michael@0: // Copyright (c) 2012 The Chromium Authors. All rights reserved.
michael@0: // Use of this source code is governed by a BSD-style license that can be
michael@0: // found in the LICENSE file.
michael@0: 
michael@0: // This file specifies a recursive data storage class called Value intended for
michael@0: // storing settings and other persistable data.
michael@0: //
michael@0: // A Value represents something that can be stored in JSON or passed to/from
michael@0: // JavaScript. As such, it is NOT a generalized variant type, since only the
michael@0: // types supported by JavaScript/JSON are supported.
michael@0: //
michael@0: // IN PARTICULAR this means that there is no support for int64 or unsigned
michael@0: // numbers. Writing JSON with such types would violate the spec. If you need
michael@0: // something like this, either use a double or make a string value containing
michael@0: // the number you want.
michael@0: 
michael@0: #ifndef BASE_VALUES_H_
michael@0: #define BASE_VALUES_H_
michael@0: 
michael@0: #include <stddef.h>
michael@0: 
michael@0: #include <iosfwd>
michael@0: #include <map>
michael@0: #include <string>
michael@0: #include <utility>
michael@0: #include <vector>
michael@0: 
michael@0: #include "base/base_export.h"
michael@0: #include "base/basictypes.h"
michael@0: #include "base/compiler_specific.h"
michael@0: #include "base/memory/scoped_ptr.h"
michael@0: #include "base/strings/string16.h"
michael@0: 
michael@0: // This file declares "using base::Value", etc. at the bottom, so that
michael@0: // current code can use these classes without the base namespace. In
michael@0: // new code, please always use base::Value, etc. or add your own
michael@0: // "using" declaration.
michael@0: // http://crbug.com/88666
michael@0: namespace base {
michael@0: 
michael@0: class DictionaryValue;
michael@0: class FundamentalValue;
michael@0: class ListValue;
michael@0: class StringValue;
michael@0: class Value;
michael@0: 
michael@0: typedef std::vector<Value*> ValueVector;
michael@0: typedef std::map<std::string, Value*> ValueMap;
michael@0: 
michael@0: // The Value class is the base class for Values. A Value can be instantiated
michael@0: // via the Create*Value() factory methods, or by directly creating instances of
michael@0: // the subclasses.
michael@0: //
michael@0: // See the file-level comment above for more information.
michael@0: class BASE_EXPORT Value {
michael@0:  public:
michael@0:   enum Type {
michael@0:     TYPE_NULL = 0,
michael@0:     TYPE_BOOLEAN,
michael@0:     TYPE_INTEGER,
michael@0:     TYPE_DOUBLE,
michael@0:     TYPE_STRING,
michael@0:     TYPE_BINARY,
michael@0:     TYPE_DICTIONARY,
michael@0:     TYPE_LIST
michael@0:     // Note: Do not add more types. See the file-level comment above for why.
michael@0:   };
michael@0: 
michael@0:   virtual ~Value();
michael@0: 
michael@0:   static Value* CreateNullValue();
michael@0:   // DEPRECATED: Do not use the following 5 functions. Instead, use
michael@0:   // new FundamentalValue or new StringValue.
michael@0:   static FundamentalValue* CreateBooleanValue(bool in_value);
michael@0:   static FundamentalValue* CreateIntegerValue(int in_value);
michael@0:   static FundamentalValue* CreateDoubleValue(double in_value);
michael@0:   static StringValue* CreateStringValue(const std::string& in_value);
michael@0:   static StringValue* CreateStringValue(const string16& in_value);
michael@0: 
michael@0:   // Returns the type of the value stored by the current Value object.
michael@0:   // Each type will be implemented by only one subclass of Value, so it's
michael@0:   // safe to use the Type to determine whether you can cast from
michael@0:   // Value* to (Implementing Class)*.  Also, a Value object never changes
michael@0:   // its type after construction.
michael@0:   Type GetType() const { return type_; }
michael@0: 
michael@0:   // Returns true if the current object represents a given type.
