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// 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.
#ifndef CHROME_BROWSER_VALUE_STORE_VALUE_STORE_H_
#define CHROME_BROWSER_VALUE_STORE_VALUE_STORE_H_
#include <string>
#include <vector>
#include "base/memory/scoped_ptr.h"
#include "base/values.h"
#include "chrome/browser/value_store/value_store_change.h"
// Interface for a storage area for Value objects.
class ValueStore {
public:
// The result of a read operation (Get).
class ReadResultType {
public:
// Ownership of |settings| taken.
explicit ReadResultType(DictionaryValue* settings);
explicit ReadResultType(const std::string& error);
~ReadResultType();
// Gets the settings read from the storage. Note that this represents
// the root object. If you request the value for key "foo", that value will
// be in |settings.foo|.
// Must only be called if HasError() is false.
scoped_ptr<DictionaryValue>& settings();
// Gets whether the operation failed.
bool HasError() const;
// Gets the error message describing the failure.
// Must only be called if HasError() is true.
const std::string& error() const;
private:
scoped_ptr<DictionaryValue> settings_;
const std::string error_;
DISALLOW_COPY_AND_ASSIGN(ReadResultType);
};
typedef scoped_ptr<ReadResultType> ReadResult;
// The result of a write operation (Set/Remove/Clear).
class WriteResultType {
public:
// Ownership of |changes| taken.
explicit WriteResultType(ValueStoreChangeList* changes);
explicit WriteResultType(const std::string& error);
~WriteResultType();
// Gets the list of changes to the settings which resulted from the write.
// Must only be called if HasError() is false.
const ValueStoreChangeList& changes() const;
// Gets whether the operation failed.
bool HasError() const;
// Gets the error message describing the failure.
// Must only be called if HasError() is true.
const std::string& error() const;
private:
const scoped_ptr<ValueStoreChangeList> changes_;
const std::string error_;
DISALLOW_COPY_AND_ASSIGN(WriteResultType);
};
typedef scoped_ptr<WriteResultType> WriteResult;
// Options for write operations.
enum WriteOptionsValues {
// Callers should usually use this.
DEFAULTS = 0,
// Ignore any quota restrictions.
IGNORE_QUOTA = 1<<1,
// Don't generate the changes for a WriteResult.
NO_GENERATE_CHANGES = 1<<2,
// Don't check the old value before writing a new value. This will also
// result in an empty |old_value| in the WriteResult::changes list.
NO_CHECK_OLD_VALUE = 1<<3
};
typedef int WriteOptions;
virtual ~ValueStore() {}
// Helpers for making a Read/WriteResult.
template<typename T>
static ReadResult MakeReadResult(T arg) {
return ReadResult(new ReadResultType(arg));
}
template<typename T>
static WriteResult MakeWriteResult(T arg) {
return WriteResult(new WriteResultType(arg));
}
// Gets the amount of space being used by a single value, in bytes.
// Note: The GetBytesInUse methods are only used by extension settings at the
// moment. If these become more generally useful, the
// SettingsStorageQuotaEnforcer and WeakUnlimitedSettingsStorage classes
// should be moved to the value_store directory.
virtual size_t GetBytesInUse(const std::string& key) = 0;
// Gets the total amount of space being used by multiple values, in bytes.
virtual size_t GetBytesInUse(const std::vector<std::string>& keys) = 0;
// Gets the total amount of space being used by this storage area, in bytes.
virtual size_t GetBytesInUse() = 0;
// Gets a single value from storage.
virtual ReadResult Get(const std::string& key) = 0;
// Gets multiple values from storage.
virtual ReadResult Get(const std::vector<std::string>& keys) = 0;
// Gets all values from storage.
virtual ReadResult Get() = 0;
// Sets a single key to a new value.
virtual WriteResult Set(
WriteOptions options, const std::string& key, const Value& value) = 0;
// Sets multiple keys to new values.
virtual WriteResult Set(
WriteOptions options, const DictionaryValue& values) = 0;
// Removes a key from the storage.
virtual WriteResult Remove(const std::string& key) = 0;
// Removes multiple keys from the storage.
virtual WriteResult Remove(const std::vector<std::string>& keys) = 0;
// Clears the storage.
virtual WriteResult Clear() = 0;
};
#endif // CHROME_BROWSER_VALUE_STORE_VALUE_STORE_H_
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