BadNullCoalescingAssignExpression.cs

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using BadScript2.Common;
using BadScript2.Parser.Expressions.Binary;
using BadScript2.Runtime;
using BadScript2.Runtime.Error;
using BadScript2.Runtime.Objects;
 
namespace BadScript2.Parser.Expressions.Access;
 
public class BadNullCoalescingAssignExpression : BadBinaryExpression
{
    public BadNullCoalescingAssignExpression(
        BadExpression left,
        BadExpression right,
        BadSourcePosition position) : base(
        left,
        right,
        position
    ) { }
 
 
    protected override IEnumerable<BadObject> InnerExecute(BadExecutionContext context)
    {
        BadObject left = BadObject.Null;
 
        foreach (BadObject o in Left.Execute(context))
        {
            left = o;
        }
 
        if (left is not BadObjectReference leftRef)
        {
            throw new BadRuntimeException("Left side of null coalescing assignment must be a reference", Position);
        }
 
        left = left.Dereference();
 
        if (left == BadObject.Null)
        {
            BadObject rVal = BadObject.Null;
 
            foreach (BadObject o in Right.Execute(context))
            {
                yield return o;
 
                rVal = o;
            }
 
            rVal = rVal.Dereference();
            leftRef.Set(rVal);
 
            yield return rVal;
        }
        else
        {
            yield return left;
        }
    }
 
 
    protected override string GetSymbol()
    {
        return "??=";
    }
}