michael@0:   bool IsType(Type type) const { return type == type_; }
michael@0: 
michael@0:   // These methods allow the convenient retrieval of the contents of the Value.
michael@0:   // If the current object can be converted into the given type, the value is
michael@0:   // returned through the |out_value| parameter and true is returned;
michael@0:   // otherwise, false is returned and |out_value| is unchanged.
michael@0:   virtual bool GetAsBoolean(bool* out_value) const;
michael@0:   virtual bool GetAsInteger(int* out_value) const;
michael@0:   virtual bool GetAsDouble(double* out_value) const;
michael@0:   virtual bool GetAsString(std::string* out_value) const;
michael@0:   virtual bool GetAsString(string16* out_value) const;
michael@0:   virtual bool GetAsList(ListValue** out_value);
michael@0:   virtual bool GetAsList(const ListValue** out_value) const;
michael@0:   virtual bool GetAsDictionary(DictionaryValue** out_value);
michael@0:   virtual bool GetAsDictionary(const DictionaryValue** out_value) const;
michael@0:   // Note: Do not add more types. See the file-level comment above for why.
michael@0: 
michael@0:   // This creates a deep copy of the entire Value tree, and returns a pointer
michael@0:   // to the copy.  The caller gets ownership of the copy, of course.
michael@0:   //
michael@0:   // Subclasses return their own type directly in their overrides;
michael@0:   // this works because C++ supports covariant return types.
michael@0:   virtual Value* DeepCopy() const;
michael@0: 
michael@0:   // Compares if two Value objects have equal contents.
michael@0:   virtual bool Equals(const Value* other) const;
michael@0: 
michael@0:   // Compares if two Value objects have equal contents. Can handle NULLs.
michael@0:   // NULLs are considered equal but different from Value::CreateNullValue().
michael@0:   static bool Equals(const Value* a, const Value* b);
michael@0: 
michael@0:  protected:
michael@0:   // These aren't safe for end-users, but they are useful for subclasses.
michael@0:   explicit Value(Type type);
michael@0:   Value(const Value& that);
michael@0:   Value& operator=(const Value& that);
michael@0: 
michael@0:  private:
michael@0:   Type type_;
michael@0: };
michael@0: 
michael@0: // FundamentalValue represents the simple fundamental types of values.
michael@0: class BASE_EXPORT FundamentalValue : public Value {
michael@0:  public:
michael@0:   explicit FundamentalValue(bool in_value);
michael@0:   explicit FundamentalValue(int in_value);
michael@0:   explicit FundamentalValue(double in_value);
michael@0:   virtual ~FundamentalValue();
michael@0: 
michael@0:   // Overridden from Value:
michael@0:   virtual bool GetAsBoolean(bool* out_value) const OVERRIDE;
michael@0:   virtual bool GetAsInteger(int* out_value) const OVERRIDE;
michael@0:   virtual bool GetAsDouble(double* out_value) const OVERRIDE;
michael@0:   virtual FundamentalValue* DeepCopy() const OVERRIDE;
michael@0:   virtual bool Equals(const Value* other) const OVERRIDE;
michael@0: 
michael@0:  private:
michael@0:   union {
michael@0:     bool boolean_value_;
michael@0:     int integer_value_;
michael@0:     double double_value_;
michael@0:   };
michael@0: };
michael@0: 
michael@0: class BASE_EXPORT StringValue : public Value {
michael@0:  public:
michael@0:   // Initializes a StringValue with a UTF-8 narrow character string.
michael@0:   explicit StringValue(const std::string& in_value);
michael@0: 
michael@0:   // Initializes a StringValue with a string16.
