Fix filtering items in the contents treeview

When filtering the items in the contents panel, we start iterating over
them using rootIndex() to get all the children, don't do the same loop
for each and every item, one go is enough.

Also only use a regular expression if the regularExpression option is
enabled, otherwise just use string operations, the latter is always
faster. With this change, both regex and non-regex search are faster.

BUG: 421469

ui/ktreeviewsearchline.cpp

@@ -64,7 +64,7 @@ class KTreeViewSearchLine::Private
     void slotRegularExpression();
 
     void checkItemParentsNotVisible(QTreeView *treeView);
-    bool checkItemParentsVisible(QTreeView *treeView, const QModelIndex &index);
+    bool filterItems(QTreeView *treeView, const QModelIndex &index);
 };
 
 ////////////////////////////////////////////////////////////////////////////////
@@ -129,12 +129,12 @@ void KTreeViewSearchLine::Private::slotRegularExpression()
  *  \return \c true if an item which should be visible is found, \c false if all items found should be hidden. If this function
  *             returns true and \p highestHiddenParent was not 0, highestHiddenParent will have been shown.
  */
-bool KTreeViewSearchLine::Private::checkItemParentsVisible( QTreeView *treeView, const QModelIndex &index )
+bool KTreeViewSearchLine::Private::filterItems( QTreeView *treeView, const QModelIndex &index )
 {
   bool childMatch = false;
   const int rowcount = treeView->model()->rowCount( index );
   for ( int i = 0; i < rowcount; ++i )
-    childMatch |= checkItemParentsVisible( treeView, treeView->model()->index( i, 0, index ) );
+    childMatch |= filterItems( treeView, treeView->model()->index( i, 0, index ) );
 
   // Should this item be shown? It should if any children should be, or if it matches.
   const QModelIndex parentindex = index.parent();
@@ -211,8 +211,7 @@ void KTreeViewSearchLine::updateSearch( QTreeView *treeView )
 
   bool wasUpdateEnabled = treeView->updatesEnabled();
   treeView->setUpdatesEnabled( false );
-  for ( int i = 0; i < treeView->model()->rowCount(); ++i )
-    d->checkItemParentsVisible( treeView, treeView->rootIndex() );
+  d->filterItems( treeView, treeView->rootIndex() );
   treeView->setUpdatesEnabled( wasUpdateEnabled );
 
   if ( currentIndex.isValid() )
@@ -259,10 +258,11 @@ bool KTreeViewSearchLine::itemMatches( const QModelIndex &parentIndex, int row,
     return false;
 
   // Construct a regular expression object with the right options.
-  QRegularExpression re(
-      d->regularExpression ? pattern : QRegularExpression::escape(pattern),
-      d->caseSensitive ? QRegularExpression::NoPatternOption : QRegularExpression::CaseInsensitiveOption );
-  QRegularExpressionMatch match;
+  QRegularExpression re;
+  if (d->regularExpression) {
+    re.setPattern(pattern);
+    re.setPatternOptions(d->caseSensitive ? QRegularExpression::NoPatternOption : QRegularExpression::CaseInsensitiveOption);
+  }
 
   // If the search column list is populated, search just the columns
   // specified.  If it is empty default to searching all of the columns.
@@ -270,9 +270,10 @@ bool KTreeViewSearchLine::itemMatches( const QModelIndex &parentIndex, int row,
   const int columncount = model->columnCount( parentIndex );
   for ( int i = 0; i < columncount; ++i) {
     const QString str = model->data( model->index( row, i, parentIndex ), Qt::DisplayRole ).toString();
-    match = re.match( str );
-    if ( match.hasMatch() ) {
-        return true;
+    if (d->regularExpression) {
+      return str.contains(re);
+    } else {
+      return str.contains(pattern, d->caseSensitive? Qt::CaseSensitive : Qt::CaseInsensitive);
     }
   }