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SciJava Common is a shared library for SciJava software. It provides a plugin framework, with an extensible mechanism for service discovery, backed by its own annotation processor, so that plugins can be loaded dynamically. It is used by downstream projects in the SciJava ecosystem, such as ImageJ and SCIFIO.
/*
* #%L
* SciJava Common shared library for SciJava software.
* %%
* Copyright (C) 2009 - 2017 Board of Regents of the University of
* Wisconsin-Madison, Broad Institute of MIT and Harvard, and Max Planck
* Institute of Molecular Cell Biology and Genetics.
* %%
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDERS OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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package org.scijava.console;
import java.io.OutputStream;
import java.io.PrintStream;
import java.util.ArrayList;
import java.util.LinkedList;
import java.util.List;
import org.scijava.Context;
import org.scijava.console.OutputEvent.Source;
import org.scijava.log.LogService;
import org.scijava.plugin.AbstractHandlerService;
import org.scijava.plugin.Parameter;
import org.scijava.plugin.Plugin;
import org.scijava.service.Service;
import org.scijava.thread.ThreadService;
import org.scijava.thread.ThreadService.ThreadContext;
/**
* Default service for managing interaction with the console.
*
* @author Curtis Rueden
*/
@Plugin(type = Service.class)
public class DefaultConsoleService extends
AbstractHandlerService, ConsoleArgument> implements
ConsoleService
{
@Parameter
private ThreadService threadService;
@Parameter
private LogService log;
private MultiPrintStream sysout, syserr;
private OutputStreamReporter out, err;
/** List of listeners for {@code stdout} and {@code stderr} output. */
private ArrayList listeners;
private OutputListener[] cachedListeners;
// -- ConsoleService methods --
@Override
public void processArgs(final String... args) {
log.debug("Received command line arguments:");
final LinkedList argList = new LinkedList<>();
for (final String arg : args) {
log.debug("\t" + arg);
argList.add(arg);
}
final List previousArgs = new ArrayList<>();
while (!argList.isEmpty()) {
final ConsoleArgument handler = getHandler(argList);
if (handler == null) {
// ignore invalid command line argument
final String arg = argList.removeFirst();
log.warn("Ignoring invalid argument: " + arg);
continue;
}
// keep a copy of the argument list prior to handling
previousArgs.clear();
previousArgs.addAll(argList);
// process the argument
handler.handle(argList);
// verify that the handler did something to the list;
// this guards against bugs which would cause infinite loops
if (sameElements(previousArgs, argList)) {
// skip improperly handled argument
final String arg = argList.removeFirst();
log.warn("Plugin '" + handler.getClass().getName() +
"' failed to handle argument: " + arg);
}
}
}
@Override
public void addOutputListener(final OutputListener l) {
if (listeners == null) initListeners();
synchronized (listeners) {
listeners.add(l);
cacheListeners();
}
}
@Override
public void removeOutputListener(final OutputListener l) {
if (listeners == null) initListeners();
synchronized (listeners) {
listeners.remove(l);
cacheListeners();
}
}
@Override
public void notifyListeners(final OutputEvent event) {
if (listeners == null) initListeners();
final OutputListener[] toNotify = cachedListeners;
for (final OutputListener l : toNotify)
l.outputOccurred(event);
}
// -- Disposable methods --
@Override
public void dispose() {
if (out != null) sysout.getParent().removeOutputStream(out);
if (err != null) syserr.getParent().removeOutputStream(err);
}
// -- Helper methods - lazy initialization --
/** Initializes {@link #listeners} and related data structures. */
private synchronized void initListeners() {
if (listeners != null) return; // already initialized
sysout = multiPrintStream(System.out);
if (System.out != sysout) System.setOut(sysout);
out = new OutputStreamReporter(Source.STDOUT);
sysout.getParent().addOutputStream(out);
syserr = multiPrintStream(System.err);
if (System.err != syserr) System.setErr(syserr);
err = new OutputStreamReporter(Source.STDERR);
syserr.getParent().addOutputStream(err);
listeners = new ArrayList<>();
cachedListeners = listeners.toArray(new OutputListener[0]);
}
// -- Helper methods --
private void cacheListeners() {
cachedListeners = listeners.toArray(new OutputListener[listeners.size()]);
}
private MultiPrintStream multiPrintStream(final PrintStream ps) {
if (ps instanceof MultiPrintStream) return (MultiPrintStream) ps;
return new MultiPrintStream(ps);
}
/**
* Gets whether two lists have exactly the same elements in them.
*
* We cannot use {@link List#equals(Object)} because want to check for
* identical references, not per-element object equality.
*
*/
private boolean sameElements(final List l1,
final List l2)
{
if (l1.size() != l2.size()) return false;
for (int i = 0; i < l1.size(); i++) {
if (l1.get(i) != l2.get(i)) return false;
}
return true;
}
// -- Helper classes --
/**
* An output stream that publishes its output to the {@link OutputListener}s
* of its associated {@link ConsoleService}.
*/
private class OutputStreamReporter extends OutputStream {
/** Source of the output stream; i.e., {@code stdout} or {@code stderr}. */
private final Source source;
public OutputStreamReporter(final Source source) {
this.source = source;
}
// -- OutputStream methods --
@Override
public void write(final int b) {
final ThreadContext relevance = getRelevance();
if (relevance == ThreadContext.OTHER) return; // different context
publish(relevance, "" + b);
}
@Override
public void write(final byte[] buf, final int off, final int len) {
final ThreadContext relevance = getRelevance();
if (relevance == ThreadContext.OTHER) return; // different context
publish(relevance, new String(buf, off, len));
}
// -- Helper methods --
private ThreadContext getRelevance() {
return threadService.getThreadContext(Thread.currentThread());
}
private void publish(final ThreadContext relevance, final String output) {
final Context context = getContext();
final boolean contextual = relevance == ThreadContext.SAME;
final OutputEvent event =
new OutputEvent(context, source, output, contextual);
notifyListeners(event);
}
}
}