michael@0:   explicit StringValue(const string16& in_value);
michael@0: 
michael@0:   virtual ~StringValue();
michael@0: 
michael@0:   // Overridden from Value:
michael@0:   virtual bool GetAsString(std::string* out_value) const OVERRIDE;
michael@0:   virtual bool GetAsString(string16* out_value) const OVERRIDE;
michael@0:   virtual StringValue* DeepCopy() const OVERRIDE;
michael@0:   virtual bool Equals(const Value* other) const OVERRIDE;
michael@0: 
michael@0:  private:
michael@0:   std::string value_;
michael@0: };
michael@0: 
michael@0: class BASE_EXPORT BinaryValue: public Value {
michael@0:  public:
michael@0:   // Creates a BinaryValue with a null buffer and size of 0.
michael@0:   BinaryValue();
michael@0: 
michael@0:   // Creates a BinaryValue, taking ownership of the bytes pointed to by
michael@0:   // |buffer|.
michael@0:   BinaryValue(scoped_ptr<char[]> buffer, size_t size);
michael@0: 
michael@0:   virtual ~BinaryValue();
michael@0: 
michael@0:   // For situations where you want to keep ownership of your buffer, this
michael@0:   // factory method creates a new BinaryValue by copying the contents of the
michael@0:   // buffer that's passed in.
michael@0:   static BinaryValue* CreateWithCopiedBuffer(const char* buffer, size_t size);
michael@0: 
michael@0:   size_t GetSize() const { return size_; }
michael@0: 
michael@0:   // May return NULL.
michael@0:   char* GetBuffer() { return buffer_.get(); }
michael@0:   const char* GetBuffer() const { return buffer_.get(); }
michael@0: 
michael@0:   // Overridden from Value:
michael@0:   virtual BinaryValue* DeepCopy() const OVERRIDE;
michael@0:   virtual bool Equals(const Value* other) const OVERRIDE;
michael@0: 
michael@0:  private:
michael@0:   scoped_ptr<char[]> buffer_;
michael@0:   size_t size_;
michael@0: 
michael@0:   DISALLOW_COPY_AND_ASSIGN(BinaryValue);
michael@0: };
michael@0: 
michael@0: // DictionaryValue provides a key-value dictionary with (optional) "path"
michael@0: // parsing for recursive access; see the comment at the top of the file. Keys
michael@0: // are |std::string|s and should be UTF-8 encoded.
michael@0: class BASE_EXPORT DictionaryValue : public Value {
michael@0:  public:
michael@0:   DictionaryValue();
michael@0:   virtual ~DictionaryValue();
michael@0: 
michael@0:   // Overridden from Value:
michael@0:   virtual bool GetAsDictionary(DictionaryValue** out_value) OVERRIDE;
michael@0:   virtual bool GetAsDictionary(
michael@0:       const DictionaryValue** out_value) const OVERRIDE;
michael@0: 
michael@0:   // Returns true if the current dictionary has a value for the given key.
michael@0:   bool HasKey(const std::string& key) const;
michael@0: 
michael@0:   // Returns the number of Values in this dictionary.
michael@0:   size_t size() const { return dictionary_.size(); }
michael@0: 
michael@0:   // Returns whether the dictionary is empty.
michael@0:   bool empty() const { return dictionary_.empty(); }
michael@0: 
michael@0:   // Clears any current contents of this dictionary.
michael@0:   void Clear();
michael@0: 
michael@0:   // Sets the Value associated with the given path starting from this object.
michael@0:   // A path has the form "<key>" or "<key>.<key>.[...]", where "." indexes
michael@0:   // into the next DictionaryValue down.  Obviously, "." can't be used
michael@0:   // within a key, but there are no other restrictions on keys.
michael@0:   // If the key at any step of the way doesn't exist, or exists but isn't
michael@0:   // a DictionaryValue, a new DictionaryValue will be created and attached
michael@0:   // to the path in that location.
michael@0:   // Note that the dictionary takes ownership of the value referenced by
michael@0:   // |in_value|, and therefore |in_value| must be non-NULL.
michael@0:   void Set(const std::string& path, Value* in_value);
michael@0: 
michael@0:   // Convenience forms of Set().  These methods will replace any existing
michael@0:   // value at that path, even if it has a different type.
