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/*
* Copyright (C) 2008, Shawn O. Pearce <spearce@spearce.org> and others
*
* This program and the accompanying materials are made available under the
* terms of the Eclipse Distribution License v. 1.0 which is available at
* https://www.eclipse.org/org/documents/edl-v10.php.
*
* SPDX-License-Identifier: BSD-3-Clause
*/
package org.eclipse.jgit.pgm;
import static java.nio.charset.StandardCharsets.UTF_8;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.URL;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.Map;
/**
* List of all commands known by jgit's command line tools.
* <p>
* Commands are implementations of {@link org.eclipse.jgit.pgm.TextBuiltin},
* with an optional {@link org.eclipse.jgit.pgm.Command} class annotation to
* insert additional documentation or override the default command name (which
* is guessed from the class name).
* <p>
* Commands may be registered by adding them to a services file in the same JAR
* (or classes directory) as the command implementation. The service file name
* is <code>META-INF/services/org.eclipse.jgit.pgm.TextBuiltin</code> and it
* contains one concrete implementation class name per line.
* <p>
* Command registration is identical to Java 6's services, however the catalog
* uses a lightweight wrapper to delay creating a command instance as much as
* possible. This avoids initializing the AWT or SWT GUI toolkits even if the
* command's constructor might require them.
*/
public class CommandCatalog {
private static final CommandCatalog INSTANCE = new CommandCatalog();
/**
* Locate a single command by its user friendly name.
*
* @param name
* name of the command. Typically in dash-lower-case-form, which
* was derived from the DashLowerCaseForm class name.
* @return the command instance; null if no command exists by that name.
*/
public static CommandRef get(String name) {
return INSTANCE.commands.get(name);
}
/**
* Get all commands sorted by their name
*
* @return all known commands, sorted by command name.
*/
public static CommandRef[] all() {
return toSortedArray(INSTANCE.commands.values());
}
/**
* Get all common commands sorted by their name
*
* @return all common commands, sorted by command name.
*/
public static CommandRef[] common() {
final ArrayList<CommandRef> common = new ArrayList<>();
for (CommandRef c : INSTANCE.commands.values())
if (c.isCommon())
common.add(c);
return toSortedArray(common);
}
private static CommandRef[] toSortedArray(Collection<CommandRef> c) {
final CommandRef[] r = c.toArray(new CommandRef[0]);
Arrays.sort(r, (CommandRef o1, CommandRef o2) -> o1.getName()
.compareTo(o2.getName()));
return r;
}
private final ClassLoader ldr;
private final Map<String, CommandRef> commands;
private CommandCatalog() {
ldr = Thread.currentThread().getContextClassLoader();
commands = new HashMap<>();
final Enumeration<URL> catalogs = catalogs();
while (catalogs.hasMoreElements())
scan(catalogs.nextElement());
}
private Enumeration<URL> catalogs() {
try {
final String pfx = "META-INF/services/"; //$NON-NLS-1$
return ldr.getResources(pfx + TextBuiltin.class.getName());
} catch (IOException err) {
return Collections.emptyEnumeration();
}
}
private void scan(URL cUrl) {
try (BufferedReader cIn = new BufferedReader(
new InputStreamReader(cUrl.openStream(), UTF_8))) {
String line;
while ((line = cIn.readLine()) != null) {
if (line.length() > 0 && !line.startsWith("#")) //$NON-NLS-1$
load(line);
}
} catch (IOException e) {
// Ignore errors
}
}
private void load(String cn) {
final Class<? extends TextBuiltin> clazz;
try {
clazz = Class.forName(cn, false, ldr).asSubclass(TextBuiltin.class);
} catch (ClassNotFoundException | ClassCastException notBuiltin) {
// Doesn't exist, even though the service entry is present.
// Isn't really a builtin, even though its listed as such.
return;
}
final CommandRef cr;
final Command a = clazz.getAnnotation(Command.class);
if (a != null)
cr = new CommandRef(clazz, a);
else
cr = new CommandRef(clazz);
commands.put(cr.getName(), cr);
}
}
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