/// <summary>
/// Generates a new typed equals method using the given fields.
/// </summary>
/// <param name="typeBuilder">The type builder to use.</param>
/// <param name="fieldsToUse">All fields to use to compute the hash code.</param>
/// <returns>The created equals function.</returns>
public static MethodInfo GenerateEquals(
this TypeBuilder typeBuilder,
FieldInfo[] fieldsToUse)
{
var equals = typeBuilder.DefineMethod(
EqualsInfo.Name,
MethodAttributes.Public | MethodAttributes.Virtual |
MethodAttributes.NewSlot | MethodAttributes.Final,
typeof(bool),
new Type[] { typeBuilder });
var emitter = new ILEmitter(equals.GetILGenerator());
var falseLabel = emitter.DeclareLabel();
foreach (var field in fieldsToUse)
{
emitter.Emit(OpCodes.Ldarg_0);
emitter.Emit(OpCodes.Ldflda, field);
emitter.Emit(ArgumentOperation.Load, 1);
emitter.Emit(OpCodes.Ldfld, field);
emitter.EmitCall(field.FieldType.GetMethod(
EqualsInfo.Name,
new Type[] { field.FieldType }));
// IMPORTANT: Each field can branch to the false label. However, if we
// have a large number of fields, depending on the number of IL bytes we
// emit per field, we may not be able to reach the false label using a
// 1-byte branch. In that case, we should instead use a 4-byte branch.
emitter.Emit(
fieldsToUse.Length < 7 ? OpCodes.Brfalse_S : OpCodes.Brfalse,
falseLabel);
}
emitter.EmitConstant(1);
emitter.Emit(OpCodes.Ret);
emitter.MarkLabel(falseLabel);
emitter.EmitConstant(0);
emitter.Emit(OpCodes.Ret);
emitter.Finish();
var equalityInstance = typeof(IEquatable <>).MakeGenericType(typeBuilder);
typeBuilder.AddInterfaceImplementation(equalityInstance);
return(equals);
}
/// <summary>
/// Generates a new hash code function.
/// </summary>
/// <param name="typeBuilder">The type builder to use.</param>
/// <param name="fieldsToUse">All fields to use to compute the hash code.</param>
/// <returns>The created hash code function.</returns>
public static MethodInfo GenerateHashCode(
this TypeBuilder typeBuilder,
FieldInfo[] fieldsToUse)
{
var getHashCode = typeBuilder.DefineMethod(
GetHashCodeInfo.Name,
MethodAttributes.Public | MethodAttributes.Virtual,
typeof(int),
Array.Empty <Type>());
var emitter = new ILEmitter(getHashCode.GetILGenerator());
var result = emitter.DeclareLocal(typeof(int));
emitter.EmitConstant(0);
emitter.Emit(LocalOperation.Store, result);
foreach (var field in fieldsToUse)
{
emitter.Emit(LocalOperation.Load, result);
emitter.Emit(OpCodes.Ldarg_0);
emitter.Emit(OpCodes.Ldflda, field);
emitter.EmitCall(field.FieldType.GetMethod(
GetHashCodeInfo.Name,
BindingFlags.Public | BindingFlags.Instance));
emitter.Emit(OpCodes.Xor);
emitter.Emit(LocalOperation.Store, result);
}
emitter.Emit(LocalOperation.Load, result);
emitter.Emit(OpCodes.Ret);
emitter.Finish();
typeBuilder.DefineMethodOverride(getHashCode, GetHashCodeInfo);
return(getHashCode);
}
/// <summary>
/// Generates a new typed equals method using the given fields.
/// </summary>
/// <param name="typeBuilder">The type builder to use.</param>
/// <param name="fieldsToUse">All fields to use to compute the hash code.</param>
/// <returns>The created equals function.</returns>
public static MethodInfo GenerateEquals(
this TypeBuilder typeBuilder,
FieldInfo[] fieldsToUse)
{
var equals = typeBuilder.DefineMethod(
EqualsInfo.Name,
MethodAttributes.Public | MethodAttributes.Virtual |
MethodAttributes.NewSlot | MethodAttributes.Final,
typeof(bool),
new Type[] { typeBuilder });
var emitter = new ILEmitter(equals.GetILGenerator());
var falseLabel = emitter.DeclareLabel();
foreach (var field in fieldsToUse)
{
emitter.Emit(OpCodes.Ldarg_0);
emitter.Emit(OpCodes.Ldflda, field);
emitter.Emit(ArgumentOperation.Load, 1);
emitter.Emit(OpCodes.Ldfld, field);
emitter.EmitCall(field.FieldType.GetMethod(
EqualsInfo.Name,
new Type[] { field.FieldType }));
emitter.Emit(OpCodes.Brfalse_S, falseLabel);
}
emitter.EmitConstant(1);
emitter.Emit(OpCodes.Ret);
emitter.MarkLabel(falseLabel);
emitter.EmitConstant(0);
emitter.Emit(OpCodes.Ret);
emitter.Finish();
var equalityInstance = typeof(IEquatable <>).MakeGenericType(typeBuilder);
typeBuilder.AddInterfaceImplementation(equalityInstance);
return(equals);
}
