net.sf.saxon.lib.ModuleURIResolver Maven / Gradle / Ivy
Show all versions of Saxon-HE Show documentation
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// Copyright (c) 2018-2022 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.trans.XPathException;
import javax.xml.transform.stream.StreamSource;
/**
* A ModuleURIResolver is used when resolving references to
* query modules. It takes as input a URI that identifies the module to be loaded, and a set of
* location hints, and returns one or more StreamSource objects containing the queries
* to be imported.
*/
public interface ModuleURIResolver {
/**
* Locate a query module, or a set of query modules, given the identifying URI and
* a set of associated location hints.
* The module URI resolver is generally invoked when locating library modules. When a
* module import declaration is encountered in the query source, Saxon first expands any
* relative URIs appearing in the location hints to absolute URIs by resolving against
* the base URI of the module. It then discards any absolutized location hints that have
* previously been used in processing other module import declarations. If there are no
* remaining location hints, and if a module with the requested module URI has already
* been loaded, then the module URI resolver is not called (it is assumed this is a duplicate
* request). In all other cases, the module URI resolver is called, passing the requested
* module namespace URI and the list of absolutized location hints excluding any that have
* been used in a previous request.
* The module URI resolver is also
* invoked when loading the main query module in cases where this is provided in the form
* of a URI: specifically, when running a query from the command line specifying the -u
* option, or with a supplied query file name that starts with "http:" or "file:". When
* locating the main query module, the moduleURI and baseURI parameters will be null, and
* the resolver must either return null (which delegates to the standard ModuleURIResolver),
* or must return a singleton StreamSource, that is, an array of length 1.
*
* @param moduleURI the module URI of the module to be imported; or null when
* loading a non-library module.
* @param baseURI The base URI of the module containing the "import module" declaration;
* null if no base URI is known
* @param locations The set of URIs specified in the "at" clause of "import module",
* which serve as location hints for the module. The values supplied are absolute URIs
* formed by resolving the relative URI appearing in the query against the base URI of the query.
* @return an array of {@link StreamSource} objects each identifying the contents of a query module to be
* imported. Each StreamSource must contain a
* non-null absolute System ID which will be used as the base URI of the imported module,
* and either an {@link java.io.InputStream} or an {@link java.io.Reader} representing the text of the module.
* The contained InputStream or Reader must be positioned at the start of the
* content to be read; it will be consumed by the system and will be closed after use.
* The method may alternatively return null, in which case the system attempts to resolve the URI using the
* standard module URI resolver. The standard module URI resolver attempts to dereference each one of the
* location hints to locate a query module. If there are no location hints, or if any location hint
* cannot be dereferenced, it reports a fatal error.
* @throws XPathException if the module cannot be located, and if delegation to the default
* module resolver is not required.
*/
StreamSource[] resolve(String moduleURI, String baseURI, String[] locations) throws XPathException;
}