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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.
*
* 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
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* #L%
*/
package org.scijava;
/**
* Constants for specifying an item's priority.
*
* @author Johannes Schindelin
* @author Curtis Rueden
* @see org.scijava.Prioritized#getPriority()
* @see org.scijava.plugin.Plugin#priority()
*/
public final class Priority {
private Priority() {
// prevent instantiation of utility class
}
/** Priority for items that must be sorted first. */
public static final double FIRST_PRIORITY = Double.POSITIVE_INFINITY;
/** Priority for items that strongly prefer to be sorted early. */
public static final double VERY_HIGH_PRIORITY = +10000;
/** Priority for items that prefer to be sorted earlier. */
public static final double HIGH_PRIORITY = +100;
/** Default priority for items. */
public static final double NORMAL_PRIORITY = 0;
/** Priority for items that prefer to be sorted later. */
public static final double LOW_PRIORITY = -100;
/** Priority for items that strongly prefer to be sorted late. */
public static final double VERY_LOW_PRIORITY = -10000;
/** Priority for items that must be sorted last. */
public static final double LAST_PRIORITY = Double.NEGATIVE_INFINITY;
/**
* Compares two {@link Prioritized} objects.
*
* Note: this method provides a natural ordering that may be inconsistent with
* equals. That is, two unequal objects may often have the same priority, and
* thus return 0 when compared in this fashion. Hence, if this method is used
* as a basis for implementing {@link Comparable#compareTo} or
* {@link java.util.Comparator#compare}, that implementation may want to
* impose logic beyond that of this method, for breaking ties, if a total
* ordering consistent with equals is always required.
*
*
* @return -1 if {@code p1}'s priority is higher than {@code p2}'s, 1 if
* {@code p2}'s priority is higher than {@code p1}'s, or 0 if they
* have the same priority.
* @see org.scijava.util.ClassUtils#compare(Class, Class)
*/
public static int compare(final Prioritized p1, final Prioritized p2) {
final double priority1 =
p1 == null ? Double.NEGATIVE_INFINITY : p1.getPriority();
final double priority2 =
p2 == null ? Double.NEGATIVE_INFINITY : p2.getPriority();
if (priority1 == priority2) return 0;
// NB: We invert the ordering here, so that large values come first,
// rather than the typical natural ordering of smaller values first.
return priority1 > priority2 ? -1 : 1;
}
/**
* Injects the specified priority into the given object. Note that this is
* only possible if the given object implements the {@link Prioritized}
* interface.
*
* @param o The object to which the priority should be assigned.
* @return true If the priority was successfully injected.
*/
public static boolean inject(final Object o, final double priority) {
if (!(o instanceof Prioritized)) return false;
((Prioritized) o).setPriority(priority);
return true;
}
}