log rewritten instructions (#247)

src/StardewModdingAPI.AssemblyRewriters/Framework/BaseFieldFinder.cs

@@ -6,6 +6,13 @@ namespace StardewModdingAPI.AssemblyRewriters.Framework
     /// <summary>Base class for a field finder.</summary>
     public abstract class BaseFieldFinder : IInstructionFinder
     {
+        /*********
+        ** Accessors
+        *********/
+        /// <summary>A brief noun phrase indicating what the instruction finder matches.</summary>
+        public abstract string NounPhrase { get; }
+
+
         /*********
         ** Public methods
         *********/

src/StardewModdingAPI.AssemblyRewriters/Framework/BaseMethodFinder.cs

@@ -9,6 +9,13 @@ namespace StardewModdingAPI.AssemblyRewriters.Framework
     /// <summary>Base class for a method finder.</summary>
     public abstract class BaseMethodFinder : IInstructionFinder
     {
+        /*********
+        ** Accessors
+        *********/
+        /// <summary>A brief noun phrase indicating what the instruction finder matches.</summary>
+        public abstract string NounPhrase { get; }
+
+
         /*********
         ** Public methods
         *********/

src/StardewModdingAPI.AssemblyRewriters/IInstructionFinder.cs

@@ -5,6 +5,16 @@ namespace StardewModdingAPI.AssemblyRewriters
     /// <summary>Finds CIL instructions considered incompatible.</summary>
     public interface IInstructionFinder
     {
+        /*********
+        ** Accessors
+        *********/
+        /// <summary>A brief noun phrase indicating what the instruction finder matches.</summary>
+        string NounPhrase { get; }
+
+
+        /*********
+        ** Methods
+        *********/
         /// <summary>Get whether a CIL instruction matches.</summary>
         /// <param name="instruction">The IL instruction.</param>
         /// <param name="platformChanged">Whether the mod was compiled on a different platform.</param>

src/StardewModdingAPI.AssemblyRewriters/IInstructionRewriter.cs

@@ -6,6 +6,9 @@ namespace StardewModdingAPI.AssemblyRewriters
     /// <summary>Rewrites a CIL instruction for compatibility.</summary>
     public interface IInstructionRewriter : IInstructionFinder
     {
+        /*********
+        ** Methods
+        *********/
         /// <summary>Rewrite a CIL instruction for compatibility.</summary>
         /// <param name="module">The module being rewritten.</param>
         /// <param name="cil">The CIL rewriter.</param>

src/StardewModdingAPI.AssemblyRewriters/Rewriters/Crossplatform/SpriteBatch_MethodRewriter.cs

@@ -12,6 +12,13 @@ namespace StardewModdingAPI.AssemblyRewriters.Rewriters.Crossplatform
     [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 SpriteBatch_MethodRewriter : BaseMethodRewriter
     {
+        /*********
+        ** Accessors
+        *********/
+        /// <summary>A brief noun phrase indicating what the instruction finder matches.</summary>
+        public override string NounPhrase { get; } = $"{nameof(SpriteBatch)} methods";
+
+
         /*********
         ** Protected methods
         *********/

src/StardewModdingAPI.AssemblyRewriters/Rewriters/SDV1_2/Game1_ActiveClickableMenu_FieldRewriter.cs

@@ -11,6 +11,13 @@ namespace StardewModdingAPI.AssemblyRewriters.Rewriters.SDV1_2
     [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_ActiveClickableMenu_FieldRewriter : BaseFieldRewriter
     {
+        /*********
+        ** Accessors
+        *********/
+        /// <summary>A brief noun phrase indicating what the instruction finder matches.</summary>
+        public override string NounPhrase { get; } = $"{nameof(Game1)}.{nameof(Game1.activeClickableMenu)} field";
+
+
         /*********
         ** Protected methods
         *********/

src/StardewModdingAPI.AssemblyRewriters/Rewriters/SDV1_2/Game1_GameMode_FieldRewriter.cs

@@ -11,6 +11,13 @@ namespace StardewModdingAPI.AssemblyRewriters.Rewriters.SDV1_2
     [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
     {
+        /*********
+        ** Accessors
+        *********/
+        /// <summary>A brief noun phrase indicating what the instruction finder matches.</summary>
+        public override string NounPhrase { get; } = $"{nameof(Game1)}.{nameof(Game1.gameMode)} field";
+
+
         /*********
         ** Protected methods
         *********/

src/StardewModdingAPI.AssemblyRewriters/Rewriters/SDV1_2/Game1_Player_FieldRewriter.cs

@@ -11,6 +11,13 @@ namespace StardewModdingAPI.AssemblyRewriters.Rewriters.SDV1_2
     [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_Player_FieldRewriter : BaseFieldRewriter
     {
+        /*********
+        ** Accessors
+        *********/
+        /// <summary>A brief noun phrase indicating what the instruction finder matches.</summary>
+        public override string NounPhrase { get; } = $"{nameof(Game1)}.{nameof(Game1.player)} field";
+
+
         /*********
         ** Protected methods
         *********/

src/StardewModdingAPI/Framework/AssemblyLoader.cs

@@ -162,6 +162,7 @@ namespace StardewModdingAPI.Framework
         private bool RewriteAssembly(AssemblyDefinition assembly)
         {
             ModuleDefinition module = assembly.MainModule;
+            HashSet<string> loggedRewrites = new HashSet<string>();
 
             // swap assembly references if needed (e.g. XNA => MonoGame)
             bool platformChanged = false;
@@ -170,6 +171,7 @@ namespace StardewModdingAPI.Framework
                 // remove old assembly reference
                 if (this.AssemblyMap.RemoveNames.Any(name => module.AssemblyReferences[i].Name == name))
                 {
+                    this.LogOnce(this.Monitor, loggedRewrites, $"Rewriting {assembly.Name.Name} for OS...");
                     platformChanged = true;
                     module.AssemblyReferences.RemoveAt(i);
                     i--;
@@ -197,14 +199,16 @@ namespace StardewModdingAPI.Framework
                 if (!canRewrite)
                     continue;
 
-                // prepare method
-                ILProcessor cil = method.Body.GetILProcessor();
-
                 // rewrite instructions
+                ILProcessor cil = method.Body.GetILProcessor();
                 foreach (Instruction op in cil.Body.Instructions.ToArray())
                 {
                     IInstructionRewriter rewriter = rewriters.FirstOrDefault(p => p.IsMatch(op, platformChanged));
-                    rewriter?.Rewrite(module, cil, op, this.AssemblyMap);
+                    if (rewriter != null)
+                    {
+                        this.LogOnce(this.Monitor, loggedRewrites, $"Rewriting {assembly.Name.Name} to fix {rewriter.NounPhrase}...");
+                        rewriter.Rewrite(module, cil, op, this.AssemblyMap);
+                    }
                 }
 
                 // finalise method
@@ -244,5 +248,19 @@ namespace StardewModdingAPI.Framework
                 select method
             );
         }
+
+        /// <summary>Log a message for the player or developer the first time it occurs.</summary>
+        /// <param name="monitor">The monitor through which to log the message.</param>
+        /// <param name="hash">The hash of logged messages.</param>
+        /// <param name="message">The message to log.</param>
+        /// <param name="level">The log severity level.</param>
+        private void LogOnce(IMonitor monitor, HashSet<string> hash, string message, LogLevel level = LogLevel.Trace)
+        {
+            if (!hash.Contains(message))
+            {
+                this.Monitor.Log(message, level);
+                hash.Add(message);
+            }
+        }
     }
 }