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Package: RankingHelper
RankingHelper
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| RankingHelper(Class, double) |
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| RankingHelper(Class, double, Double) |
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| createWarning(List, double) |
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| getHighestRankingElement(Collection, RankingHelper.RankTester) |
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| reportClashingPriorities(String) |
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Coverage
1: /*******************************************************************************
2: * Copyright (c) 2011-2018 EclipseSource Muenchen GmbH and others.
3: *
4: * All rights reserved. This program and the accompanying materials
5: * are made available under the terms of the Eclipse Public License 2.0
6: * which accompanies this distribution, and is available at
7: * https://www.eclipse.org/legal/epl-2.0/
8: *
9: * SPDX-License-Identifier: EPL-2.0
10: *
11: * Contributors:
12: * Mat Hansen - initial API and implementation
13: * Christian W. Damus - bug 533522
14: ******************************************************************************/
15: package org.eclipse.emfforms.common;
16:
17: import static java.lang.Double.doubleToLongBits;
18:
19: import java.text.MessageFormat;
20: import java.util.ArrayList;
21: import java.util.Collection;
22: import java.util.List;
23:
24: import org.eclipse.emfforms.spi.common.report.AbstractReport;
25: import org.eclipse.emfforms.spi.common.report.ReportService;
26: import org.osgi.framework.Bundle;
27: import org.osgi.framework.BundleContext;
28: import org.osgi.framework.FrameworkUtil;
29: import org.osgi.framework.ServiceReference;
30:
31: /**
32: * Ranking helper class to generically handle prioritization use cases.
33: * This class assumes that priorities are in ascending order (higher rank means higher priority).
34: *
35: * @author Mat Hansen <mhansen@eclipsesource.com>
36: * @since 1.14
37: *
38: * @param <T> the type for the rank comparison
39: */
40: public class RankingHelper<T> {
41:
42: /**
43: * Value used to initialize the rank comparison in case no initialRank value is passed.
44: */
45: public static final double DEFAULT_INITIAL_RANK = -1d;
46:
47: private final Class<?> elementClass;
48: private final double initialRank;
49: private final Double ignoreRankValue;
50:
51: /**
52: * Constructor which disables ignore rank feature.
53: *
54: * @param elementClass the class the prioritization is based on, required for logging purposes
55: * @param initialRank the initialization value for the rank comparison (see INITIAL_RANK)
56: */
57: public RankingHelper(Class<?> elementClass, double initialRank) {
58: this(elementClass, initialRank, null);
59: }
60:
61: /**
62: * The main constructor.
63: *
64: * @param elementClass the class the prioritization is based on, required for logging purposes
65: * @param initialRank the initialization value for the rank comparison (see INITIAL_RANK)
66: * @param ignoreRankValue a specific value which will result in the given element being omitted.
67: * Must be non-null otherwise this feature is not enabled.
68: */
69: public RankingHelper(Class<?> elementClass, double initialRank, Double ignoreRankValue) {
70: this.elementClass = elementClass;
71: this.initialRank = initialRank;
72: this.ignoreRankValue = ignoreRankValue;
73: }
74:
75: /**
76: * Helper callback interface for rank testing.
77: *
78: * @param <T> the type for the rank comparison.
79: * @see RankingHelper
80: */
81: public interface RankTester<T> {
82:
83: /**
84: * Callback method which should delegate to the actual ranking element.
85: *
86: * @param element the element to get the rank/priority for
87: * @return numeric priority value. Higher value means higher priority.
88: */
89: double getRank(T element);
90:
91: }
92:
93: /**
94: * Determine the highest ranking element by iterating over all elements and calling rankTester.getRank().
95: *
96: * @param elements the elements to consider
97: * @param rankTester the tester instance to fetch a rank/priority for a given element
98: * @return the highest ranking element found (may be null)
99: */
100: public T getHighestRankingElement(final Collection<T> elements,
101: final RankTester<T> rankTester) {
102:
103: final List<T> highestRankingElements = new ArrayList<T>();
104: double highestRank = initialRank;
105:
106:• for (final T element : elements) {
107:
108: final double rank = rankTester.getRank(element);
109:
110: // Don't use Double.equals(Double) because that requires creating a boxed Double
111: // every time (as seen in a profiler), and we do this operation a lot in large models
112:• if (ignoreRankValue != null && doubleToLongBits(ignoreRankValue.doubleValue()) == doubleToLongBits(rank)) {
113: continue;
114:• } else if (rank >= highestRank) {
115:• if (rank > highestRank) {
116: highestRank = rank;
117: highestRankingElements.clear();
118: }
119: highestRankingElements.add(element);
120: }
121:
122: }
123:
124:• if (highestRankingElements.size() > 1) {
125: reportClashingPriorities(createWarning(highestRankingElements, highestRank));
126: }
127:
128:• if (highestRankingElements.isEmpty()) {
129: return null;
130: }
131: return highestRankingElements.get(0);
132: }
133:
134: /**
135: * Create warning about clashing priorities.
136: *
137: * @param highestRankingElements list of clashing elements
138: * @param rank the rank of the elements
139: * @return the warning message
140: */
141: protected String createWarning(List<T> highestRankingElements, double rank) {
142: final String warning = "Priority clash while trying to find highest ranking instance of {1}.\n" + //$NON-NLS-1$
143: "Instance {2} clashes with {3}{4,choice, 0#|0< and {4,number,integer} more}, reporting rank {0,number}."; //$NON-NLS-1$
144:
145: final Object[] arguments = new Object[] {
146: rank,
147: elementClass,
148: highestRankingElements.get(0).getClass(),
149: highestRankingElements.get(1).getClass(),
150: highestRankingElements.size() - 2
151: };
152:
153: return MessageFormat.format(warning, arguments);
154: }
155:
156: /**
157: * Report clashing priorities using ReportService.
158: *
159: * @param warningMessage the warning message
160: */
161: protected void reportClashingPriorities(String warningMessage) {
162:
163: final Bundle bundle = FrameworkUtil.getBundle(getClass());
164:• if (bundle != null) {
165:
166: // we fetch the report service for every error individually
167: // because this shouldn't happen very often
168: final BundleContext bundleContext = bundle.getBundleContext();
169: final ServiceReference<ReportService> serviceReference = bundleContext
170: .getServiceReference(ReportService.class);
171: final ReportService reportService = bundleContext.getService(serviceReference);
172:
173: reportService
174: .report(new AbstractReport(warningMessage, 2));
175:
176: bundleContext.ungetService(serviceReference);
177:
178: } else {
179: // we still want to complain in case we have no OSGi context
180: System.err.println(warningMessage);
181: }
182:
183: }
184:
185: }