/// <summary> /// 写入类型转换的 IL 指令。 /// </summary> /// <param name="generator">IL 的指令生成器。</param> /// <param name="inputType">要转换的对象的类型。</param> /// <param name="outputType">要将输入对象转换到的类型。</param> /// <param name="isChecked">是否执行溢出检查。</param> public override void Emit(ILGenerator generator, Type inputType, Type outputType, bool isChecked) { Contract.Assume(inputType.IsNullable()); Type inputUnderlyingType = Nullable.GetUnderlyingType(inputType); generator.EmitCall(inputType.GetMethod("get_Value")); if (inputUnderlyingType != outputType) { Conversion conversion = ConversionFactory.GetConversion(inputUnderlyingType, outputType); Contract.Assume(conversion != null); conversion.Emit(generator, inputUnderlyingType, outputType, isChecked); } }
/// <summary> /// 写入类型转换的 IL 指令。 /// </summary> /// <param name="generator">IL 的指令生成器。</param> /// <param name="inputType">要被转换的类型。</param> /// <param name="outputType">要转换到的类型。</param> /// <param name="isChecked">是否执行溢出检查。</param> public override void Emit(ILGenerator generator, Type inputType, Type outputType, bool isChecked) { Contract.Assume(inputType.IsNullable()); Type inputUnderlyingType = Nullable.GetUnderlyingType(inputType); Type outputUnderlyingType = Nullable.GetUnderlyingType(outputType); // 定义变量和标签 LocalBuilder inputLocal = generator.GetLocal(inputType); Label trueCase = generator.DefineLabel(); Label endConvert = generator.DefineLabel(); // inputLocal = value; generator.Emit(OpCodes.Stloc, inputLocal); // if (input.HasValue) generator.Emit(OpCodes.Ldloca, inputLocal); MethodInfo hasValue = inputType.GetMethod("get_HasValue"); generator.Emit(OpCodes.Call, hasValue); generator.Emit(OpCodes.Brtrue, trueCase); // return null if (outputUnderlyingType != null) { // Nullable<T>。 generator.EmitDefault(outputType); } else { // 引用类型。 generator.Emit(OpCodes.Ldnull); } generator.Emit(OpCodes.Br, endConvert); // else generator.MarkLabel(trueCase); // (outputType)input.GetValueOrDefault(); generator.Emit(OpCodes.Ldloca, inputLocal); generator.FreeLocal(inputLocal); MethodInfo getValueOrDefault = inputType.GetMethod("GetValueOrDefault", Type.EmptyTypes); generator.Emit(OpCodes.Call, getValueOrDefault); ConversionFactory.GetConversion(inputUnderlyingType, outputUnderlyingType ?? outputType) .Emit(generator, inputUnderlyingType, outputUnderlyingType ?? outputType, isChecked); if (outputUnderlyingType != null) { ConstructorInfo ctor = outputType.GetConstructor(new[] { outputUnderlyingType }); Contract.Assume(ctor != null); generator.Emit(OpCodes.Newobj, ctor); } generator.MarkLabel(endConvert); }
/// <summary> /// 写入类型转换的 IL 指令。 /// </summary> /// <param name="generator">IL 的指令生成器。</param> /// <param name="inputType">要转换的对象的类型。</param> /// <param name="outputType">要将输入对象转换到的类型。</param> /// <param name="isChecked">是否执行溢出检查。</param> public override void Emit(ILGenerator generator, Type inputType, Type outputType, bool isChecked) { Contract.Assume(outputType.IsNullable()); var outputUnderlyingType = Nullable.GetUnderlyingType(outputType); if (inputType != outputUnderlyingType) { var conversion = ConversionFactory.GetConversion(inputType, outputUnderlyingType); Contract.Assume(conversion != null); conversion.Emit(generator, inputType, outputUnderlyingType, isChecked); } var ctor = outputType.GetConstructor(new[] { outputUnderlyingType }); Contract.Assume(ctor != null); generator.Emit(OpCodes.Newobj, ctor); }