michael@0:   void SetBoolean(const std::string& path, bool in_value);
michael@0:   void SetInteger(const std::string& path, int in_value);
michael@0:   void SetDouble(const std::string& path, double in_value);
michael@0:   void SetString(const std::string& path, const std::string& in_value);
michael@0:   void SetString(const std::string& path, const string16& in_value);
michael@0: 
michael@0:   // Like Set(), but without special treatment of '.'.  This allows e.g. URLs to
michael@0:   // be used as paths.
michael@0:   void SetWithoutPathExpansion(const std::string& key, Value* in_value);
michael@0: 
michael@0:   // Convenience forms of SetWithoutPathExpansion().
michael@0:   void SetBooleanWithoutPathExpansion(const std::string& path, bool in_value);
michael@0:   void SetIntegerWithoutPathExpansion(const std::string& path, int in_value);
michael@0:   void SetDoubleWithoutPathExpansion(const std::string& path, double in_value);
michael@0:   void SetStringWithoutPathExpansion(const std::string& path,
michael@0:                                      const std::string& in_value);
michael@0:   void SetStringWithoutPathExpansion(const std::string& path,
michael@0:                                      const string16& in_value);
michael@0: 
michael@0:   // Gets the Value associated with the given path starting from this object.
michael@0:   // A path has the form "<key>" or "<key>.<key>.[...]", where "." indexes
michael@0:   // into the next DictionaryValue down.  If the path can be resolved
michael@0:   // successfully, the value for the last key in the path will be returned
michael@0:   // through the |out_value| parameter, and the function will return true.
michael@0:   // Otherwise, it will return false and |out_value| will be untouched.
michael@0:   // Note that the dictionary always owns the value that's returned.
michael@0:   bool Get(const std::string& path, const Value** out_value) const;
michael@0:   bool Get(const std::string& path, Value** out_value);
michael@0: 
michael@0:   // These are convenience forms of Get().  The value will be retrieved
michael@0:   // and the return value will be true if the path is valid and the value at
michael@0:   // the end of the path can be returned in the form specified.
michael@0:   bool GetBoolean(const std::string& path, bool* out_value) const;
michael@0:   bool GetInteger(const std::string& path, int* out_value) const;
michael@0:   bool GetDouble(const std::string& path, double* out_value) const;
michael@0:   bool GetString(const std::string& path, std::string* out_value) const;
michael@0:   bool GetString(const std::string& path, string16* out_value) const;
michael@0:   bool GetStringASCII(const std::string& path, std::string* out_value) const;
michael@0:   bool GetBinary(const std::string& path, const BinaryValue** out_value) const;
michael@0:   bool GetBinary(const std::string& path, BinaryValue** out_value);
michael@0:   bool GetDictionary(const std::string& path,
michael@0:                      const DictionaryValue** out_value) const;
michael@0:   bool GetDictionary(const std::string& path, DictionaryValue** out_value);
michael@0:   bool GetList(const std::string& path, const ListValue** out_value) const;
michael@0:   bool GetList(const std::string& path, ListValue** out_value);
michael@0: 
michael@0:   // Like Get(), but without special treatment of '.'.  This allows e.g. URLs to
michael@0:   // be used as paths.
michael@0:   bool GetWithoutPathExpansion(const std::string& key,
michael@0:                                const Value** out_value) const;
michael@0:   bool GetWithoutPathExpansion(const std::string& key, Value** out_value);
michael@0:   bool GetBooleanWithoutPathExpansion(const std::string& key,
michael@0:                                       bool* out_value) const;
michael@0:   bool GetIntegerWithoutPathExpansion(const std::string& key,
michael@0:                                       int* out_value) const;
michael@0:   bool GetDoubleWithoutPathExpansion(const std::string& key,
michael@0:                                      double* out_value) const;
michael@0:   bool GetStringWithoutPathExpansion(const std::string& key,
michael@0:                                      std::string* out_value) const;
michael@0:   bool GetStringWithoutPathExpansion(const std::string& key,
michael@0:                                      string16* out_value) const;
michael@0:   bool GetDictionaryWithoutPathExpansion(
michael@0:       const std::string& key,
michael@0:       const DictionaryValue** out_value) const;
michael@0:   bool GetDictionaryWithoutPathExpansion(const std::string& key,
michael@0:                                          DictionaryValue** out_value);
michael@0:   bool GetListWithoutPathExpansion(const std::string& key,
michael@0:                                    const ListValue** out_value) const;
michael@0:   bool GetListWithoutPathExpansion(const std::string& key,
michael@0:                                    ListValue** out_value);
michael@0: 
michael@0:   // Removes the Value with the specified path from this dictionary (or one
michael@0:   // of its child dictionaries, if the path is more than just a local key).
