001/*
002 * JDrupes Builder
003 * Copyright (C) 2026 Michael N. Lipp
004 * 
005 * This program is free software: you can redistribute it and/or modify
006 * it under the terms of the GNU Affero General Public License as
007 * published by the Free Software Foundation, either version 3 of the
008 * License, or (at your option) any later version.
009 *
010 * This program is distributed in the hope that it will be useful,
011 * but WITHOUT ANY WARRANTY; without even the implied warranty of
012 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
013 * GNU Affero General Public License for more details.
014 *
015 * You should have received a copy of the GNU Affero General Public License
016 * along with this program.  If not, see <https://www.gnu.org/licenses/>.
017 */
018
019package org.jdrupes.builder.api;
020
021import java.util.stream.Stream;
022
023/// This interface must be made available to the [BuildContext]
024/// by implementations of resource providers.
025///
026@SuppressWarnings("PMD.ImplicitFunctionalInterface")
027public interface ResourceProviderSpi {
028
029    /// Provide the requested resources. This method is not intended
030    /// to be invoked directly. Rather, it must be invoked via
031    /// [BuildContext#resources].
032    /// 
033    /// When properly invoked through [BuildContext#resources], this
034    /// method is never invoked concurrently for the same request.
035    /// It may, however, be invoked concurrently for different requests.
036    /// Providers that evaluate all possibly provided resources anyway
037    /// and return only a subset for some kinds of request should
038    /// therefore invoke themselves (through [BuildContext#resources])
039    /// with a request for all resources and filter the (automatically
040    /// cached) result.
041    ///
042    /// @param <T> the type of the requested (and provided) resource
043    /// @param requested the requested resources
044    /// @return the provided resource(s) as stream
045    ///
046    <T extends Resource> Stream<T> provide(ResourceRequest<T> requested);
047}