using System; using Mono.Cecil; using Mono.Cecil.Cil; namespace StardewModdingAPI.Framework.ModLoading.Rewriters { /// <summary>Rewrites virtual calls to the <see cref="Mod.Entry"/> method.</summary> internal class VirtualEntryCallRemover : IInstructionHandler { /********* ** Properties *********/ /// <summary>The type containing the method.</summary> private readonly Type ToType; /// <summary>The name of the method.</summary> private readonly string MethodName; /********* ** Accessors *********/ /// <summary>A brief noun phrase indicating what the instruction finder matches.</summary> public string NounPhrase { get; } /********* ** Public methods *********/ /// <summary>Construct an instance.</summary> public VirtualEntryCallRemover() { this.ToType = typeof(Mod); this.MethodName = nameof(Mod.Entry); this.NounPhrase = $"{this.ToType.Name}::{this.MethodName}"; } /// <summary>Perform the predefined logic for a method if applicable.</summary> /// <param name="module">The assembly module containing the instruction.</param> /// <param name="method">The method definition containing the instruction.</param> /// <param name="assemblyMap">Metadata for mapping assemblies to the current platform.</param> /// <param name="platformChanged">Whether the mod was compiled on a different platform.</param> public InstructionHandleResult Handle(ModuleDefinition module, MethodDefinition method, PlatformAssemblyMap assemblyMap, bool platformChanged) { return InstructionHandleResult.None; } /// <summary>Perform the predefined logic for an instruction if applicable.</summary> /// <param name="module">The assembly module containing the instruction.</param> /// <param name="cil">The CIL processor.</param> /// <param name="instruction">The instruction to handle.</param> /// <param name="assemblyMap">Metadata for mapping assemblies to the current platform.</param> /// <param name="platformChanged">Whether the mod was compiled on a different platform.</param> public InstructionHandleResult Handle(ModuleDefinition module, ILProcessor cil, Instruction instruction, PlatformAssemblyMap assemblyMap, bool platformChanged) { if (!this.IsMatch(instruction)) return InstructionHandleResult.None; // get instructions comprising method call int index = cil.Body.Instructions.IndexOf(instruction); Instruction loadArg0 = cil.Body.Instructions[index - 2]; Instruction loadArg1 = cil.Body.Instructions[index - 1]; if (loadArg0.OpCode != OpCodes.Ldarg_0) throw new InvalidOperationException($"Unexpected instruction sequence while removing virtual {this.ToType.Name}.{this.MethodName} call: found {loadArg0.OpCode.Name} instead of {OpCodes.Ldarg_0.Name}"); if (loadArg1.OpCode != OpCodes.Ldarg_1) throw new InvalidOperationException($"Unexpected instruction sequence while removing virtual {this.ToType.Name}.{this.MethodName} call: found {loadArg1.OpCode.Name} instead of {OpCodes.Ldarg_1.Name}"); // remove method call cil.Remove(loadArg0); cil.Remove(loadArg1); cil.Remove(instruction); return InstructionHandleResult.Rewritten; } /********* ** Protected methods *********/ /// <summary>Get whether a CIL instruction matches.</summary> /// <param name="instruction">The IL instruction.</param> protected bool IsMatch(Instruction instruction) { MethodReference methodRef = RewriteHelper.AsMethodReference(instruction); return methodRef != null && methodRef.DeclaringType.FullName == this.ToType.FullName && methodRef.Name == this.MethodName; } } }