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// Copyright (c) 2006-2008 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_META_TABLE_HELPER_H__
#define CHROME_BROWSER_META_TABLE_HELPER_H__
#include <string>
#include "base/basictypes.h"
struct sqlite3;
class SQLStatement;
// MetaTableHelper maintains arbitrary key/value pairs in a table, as well
// as version information. MetaTableHelper is used by both WebDatabase and
// HistoryDatabase to maintain version information.
//
// To use a MetalTableHelper you must invoke the init method specifying the
// database to use.
class MetaTableHelper {
public:
// Creates a new MetaTableHelper. After construction you must invoke
// Init with the appropriate database.
MetaTableHelper();
~MetaTableHelper();
// Initializes the MetaTableHelper, creating the meta table if necessary. For
// new tables, it will initialize the version number to |version| and the
// compatible version number to |compatible_version|.
//
// The name of the database in the sqlite connection (for tables named with
// the "db_name.table_name" scheme is given in |db_name|. If empty, it is
// assumed there is no database name.
bool Init(const std::string& db_name,
int version,
int compatible_version,
sqlite3* db);
// Version number. This should be the version number of the creator of the
// file. GetVersionNumber will return 0 if there is no version number.
// See also *CompatibleVersionNumber.
void SetVersionNumber(int version);
int GetVersionNumber();
// The compatible version number is the lowest version that this file format
// is readable by. If an addition or other non-critical change is made to the
// file in such a way that it could be read or written non-catastrophically
// by an older version, this number tells us which version that is.
//
// Any version newer than this should be able to interpret the file. Any
// version older than this should not touch the file or else it might
// corrupt it.
//
// GetCompatibleVersionNumber will return 0 if there is none.
void SetCompatibleVersionNumber(int version);
int GetCompatibleVersionNumber();
// Arbitrary key/value pair with a wstring value.
bool SetValue(const std::string& key, const std::wstring& value);
bool GetValue(const std::string& key, std::wstring* value);
// Arbitrary key/value pair with an int value.
bool SetValue(const std::string& key, int value);
bool GetValue(const std::string& key, int* value);
// Arbitrary key/value pair with an int64 value.
bool SetValue(const std::string& key, int64 value);
bool GetValue(const std::string& key, int64* value);
private:
friend class MetaTableHelperTest;
// Appends the meta table name to the SQL statement.
static void appendMetaTableName(const std::string& db_name, std::string* sql);
// Conveniences to prepare the two types of statements used by
// MetaTableHelper.
bool PrepareSetStatement(SQLStatement* statement, const std::string& key);
bool PrepareGetStatement(SQLStatement* statement, const std::string& key);
sqlite3* db_;
// Name of the database within the connection, if there is one. When empty,
// there is no special database name.
std::string db_name_;
DISALLOW_EVIL_CONSTRUCTORS(MetaTableHelper);
};
#endif // CHROME_BROWSER_META_TABLE_HELPER_H__
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