using System; using System.Reflection; using Mono.Cecil; using Mono.Cecil.Cil; using StardewModdingAPI.Framework.ModLoading.Framework; namespace StardewModdingAPI.Framework.ModLoading.Rewriters { /// <summary>Rewrites references to one field with another.</summary> internal class FieldReplaceRewriter : BaseInstructionHandler { /********* ** Fields *********/ /// <summary>The type containing the field to which references should be rewritten.</summary> private readonly Type Type; /// <summary>The field name to which references should be rewritten.</summary> private readonly string FromFieldName; /// <summary>The new field to reference.</summary> private readonly FieldInfo ToField; /********* ** Public methods *********/ /// <summary>Construct an instance.</summary> /// <param name="fromType">The type whose field to rewrite.</param> /// <param name="fromFieldName">The field name to rewrite.</param> /// <param name="toType">The new type which will have the field.</param> /// <param name="toFieldName">The new field name to reference.</param> public FieldReplaceRewriter(Type fromType, string fromFieldName, Type toType, string toFieldName) : base(defaultPhrase: $"{fromType.FullName}.{fromFieldName} field") { this.Type = fromType; this.FromFieldName = fromFieldName; this.ToField = toType.GetField(toFieldName); if (this.ToField == null) throw new InvalidOperationException($"The {toType.FullName} class doesn't have a {toFieldName} field."); } /// <summary>Construct an instance.</summary> /// <param name="type">The type whose field to rewrite.</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) : this(type, fromFieldName, type, toFieldName) { } /// <inheritdoc /> public override bool Handle(ModuleDefinition module, ILProcessor cil, Instruction instruction) { // get field reference FieldReference fieldRef = RewriteHelper.AsFieldReference(instruction); if (!RewriteHelper.IsFieldReferenceTo(fieldRef, this.Type.FullName, this.FromFieldName)) return false; // replace with new field instruction.Operand = module.ImportReference(this.ToField); return this.MarkRewritten(); } } }