michael@0:   // If |out_value| is non-NULL, the removed Value will be passed out via
michael@0:   // |out_value|.  If |out_value| is NULL, the removed value will be deleted.
michael@0:   // This method returns true if |path| is a valid path; otherwise it will
michael@0:   // return false and the DictionaryValue object will be unchanged.
michael@0:   virtual bool Remove(const std::string& path, scoped_ptr<Value>* out_value);
michael@0: 
michael@0:   // Like Remove(), but without special treatment of '.'.  This allows e.g. URLs
michael@0:   // to be used as paths.
michael@0:   virtual bool RemoveWithoutPathExpansion(const std::string& key,
michael@0:                                           scoped_ptr<Value>* out_value);
michael@0: 
michael@0:   // Makes a copy of |this| but doesn't include empty dictionaries and lists in
michael@0:   // the copy.  This never returns NULL, even if |this| itself is empty.
michael@0:   DictionaryValue* DeepCopyWithoutEmptyChildren() const;
michael@0: 
michael@0:   // Merge |dictionary| into this dictionary. This is done recursively, i.e. any
michael@0:   // sub-dictionaries will be merged as well. In case of key collisions, the
michael@0:   // passed in dictionary takes precedence and data already present will be
michael@0:   // replaced. Values within |dictionary| are deep-copied, so |dictionary| may
michael@0:   // be freed any time after this call.
michael@0:   void MergeDictionary(const DictionaryValue* dictionary);
michael@0: 
michael@0:   // Swaps contents with the |other| dictionary.
michael@0:   virtual void Swap(DictionaryValue* other);
michael@0: 
michael@0:   // This class provides an iterator over both keys and values in the
michael@0:   // dictionary.  It can't be used to modify the dictionary.
michael@0:   class BASE_EXPORT Iterator {
michael@0:    public:
michael@0:     explicit Iterator(const DictionaryValue& target);
michael@0: 
michael@0:     bool IsAtEnd() const { return it_ == target_.dictionary_.end(); }
michael@0:     void Advance() { ++it_; }
michael@0: 
michael@0:     const std::string& key() const { return it_->first; }
michael@0:     const Value& value() const { return *it_->second; }
michael@0: 
michael@0:    private:
michael@0:     const DictionaryValue& target_;
michael@0:     ValueMap::const_iterator it_;
michael@0:   };
michael@0: 
michael@0:   // Overridden from Value:
michael@0:   virtual DictionaryValue* DeepCopy() const OVERRIDE;
michael@0:   virtual bool Equals(const Value* other) const OVERRIDE;
michael@0: 
michael@0:  private:
michael@0:   ValueMap dictionary_;
michael@0: 
michael@0:   DISALLOW_COPY_AND_ASSIGN(DictionaryValue);
michael@0: };
michael@0: 
michael@0: // This type of Value represents a list of other Value values.
michael@0: class BASE_EXPORT ListValue : public Value {
michael@0:  public:
michael@0:   typedef ValueVector::iterator iterator;
michael@0:   typedef ValueVector::const_iterator const_iterator;
michael@0: 
michael@0:   ListValue();
michael@0:   virtual ~ListValue();
michael@0: 
michael@0:   // Clears the contents of this ListValue
michael@0:   void Clear();
michael@0: 
michael@0:   // Returns the number of Values in this list.
