using System; using System.Reflection; using Mono.Cecil; using Mono.Cecil.Cil; using StardewModdingAPI.Framework.ModLoading.Finders; namespace StardewModdingAPI.Framework.ModLoading.Rewriters { /// <summary>Rewrites references to one field with another.</summary> internal class FieldReplaceRewriter : FieldFinder { /********* ** Properties *********/ /// <summary>The new field to reference.</summary> private readonly FieldInfo ToField; /********* ** Public methods *********/ /// <summary>Construct an instance.</summary> /// <param name="type">The type whose field to which references should be rewritten.</param> /// <param name="fromFieldName">The field name to rewrite.</param> /// <param name="toFieldName">The new field name to reference.</param> public FieldReplaceRewriter(Type type, string fromFieldName, string toFieldName) : base(type.FullName, fromFieldName, InstructionHandleResult.None) { this.ToField = type.GetField(toFieldName); if (this.ToField == null) throw new InvalidOperationException($"The {type.FullName} class doesn't have a {toFieldName} field."); } /// <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 override InstructionHandleResult Handle(ModuleDefinition module, ILProcessor cil, Instruction instruction, PlatformAssemblyMap assemblyMap, bool platformChanged) { if (!this.IsMatch(instruction)) return InstructionHandleResult.None; FieldReference newRef = module.Import(this.ToField); cil.Replace(instruction, cil.Create(instruction.OpCode, newRef)); return InstructionHandleResult.Rewritten; } } }