Initial set up for item use

PkmnLib.Dynamic/ScriptHandling/Registry/ItemScriptAttribute.cs

@@ -0,0 +1,20 @@
+using JetBrains.Annotations;
+using PkmnLib.Static.Utils;
+
+namespace PkmnLib.Dynamic.ScriptHandling.Registry;
+
+[AttributeUsage(AttributeTargets.Class)]
+[MeansImplicitUse]
+public class ItemScriptAttribute : Attribute
+{
+    /// <summary>
+    /// The name of the script.
+    /// </summary>
+    public StringKey Name { get; }
+
+    /// <inheritdoc cref="ItemScriptAttribute"/>
+    public ItemScriptAttribute(string name)
+    {
+        Name = name;
+    }
+}

PkmnLib.Dynamic/ScriptHandling/Registry/ScriptRegistry.cs

@@ -13,6 +13,7 @@ namespace PkmnLib.Dynamic.ScriptHandling.Registry;
 public class ScriptRegistry
 {
     private readonly Dictionary<(ScriptCategory category, StringKey name), Func<Script>> _scriptTypes = new();
+    private readonly Dictionary<StringKey, Func<ItemScript>> _itemScriptTypes = new();
     private IBattleStatCalculator? _battleStatCalculator;
     private IDamageCalculator? _damageCalculator;
     private IMiscLibrary? _miscLibrary;
@@ -32,6 +33,15 @@ public class ScriptRegistry
 
             RegisterScriptType(attribute.Category, attribute.Name, type);
         }
+        var itemBaseType = typeof(ItemScript);
+        foreach (var type in assembly.GetTypes().Where(t => itemBaseType.IsAssignableFrom(t)))
+        {
+            var attribute = type.GetCustomAttribute<ItemScriptAttribute>();
+            if (attribute == null)
+                continue;
+
+            RegisterItemScriptType(attribute.Name, type);
+        }
     }
 
     /// <summary>
@@ -52,6 +62,25 @@ public class ScriptRegistry
         // This is more performant than using Activator.CreateInstance.
         _scriptTypes[(category, name)] = Expression.Lambda<Func<Script>>(Expression.New(constructor)).Compile();
     }
+    
+    /// <summary>
+    /// Register an item script type with the given name.
+    /// </summary>
+    [PublicAPI]
+    public void RegisterItemScriptType(StringKey name, Type type)
+    {
+        if (type == null)
+            throw new ArgumentNullException(nameof(type));
+
+        var constructor = type.GetConstructor(BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance,
+            null, Type.EmptyTypes, null);
+        if (constructor == null)
+            throw new ArgumentException($"Type {type} does not have a parameterless constructor.");
+
+        // We create a lambda that creates a new instance of the script type.
+        // This is more performant than using Activator.CreateInstance.
+        _itemScriptTypes[name] = Expression.Lambda<Func<ItemScript>>(Expression.New(constructor)).Compile();
+    }
 
     /// <summary>
     /// Register a battle stat calculator.
@@ -71,7 +100,8 @@ public class ScriptRegistry
     public void RegisterMiscLibrary<T>(T miscLibrary) where T : IMiscLibrary
         => _miscLibrary = miscLibrary;
 
-    internal Dictionary<(ScriptCategory category, StringKey name), Func<Script>> ScriptTypes => _scriptTypes;
+    internal IReadOnlyDictionary<(ScriptCategory category, StringKey name), Func<Script>> ScriptTypes => _scriptTypes;
+    internal IReadOnlyDictionary<StringKey, Func<ItemScript>> ItemScriptTypes => _itemScriptTypes;
     internal IBattleStatCalculator? BattleStatCalculator => _battleStatCalculator;
     internal IDamageCalculator? DamageCalculator => _damageCalculator;
     internal IMiscLibrary? MiscLibrary => _miscLibrary;