's 78 // safe to use the ValueType to determine whether you can cast from 79 // Value* to (Implementing Class)*. Also, a Value object never changes 80 // its type after construction. 81 ValueType GetType() const { return type_; } 82 83 // Returns true if the current object represents a given type. 84 bool IsType(ValueType type) const { return type == type_; } 85 86 // These methods allow the convenient retrieval of settings. 87 // If the current setting object can be converted into the given type, 88 // the value is returned through the |out_value| parameter and true is 89 // returned; otherwise, false is returned and |out_value| is unchanged. 90 virtual bool GetAsBoolean(bool* out_value) const; 91 virtual bool GetAsInteger(int* out_value) const; 92 virtual bool GetAsReal(double* out_value) const; 93 virtual bool GetAsString(std::string* out_value) const; 94 virtual bool GetAsString(string16* out_value) const; 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 virtual Value* DeepCopy() const; 99 100 // Compares if two Value objects have equal contents. 101 virtual bool Equals(const Value* other) const; 102 103 protected: 104 // This isn't safe for end-users (they should use the Create*Value() 105 // static methods above), but it's useful for subclasses. 106 explicit Value(ValueType type); 107 108 private: 109 Value(); 110 111 ValueType type_; 112 113 DISALLOW_COPY_AND_ASSIGN(Value); 114}; 115 116// FundamentalValue represents the simple fundamental types of values. 117class FundamentalValue : public Value { 118 public: 119 explicit FundamentalValue(bool in_value); 120 explicit FundamentalValue(int in_value); 121 explicit FundamentalValue(double in_value); 122 ~FundamentalValue(); 123 124 // Subclassed methods 125 virtual bool GetAsBoolean(bool* out_value) const; 126 virtual bool GetAsInteger(int* out_value) const; 127 virtual bool GetAsReal(double* out_value) const; 128 virtual Value* DeepCopy() const; 129 virtual bool Equals(const Value* other) const; 130 131 private: 132 union { 133 bool boolean_value_; 134 int integer_value_; 135 double real_value_; 136 }; 137 138 DISALLOW_COPY_AND_ASSIGN(FundamentalValue); 139}; 140 141class StringValue : public Value { 142 public: 143 // Initializes a StringValue with a UTF-8 narrow character string. 144 explicit StringValue(const std::string& in_value); 145 146 // Initializes a StringValue with a string16. 147 explicit StringValue(const string16& in_value); 148 149 ~StringValue(); 150 151 // Subclassed methods 152 bool GetAsString(std::string* out_value) const; 153 bool GetAsString(string16* out_value) const; 154 Value* DeepCopy() const; 155 virtual bool Equals(const Value* other) const; 156 157 private: 158 std::string value_; 159 160 DISALLOW_COPY_AND_ASSIGN(StringValue); 161}; 162 163class BinaryValue: public Value { 164 public: 165 // Creates a Value to represent a binary buffer. The new object takes 166 // ownership of the pointer passed in, if successful. 167 // Returns NULL if buffer is NULL. 168 static BinaryValue* Create(char* buffer, size_t size); 169 170 // For situations where you want to keep ownership of your buffer, this 171 // factory method creates a new BinaryValue by copying the contents of the 172 // buffer that's passed in. 173 // Returns NULL if buffer is NULL. 174 static BinaryValue* CreateWithCopiedBuffer(const char* buffer, size_t size); 175 176 ~BinaryValue(); 177 178 // Subclassed methods 179 Value* DeepCopy() const; 180 virtual bool Equals(const Value* other) const; 181 182 size_t GetSize() const { return size_; } 183 char* GetBuffer() { return buffer_; } 184 const char* GetBuffer() const { return buffer_; } 185 186 private: 187 // Constructor is private so that only objects with valid buffer pointers 188 // and size values can be created. 189 BinaryValue(char* buffer, size_t size); 190 191 char* buffer_; 192 size_t size_; 193 194 DISALLOW_COPY_AND_ASSIGN(BinaryValue); 195}; 196 197// DictionaryValue provides a key-value dictionary with (optional) "path" 198// parsing for recursive access; see the comment at the top of the file. Keys 199// are |std::string|s and should be UTF-8 encoded. 