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
35namespace base {
36
37class BinaryValue;
38class DictionaryValue;
39class FundamentalValue;
40class ListValue;
41class StringValue;
42class Value;
43
44typedef std::vector<Value*> ValueVector;
45typedef 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.
52class 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.
75  Type GetType() const { return type_; }
76
77  // Returns true if the current object represents a given 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.
123class 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
147class 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
168class 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
184  size_t GetSize() const { return size_; }
185
186  // May return NULL.
187  char* GetBuffer() { return buffer_.get(); }
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.
205class 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.
221  size_t size() const { return dictionary_.size(); }
222
223  // Returns whether the dictionary is 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
353    bool IsAtEnd() const { return it_ == target_.dictionary_.end(); }
354    void Advance() { ++it_; }
355
356    const std::string& key() const { return it_->first; }
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.
377class 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.
392  size_t GetSize() const { return list_.size(); }
393
394  // Returns whether the list is 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.
478  iterator begin() { return list_.begin(); }
479  iterator end() { return list_.end(); }
480
481  const_iterator begin() const { return list_.begin(); }
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.
503BASE_EXPORT std::ostream& operator<<(std::ostream& out, const Value& value);
504
505BASE_EXPORT inline std::ostream& operator<<(std::ostream& out,
506                                            const FundamentalValue& value) {
507  return out << static_cast<const Value&>(value);
508}
509
510BASE_EXPORT inline std::ostream& operator<<(std::ostream& out,
511                                            const StringValue& value) {
512  return out << static_cast<const Value&>(value);
513}
514
515BASE_EXPORT inline std::ostream& operator<<(std::ostream& out,
516                                            const DictionaryValue& value) {
517  return out << static_cast<const Value&>(value);
518}
519
520BASE_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