Improvements to Session::getDynamicTitle()

Walk over LocalTabTitle just once looking for percent signs, and doing
the appropriate substitution based on the next character.

This not only is slightly more performant, but also avoids trouble if
one of the substitutions happens to contain a percent sign.

src/session/Session.cpp

@@ -1127,48 +1127,100 @@ QString Session::getDynamicTitle()
     QString title = tabTitleFormat(Session::LocalTabTitle);
     // search for and replace known marker
 
-    int UID = process->userId(&ok);
-    if (!ok) {
-        title.replace(QLatin1String("%B"), QStringLiteral("-"));
-    } else {
-        // title.replace(QLatin1String("%I"), QString::number(UID));
-        if (UID == 0) {
-            title.replace(QLatin1String("%B"), QStringLiteral("#"));
-        } else {
-            title.replace(QLatin1String("%B"), QStringLiteral("$"));
-        }
-    }
-
-    title.replace(QLatin1String("%u"), process->userName());
-    title.replace(QLatin1String("%h"), Konsole::ProcessInfo::localHost());
-    title.replace(QLatin1String("%n"), process->name(&ok));
-
-    title.replace(QLatin1String("%w"), userTitle());
-    title.replace(QLatin1String("%#"), QString::number(sessionId()));
-
     QString dir = _reportedWorkingUrl.toLocalFile();
-    ok = true;
+    bool dirOk = true;
     if (dir.isEmpty()) {
         // update current directory from process
         updateWorkingDirectory();
         // Previous process may have been freed in updateSessionProcessInfo()
         process = getProcessInfo();
-        dir = process->currentDir(&ok);
+        dir = process->currentDir(&dirOk);
     }
-    if (!ok) {
-        title.replace(QLatin1String("%d"), QStringLiteral("-"));
-        title.replace(QLatin1String("%D"), QStringLiteral("-"));
-    } else {
-        // allow for shortname to have the ~ as homeDir
-        const QString homeDir = process->userHomeDir();
-        if (!homeDir.isEmpty()) {
-            if (dir.startsWith(homeDir)) {
-                dir.remove(0, homeDir.length());
-                dir.prepend(QLatin1Char('~'));
+
+    int pos = 0;
+    while ((pos = title.indexOf(QLatin1Char('%'), pos)) != -1) {
+        if (pos >= title.size() - 1) {
+            break;
+        }
+
+        switch (title.at(pos + 1).toLatin1()) {
+        case 'B': {
+            int UID = process->userId(&ok);
+            if (!ok) {
+                title.replace(pos, 2, QStringLiteral("-"));
+                pos--;
+            } else {
+                // title.replace(QLatin1String("%I"), QString::number(UID));
+                if (UID == 0) {
+                    title.replace(pos, 2, QStringLiteral("#"));
+                    pos--;
+                } else {
+                    title.replace(pos, 2, QStringLiteral("$"));
+                    pos--;
+                }
+            }
+        } break;
+        case 'u': {
+            QString replacement = process->userName();
+            title.replace(pos, 2, replacement);
+            pos += replacement.size() - 2;
+        } break;
+        case 'h': {
+            QString replacement = Konsole::ProcessInfo::localHost();
+            title.replace(pos, 2, replacement);
+            pos += replacement.size() - 2;
+        } break;
+        case 'n': {
+            QString replacement = process->name(&ok);
+            title.replace(pos, 2, replacement);
+            pos += replacement.size() - 2;
+        } break;
+        case 'w': {
+            QString replacement = userTitle();
+            title.replace(pos, 2, replacement);
+            pos += replacement.size() - 2;
+        } break;
+        case '#': {
+            QString replacement = QString::number(sessionId());
+            title.replace(pos, 2, replacement);
+            pos += replacement.size() - 2;
+        } break;
+        case 'd':
+            if (!dirOk) {
+                title.replace(pos, 2, QStringLiteral("-"));
+                pos--;
+            } else {
+                // allow for shortname to have the ~ as homeDir
+                const QString homeDir = process->userHomeDir();
+                if (!homeDir.isEmpty()) {
+                    if (dir.startsWith(homeDir)) {
+                        dir.remove(0, homeDir.length());
+                        dir.prepend(QLatin1Char('~'));
+                    }
+                }
+                const QString replacement = process->formatShortDir(dir);
+                title.replace(pos, 2, replacement);
+                pos += replacement.size() - 2;
+            }
+            break;
+        case 'D':
+            if (!dirOk) {
+                title.replace(pos, 2, QStringLiteral("-"));
+                pos--;
+            } else {
+                // allow for shortname to have the ~ as homeDir
+                const QString homeDir = process->userHomeDir();
+                if (!homeDir.isEmpty()) {
+                    if (dir.startsWith(homeDir)) {
+                        dir.remove(0, homeDir.length());
+                        dir.prepend(QLatin1Char('~'));
+                    }
+                }
+                title.replace(pos, 2, dir);
+                pos += dir.size() - 2;
             }
+            break;
         }
-        title.replace(QLatin1String("%D"), dir);
-        title.replace(QLatin1String("%d"), process->formatShortDir(dir));
     }
 
     return title;