qsql: apply Qt's PIMPL idiom to Q*ResultPrivate

QResult and QResultPrivate are not derived from QObject and
QObjectPrivate respectively, but can still benefit from Qt's
PIMPL idiom. There are several interrelated aspects to this:

  - Base all driver ResultPrivate classes on QResultPrivate.
    Previously, each level in the Result hierarchy tended to keep
    its own private data class.

  - The ResultPrivate class initializes its own Result (q_ptr)
    and Driver members. This ensures that these pointers are
    correctly set in time for the ResultPrivate constructors
    and Result constructors. This is more efficient and makes
    it a lot easier to follow what's being allocated, initialized,
    and cleaned-up.

  - Use macros Q_DECLARE_PRIVATE, Q_DECLARE_PUBLIC, Q_D, and
    Q_Q for access to and from ResultPrivate objects.

  - ResultPrivate classes refer frequently to their counterpart
    DriverPrivate. Various patterns were used to do this. Now
    Q_DECLARE_SQLDRIVER_PRIVATE arranges this uniformly while
    hiding ugly casting. It creates a public method in the
    ResultPrivate returning the correctly typed pointer to the
    corresponding DriverPrivate object. Since the method is public,
    the Result class and helper classes and functions can also use it.

  - The explicit const is removed from QResultPrivate::sqldriver,
    even though it is treated (mostly) like a const within the
    context of Result and ResultPrivate. This is the same pattern
    seen in Qt's PIMPL idiom. The macro created getter methods
    take care of const.

  - qsql_mysql was using a signal/slot connection to zero its own
    copy of the driver pointer when the driver was destroyed. This is
    no longer necessary.

Change-Id: Ida4933bc92fb3e9a05ea4b53b48085894734e36e
Reviewed-by: Israel Lins Albuquerque <israelins85@yahoo.com.br>
Reviewed-by: Mark Brand <mabrand@mabrand.nl>

1 files changed, 32 insertions, 18 deletions

diff --git a/src/sql/drivers/sqlite/qsql_sqlite.cpp b/src/sql/drivers/sqlite/qsql_sqlite.cpp
index 4286f5b338..5f6ccf3990 100644
--- a/src/sql/drivers/sqlite/qsql_sqlite.cpp
+++ b/src/sql/drivers/sqlite/qsql_sqlite.cpp
@@ -105,8 +105,9 @@ class QSQLiteResultPrivate;
 
 class QSQLiteResult : public QSqlCachedResult
 {
+    Q_DECLARE_PRIVATE(QSQLiteResult)
     friend class QSQLiteDriver;
-    friend class QSQLiteResultPrivate;
+
 public:
     explicit QSQLiteResult(const QSQLiteDriver* db);
     ~QSQLiteResult();
@@ -123,13 +124,12 @@ protected:
     QSqlRecord record() const Q_DECL_OVERRIDE;
     void detachFromResultSet() Q_DECL_OVERRIDE;
     void virtual_hook(int id, void *data) Q_DECL_OVERRIDE;
-
-private:
-    QSQLiteResultPrivate* d;
 };
 
 class QSQLiteDriverPrivate : public QSqlDriverPrivate
 {
+    Q_DECLARE_PUBLIC(QSQLiteDriver)
+
 public:
     inline QSQLiteDriverPrivate() : QSqlDriverPrivate(), access(0) { dbmsType = QSqlDriver::SQLite; }
     sqlite3 *access;
@@ -137,17 +137,19 @@ public:
 };
 
 
-class QSQLiteResultPrivate
+class QSQLiteResultPrivate: public QSqlCachedResultPrivate
 {
+    Q_DECLARE_PUBLIC(QSQLiteResult)
+
 public:
-    QSQLiteResultPrivate(QSQLiteResult *res);
+    Q_DECLARE_SQLDRIVER_PRIVATE(QSQLiteDriver)
+    QSQLiteResultPrivate(QSQLiteResult *q, const QSQLiteDriver *drv);
     void cleanup();
     bool fetchNext(QSqlCachedResult::ValueCache &values, int idx, bool initialFetch);
     // initializes the recordInfo and the cache
     void initColumns(bool emptyResultset);
     void finalize();
 
-    QSQLiteResult* q;
     sqlite3 *access;
 
     sqlite3_stmt *stmt;
@@ -158,13 +160,17 @@ public:
     QVector<QVariant> firstRow;
 };
 
