////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// Copyright (c) 2017 Saxonica Limited.
// This Source Code Form is subject to the terms of the Mozilla Public License, v. 2.0.
// If a copy of the MPL was not distributed with this file, You can obtain one at http://mozilla.org/MPL/2.0/.
// This Source Code Form is "Incompatible With Secondary Licenses", as defined by the Mozilla Public License, v. 2.0.
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

package net.sf.saxon.lib;

import net.sf.saxon.expr.XPathContext;
import net.sf.saxon.om.SequenceIterator;
import net.sf.saxon.trans.XPathException;


/**
 * This interface defines a CollectionURIResolver. This is a counterpart to the JAXP
 * URIResolver, but is used to map the URI of collection into a sequence of documents.
 * It is used to support the fn:collection() and fn:uri-collection() functions.
 * @deprecated since 9.7: use {@link CollectionFinder}.
 * @since 9.7: the interface is retained for backwards compatibility, but does not
 * provide access to the full capabilities of collections in XPath 3.1
 */

public interface CollectionURIResolver {

    /**
     * Resolve a URI.
     *
     * @param href    The relative URI of the collection. This corresponds to the
     *                argument supplied to the collection() function. If the collection() function
     *                was called with no arguments (to get the "default collection") this argument
     *                will be null.
     * @param base    The base URI that should be used. This is the base URI of the
     *                static context in which the call to collection() was made, typically the URI
     *                of the stylesheet or query module
     * @param context The dynamic execution context
     * @return an Iterator over the documents in the collection. The items returned
     * by this iterator must be instances either of xs:anyURI, or of node() (specifically,
     * {@link net.sf.saxon.om.NodeInfo}).
     * <p>When the fn:uri-collection() function is called: the result will consist of
     * (a) any items that are xs:anyURI values, and (b) the document URIs of any items that are
     * document nodes with a document URI.</p>
     * <p>When the fn:collection() function is called: if xs:anyURI values are returned, the corresponding
     * document will be retrieved as if by a call to the fn:doc() function: this means that
     * the system first checks to see if the document is already loaded, and if not, calls
     * the registered URIResolver to dereference the URI. This is the recommended approach
     * to ensure that the resulting collection is stable: however, it has the consequence
     * that the documents will by default remain in memory for the duration of the query
     * or transformation.</p>
     * <p>
     * If the collection URI is not recognized, the method may either return an empty iterator,
     * in which case no error is reported, or it may throw an exception, in which case
     * the query or transformation fails. Returning null has the same effect as returning
     * an empty iterator.</p>
     * @throws net.sf.saxon.trans.XPathException if any failure occurs
     */


    SequenceIterator resolve(String href, String base, XPathContext context) throws XPathException;


}

