From 07057188e3e42246cf006b43963d0bdcdaa159f5 Mon Sep 17 00:00:00 2001
From: Giuseppe D'Angelo <giuseppe.dangelo@kdab.com>
Date: Tue, 27 Jul 2021 16:03:23 +0200
Subject: QFileSystemModel: cache the name filters regexps
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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>
---
 src/gui/itemmodels/qfilesystemmodel_p.h | 4 ++++
 1 file changed, 4 insertions(+)

(limited to 'src/gui/itemmodels/qfilesystemmodel_p.h')

diff --git a/src/gui/itemmodels/qfilesystemmodel_p.h b/src/gui/itemmodels/qfilesystemmodel_p.h
index 4acd6a92df..70468460e8 100644
--- a/src/gui/itemmodels/qfilesystemmodel_p.h
+++ b/src/gui/itemmodels/qfilesystemmodel_p.h
@@ -64,6 +64,8 @@
 #include <qtimer.h>
 #include <qhash.h>
 
+#include <vector>
+
 QT_REQUIRE_CONFIG(filesystemmodel);
 
 QT_BEGIN_NAMESPACE
@@ -291,6 +293,8 @@ public:
     QHash<const QFileSystemNode*, bool> bypassFilters;
 #if QT_CONFIG(regularexpression)
     QStringList nameFilters;
+    std::vector<QRegularExpression> nameFiltersRegexps;
+    void rebuildNameFilterRegexps();
 #endif
     QHash<QString, QString> resolvedSymLinks;
 
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