q3sqlmanager_p.cpp

奇趣公司比较新的qt/emd版本

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#include "q3sqlmanager_p.h"

#ifndef QT_NO_SQL

#include "qapplication.h"
#include "qcursor.h"
#include "qwidget.h"
#include "q3sqlcursor.h"
#include "qsqlfield.h"
#include "q3sqlform.h"
#include "qsqldriver.h"
#include "qstring.h"
#include "qmessagebox.h"
#include "qbitarray.h"

//#define QT_DEBUG_DATAMANAGER

class Q3SqlCursorManagerPrivate
{
public:
    Q3SqlCursorManagerPrivate()
        : cur(0), autoDelete(false)
    {}

    QString ftr;
    QStringList srt;
    Q3SqlCursor* cur;
    bool autoDelete;
};

static QSqlIndex indexFromStringList(const QStringList& l, const Q3SqlCursor* cursor)
{
    QSqlIndex newSort;
    for (int i = 0; i < l.count(); ++i) {
        QString f = l[i];
        bool desc = false;
        if (f.mid(f.length()-3) == QLatin1String("ASC"))
            f = f.mid(0, f.length()-3);
        if (f.mid(f.length()-4) == QLatin1String("DESC")) {
            desc = true;
            f = f.mid(0, f.length()-4);
        }
        int dot = f.lastIndexOf(QLatin1Char('.'));
        if (dot != -1)
            f = f.mid(dot+1);
        const QSqlField field = cursor->field(f.trimmed());
        if (field.isValid())
            newSort.append(field, desc);
        else
            qWarning("QSqlIndex::indexFromStringList: unknown field: '%s'", f.latin1());
    }
    return newSort;
}


/*!
  \class Q3SqlCursorManager qsqlmanager_p.h
  \brief The Q3SqlCursorManager class manages a database cursor.

  \compat
  \internal

  This class provides common cursor management functionality.  This
  includes saving and applying sorts and filters, refreshing (i.e.,
  re-selecting) the cursor and searching for records within the
  cursor.

*/

/*!  \internal

  Constructs a cursor manager.

*/

Q3SqlCursorManager::Q3SqlCursorManager()
{
    d = new Q3SqlCursorManagerPrivate;
}


/*! \internal

  Destroys the object and frees any allocated resources.

*/

Q3SqlCursorManager::~Q3SqlCursorManager()
{
    if (d->autoDelete)
        delete d->cur;
    delete d;
}

/*! \internal

  Sets the manager's sort to the index \a sort.  To apply the new
  sort, use refresh().

 */

void Q3SqlCursorManager::setSort(const QSqlIndex& sort)
{
    setSort(sort.toStringList());
}

/*! \internal

  Sets the manager's sort to the stringlist \a sort.  To apply the
  new sort, use refresh().

 */

void Q3SqlCursorManager::setSort(const QStringList& sort)
{
    d->srt = sort;
}

/*! \internal

  Returns the current sort, or an empty stringlist if there is none.

*/

QStringList  Q3SqlCursorManager::sort() const
{
    return d->srt;
}

/*! \internal

  Sets the manager's filter to the string \a filter.  To apply the
  new filter, use refresh().

*/

void Q3SqlCursorManager::setFilter(const QString& filter)
{
    d->ftr = filter;
}

/*! \internal

  Returns the current filter, or an empty string if there is none.

*/

QString Q3SqlCursorManager::filter() const
{
    return d->ftr;
}

/*! \internal

  Sets auto-delete to \a enable.  If true, the default cursor will
  be deleted when necessary.

  \sa autoDelete()
*/

void Q3SqlCursorManager::setAutoDelete(bool enable)
{
    d->autoDelete = enable;
}


/*! \internal

  Returns true if auto-deletion is enabled, otherwise false.

  \sa setAutoDelete()

*/

bool Q3SqlCursorManager::autoDelete() const
{
    return d->autoDelete;
}

/*! \internal

  Sets the default cursor used by the manager to \a cursor.  If \a
  autoDelete is true (the default is false), the manager takes
  ownership of the \a cursor pointer, which will be deleted when the
  manager is destroyed, or when setCursor() is called again. To
  activate the \a cursor use refresh().

  \sa cursor()

*/

void Q3SqlCursorManager::setCursor(Q3SqlCursor* cursor, bool autoDelete)
{
    if (d->autoDelete)
        delete d->cur;
    d->cur = cursor;
    d->autoDelete = autoDelete;
}

/*! \internal

  Returns a pointer to the default cursor used for navigation, or 0
  if there is no default cursor.

  \sa setCursor()

*/

Q3SqlCursor* Q3SqlCursorManager::cursor() const
{
    return d->cur;
}


/*! \internal

  Refreshes the manager using the default cursor.  The manager's
  filter and sort are applied.  Returns true on success, false if an
  error occurred or there is no current cursor.

  \sa setFilter() setSort()

*/

bool Q3SqlCursorManager::refresh()
{
    Q3SqlCursor* cur = cursor();
    if (!cur)
        return false;
    QString currentFilter = d->ftr;
    QStringList currentSort = d->srt;
    QSqlIndex newSort = indexFromStringList(currentSort, cur);
    return cur->select(currentFilter, newSort);
}

/* \internal

   Returns true if the \a buf field values that correspond to \a idx
   match the field values in \a cur that correspond to \a idx.
*/

static bool index_matches(const Q3SqlCursor* cur, const QSqlRecord* buf,
                           const QSqlIndex& idx)
{
    bool indexEquals = false;
    for (int i = 0; i < idx.count(); ++i) {
        const QString fn(idx.field(i).name());
        if (cur->value(fn) == buf->value(fn))
            indexEquals = true;
        else {
            indexEquals = false;
            break;
        }
    }
    return indexEquals;
}

