com.redhat.ceylon.langtools.tools.javac.processing.ServiceProxy Maven / Gradle / Ivy
/*
* Copyright (c) 2006, 2008, 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
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*/
package com.redhat.ceylon.langtools.tools.javac.processing;
import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.MalformedURLException;
import java.net.URL;
/**
* Utility class to determine if a service can be found on the
* path that might be used to create a class loader.
*
* This is NOT part of any supported API.
* If you write code that depends on this, you do so at your own risk.
* This code and its internal interfaces are subject to change or
* deletion without notice.
*
*/
// based on sun.misc.Service
class ServiceProxy {
static class ServiceConfigurationError extends Error {
static final long serialVersionUID = 7732091036771098303L;
ServiceConfigurationError(String msg) {
super(msg);
}
}
private static final String prefix = "META-INF/services/";
private static void fail(Class service, String msg)
throws ServiceConfigurationError {
throw new ServiceConfigurationError(service.getName() + ": " + msg);
}
private static void fail(Class service, URL u, int line, String msg)
throws ServiceConfigurationError {
fail(service, u + ":" + line + ": " + msg);
}
/**
* Parse the content of the given URL as a provider-configuration file.
*
* @param service
* The service class for which providers are being sought;
* used to construct error detail strings
*
* @param url
* The URL naming the configuration file to be parsed
*
* @return true if the name of a service is found
*
* @throws ServiceConfigurationError
* If an I/O error occurs while reading from the given URL, or
* if a configuration-file format error is detected
*/
private static boolean parse(Class service, URL u) throws ServiceConfigurationError {
InputStream in = null;
BufferedReader r = null;
try {
in = u.openStream();
r = new BufferedReader(new InputStreamReader(in, "utf-8"));
int lc = 1;
String ln;
while ((ln = r.readLine()) != null) {
int ci = ln.indexOf('#');
if (ci >= 0) ln = ln.substring(0, ci);
ln = ln.trim();
int n = ln.length();
if (n != 0) {
if ((ln.indexOf(' ') >= 0) || (ln.indexOf('\t') >= 0))
fail(service, u, lc, "Illegal configuration-file syntax");
int cp = ln.codePointAt(0);
if (!Character.isJavaIdentifierStart(cp))
fail(service, u, lc, "Illegal provider-class name: " + ln);
for (int i = Character.charCount(cp); i < n; i += Character.charCount(cp)) {
cp = ln.codePointAt(i);
if (!Character.isJavaIdentifierPart(cp) && (cp != '.'))
fail(service, u, lc, "Illegal provider-class name: " + ln);
}
return true;
}
}
} catch (FileNotFoundException x) {
return false;
} catch (IOException x) {
fail(service, ": " + x);
} finally {
try {
if (r != null) r.close();
} catch (IOException y) {
fail(service, ": " + y);
}
try {
if (in != null) in.close();
} catch (IOException y) {
fail(service, ": " + y);
}
}
return false;
}
/**
* Return true if a description for at least one service is found in the
* service configuration files in the given URLs.
*/
public static boolean hasService(Class service, URL[] urls)
throws ServiceConfigurationError {
for (URL url: urls) {
try {
String fullName = prefix + service.getName();
URL u = new URL(url, fullName);
boolean found = parse(service, u);
if (found)
return true;
} catch (MalformedURLException e) {
// should not happen; ignore it if it does
}
}
return false;
}
}