rewrite HarmonyMethod to allow null (#711)

1 files changed, 45 insertions, 0 deletions

diff --git a/src/SMAPI/Framework/ModLoading/RewriteFacades/HarmonyMethodFacade.cs b/src/SMAPI/Framework/ModLoading/RewriteFacades/HarmonyMethodFacade.cs
new file mode 100644
index 00000000..44c97401
--- /dev/null
+++ b/src/SMAPI/Framework/ModLoading/RewriteFacades/HarmonyMethodFacade.cs
@@ -0,0 +1,45 @@
+using System;
+using System.Diagnostics.CodeAnalysis;
+using System.Reflection;
+using HarmonyLib;
+
+namespace StardewModdingAPI.Framework.ModLoading.RewriteFacades
+{
+    /// <summary>Maps Harmony 1.x <see cref="HarmonyMethod"/> methods to Harmony 2.x to avoid breaking older mods.</summary>
+    /// <remarks>This is public to support SMAPI rewriting and should not be referenced directly by mods.</remarks>
+    [SuppressMessage("ReSharper", "UnusedMember.Global", Justification = "Used via assembly rewriting")]
+    [SuppressMessage("ReSharper", "CS1591", Justification = "Documentation not needed for facade classes.")]
+    public class HarmonyMethodFacade : HarmonyMethod
+    {
+        /*********
+        ** Public methods
+        *********/
+        public HarmonyMethodFacade(MethodInfo method)
+        {
+            this.ImportMethodImpl(method);
+        }
+
+        public HarmonyMethodFacade(Type type, string name, Type[] parameters = null)
+        {
+            this.ImportMethodImpl(AccessTools.Method(type, name, parameters));
+        }
+
+
+        /*********
+        ** Private methods
+        *********/
+        /// <summary>Import a method directly using the internal HarmonyMethod code.</summary>
+        /// <param name="methodInfo">The method to import.</param>
+        private void ImportMethodImpl(MethodInfo methodInfo)
+        {
+            // A null method is no longer allowed in the constructor with Harmony 2.0, but the
+            // internal code still handles null fine. For backwards compatibility, this bypasses
+            // the new restriction when the mod hasn't been updated for Harmony 2.0 yet.
+
+            MethodInfo importMethod = typeof(HarmonyMethod).GetMethod("ImportMethod", BindingFlags.Instance | BindingFlags.NonPublic);
+            if (importMethod == null)
+                throw new InvalidOperationException("Can't find 'HarmonyMethod.ImportMethod' method");
+            importMethod.Invoke(this, new object[] { methodInfo });
+        }
+    }
+}