private bool EmitNullableSource(CompilationContext context, Type sourceType, Type targetType)
{
#if NETSTANDARD
var reflectingSourceType = sourceType.GetTypeInfo();
#else
var reflectingSourceType = sourceType;
#endif
var sourceUnderlingType = reflectingSourceType.GetGenericArguments()[0];
var converter = GetConvertEmitter(sourceUnderlingType, targetType);
if (converter != null)
{
var target = context.DeclareLocal(targetType);
var local = context.DeclareLocal(sourceType);
context.Emit(OpCodes.Stloc, local);
context.EmitNullableExpression(local, ctx =>
{
converter(ctx);
ctx.Emit(OpCodes.Stloc, target);
}, ctx =>
{
context.EmitDefault(targetType);
context.Emit(OpCodes.Stloc, target);
});
context.Emit(OpCodes.Ldloc, target);
return(true);
}
return(false);
}
public override void Emit(Type sourceType, Type targetType, CompilationContext context)
{
#if NetCore
var reflectingTargetType = targetType.GetTypeInfo();
#else
var reflectingTargetType = targetType;
#endif
var target = context.DeclareLocal(targetType);
var local = context.DeclareLocal(sourceType);
context.Emit(OpCodes.Stloc, local);
if (targetType.IsNullable())
{
var labelEnd = context.DefineLabel();
var labelFirst = context.DefineLabel();
// if(source == null)
context.Emit(OpCodes.Ldloc, local);
context.Emit(OpCodes.Brtrue, labelFirst);
// target = null;
context.Emit(OpCodes.Ldloca, target);
context.Emit(OpCodes.Initobj, targetType);
// goto end;
context.Emit(OpCodes.Br, labelEnd);
context.MakeLabel(labelFirst);
// if(string.IsNullOrWhiteSpace(source))
var labelSecond = context.DefineLabel();
context.Emit(OpCodes.Ldloc, local);
context.EmitCall(_checkEmptyMethod);
context.Emit(OpCodes.Brfalse, labelSecond);
// target = new Nullable<T>(default(T));
context.EmitDefault(reflectingTargetType.GetGenericArguments()[0]);
context.Emit(OpCodes.Newobj, reflectingTargetType.GetConstructors()[0]);
context.Emit(OpCodes.Stloc, target);
// goto end;
context.Emit(OpCodes.Br, labelEnd);
context.MakeLabel(labelSecond);
// target = new Nullable<$EnumType$>(($EnumType$)Enum.Parse(typeof($EnumType$),source));
// or
// target = new Nullable<$TargetType$>($TargetType$.Parse(source));
var underlingType = reflectingTargetType.GetGenericArguments()[0];
#if NetCore
if (underlingType.GetTypeInfo().IsEnum)
#else
if (underlingType.IsEnum)
#endif
{
context.EmitTypeOf(underlingType);
}
context.Emit(OpCodes.Ldloc, local);
context.EmitCall(_stringTrimMethod);
context.EmitCall(GetConvertMethod(underlingType));
context.EmitCast(underlingType);
context.Emit(OpCodes.Newobj, reflectingTargetType.GetConstructors()[0]);
context.Emit(OpCodes.Stloc, target);
context.MakeLabel(labelEnd);
context.Emit(OpCodes.Ldloc, target);
}
else
{
// if(!string.IsNullOrWhiteSpace(source))
var label = context.DefineLabel();
context.Emit(OpCodes.Ldloc, local);
context.EmitCall(_checkEmptyMethod);
context.Emit(OpCodes.Brtrue, label);
// target = ($EnumType$)Enum.Parse(typeof($EnumType$),source);
// or
// target = $TargetType$.Parse(source);
if (reflectingTargetType.IsEnum)
{
context.EmitTypeOf(targetType);
}
context.Emit(OpCodes.Ldloc, local);
context.EmitCall(_stringTrimMethod);
context.EmitCall(GetConvertMethod(targetType));
context.EmitCast(targetType);
context.Emit(OpCodes.Stloc, target);
// goto end;
var labelEnd = context.DefineLabel();
context.Emit(OpCodes.Br, labelEnd);
// target = default(T);
context.MakeLabel(label);
context.EmitDefault(targetType);
context.Emit(OpCodes.Stloc, target);
context.MakeLabel(labelEnd);
context.Emit(OpCodes.Ldloc, target);
}
}