add field rewriter for the `Game1.gameMode` change in SDV 1.2 (#231)

1 files changed, 42 insertions, 0 deletions

diff --git a/src/StardewModdingAPI.AssemblyRewriters/Rewriters/SDV1_2/Game1_GameMode_FieldRewriter.cs b/src/StardewModdingAPI.AssemblyRewriters/Rewriters/SDV1_2/Game1_GameMode_FieldRewriter.cs
new file mode 100644
index 00000000..e8cf3d13
--- /dev/null
+++ b/src/StardewModdingAPI.AssemblyRewriters/Rewriters/SDV1_2/Game1_GameMode_FieldRewriter.cs
@@ -0,0 +1,42 @@
+using System.Diagnostics.CodeAnalysis;
+using Mono.Cecil;
+using Mono.Cecil.Cil;
+using StardewModdingAPI.AssemblyRewriters.Framework;
+using StardewValley;
+
+namespace StardewModdingAPI.AssemblyRewriters.Rewriters.SDV1_2
+{
+    /// <summary>Rewrites field references to <see cref="Game1.gameMode"/>.</summary>
+    /// <remarks>Stardew Valley changed the <see cref="Game1.gameMode"/> field to a property, which broke many mods that reference it.</remarks>
+    [SuppressMessage("ReSharper", "InconsistentNaming", Justification = "This class is not meant to be used directly, and is deliberately named to make it easier to know what it changes at a glance.")]
+    public class Game1_GameMode_FieldRewriter : BaseFieldRewriter
+    {
+        /*********
+        ** Protected methods
+        *********/
+        /// <summary>Get whether a field reference should be rewritten.</summary>
+        /// <param name="instruction">The IL instruction.</param>
+        /// <param name="fieldRef">The field reference.</param>
+        /// <param name="platformChanged">Whether the mod was compiled on a different platform.</param>
+        protected override bool ShouldRewrite(Instruction instruction, FieldReference fieldRef, bool platformChanged)
+        {
+            return
+                (instruction.OpCode == OpCodes.Ldsfld || instruction.OpCode == OpCodes.Stsfld) // static field
+                && fieldRef.DeclaringType.FullName == typeof(Game1).FullName
+                && fieldRef.Name == nameof(Game1.gameMode);
+        }
+
+        /// <summary>Rewrite a method for compatibility.</summary>
+        /// <param name="module">The module being rewritten.</param>
+        /// <param name="cil">The CIL rewriter.</param>
+        /// <param name="instruction">The instruction which references the field.</param>
+        /// <param name="fieldRef">The field reference invoked by the <paramref name="instruction"/>.</param>
+        /// <param name="assemblyMap">Metadata for mapping assemblies to the current platform.</param>
+        protected override void Rewrite(ModuleDefinition module, ILProcessor cil, Instruction instruction, FieldReference fieldRef, PlatformAssemblyMap assemblyMap)
+        {
+            string methodPrefix = instruction.OpCode == OpCodes.Ldsfld ? "get" : "set";
+            MethodReference propertyRef = module.Import(typeof(Game1).GetMethod($"{methodPrefix}_{nameof(Game1.gameMode)}"));
+            cil.Replace(instruction, cil.Create(OpCodes.Call, propertyRef));
+        }
+    }
+}