200class DictionaryValue : public Value { 201 public: 202 DictionaryValue(); 203 ~DictionaryValue(); 204 205 // Subclassed methods 206 Value* DeepCopy() const; 207 virtual bool Equals(const Value* other) const; 208 209 // Returns true if the current dictionary has a value for the given key. 210 bool HasKey(const std::string& key) const; 211 212 // Returns the number of Values in this dictionary. 213 size_t size() const { return dictionary_.size(); } 214 215 // Returns whether the dictionary is empty. 216 bool empty() const { return dictionary_.empty(); } 217 218 // Clears any current contents of this dictionary. 219 void Clear(); 220 221 // Sets the Value associated with the given path starting from this object. 222 // A path has the form "<key>" or "<key>.<key>.[...]", where "." indexes 223 // into the next DictionaryValue down. Obviously, "." can't be used 224 // within a key, but there are no other restrictions on keys. 225 // If the key at any step of the way doesn't exist, or exists but isn't 226 // a DictionaryValue, a new DictionaryValue will be created and attached 227 // to the path in that location. 228 // Note that the dictionary takes ownership of the value referenced by 229 // |in_value|, and therefore |in_value| must be non-NULL. 230 void Set(const std::string& path, Value* in_value); 231 232 // Convenience forms of Set(). These methods will replace any existing 233 // value at that path, even if it has a different type. 234 void SetBoolean(const std::string& path, bool in_value); 235 void SetInteger(const std::string& path, int in_value); 236 void SetReal(const std::string& path, double in_value); 237 void SetString(const std::string& path, const std::string& in_value); 238 void SetString(const std::string& path, const string16& in_value); 239 240 // Like Set(), but without special treatment of '.'. This allows e.g. URLs to 241 // be used as paths. 242 void SetWithoutPathExpansion(const std::string& key, Value* in_value); 243 244 // Gets the Value associated with the given path starting from this object. 245 // A path has the form "<key>" or "<key>.<key>.[...]", where "." indexes 246 // into the next DictionaryValue down. If the path can be resolved 247 // successfully, the value for the last key in the path will be returned 248 // through the |out_value| parameter, and the function will return true. 249 // Otherwise, it will return false and |out_value| will be untouched. 250 // Note that the dictionary always owns the value that's returned. 251 bool Get(const std::string& path, Value** out_value) const; 252 253 // These are convenience forms of Get(). The value will be retrieved 254 // and the return value will be true if the path is valid and the value at 255 // the end of the path can be returned in the form specified. 256 bool GetBoolean(const std::string& path, bool* out_value) const; 257 bool GetInteger(const std::string& path, int* out_value) const; 258 bool GetReal(const std::string& path, double* out_value) const; 259 bool GetString(const std::string& path, std::string* out_value) const; 260 bool GetString(const std::string& path, string16* out_value) const; 261 bool GetStringASCII(const std::string& path, std::string* out_value) const; 262 bool GetBinary(const std::string& path, BinaryValue** out_value) const; 263 bool GetDictionary(const std::string& path, 264 DictionaryValue** out_value) const; 265 bool GetList(const std::string& path, ListValue** out_value) const; 266 267 // Like Get(), but without special treatment of '.'. This allows e.g. URLs to 268 // be used as paths. 