QFileSystemModel: cache the name filters regexps

In order to filter out file names based on the user's settings,
QFileSystemModel used to have a loop that tested if a given file
name matched one of the filters. The problem is that each filter
(a wildcard) was converted to a QRegularExpression _inside_ the loop.
This causes a quadratic behavior (number of files * number of filters).

Instead, build the regexps once when the filters are set (or the case
sensitivity is changed, as that affects the filtering), and simply
_use_ them in the loop.

Simplify and correct some related code as a drive by.

Done-with: Jean-Michaël Celerier
Fixes: QTBUG-95383
Pick-to: 6.2 6.1 5.15
Change-Id: I6bc336364c145bb05793a8f867545d7715d35832
Reviewed-by: Samuel Gaist <samuel.gaist@idiap.ch>
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>

0 files changed, 0 insertions, 0 deletions