/*
  Return less than, equal to or greater than 0 if buf1 is less than,
  equal to or greater than buf2 according to fields described in idx.
  (### Currently only uses first field.)
*/

static int compare_recs(const QSqlRecord* buf1, const QSqlRecord* buf2,
                         const QSqlIndex& idx)
{
    int cmp = 0;

    int i = 0;
    const QString fn(idx.field(i).name());
    const QSqlField f1 = buf1->field(fn);

    if (f1.isValid()) {
        switch (f1.type()) { // ### more types?
        case QVariant::String:
            cmp = f1.value().toString().trimmed().compare(
                          buf2->value(fn).toString().trimmed());
            break;
        default:
            if (f1.value().toDouble() < buf2->value(fn).toDouble())
                cmp = -1;
            else if (f1.value().toDouble() > buf2->value(fn).toDouble())
                cmp = 1;
        }
    }

    if (idx.isDescending(i))
        cmp = -cmp;
    return cmp;
}

#ifdef QT_DEBUG_DATAMANAGER
static void debug_datamanager_buffer(const QString& msg, QSqlRecord* cursor)
{
    qDebug("+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++");
    qDebug("%s", msg.latin1());
    for (int j = 0; j < cursor->count(); ++j) {
        qDebug("%s", (cursor->field(j)->name() + " type:"
                       + QString(cursor->field(j)->value().typeName())
                       + " value:" + cursor->field(j)->value().toString())
                       .latin1());
    }
}
#endif


/*! \internal

  Relocates the default cursor to the record matching the cursor's
edit buffer.  Only the field names specified by \a idx are used to
determine an exact match of the cursor to the edit buffer. However,
other fields in the edit buffer are also used during the search,
therefore all fields in the edit buffer should be primed with desired
values for the record being sought.  This function is typically used
to relocate a cursor to the correct position after an insert or
update.  For example:

\code
    Q3SqlCursor* myCursor = myManager.cursor();
    ...
    QSqlRecord* buf = myCursor->primeUpdate();
    buf->setValue("name", "Ola");
    buf->setValue("city", "Oslo");
    ...
    myCursor->update();  // update current record
    myCursor->select();  // refresh the cursor
    myManager.findBuffer(myCursor->primaryIndex()); // go to the updated record
\endcode

*/

//## possibly add sizeHint parameter
bool Q3SqlCursorManager::findBuffer(const QSqlIndex& idx, int atHint)
{
#ifdef QT_DEBUG_DATAMANAGER
    qDebug("Q3SqlCursorManager::findBuffer:");
#endif
    Q3SqlCursor* cur = cursor();
    if (!cur)
        return false;
    if (!cur->isActive())
        return false;
    if (!idx.count()) {
        if (cur->at() == QSql::BeforeFirst)
            cur->next();
        return false;
    }
    QSqlRecord* buf = cur->editBuffer();
    bool indexEquals = false;
#ifdef QT_DEBUG_DATAMANAGER
    qDebug(" Checking hint...");
#endif
    /* check the hint */
    if (cur->seek(atHint))
        indexEquals = index_matches(cur, buf, idx);

    if (!indexEquals) {
#ifdef QT_DEBUG_DATAMANAGER
        qDebug(" Checking current page...");
#endif
        /* check current page */
        int pageSize = 20;
        int startIdx = qMax(atHint - pageSize, 0);
        int endIdx = atHint + pageSize;
        for (int j = startIdx; j <= endIdx; ++j) {
            if (cur->seek(j)) {
                indexEquals = index_matches(cur, buf, idx);
                if (indexEquals)
                    break;
            }
        }
    }

    if (!indexEquals && cur->driver()->hasFeature(QSqlDriver::QuerySize)
         && cur->sort().count()) {
#ifdef QT_DEBUG_DATAMANAGER
        qDebug(" Using binary search...");
#endif
        // binary search based on record buffer and current sort fields
        int lo = 0;
        int hi = cur->size();
        int mid;
        if (compare_recs(buf, cur, cur->sort()) >= 0)
            lo = cur->at();
        while (lo != hi) {
            mid = lo + (hi - lo) / 2;
            if (!cur->seek(mid))
                break;
            if (index_matches(cur, buf, idx)) {
                indexEquals = true;
                break;
            }
            int c = compare_recs(buf, cur, cur->sort());
            if (c < 0) {
                hi = mid;
            } else if (c == 0) {
                // found it, but there may be duplicates
                int at = mid;
                do {
                    mid--;
                    if (!cur->seek(mid))
                        break;
                    if (index_matches(cur, buf, idx)) {
                        indexEquals = true;
                        break;
                    }
                } while (compare_recs(buf, cur, cur->sort()) == 0);

                if (!indexEquals) {
                    mid = at;
                    do {
                        mid++;
                        if (!cur->seek(mid))
                            break;
                        if (index_matches(cur, buf, idx)) {
                            indexEquals = true;
                            break;
                        }
                    } while (compare_recs(buf, cur, cur->sort()) == 0);
                }
                break;
            } else if (c > 0) {
                lo = mid + 1;
            }
        }
    }

    if (!indexEquals) {
#ifdef QT_DEBUG_DATAMANAGER
        qDebug(" Using brute search...");
#endif
#ifndef QT_NO_CURSOR
        QApplication::setOverrideCursor(Qt::WaitCursor);
#endif
        /* give up, use brute force */
        int startIdx = 0;
        if (cur->at() != startIdx) {
            cur->seek(startIdx);
        }
        for (;;) {
            indexEquals = false;
            indexEquals = index_matches(cur, buf, idx);
            if (indexEquals)
                break;
            if (!cur->next())
                break;