269 bool GetWithoutPathExpansion(const std::string& key, 270 Value** out_value) const; 271 bool GetIntegerWithoutPathExpansion(const std::string& key, 272 int* out_value) const; 273 bool GetRealWithoutPathExpansion(const std::string& key, 274 double* out_value) const; 275 bool GetStringWithoutPathExpansion(const std::string& key, 276 std::string* out_value) const; 277 bool GetStringWithoutPathExpansion(const std::string& key, 278 string16* out_value) const; 279 bool GetDictionaryWithoutPathExpansion(const std::string& key, 280 DictionaryValue** out_value) const; 281 bool GetListWithoutPathExpansion(const std::string& key, 282 ListValue** out_value) const; 283 284 // Removes the Value with the specified path from this dictionary (or one 285 // of its child dictionaries, if the path is more than just a local key). 286 // If |out_value| is non-NULL, the removed Value AND ITS OWNERSHIP will be 287 // passed out via out_value. If |out_value| is NULL, the removed value will 288 // be deleted. This method returns true if |path| is a valid path; otherwise 289 // it will return false and the DictionaryValue object will be unchanged. 290 bool Remove(const std::string& path, Value** out_value); 291 292 // Like Remove(), but without special treatment of '.'. This allows e.g. URLs 293 // to be used as paths. 294 bool RemoveWithoutPathExpansion(const std::string& key, Value** out_value); 295 296 // Makes a copy of |this| but doesn't include empty dictionaries and lists in 297 // the copy. This never returns NULL, even if |this| itself is empty. 298 DictionaryValue* DeepCopyWithoutEmptyChildren(); 299 300 // Merge a given dictionary into this dictionary. This is done recursively, 301 // i.e. any subdictionaries will be merged as well. In case of key collisions, 302 // the passed in dictionary takes precedence and data already present will be 303 // replaced. 304 void MergeDictionary(const DictionaryValue* dictionary); 305 306 // Builds a vector containing all of the paths that are different between 307 // the dictionary and a second specified dictionary. These are paths of 308 // values that are either in one dictionary or the other but not both, OR 309 // paths that are present in both dictionaries but differ in value. 310 // Path strings are in ascending lexicographical order in the generated 311 // vector. |different_paths| is cleared before added any paths. 312 void GetDifferingPaths( 313 const DictionaryValue* other, 314 std::vector<std::string>* different_paths) const; 315 316 // This class provides an iterator for the keys in the dictionary. 317 // It can't be used to modify the dictionary. 318 // 319 // YOU SHOULD ALWAYS USE THE XXXWithoutPathExpansion() APIs WITH THESE, NOT 320 // THE NORMAL XXX() APIs. This makes sure things will work correctly if any 321 // keys have '.'s in them. 322 class key_iterator 323 : private std::iterator<std::input_iterator_tag, const std::string> { 324 public: 325 explicit key_iterator(ValueMap::const_iterator itr) { itr_ = itr; } 326 key_iterator operator++() { 327 ++itr_; 328 return *this; 329 } 330 const std::string& operator*() { return itr_->first; } 331 bool operator!=(const key_iterator& other) { return itr_ != other.itr_; } 332 bool operator==(const key_iterator& other) { return itr_ == other.itr_; } 333 334 private: 335 ValueMap::const_iterator itr_; 336 }; 337 338 key_iterator begin_keys() const { return key_iterator(dictionary_.begin()); } 339 key_iterator end_keys() const { return key_iterator(dictionary_.end()); } 340 341 private: 342 // Does the actual heavy lifting for GetDifferingPaths. 343 // Returns true if a path is added to different_paths, otherwise false. 344 // The difference compuation is calculated recursively. The keys for 345 // dictionaries that are handled by recursive calls more shallow than 346 // the current one are concatenated and passed through to deeper calls in 347 // |path_prefix|. 348 bool GetDifferingPathsHelper( 349 const std::string& path_prefix, 350 const DictionaryValue* other, 351 std::vector<std::string>* different_paths) const; 352 353 ValueMap dictionary_; 354 355 DISALLOW_COPY_AND_ASSIGN(DictionaryValue); 356}; 357 358// This type of Value represents a list of other Value values. 