michael@0:   size_t GetSize() const { return list_.size(); }
michael@0: 
michael@0:   // Returns whether the list is empty.
michael@0:   bool empty() const { return list_.empty(); }
michael@0: 
michael@0:   // Sets the list item at the given index to be the Value specified by
michael@0:   // the value given.  If the index beyond the current end of the list, null
michael@0:   // Values will be used to pad out the list.
michael@0:   // Returns true if successful, or false if the index was negative or
michael@0:   // the value is a null pointer.
michael@0:   bool Set(size_t index, Value* in_value);
michael@0: 
michael@0:   // Gets the Value at the given index.  Modifies |out_value| (and returns true)
michael@0:   // only if the index falls within the current list range.
michael@0:   // Note that the list always owns the Value passed out via |out_value|.
michael@0:   bool Get(size_t index, const Value** out_value) const;
michael@0:   bool Get(size_t index, Value** out_value);
michael@0: 
michael@0:   // Convenience forms of Get().  Modifies |out_value| (and returns true)
michael@0:   // only if the index is valid and the Value at that index can be returned
michael@0:   // in the specified form.
michael@0:   bool GetBoolean(size_t index, bool* out_value) const;
michael@0:   bool GetInteger(size_t index, int* out_value) const;
michael@0:   bool GetDouble(size_t index, double* out_value) const;
michael@0:   bool GetString(size_t index, std::string* out_value) const;
michael@0:   bool GetString(size_t index, string16* out_value) const;
michael@0:   bool GetBinary(size_t index, const BinaryValue** out_value) const;
michael@0:   bool GetBinary(size_t index, BinaryValue** out_value);
michael@0:   bool GetDictionary(size_t index, const DictionaryValue** out_value) const;
michael@0:   bool GetDictionary(size_t index, DictionaryValue** out_value);
michael@0:   bool GetList(size_t index, const ListValue** out_value) const;
michael@0:   bool GetList(size_t index, ListValue** out_value);
michael@0: 
michael@0:   // Removes the Value with the specified index from this list.
michael@0:   // If |out_value| is non-NULL, the removed Value AND ITS OWNERSHIP will be
michael@0:   // passed out via |out_value|.  If |out_value| is NULL, the removed value will
michael@0:   // be deleted.  This method returns true if |index| is valid; otherwise
michael@0:   // it will return false and the ListValue object will be unchanged.
michael@0:   virtual bool Remove(size_t index, scoped_ptr<Value>* out_value);
michael@0: 
michael@0:   // Removes the first instance of |value| found in the list, if any, and
michael@0:   // deletes it. |index| is the location where |value| was found. Returns false
michael@0:   // if not found.
michael@0:   bool Remove(const Value& value, size_t* index);
michael@0: 
michael@0:   // Removes the element at |iter|. If |out_value| is NULL, the value will be
michael@0:   // deleted, otherwise ownership of the value is passed back to the caller.
michael@0:   // Returns an iterator pointing to the location of the element that
michael@0:   // followed the erased element.
michael@0:   iterator Erase(iterator iter, scoped_ptr<Value>* out_value);
michael@0: 
michael@0:   // Appends a Value to the end of the list.
michael@0:   void Append(Value* in_value);
michael@0: 
michael@0:   // Convenience forms of Append.
michael@0:   void AppendBoolean(bool in_value);
michael@0:   void AppendInteger(int in_value);
michael@0:   void AppendDouble(double in_value);
michael@0:   void AppendString(const std::string& in_value);
michael@0:   void AppendString(const string16& in_value);
michael@0:   void AppendStrings(const std::vector<std::string>& in_values);
michael@0:   void AppendStrings(const std::vector<string16>& in_values);
michael@0: 
michael@0:   // Appends a Value if it's not already present. Takes ownership of the
michael@0:   // |in_value|. Returns true if successful, or false if the value was already
michael@0:   // present. If the value was already present the |in_value| is deleted.
