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#ifndef DBATTACHERIMPL_H
#define DBATTACHERIMPL_H
#include "dbattacher.h"
class DbAttacherImpl : public DbAttacher
{
public:
/**
* @brief Creates attacher with the given database as the main.
* @param db Database that the query will be executed on.
*/
DbAttacherImpl(Db* db);
bool attachDatabases(const QString& query);
bool attachDatabases(const QList<SqliteQueryPtr>& queries);
bool attachDatabases(SqliteQueryPtr query);
void detachDatabases();
BiStrHash getDbNameToAttach() const;
QString getQuery() const;
private:
/**
* @brief Does the actual job, after having all input queries as parsed objects.
* @return true on success, false on failure.
*/
bool attachDatabases();
/**
* @brief Finds tokens representing databases in the query.
* @return List of tokens. Some tokens have non-printable value (spaces, etc), others are database names.
*/
TokenList getDbTokens();
/**
* @brief Detaches all databases currently attached by the attacher.
*
* Also clears names mappings.
*/
void detachAttached();
/**
* @brief Generates mapping of database name to its Db object for all registered databases.
*/
void prepareNameToDbMap();
/**
* @brief Groups tokens by the name of database they refer to.
* @param dbTokens Tokens representing databases in the query.
*
* This method is used to learn if some database is used more than once in the query,
* so we attach it only once, then replace all tokens referring to it by the attach name.
*/
QHash<QString,TokenList> groupDbTokens(const TokenList& dbTokens);
/**
* @brief Tries to attach all required databases.
* @param groupedDbTokens Database tokens grouped by database name, as returned from groupDbTokens().
* @return true on success, false on any problem.
*
* Major problem that can happen is when "<tt>ATTACH 'path to file'</tt>" fails for any reason. In that case
* detachAttached() is called and false is returned.
*/
bool attachAllDbs(const QHash<QString,TokenList>& groupedDbTokens);
/**
* @brief Creates token-to-token replace map to update the query.
* @param dbTokens Tokens representing databases in the query.
* @return Mapping to be used when replacing tokens in the query.
*/
QHash<TokenPtr, TokenPtr> getTokenMapping(const TokenList& dbTokens);
/**
* @brief Replaces tokens in the query.
* @param tokenMapping Map of tokens to replace.
*
* Replacing takes place in token lists of each query in the queries member.
*/
void replaceTokensInQueries(const QHash<TokenPtr, TokenPtr>& tokenMapping);
QList<SqliteQueryPtr> queries;
Db* db = nullptr;
Dialect dialect;
BiStrHash dbNameToAttach;
StrHash<Db*> nameToDbMap;
};
class DbAttacherDefaultFactory : public DbAttacherFactory
{
public:
DbAttacher* create(Db* db);
};
#endif // DBATTACHERIMPL_H
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