public static Expression TransformNullOpToConditionalOp(this NullOp s, Essentials types, Namescope scope)
{
// a ?? b -> (temp = a, temp != null ? temp : b)
// OR -> a != null ? a : b
var left = s.Left;
var right = s.Right;
var ind = TryCreateIndirection(scope, ref left);
var cond = new ReferenceOp(s.Source, types.Bool, EqualityType.NotEqual, left, new Constant(s.Source, left.ReturnType, null));
var result = new ConditionalOp(s.Source, cond, left, right);
return(ind != null
? (Expression) new SequenceOp(ind, result)
: result);
}
public virtual void WriteReferenceOp(ReferenceOp s, ExpressionUsage u)
{
Begin(u);
WriteExpression(s.Left, ExpressionUsage.Operand);
switch (s.EqualityType)
{
case EqualityType.Equal:
Write(Equals);
break;
case EqualityType.NotEqual:
Write(NotEquals);
break;
default:
throw new SourceException(s.Source, "Invalid EqualityType: " + s.EqualityType);
}
WriteExpression(s.Right, ExpressionUsage.Operand);
End(u);
}