perf(smileys): create global regex object

This prevents recompiling the regex for every message

src/persistence/smileypack.cpp

@@ -245,39 +245,50 @@ bool SmileyPack::load(const QString& filename)
         emoticons.append(emoticonList);
     }
 
+    constructRegex();
+
     loadingMutex.unlock();
     return true;
 }
 
 /**
- * @brief Replaces all found text emoticons to HTML reference with its according icon filename
- * @param msg Message where to search for emoticons
- * @return Formatted copy of message
+ * @brief Creates the regex for replacing emoticons with the path to their pictures
  */
-QString SmileyPack::smileyfied(const QString& msg)
+void SmileyPack::constructRegex()
 {
-    QMutexLocker locker(&loadingMutex);
-    QString result(msg);
-    QRegularExpression exp;
     QString allPattern = QStringLiteral("(");
 
-
-    for ( auto r = emoticonToPath.begin(); r != emoticonToPath.end(); ++r) {
-        if (r.key().toUcs4().length() == 1) {
+    // construct one big regex that matches on every emoticon
+    for (const QString& emote : emoticonToPath.keys()) {
+        if (emote.toUcs4().length() == 1) {
             // UTF-8 emoji
-            allPattern = allPattern % r.key();
+            allPattern = allPattern % emote;
         } else {
             // patterns like ":)" or ":smile:", don't match inside a word or else will hit punctuation and html tags
-            allPattern = allPattern % QStringLiteral(R"((?<=^|\s))") % QRegularExpression::escape(r.key()) % QStringLiteral(R"((?=$|\s))");
+            allPattern = allPattern % QStringLiteral(R"((?<=^|\s))") % QRegularExpression::escape(emote) % QStringLiteral(R"((?=$|\s))");
         }
         allPattern = allPattern % QStringLiteral("|");
     }
 
     allPattern[allPattern.size() - 1] = QChar(')');
 
-    exp.setPattern(allPattern);
+    // compile and optimize regex
+    smilify.setPattern(allPattern);
+    smilify.optimize();
+}
+
+/**
+ * @brief Replaces all found text emoticons to HTML reference with its according icon filename
+ * @param msg Message where to search for emoticons
+ * @return Formatted copy of message
+ */
+QString SmileyPack::smileyfied(const QString& msg)
+{
+    QMutexLocker locker(&loadingMutex);
+    QString result(msg);
+
     int replaceDiff = 0;
-    QRegularExpressionMatchIterator iter = exp.globalMatch(result);
+    QRegularExpressionMatchIterator iter = smilify.globalMatch(result);
     while (iter.hasNext()) {
         QRegularExpressionMatch match = iter.next();
         int startPos = match.capturedStart();

src/persistence/smileypack.h

@@ -23,6 +23,7 @@
 #include <QIcon>
 #include <QMap>
 #include <QMutex>
+#include <QRegularExpression>
 
 #include <memory>
 
@@ -52,12 +53,14 @@ private slots:
     ~SmileyPack() override;
 
     bool load(const QString& filename);
+    void constructRegex();
 
     mutable std::map<QString, std::shared_ptr<QIcon>> cachedIcon;
     QHash<QString, QString> emoticonToPath;
     QList<QStringList> emoticons;
     QString path;
     QTimer* cleanupTimer;
+    QRegularExpression smilify;
     mutable QMutex loadingMutex;
 };