CastOperation.cs

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using ErrorManagement;
using TypeSystem.Constraints;
namespace TypeSystem.Operations {
    public class CastOperation : TypeSystemOperation {
        #region Fields
        protected TypeExpression castType;
        protected MethodType methodAnalyzed;
        protected Location location;
        protected bool showErrorMessages;
        #endregion

        #region Constructor
        public CastOperation(TypeExpression castType, MethodType methodAnalyzed, Location location) {
            this.castType = castType;
            this.methodAnalyzed = methodAnalyzed;
            this.location = location;
        }
        #endregion

        #region (TypeExpression) --->castType
        public override object Exec(TypeExpression from, object arg) {
            if (this.castType == null)
                return null;
            if (((int)castType.AcceptOperation(new PromotionLevelOperation(from), arg) != -1) || ((int)from.AcceptOperation(new PromotionLevelOperation(castType), arg) != -1))
                return castType;
            return ReportError(from);
        }
        #endregion

        #region (TypeVarible) --->castType
        public override object Exec(TypeVariable from, object arg) {
            if (from.Substitution != null) {
                return from.Substitution.AcceptOperation(this, arg);
            }
            if (this.methodAnalyzed != null) {
                // * A constraint is added to the method analyzed
                CastConstraint constraint = new CastConstraint(from, this.castType, this.location);
                this.methodAnalyzed.AddConstraint(constraint);
                return constraint.ReturnType;
            }
            return ReportError(from);
        }
        #endregion

        #region (FieldType) --->castType
        public override object Exec(FieldType from, object arg) {
            if (from.FieldTypeExpression != null)
                return from.FieldTypeExpression.AcceptOperation(this, arg);
            return null;
        }
        #endregion


        public override object ReportError(TypeExpression from) {
            ErrorManager.Instance.NotifyError(new TypeCastError(from.FullName, this.castType.FullName, this.location));
            return null;
        }
    }
}