Greatly improve performance due to ScriptIterator changes

PkmnLib.Dynamic/ScriptHandling/ScriptIterator.cs

@@ -8,6 +8,7 @@ namespace PkmnLib.Dynamic.ScriptHandling;
 public class ScriptIterator : IEnumerable<ScriptContainer>
 {
     private readonly IReadOnlyList<IEnumerable<ScriptContainer>> _scripts;
+    private int _currentIndex = 0;
 
     /// <inheritdoc cref="ScriptIterator"/>
     public ScriptIterator(IReadOnlyList<IEnumerable<ScriptContainer>> scripts)
@@ -15,11 +16,15 @@ public class ScriptIterator : IEnumerable<ScriptContainer>
         _scripts = scripts;
     }
 
-    private IEnumerable<ScriptContainer> GetAsEnumerable()
+    /// <inheritdoc />
+    public IEnumerator<ScriptContainer> GetEnumerator()
     {
-        foreach (var enumerable in _scripts)
+        while (_currentIndex < _scripts.Count)
         {
-            if (enumerable is IScriptSet set)
+            var enumerable = _scripts[_currentIndex++];
+            switch (enumerable)
+            {
+                case IScriptSet set:
                 {
                     // We can't assume that the set remains the same size, so we need to iterate through it
                     // with a for loop.
@@ -31,22 +36,20 @@ public class ScriptIterator : IEnumerable<ScriptContainer>
                             continue;
                         yield return script;
                     }
+                    break;
                 }
-            else
-            {
-                foreach (var script in enumerable)
-                {
-                    // We can ignore empty scripts.
-                    if (script.IsEmpty)
+                case ScriptContainer { IsEmpty: true }:
                     continue;
-                    yield return script;
+                case ScriptContainer container:
+                    yield return container;
+                    break;
+                default:
+                    throw new InvalidOperationException(
+                        $"Unexpected script type: {enumerable.GetType().Name}. Expected IScriptSet or ScriptContainer.");
             }
         }
+        _currentIndex = 0;
     }
-    }
-
-    /// <inheritdoc />
-    public IEnumerator<ScriptContainer> GetEnumerator() => GetAsEnumerable().GetEnumerator();
 
     /// <inheritdoc />
     IEnumerator IEnumerable.GetEnumerator() => GetEnumerator();