-QSQLiteResultPrivate::QSQLiteResultPrivate(QSQLiteResult* res) : q(res), access(0),
-    stmt(0), skippedStatus(false), skipRow(false)
+QSQLiteResultPrivate::QSQLiteResultPrivate(QSQLiteResult *q, const QSQLiteDriver *drv)
+    : QSqlCachedResultPrivate(q, drv),
+      stmt(0),
+      skippedStatus(false),
+      skipRow(false)
 {
 }
 
 void QSQLiteResultPrivate::cleanup()
 {
+    Q_Q(QSQLiteResult);
     finalize();
     rInf.clear();
     skippedStatus = false;
@@ -185,6 +191,7 @@ void QSQLiteResultPrivate::finalize()
 
 void QSQLiteResultPrivate::initColumns(bool emptyResultset)
 {
+    Q_Q(QSQLiteResult);
     int nCols = sqlite3_column_count(stmt);
     if (nCols <= 0)
         return;
@@ -236,6 +243,7 @@ void QSQLiteResultPrivate::initColumns(bool emptyResultset)
 
 bool QSQLiteResultPrivate::fetchNext(QSqlCachedResult::ValueCache &values, int idx, bool initialFetch)
 {
+    Q_Q(QSQLiteResult);
     int res;
     int i;
 
@@ -336,20 +344,18 @@ bool QSQLiteResultPrivate::fetchNext(QSqlCachedResult::ValueCache &values, int i
 }
 
 QSQLiteResult::QSQLiteResult(const QSQLiteDriver* db)
-    : QSqlCachedResult(db)
+    : QSqlCachedResult(*new QSQLiteResultPrivate(this, db))
 {
-    d = new QSQLiteResultPrivate(this);
-    d->access = db->d_func()->access;
-    const_cast<QSQLiteDriverPrivate*>(db->d_func())->results.append(this);
+    Q_D(QSQLiteResult);
+    d->access = d->drv_d_func()->access;
+    const_cast<QSQLiteDriverPrivate*>(d->drv_d_func())->results.append(this);
 }
 
 QSQLiteResult::~QSQLiteResult()
 {
-    const QSqlDriver *sqlDriver = driver();
-    if (sqlDriver)
-        const_cast<QSQLiteDriverPrivate*>(qobject_cast<const QSQLiteDriver *>(sqlDriver)->d_func())->results.removeOne(this);
+    Q_D(QSQLiteResult);
+    const_cast<QSQLiteDriverPrivate*>(d->drv_d_func())->results.removeOne(this);
     d->cleanup();
-    delete d;
 }
 
 void QSQLiteResult::virtual_hook(int id, void *data)
@@ -366,6 +372,7 @@ bool QSQLiteResult::reset(const QString &query)
 
 bool QSQLiteResult::prepare(const QString &query)
 {
+    Q_D(QSQLiteResult);
     if (!driver() || !driver()->isOpen() || driver()->isOpenError())
         return false;
 
@@ -399,6 +406,7 @@ bool QSQLiteResult::prepare(const QString &query)
 
 bool QSQLiteResult::exec()
 {
+    Q_D(QSQLiteResult);
     const QVector<QVariant> values = boundValues();
 
     d->skippedStatus = false;
@@ -493,6 +501,7 @@ bool QSQLiteResult::exec()
 
 bool QSQLiteResult::gotoNext(QSqlCachedResult::ValueCache& row, int idx)
 {
+    Q_D(QSQLiteResult);
     return d->fetchNext(row, idx, false);
 }
 
@@ -503,11 +512,13 @@ int QSQLiteResult::size()
 
 int QSQLiteResult::numRowsAffected()
 {
+    Q_D(const QSQLiteResult);
     return sqlite3_changes(d->access);
 }
 
 QVariant QSQLiteResult::lastInsertId() const
 {
+    Q_D(const QSQLiteResult);
     if (isActive()) {
         qint64 id = sqlite3_last_insert_rowid(d->access);
         if (id)
@@ -518,6 +529,7 @@ QVariant QSQLiteResult::lastInsertId() const
 
 QSqlRecord QSQLiteResult::record() const
 {
+    Q_D(const QSQLiteResult);
     if (!isActive() || !isSelect())
         return QSqlRecord();
     return d->rInf;
@@ -525,12 +537,14 @@ QSqlRecord QSQLiteResult::record() const
 
 void QSQLiteResult::detachFromResultSet()
 {
+    Q_D(QSQLiteResult);
     if (d->stmt)
         sqlite3_reset(d->stmt);
 }
 
 QVariant QSQLiteResult::handle() const
 {
+    Q_D(const QSQLiteResult);
     return QVariant::fromValue(d->stmt);
 }
 
@@ -640,7 +654,7 @@ void QSQLiteDriver::close()
     Q_D(QSQLiteDriver);
     if (isOpen()) {
         foreach (QSQLiteResult *result, d->results) {
-            result->d->finalize();
+            result->d_func()->finalize();
         }
 
         if (sqlite3_close(d->access) != SQLITE_OK)