Split ImageJ service framework into scijava-common

This code was migrated and adapted from ImageJ:

    https://github.com/imagej/imagej

This new shared library will enable ImageJ and SCIFIO to have a common
base for plugin extensibility.

.factorypath

@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="UTF-8" standalone="no"?>
+<factorypath>
+    <factorypathentry enabled="true" id="M2_REPO/net/java/sezpoz/sezpoz/1.9/sezpoz-1.9.jar" kind="VARJAR" runInBatchMode="true"/>
+</factorypath>

.gitignore

@@ -1,2 +1,4 @@
+.classpath
 .project
 .settings
+target

.settings/org.eclipse.jdt.apt.core.prefs

@@ -0,0 +1,4 @@
+#Fri Feb 15 15:28:28 CST 2013
+org.eclipse.jdt.apt.aptEnabled=true
+org.eclipse.jdt.apt.genSrcDir=target/classes
+org.eclipse.jdt.apt.reconcileEnabled=false

pom-scijava/README.md

@@ -9,6 +9,7 @@ Maven-based SciJava code, including:
 * [ImgLib](https://github.com/imagej/imglib)
 * [LOCI](https://github.com/uw-loci/pom-loci)
 * [SCIFIO](https://github.com/imagej/minimal-ij1-plugin)
+* [SciJava Common](https://github.com/scijava/scijava-common/tree/master/scijava-common)
 
 This POM is intended for use as the parent of your own Maven-based code.
 See these examples for guidance:

pom.xml

@@ -0,0 +1,81 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0
+		http://maven.apache.org/xsd/maven-4.0.0.xsd">
+	<modelVersion>4.0.0</modelVersion>
+
+	<parent>
+		<groupId>org.scijava</groupId>
+		<artifactId>pom-scijava</artifactId>
+		<version>1.28</version>
+	</parent>
+
+	<artifactId>scijava-common</artifactId>
+	<version>1.0.0-SNAPSHOT</version>
+
+	<name>SciJava Common</name>
+	<description>SciJava Common is a service framework. It provides an extensible mechanism for service discovery, driven by the SezPoz library, so that plugins can be loaded dynamically. It is used by both ImageJ and SCIFIO.</description>
+
+	<dependencies>
+		<dependency>
+			<groupId>net.java.sezpoz</groupId>
+			<artifactId>sezpoz</artifactId>
+			<version>${sezpoz.version}</version>
+		</dependency>
+		<dependency>
+			<groupId>org.bushe</groupId>
+			<artifactId>eventbus</artifactId>
+			<version>1.4</version>
+		</dependency>
+
+		<dependency>
+			<groupId>junit</groupId>
+			<artifactId>junit</artifactId>
+			<version>${junit.version}</version>
+			<scope>test</scope>
+		</dependency>
+	</dependencies>
+
+	<build>
+		<plugins>
+			<plugin>
+				<artifactId>maven-jar-plugin</artifactId>
+				<configuration>
+					<archive>
+						<manifest>
+							<packageName>org.scijava</packageName>
+						</manifest>
+					</archive>
+				</configuration>
+			</plugin>
+			<plugin>
+				<artifactId>maven-source-plugin</artifactId>
+			</plugin>
+			<plugin>
+				<groupId>org.codehaus.mojo</groupId>
+				<artifactId>buildnumber-maven-plugin</artifactId>
+			</plugin>
+		</plugins>
+	</build>
+
+	<scm>
+		<connection>scm:git:git://github.com/scijava/scijava-common.git</connection>
+		<developerConnection>scm:git:git@github.com:scijava/scijava-common.git</developerConnection>
+		<tag>HEAD</tag>
+		<url>https://github.com/scijava/scijava-common</url>
+	</scm>
+
+	<!-- NB: for project parent -->
+	<repositories>
+		<repository>
+			<id>imagej.releases</id>
+			<url>http://maven.imagej.net/content/repositories/releases</url>
+		</repository>
+		<repository>
+			<id>imagej.snapshots</id>
+			<url>http://maven.imagej.net/content/repositories/snapshots</url>
+		</repository>
+	</repositories>
+
+</project>

src/main/java/org/scijava/AbstractContextual.java

@@ -0,0 +1,95 @@
+/*
+ * #%L
+ * ImageJ software for multidimensional image processing and analysis.
+ * %%
+ * Copyright (C) 2009 - 2013 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.
+ * 
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDERS OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ * 
+ * The views and conclusions contained in the software and documentation are
+ * those of the authors and should not be interpreted as representing official
+ * policies, either expressed or implied, of any organization.
+ * #L%
+ */
+
+package org.scijava;
+
+import java.util.List;
+
+import org.scijava.event.EventSubscriber;
+import org.scijava.event.EventUtils;
+
+/**
+ * Abstract base class for {@link Contextual} objects.
+ * <p>
+ * This class enforces a single call to {@link #setContext}, throwing an
+ * {@link IllegalStateException} if the context is already set. It also
+ * registers the object's {@link org.scijava.event.EventHandler} methods with
+ * the {@link org.scijava.event.EventService}, if any, at the time the context
+ * is assigned. This frees subclasses from the burden of maintaining
+ * {@link EventSubscriber} references manually.
+ * </p>
+ * 
+ * @author Curtis Rueden
+ */
+public abstract class AbstractContextual implements Contextual {
+
+	/** This application context associated with the object. */
+	private Context context;
+
+	/**
+	 * The list of event subscribers, maintained to avoid garbage collection.
+	 * 
+	 * @see org.scijava.event.EventService#subscribe(Object)
+	 */
+	private List<EventSubscriber<?>> subscribers;
+
+	// -- Object methods --
+
+	@Override
+	public void finalize() {
+		// unregister any event handling methods
+		EventUtils.unsubscribe(getContext(), subscribers);
+	}
+
+	// -- Contextual methods --
+
+	@Override
+	public Context getContext() {
+		return context;
+	}
+
+	@Override
+	public void setContext(final Context context) {
+		if (this.context != null) {
+			throw new IllegalStateException("Context already set");
+		}
+		this.context = context;
+
+		// NB: Subscribe to all events handled by this object.
+		// This greatly simplifies event handling for subclasses.
+		subscribers = EventUtils.subscribe(context, this);
+	}
+
+}