ProposalSorterHandle


1   /*******************************************************************************
2    * Copyright (c) 2005, 2006 IBM Corporation and others.
3    * All rights reserved. This program and the accompanying materials
4    * are made available under the terms of the Eclipse Public License v1.0
5    * which accompanies this distribution, and is available at
6    * http://www.eclipse.org/legal/epl-v10.html
7    *
8    * Contributors:
9    *     IBM Corporation - initial API and implementation
10   *******************************************************************************/
11  package org.eclipse.jdt.internal.ui.text.java;
12  
13  import java.util.Collections  ;
14  import java.util.List  ;
15  
16  import org.eclipse.core.runtime.Assert;
17  import org.eclipse.core.runtime.CoreException;
18  import org.eclipse.core.runtime.IConfigurationElement;
19  import org.eclipse.core.runtime.IStatus;
20  import org.eclipse.core.runtime.InvalidRegistryObjectException;
21  import org.eclipse.core.runtime.PerformanceStats;
22  import org.eclipse.core.runtime.Platform;
23  import org.eclipse.core.runtime.Status;
24  
25  
26  import org.eclipse.jdt.internal.corext.util.Messages;
27  
28  import org.eclipse.jdt.ui.text.java.AbstractProposalSorter;
29  import org.eclipse.jdt.ui.text.java.ContentAssistInvocationContext;
30  
31  import org.eclipse.jdt.internal.ui.JavaPlugin;
32  
33  import org.osgi.framework.Bundle;
34  
35  /**
36   * The description of an extension to the
37   * <code>org.eclipse.jdt.ui.javaCompletionProposalSorters</code> extension point. Instances are
38   * immutable.
39   * 
40   * @since 3.2
41   */
42  public final class ProposalSorterHandle {
43      /** The extension schema name of the id attribute. */
44      private static final String   ID= "id"; //$NON-NLS-1$
45      /** The extension schema name of the name attribute. */
46      private static final String   NAME= "name"; //$NON-NLS-1$
47      /** The extension schema name of the class attribute. */
48      private static final String   CLASS= "class"; //$NON-NLS-1$
49      /** The extension schema name of the activate attribute. */
50      private static final String   ACTIVATE= "activate"; //$NON-NLS-1$
51      /** The name of the performance event used to trace extensions. */
52      private static final String   PERFORMANCE_EVENT= JavaPlugin.getPluginId() + "/perf/content_assist_sorters/extensions"; //$NON-NLS-1$
53      /**
54       * If <code>true</code>, execution time of extensions is measured and extensions may be
55       * disabled if execution takes too long.
56       */
57      private static final boolean MEASURE_PERFORMANCE= PerformanceStats.isEnabled(PERFORMANCE_EVENT);
58      /** The one and only operation name. */
59      private static final String   SORT= "sort"; //$NON-NLS-1$
60  
61      /** The identifier of the extension. */
62      private final String   fId;
63      /** The name of the extension. */
64      private final String   fName;
65      /** The class name of the provided <code>AbstractProposalSorter</code>. */
66      private final String   fClass;
67      /** The activate attribute value. */
68      private final boolean fActivate;
69      /** The configuration element of this extension. */
70      private final IConfigurationElement fElement;
71      /** The computer, if instantiated, <code>null</code> otherwise. */
72      private AbstractProposalSorter fSorter;
73  
74      /**
75       * Creates a new descriptor.
76       * 
77       * @param element the configuration element to read
78       * @throws InvalidRegistryObjectException if the configuration element is not valid any longer
79       *         or does not contain mandatory attributes
80       */
81      ProposalSorterHandle(IConfigurationElement element) throws InvalidRegistryObjectException {
82          Assert.isLegal(element != null);
83          
84          fElement= element;
85          fId= element.getAttribute(ID);
86          checkNotNull(fId, ID);
87  
88          String   name= element.getAttribute(NAME);
89          if (name == null)
90              fName= fId;
91          else
92              fName= name;
93          
94          String   activateAttribute= element.getAttribute(ACTIVATE);
95          fActivate= Boolean.valueOf(activateAttribute).booleanValue();
96  
97          fClass= element.getAttribute(CLASS);
98          checkNotNull(fClass, CLASS);
99      }
100 
101     /**
102      * Checks an element that must be defined according to the extension
103      * point schema. Throws an
104      * <code>InvalidRegistryObjectException</code> if <code>obj</code>
105      * is <code>null</code>.
106      */
107     private void checkNotNull(Object   obj, String   attribute) throws InvalidRegistryObjectException {
108         if (obj == null) {
109             Object  [] args= { getId(), fElement.getContributor().getName(), attribute };
110             String   message= Messages.format(JavaTextMessages.CompletionProposalComputerDescriptor_illegal_attribute_message, args);
111             IStatus status= new Status(IStatus.WARNING, JavaPlugin.getPluginId(), IStatus.OK, message, null);
112             JavaPlugin.log(status);
113             throw new InvalidRegistryObjectException();
114         }
115     }
116 
117     /**
118      * Returns the identifier of the described extension.