359class ListValue : public Value { 360 public: 361 ListValue(); 362 ~ListValue(); 363 364 // Subclassed methods 365 Value* DeepCopy() const; 366 virtual bool Equals(const Value* other) const; 367 368 // Clears the contents of this ListValue 369 void Clear(); 370 371 // Returns the number of Values in this list. 372 size_t GetSize() const { return list_.size(); } 373 374 // Returns whether the list is empty. 375 bool empty() const { return list_.empty(); } 376 377 // Sets the list item at the given index to be the Value specified by 378 // the value given. If the index beyond the current end of the list, null 379 // Values will be used to pad out the list. 380 // Returns true if successful, or false if the index was negative or 381 // the value is a null pointer. 382 bool Set(size_t index, Value* in_value); 383 384 // Gets the Value at the given index. Modifies |out_value| (and returns true) 385 // only if the index falls within the current list range. 386 // Note that the list always owns the Value passed out via |out_value|. 387 bool Get(size_t index, Value** out_value) const; 388 389 // Convenience forms of Get(). Modifies |out_value| (and returns true) 390 // only if the index is valid and the Value at that index can be returned 391 // in the specified form. 392 bool GetBoolean(size_t index, bool* out_value) const; 393 bool GetInteger(size_t index, int* out_value) const; 394 bool GetReal(size_t index, double* out_value) const; 395 bool GetString(size_t index, std::string* out_value) const; 396 bool GetString(size_t index, string16* out_value) const; 397 bool GetBinary(size_t index, BinaryValue** out_value) const; 398 bool GetDictionary(size_t index, DictionaryValue** out_value) const; 399 bool GetList(size_t index, ListValue** out_value) const; 400 401 // Removes the Value with the specified index from this list. 402 // If |out_value| is non-NULL, the removed Value AND ITS OWNERSHIP will be 403 // passed out via |out_value|. If |out_value| is NULL, the removed value will 404 // be deleted. This method returns true if |index| is valid; otherwise 405 // it will return false and the ListValue object will be unchanged. 406 bool Remove(size_t index, Value** out_value); 407 408 // Removes the first instance of |value| found in the list, if any, and 409 // deletes it. Returns the index that it was located at (-1 for not present). 410 int Remove(const Value& value); 411 412 // Appends a Value to the end of the list. 413 void Append(Value* in_value); 414 415 // Appends a Value if it's not already present. 416 // Returns true if successful, or false if the value was already present. 417 bool AppendIfNotPresent(Value* in_value); 418 419 // Insert a Value at index. 420 // Returns true if successful, or false if the index was out of range. 421 bool Insert(size_t index, Value* in_value); 422 423 // Swaps contents with the |other| list. 424 void Swap(ListValue* other) { 425 list_.swap(other->list_); 426 } 427 428 // Iteration 429 typedef ValueVector::iterator iterator; 430 typedef ValueVector::const_iterator const_iterator; 431 432 ListValue::iterator begin() { return list_.begin(); } 433 ListValue::iterator end() { return list_.end(); } 434 435 ListValue::const_iterator begin() const { return list_.begin(); } 436 ListValue::const_iterator end() const { return list_.end(); } 437 438 private: 439 ValueVector list_; 440 441 DISALLOW_COPY_AND_ASSIGN(ListValue); 442}; 443 444// This interface is implemented by classes that know how to serialize and 445// deserialize Value objects. 446class ValueSerializer { 447 public: 448 virtual ~ValueSerializer(); 449 450 virtual bool Serialize(const Value& root) = 0; 451 452 // This method deserializes the subclass-specific format into a Value object. 453 // If the return value is non-NULL, the caller takes ownership of returned 454 // Value. If the return value is NULL, and if error_code is non-NULL, 455 // error_code will be set with the underlying error. 456 // If |error_message| is non-null, it will be filled in with a formatted 457 // error message including the location of the error if appropriate. 458 virtual Value* Deserialize(int* error_code, std::string* error_str) = 0; 459}; 460 461#endif // BASE_VALUES_H_ 462