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// Copyright (c) 2010 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 setting and other persistable data. It includes the ability to
// specify (recursive) lists and dictionaries, so it's fairly expressive.
// However, the API is optimized for the common case, namely storing a
// hierarchical tree of simple values. Given a DictionaryValue root, you can
// easily do things like:
//
// root->SetString("global.pages.homepage", "http://goateleporter.com");
// std::string homepage = "http://google.com"; // default/fallback value
// root->GetString("global.pages.homepage", &homepage);
//
// where "global" and "pages" are also DictionaryValues, and "homepage" is a
// string setting. If some elements of the path didn't exist yet, the
// SetString() method would create the missing elements and attach them to root
// before attaching the homepage value.
#ifndef BASE_VALUES_H_
#define BASE_VALUES_H_
#pragma once
#include <iterator>
#include <map>
#include <string>
#include <vector>
#include "base/basictypes.h"
#include "base/string16.h"
#include "build/build_config.h"
class Value;
class FundamentalValue;
class StringValue;
class BinaryValue;
class DictionaryValue;
class ListValue;
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.
class Value {
public:
virtual ~Value();
// Convenience methods for creating Value objects for various
// kinds of values without thinking about which class implements them.
// These can always be expected to return a valid Value*.
static Value* CreateNullValue();
static Value* CreateBooleanValue(bool in_value);
static Value* CreateIntegerValue(int in_value);
static Value* CreateRealValue(double in_value);
static Value* CreateStringValue(const std::string& in_value);
static Value* CreateStringValue(const string16& in_value);
// This one can return NULL if the input isn't valid. If the return value
// is non-null, the new object has taken ownership of the buffer pointer.
static BinaryValue* CreateBinaryValue(char* buffer, size_t size);
typedef enum {
TYPE_NULL = 0,
TYPE_BOOLEAN,
TYPE_INTEGER,
TYPE_REAL,
TYPE_STRING,
TYPE_BINARY,
TYPE_DICTIONARY,
TYPE_LIST
} ValueType;
// 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 ValueType to determine whether you can cast from
// Value* to (Implementing Class)*. Also, a Value object never changes
// its type after construction.
ValueType GetType() const { return type_; }
// Returns true if the current object represents a given type.
bool IsType(ValueType type) const { return type == type_; }
// These methods allow the convenient retrieval of settings.
// If the current setting 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 GetAsReal(double* out_value) const;
virtual bool GetAsString(std::string* out_value) const;
virtual bool GetAsString(string16* out_value) const;
// 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.
virtual Value* DeepCopy() const;
// Compares if two Value objects have equal contents.
virtual bool Equals(const Value* other) const;
protected:
// This isn't safe for end-users (they should use the Create*Value()
// static methods above), but it's useful for subclasses.
explicit Value(ValueType type);
private:
Value();
ValueType type_;
DISALLOW_COPY_AND_ASSIGN(Value);
};
// FundamentalValue represents the simple fundamental types of values.
class FundamentalValue : public Value {
public:
explicit FundamentalValue(bool in_value);
explicit FundamentalValue(int in_value);
explicit FundamentalValue(double in_value);
~FundamentalValue();
// Subclassed methods
virtual bool GetAsBoolean(bool* out_value) const;
virtual bool GetAsInteger(int* out_value) const;
virtual bool GetAsReal(double* out_value) const;
virtual Value* DeepCopy() const;
virtual bool Equals(const Value* other) const;
private:
union {
bool boolean_value_;
int integer_value_;
double real_value_;
};
DISALLOW_COPY_AND_ASSIGN(FundamentalValue);
};
class 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);
~StringValue();
// Subclassed methods
bool GetAsString(std::string* out_value) const;
bool GetAsString(string16* out_value) const;
Value* DeepCopy() const;
virtual bool Equals(const Value* other) const;
private:
std::string value_;
DISALLOW_COPY_AND_ASSIGN(StringValue);
};
class BinaryValue: public Value {
public:
// Creates a Value to represent a binary buffer. The new object takes
// ownership of the pointer passed in, if successful.
// Returns NULL if buffer is NULL.
static BinaryValue* Create(char* buffer, size_t size);
// 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.
// Returns NULL if buffer is NULL.
static BinaryValue* CreateWithCopiedBuffer(const char* buffer, size_t size);
~BinaryValue();
// Subclassed methods
Value* DeepCopy() const;
virtual bool Equals(const Value* other) const;
size_t GetSize() const { return size_; }
char* GetBuffer() { return buffer_; }
const char* GetBuffer() const { return buffer_; }
private:
// Constructor is private so that only objects with valid buffer pointers
// and size values can be created.
