/* * Copyright (c) 2014, 2016, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. Oracle designates this * particular file as subject to the "Classpath" exception as provided * by Oracle in the LICENSE file that accompanied this code. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */ package com.oracle.truffle.api.impl; import java.util.Collections; import java.util.LinkedHashSet; import java.util.Set; import com.oracle.truffle.api.Truffle; import com.oracle.truffle.api.TruffleRuntime; /** * Locator that allows the users of the Truffle API to find implementations of languages to be * available in {@link com.oracle.truffle.api.vm.PolyglotEngine}. A {@link TruffleRuntime} can * provide the locator via its {@link TruffleRuntime#getCapability(java.lang.Class)} method. * * @since 0.18 */ public abstract class TruffleLocator { /** * Creates the set of classloaders to be used by the system. * * @return set of classloaders to search registrations in */ static Set<ClassLoader> loaders() { Iterable<TruffleLocator> allLocators; TruffleLocator locator = Truffle.getRuntime().getCapability(TruffleLocator.class); if (locator != null) { allLocators = Collections.singleton(locator); } else { allLocators = Collections.emptyList(); } Set<ClassLoader> found = new LinkedHashSet<>(); Response response = new Response(found); for (TruffleLocator test : allLocators) { test.locate(response); } found.add(ClassLoader.getSystemClassLoader()); found.add(TruffleLocator.class.getClassLoader()); return found; } /** * Utility method to load a class from one of the located classloaders. Please note that this * method is used in tests using reflection. Do not remove. * * @param name class to search for * @return the class or <code>null</code> if none of the loaders knows the class */ static Class<?> loadClass(String name) { for (ClassLoader loader : loaders()) { if (loader == null) { continue; } try { return loader.loadClass(name); } catch (ClassNotFoundException ex) { continue; } } return null; } /** * Called to locate languages and other parts of the system. * * @param response the response to fill in with found languages * @since 0.18 */ protected abstract void locate(Response response); /** * Callback to register languages. * * @since 0.18 */ public static final class Response { private final Set<ClassLoader> loaders; Response(Set<ClassLoader> loaders) { this.loaders = loaders; } /** * Register a classloader to be used to find implementations of the languages. Can be called * multiple times to register as many classloaders as necessary. * * @param languageLoader the classloader to use * @since 0.18 */ public void registerClassLoader(ClassLoader languageLoader) { loaders.add(languageLoader); } } }