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