[DeckList] Extract deck root seeking and body reading in XML load (#7324)

Co-authored-by: Lukas Brübach <Bruebach.Lukas@bdosecurity.de>

libcockatrice_deck_list/libcockatrice/deck_list/deck_list.cpp

@@ -184,6 +184,27 @@ void DeckList::write(QXmlStreamWriter *xml) const
     xml->writeEndElement(); // Close "cockatrice_deck"
 }
 
+bool DeckList::seekToNextElement(QXmlStreamReader *xml)
+{
+    while (!xml->atEnd()) {
+        xml->readNext();
+        if (xml->isStartElement()) {
+            return true;
+        }
+    }
+    return false;
+}
+
+void DeckList::readDeckBody(QXmlStreamReader *xml)
+{
+    while (!xml->atEnd()) {
+        xml->readNext();
+        if (!readElement(xml)) {
+            break;
+        }
+    }
+}
+
 bool DeckList::loadFromXml(QXmlStreamReader *xml)
 {
     if (xml->error()) {
@@ -192,19 +213,11 @@ bool DeckList::loadFromXml(QXmlStreamReader *xml)
     }
 
     cleanList();
-    while (!xml->atEnd()) {
+    while (seekToNextElement(xml)) {
-        xml->readNext();
+        if (xml->name().toString() != "cockatrice_deck") {
-        if (xml->isStartElement()) {
+            return false;
-            if (xml->name().toString() != "cockatrice_deck") {
-                return false;
-            }
-            while (!xml->atEnd()) {
-                xml->readNext();
-                if (!readElement(xml)) {
-                    break;
-                }
-            }
         }
+        readDeckBody(xml);
     }
     refreshDeckHash();
     if (xml->error()) {

libcockatrice_deck_list/libcockatrice/deck_list/deck_list.h

@@ -106,6 +106,22 @@ private:
      */
     mutable QString cachedDeckHash;
 
+    /** @name XML load helpers */
+    ///@{
+    /**
+     * @brief Advances to the next element in the XML stream.
+     * @param xml Reader to advance past non-element tokens.
+     * @return true when a start element was reached, false at end of stream.
+     */
+    bool seekToNextElement(QXmlStreamReader *xml);
+
+    /**
+     * @brief Reads the contents of a `cockatrice_deck` element into this deck.
+     * @param xml Reader positioned at the deck element, stopped at its end.
+     */
+    void readDeckBody(QXmlStreamReader *xml);
+    ///@}
+
 public:
     /** @name Metadata setters */
     ///@{