michael@0:   bool AppendIfNotPresent(Value* in_value);
michael@0: 
michael@0:   // Insert a Value at index.
michael@0:   // Returns true if successful, or false if the index was out of range.
michael@0:   bool Insert(size_t index, Value* in_value);
michael@0: 
michael@0:   // Searches for the first instance of |value| in the list using the Equals
michael@0:   // method of the Value type.
michael@0:   // Returns a const_iterator to the found item or to end() if none exists.
michael@0:   const_iterator Find(const Value& value) const;
michael@0: 
michael@0:   // Swaps contents with the |other| list.
michael@0:   virtual void Swap(ListValue* other);
michael@0: 
michael@0:   // Iteration.
michael@0:   iterator begin() { return list_.begin(); }
michael@0:   iterator end() { return list_.end(); }
michael@0: 
michael@0:   const_iterator begin() const { return list_.begin(); }
michael@0:   const_iterator end() const { return list_.end(); }
michael@0: 
michael@0:   // Overridden from Value:
michael@0:   virtual bool GetAsList(ListValue** out_value) OVERRIDE;
michael@0:   virtual bool GetAsList(const ListValue** out_value) const OVERRIDE;
michael@0:   virtual ListValue* DeepCopy() const OVERRIDE;
michael@0:   virtual bool Equals(const Value* other) const OVERRIDE;
michael@0: 
michael@0:  private:
michael@0:   ValueVector list_;
michael@0: 
michael@0:   DISALLOW_COPY_AND_ASSIGN(ListValue);
michael@0: };
michael@0: 
michael@0: // This interface is implemented by classes that know how to serialize and
michael@0: // deserialize Value objects.
michael@0: class BASE_EXPORT ValueSerializer {
michael@0:  public:
michael@0:   virtual ~ValueSerializer();
michael@0: 
michael@0:   virtual bool Serialize(const Value& root) = 0;
michael@0: 
michael@0:   // This method deserializes the subclass-specific format into a Value object.
michael@0:   // If the return value is non-NULL, the caller takes ownership of returned
michael@0:   // Value. If the return value is NULL, and if error_code is non-NULL,
michael@0:   // error_code will be set with the underlying error.
michael@0:   // If |error_message| is non-null, it will be filled in with a formatted
michael@0:   // error message including the location of the error if appropriate.
michael@0:   virtual Value* Deserialize(int* error_code, std::string* error_str) = 0;
michael@0: };
michael@0: 
michael@0: // Stream operator so Values can be used in assertion statements.  In order that
michael@0: // gtest uses this operator to print readable output on test failures, we must
michael@0: // override each specific type. Otherwise, the default template implementation
michael@0: // is preferred over an upcast.
michael@0: BASE_EXPORT std::ostream& operator<<(std::ostream& out, const Value& value);
michael@0: 
michael@0: BASE_EXPORT inline std::ostream& operator<<(std::ostream& out,
michael@0:                                             const FundamentalValue& value) {
michael@0:   return out << static_cast<const Value&>(value);
michael@0: }
michael@0: 
michael@0: BASE_EXPORT inline std::ostream& operator<<(std::ostream& out,
michael@0:                                             const StringValue& value) {
michael@0:   return out << static_cast<const Value&>(value);
michael@0: }
michael@0: 
michael@0: BASE_EXPORT inline std::ostream& operator<<(std::ostream& out,
michael@0:                                             const DictionaryValue& value) {
michael@0:   return out << static_cast<const Value&>(value);
michael@0: }
michael@0: 
michael@0: BASE_EXPORT inline std::ostream& operator<<(std::ostream& out,
michael@0:                                             const ListValue& value) {
michael@0:   return out << static_cast<const Value&>(value);
michael@0: }
michael@0: 
michael@0: }  // namespace base
michael@0: 
michael@0: // http://crbug.com/88666
michael@0: using base::DictionaryValue;
michael@0: using base::ListValue;
michael@0: using base::StringValue;
michael@0: using base::Value;
michael@0: 
michael@0: #endif  // BASE_VALUES_H_