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 /* This file is part of the KDE project
    Copyright (C) 2003 Adam Pigg <adam@piggz.co.uk>
    Copyright (C) 2010-2016 Jarosław Staniek <staniek@kde.org>
 
    This program is free software; you can redistribute it and/or
    modify it under the terms of the GNU Library General Public
    License as published by the Free Software Foundation; either
    version 2 of the License, or (at your option) any later version.
 
    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
    Library General Public License for more details.
 
    You should have received a copy of the GNU Library General Public License
    along with this program; see the file COPYING.  If not, write to
    the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  * Boston, MA 02110-1301, USA.
 */
 
 #ifndef KDB_POSTGRESQLDRIVER_H
 #define KDB_POSTGRESQLDRIVER_H
 
 #include "KDbDriver.h"
 
 class KDbConnection;
 
 //! PostgreSQL database driver.
 class PostgresqlDriver : public KDbDriver
 {
     Q_OBJECT
 
 public:
     PostgresqlDriver(QObject *parent, const QVariantList &args);
 
     ~PostgresqlDriver() override;
 
     //! @todo implement
     bool isSystemObjectName(const QString& name) const override;
 
     bool isSystemDatabaseName(const QString& name) const override;
 
     //! Escape a string for use as a value
     KDbEscapedString escapeString(const QString& str) const override;
     KDbEscapedString escapeString(const QByteArray& str) const override;
     //! Overrides the default implementation to allow for NUMERIC type natively
     QString sqlTypeName(KDbField::Type type, const KDbField &field) const override;
 
     //! Escape BLOB value @a array
     KDbEscapedString escapeBLOB(const QByteArray& array) const override;
 
     //! Converts information converted from PQfmod() to length. -1 if missing.
     inline static int pqfmodToLength(int pqfmod) {
         int len;
         if (pqfmod > 0) {
             const int PGSQL_VAR_HDRSZ = 4;
             len = pqfmod - PGSQL_VAR_HDRSZ; //!< See e.g. postgis_get_char_length()
         } else {
             len = -1;
         }
         return len;
     }
 
     //! Uses information obtained from PQfmod() and adjust type @a t if possible.
     //! Also sets @a maxTextLength.
     //! @todo using pqfmod not tested
     //! @todo more types such as decimal
     inline static KDbField::Type typeForSize(KDbField::Type t, int pqfmod, int *maxTextLength) {
         KDbField::Type newType = t;
         if (maxTextLength) {
             *maxTextLength = -1;
         }
         if (t == KDbField::Integer) {
             if (pqfmod == 1) {
                 newType = KDbField::Byte;
             } else if (pqfmod == 2) {
                 newType = KDbField::ShortInteger;
             } else if (pqfmod == 8) {
                 newType = KDbField::BigInteger;
             }
         } else if (t == KDbField::LongText) {
             const int len = pqfmodToLength(pqfmod);
             if (len > 0 && len <= 255) {
                 newType = KDbField::Text;
                 if (maxTextLength) {
                     *maxTextLength = len;
                 }
             }
         }
         return newType;
     }
 
     //! @return KDb field type for PostgreSQL type @a pqtype and modifier @a pqfmod.
     //! If type cannot be found KDbField::InvalidType is returned.
     //! Used in cursors to speed up data conversion.
     inline KDbField::Type pgsqlToKDbType(int pqtype, int pqfmod, int *maxTextLength) const {
         KDbField::Type t = m_pgsqlToKDbTypes.value(pqtype, KDbField::InvalidType);
         return typeForSize(t, pqfmod, maxTextLength);
     }
 
     //! Generates native (driver-specific) HEX() function call.
     //! Uses UPPER(ENCODE(val, 'hex')).
     //! See https://www.postgresql.org/docs/9.3/static/functions-string.html#FUNCTIONS-STRING-OTHER */
     KDbEscapedString hexFunctionToString(const KDbNArgExpression &args,
                                          KDbQuerySchemaParameterValueListIterator* params,
                                          KDb::ExpressionCallStack* callStack) const override;
 
     //! Generates native (driver-specific) IFNULL() function call.
     //! Uses COALESCE().
     KDbEscapedString ifnullFunctionToString(const KDbNArgExpression &args,
                                             KDbQuerySchemaParameterValueListIterator* params,
                                             KDb::ExpressionCallStack* callStack) const override;
 
     //! Generates native (driver-specific) LENGTH() function call.
     //! For text types default LENGTH(val) is used, for BLOBs OCTET_LENGTH(val) is used because
     //! LENGTH(val) for BLOB returns number of bits.
     KDbEscapedString lengthFunctionToString(const KDbNArgExpression &args,
                                             KDbQuerySchemaParameterValueListIterator* params,
                                             KDb::ExpressionCallStack* callStack) const override;
 
     //! Generates native (driver-specific) GREATEST() and LEAST() function calls.
     //! Since PostgreSQL's LEAST()/GREATEST() function ignores NULL values, it only returns NULL
     //! if all the expressions evaluate to NULL. So this is used for F(v0,..,vN):
     //! (CASE WHEN (v0) IS NULL OR .. OR (vN) IS NULL THEN NULL ELSE F(v0,..,vN) END)
     //! where F == GREATEST or LEAST.
     KDbEscapedString greatestOrLeastFunctionToString(const QString &name,
                                                      const KDbNArgExpression &args,
                                                      KDbQuerySchemaParameterValueListIterator* params,
                                                      KDb::ExpressionCallStack* callStack) const override;
 
     //! Generates native (driver-specific) UNICODE() function call.
     //! Uses ASCII(X).
     KDbEscapedString unicodeFunctionToString(const KDbNArgExpression &args,
                                              KDbQuerySchemaParameterValueListIterator* params,
                                              KDb::ExpressionCallStack* callStack) const override;
 
 protected:
     QString drv_escapeIdentifier(const QString& str) const override;
     QByteArray drv_escapeIdentifier(const QByteArray& str) const override;
     KDbConnection *drv_createConnection(const KDbConnectionData& connData,
                                         const KDbConnectionOptions &options) override;
     bool drv_isSystemFieldName(const QString& name)const override;
 
 private:
     void initPgsqlToKDbMap();
 
     static const char *m_keywords[];
     QMap<int, KDbField::Type> m_pgsqlToKDbTypes;
     Q_DISABLE_COPY(PostgresqlDriver)
 };
 
 #endif // KDB_DRIVER_POSTGRESQLDRIVER_H