1 files changed, 77 insertions, 0 deletions
diff --git a/src/SMAPI.Internal.Patching/PatchHelper.cs b/src/SMAPI.Internal.Patching/PatchHelper.cs
new file mode 100644
index 00000000..fc79ddf2
--- /dev/null
+++ b/src/SMAPI.Internal.Patching/PatchHelper.cs
@@ -0,0 +1,77 @@
+using System;
+using System.Linq;
+using System.Reflection;
+using System.Text;
+using HarmonyLib;
+
+namespace StardewModdingAPI.Internal.Patching
+{
+    /// <summary>Provides utility methods for patching game code with Harmony.</summary>
+    internal static class PatchHelper
+    {
+        /*********
+        ** Public methods
+        *********/
+        /// <summary>Get a constructor and assert that it was found.</summary>
+        /// <typeparam name="TTarget">The type containing the method.</typeparam>
+        /// <param name="parameters">The method parameter types, or <c>null</c> if it's not overloaded.</param>
+        /// <exception cref="InvalidOperationException">The type has no matching constructor.</exception>
+        public static ConstructorInfo RequireConstructor<TTarget>(Type[] parameters = null)
+        {
+            return
+                AccessTools.Constructor(typeof(TTarget), parameters)
+                ?? throw new InvalidOperationException($"Can't find constructor {PatchHelper.GetMethodString(typeof(TTarget), null, parameters)} to patch.");
+        }
+
+        /// <summary>Get a method and assert that it was found.</summary>
+        /// <typeparam name="TTarget">The type containing the method.</typeparam>
+        /// <param name="name">The method name.</param>
+        /// <param name="parameters">The method parameter types, or <c>null</c> if it's not overloaded.</param>
+        /// <param name="generics">The method generic types, or <c>null</c> if it's not generic.</param>
+        /// <exception cref="InvalidOperationException">The type has no matching method.</exception>
+        public static MethodInfo RequireMethod<TTarget>(string name, Type[] parameters = null, Type[] generics = null)
+        {
+            return
+                AccessTools.Method(typeof(TTarget), name, parameters, generics)
+                ?? throw new InvalidOperationException($"Can't find method {PatchHelper.GetMethodString(typeof(TTarget), name, parameters, generics)} to patch.");
+        }
+
+        /// <summary>Get a human-readable representation of a method target.</summary>
+        /// <param name="type">The type containing the method.</param>
+        /// <param name="name">The method name, or <c>null</c> for a constructor.</param>
+        /// <param name="parameters">The method parameter types, or <c>null</c> if it's not overloaded.</param>
+        /// <param name="generics">The method generic types, or <c>null</c> if it's not generic.</param>
+        public static string GetMethodString(Type type, string name, Type[] parameters = null, Type[] generics = null)
+        {
+            StringBuilder str = new StringBuilder();
+
+            // type
+            str.Append(type.FullName);
+
+            // method name (if not constructor)
+            if (name != null)
+            {
+                str.Append('.');
+                str.Append(name);
+            }
+
+            // generics
+            if (generics?.Any() == true)
+            {
+                str.Append('<');
+                str.Append(string.Join(", ", generics.Select(p => p.FullName)));
+                str.Append('>');
+            }
+
+            // parameters
+            if (parameters?.Any() == true)
+            {
+                str.Append('(');
+                str.Append(string.Join(", ", parameters.Select(p => p.FullName)));
+                str.Append(')');
+            }
+
+            return str.ToString();
+        }
+    }
+}