Invercargill/src/lib/Expressions/LotPropertyAccessor.vala

using Invercargill.DataStructures;

namespace Invercargill.Expressions {

    /**
     * Property accessor for types implementing the Lot<T> interface.
     * 
     * Provides access to Lot properties:
     * - `length`: The number of items in the Lot (uint)
     * 
     * Example usage in expressions:
     * {{{
     * items.length          // Returns the number of items in the Lot
     * }}}
     */
    public class LotPropertyAccessor : Object, PropertyAccessor {

        /**
         * The Lot value being accessed.
         */
        private Lot<Object>? _lot;

        /**
         * Creates a new LotPropertyAccessor.
         * 
         * @param lot The Lot value to access properties on
         */
        public LotPropertyAccessor(Lot<Object>? lot) {
            _lot = lot;
        }

        /**
         * {@inheritDoc}
         */
        public bool has_property(string property) {
            return property == "length";
        }

        /**
         * {@inheritDoc}
         */
        public Enumerable<string> get_property_names() {
            return new Wrappers.Array<string>(new string[]{"length"});
        }

        /**
         * {@inheritDoc}
         */
        public Element read_property(string property) throws ExpressionError {
            switch (property) {
                case "length":
                    return new NativeElement<uint>(_lot != null ? _lot.length : 0);
                
                default:
                    throw new ExpressionError.NON_EXISTANT_PROPERTY(
                        @"Unknown Lot property: $property"
                    );
            }
        }

        /**
         * {@inheritDoc}
         */
        public Type get_property_type(string property) throws ExpressionError {
            switch (property) {
                case "length":
                    return typeof(uint);
                
                default:
                    throw new ExpressionError.NON_EXISTANT_PROPERTY(
                        @"Unknown Lot property: $property"
                    );
            }
        }

    }

    /**
     * Factory for creating LotPropertyAccessor instances.
     * 
     * This factory is registered with the TypeAccessorRegistry to provide
     * property access for Lot<T> values.
     */
    public class LotPropertyAccessorFactory : Object, PropertyAccessorFactory {

        /**
         * {@inheritDoc}
         */
        public PropertyAccessor? create(Element element) {
            // Check if the element's value implements Lot
            // We need to check for Lot<Object> since we can't check for Lot<T> generically
            Lot<Object>? lot;
            if (element.try_get_as(out lot)) {
                return new LotPropertyAccessor(lot);
            }
            return null;
        }

    }

}