BinaryValue(char* buffer, size_t size);
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 DictionaryValue : public Value {
public:
DictionaryValue();
~DictionaryValue();
// Subclassed methods
Value* DeepCopy() const;
virtual bool Equals(const Value* other) const;
// 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 SetReal(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);
// 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.
bool Get(const std::string& path, Value** out_value) const;
// 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.
bool GetBoolean(const std::string& path, bool* out_value) const;
bool GetInteger(const std::string& path, int* out_value) const;
bool GetReal(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, BinaryValue** out_value) const;
bool GetDictionary(const std::string& path,
DictionaryValue** out_value) const;
bool GetList(const std::string& path, ListValue** out_value) const;
// Like Get(), but without special treatment of '.'. This allows e.g. URLs to
// be used as paths.
bool GetWithoutPathExpansion(const std::string& key,
Value** out_value) const;
bool GetIntegerWithoutPathExpansion(const std::string& key,
int* out_value) const;
bool GetRealWithoutPathExpansion(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,
DictionaryValue** out_value) const;
bool GetListWithoutPathExpansion(const std::string& key,
ListValue** out_value) const;
// 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 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 |path| is a valid path; otherwise
// it will return false and the DictionaryValue object will be unchanged.
bool Remove(const std::string& path, Value** out_value);
// Like Remove(), but without special treatment of '.'. This allows e.g. URLs
// to be used as paths.
bool RemoveWithoutPathExpansion(const std::string& key, 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();
// Merge a given dictionary into this dictionary. This is done recursively,
// i.e. any subdictionaries will be merged as well. In case of key collisions,
// the passed in dictionary takes precedence and data already present will be
// replaced.
void MergeDictionary(const DictionaryValue* dictionary);
// Builds a vector containing all of the paths that are different between
// the dictionary and a second specified dictionary. These are paths of
// values that are either in one dictionary or the other but not both, OR
// paths that are present in both dictionaries but differ in value.
// Path strings are in ascending lexicographical order in the generated
// vector. |different_paths| is cleared before added any paths.
void GetDifferingPaths(
const DictionaryValue* other,
std::vector<std::string>* different_paths) const;
// This class provides an iterator for the keys in the dictionary.
// It can't be used to modify the dictionary.
//
// YOU SHOULD ALWAYS USE THE XXXWithoutPathExpansion() APIs WITH THESE, NOT
// THE NORMAL XXX() APIs. This makes sure things will work correctly if any
// keys have '.'s in them.
class key_iterator
: private std::iterator<std::input_iterator_tag, const std::string> {
public:
explicit key_iterator(ValueMap::const_iterator itr) { itr_ = itr; }
key_iterator operator++() {
++itr_;
return *this;
}
const std::string& operator*() { return itr_->first; }
bool operator!=(const key_iterator& other) { return itr_ != other.itr_; }
bool operator==(const key_iterator& other) { return itr_ == other.itr_; }
private:
ValueMap::const_iterator itr_;
};
key_iterator begin_keys() const { return key_iterator(dictionary_.begin()); }
key_iterator end_keys() const { return key_iterator(dictionary_.end()); }
private:
// Does the actual heavy lifting for GetDifferingPaths.
// Returns true if a path is added to different_paths, otherwise false.
// The difference compuation is calculated recursively. The keys for
// dictionaries that are handled by recursive calls more shallow than
// the current one are concatenated and passed through to deeper calls in
// |path_prefix|.
bool GetDifferingPathsHelper(
const std::string& path_prefix,
const DictionaryValue* other,
std::vector<std::string>* different_paths) const;
ValueMap dictionary_;
DISALLOW_COPY_AND_ASSIGN(DictionaryValue);
};
// This type of Value represents a list of other Value values.
class ListValue : public Value {
public:
ListValue();
~ListValue();
// Subclassed methods
Value* DeepCopy() const;
virtual bool Equals(const Value* other) const;
// 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|.
bool Get(size_t index, Value** out_value) const;
// 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.
bool GetBoolean(size_t index, bool* out_value) const;
bool GetInteger(size_t index, int* out_value) const;
bool GetReal(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, BinaryValue** out_value) const;
bool GetDictionary(size_t index, DictionaryValue** out_value) const;
bool GetList(size_t index, ListValue** out_value) const;
// 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.
bool Remove(size_t index, Value** out_value);
// Removes the first instance of |value| found in the list, if any, and
// deletes it. Returns the index that it was located at (-1 for not present).
int Remove(const Value& value);
// Appends a Value to the end of the list.
void Append(Value* in_value);
// Appends a Value if it's not already present.
// Returns true if successful, or false if the value was already present.
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);
// Swaps contents with the |other| list.
void Swap(ListValue* other) {
list_.swap(other->list_);
}
// Iteration
typedef ValueVector::iterator iterator;
typedef ValueVector::const_iterator const_iterator;
ListValue::iterator begin() { return list_.begin(); }
ListValue::iterator end() { return list_.end(); }
ListValue::const_iterator begin() const { return list_.begin(); }
ListValue::const_iterator end() const { return list_.end(); }
private:
ValueVector list_;
DISALLOW_COPY_AND_ASSIGN(ListValue);
};
// This interface is implemented by classes that know how to serialize and
// deserialize Value objects.
class 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;
};
#endif // BASE_VALUES_H_