119      *
120      * @return Returns the id
121      */
122     public String   getId() {
123         return fId;
124     }
125 
126     /**
127      * Returns the name of the described extension.
128      * 
129      * @return Returns the name
130      */
131     public String   getName() {
132         return fName;
133     }
134     
135     /**
136      * Returns a cached instance of the sorter as described in the extension's xml. The sorter is
137      * {@link #createSorter() created} the first time that this method is called and then cached.
138      * 
139      * @return a new instance of the proposal sorter as described by this descriptor
140      * @throws CoreException if the creation fails
141      * @throws InvalidRegistryObjectException if the extension is not valid any longer (e.g. due to
142      *         plug-in unloading)
143      */
144     private synchronized AbstractProposalSorter getSorter() throws CoreException, InvalidRegistryObjectException {
145         if (fSorter == null && (fActivate || isPluginLoaded()))
146             fSorter= createSorter();
147         return fSorter;
148     }
149 
150     private boolean isPluginLoaded() throws InvalidRegistryObjectException {
151         Bundle bundle= getBundle();
152         return bundle != null && bundle.getState() == Bundle.ACTIVE;
153     }
154 
155     private Bundle getBundle() throws InvalidRegistryObjectException {
156         String   symbolicName= fElement.getContributor().getName();
157         Bundle bundle= Platform.getBundle(symbolicName);
158         return bundle;
159     }
160 
161     /**
162      * Returns a new instance of the sorter as described in the
163      * extension's xml.
164      * 
165      * @return a new instance of the completion proposal computer as
166      *         described by this descriptor
167      * @throws CoreException if the creation fails
168      * @throws InvalidRegistryObjectException if the extension is not
169      *         valid any longer (e.g. due to plug-in unloading)
170      */
171     private AbstractProposalSorter createSorter() throws CoreException, InvalidRegistryObjectException {
172         return (AbstractProposalSorter) fElement.createExecutableExtension(CLASS);
173     }
174     
175     /**
176      * Safely computes completion proposals through the described extension. If the extension throws
177      * an exception or otherwise does not adhere to the contract described in
178      * {@link AbstractProposalSorter}, the list is returned as is.
179      * 
180      * @param context the invocation context passed on to the extension
181      * @param proposals the list of computed completion proposals to be sorted (element type:
182      *        {@link org.eclipse.jface.text.contentassist.ICompletionProposal}), must be writable
183      */
184     public void sortProposals(ContentAssistInvocationContext context, List   proposals) {
185         IStatus status;
186         try {
187             AbstractProposalSorter sorter= getSorter();
188             
189             PerformanceStats stats= startMeter(SORT, sorter);
190             
191             sorter.beginSorting(context);
192             Collections.sort(proposals, sorter);
193             sorter.endSorting();
194             
195             status= stopMeter(stats, SORT);
196             
197             // valid result
198             if (status == null)
199                 return;
200             
201             status= createAPIViolationStatus(SORT);
202             
203         } catch (InvalidRegistryObjectException x) {
204             status= createExceptionStatus(x);
205         } catch (CoreException x) {
206             status= createExceptionStatus(x);
207         } catch (RuntimeException   x) {
208             status= createExceptionStatus(x);
209         }
210 
211         JavaPlugin.log(status);
212         return;
213     }
214 
215     private IStatus stopMeter(final PerformanceStats stats, String   operation) {
216         if (MEASURE_PERFORMANCE) {
217             stats.endRun();
218             if (stats.isFailure())
219                 return createPerformanceStatus(operation);
220         }
221         return null;
222     }
223 
224     private PerformanceStats startMeter(String   context, AbstractProposalSorter sorter) {
225         final PerformanceStats stats;
226         if (MEASURE_PERFORMANCE) {
227             stats= PerformanceStats.getStats(PERFORMANCE_EVENT, sorter);
228             stats.startRun(context);
229         } else {
230             stats= null;
231         }
232         return stats;
233     }
234 
235     private Status createExceptionStatus(InvalidRegistryObjectException x) {
236         // extension has become invalid - log & disable
237         String   disable= createBlameMessage();
238         String   reason= JavaTextMessages.CompletionProposalComputerDescriptor_reason_invalid;
239         return new Status(IStatus.INFO, JavaPlugin.getPluginId(), IStatus.OK, disable + " " + reason, x); //$NON-NLS-1$
240     }
241 
242     private Status createExceptionStatus(CoreException x) {
243         // unable to instantiate the extension - log & disable
244         String   disable= createBlameMessage();
245         String   reason= JavaTextMessages.CompletionProposalComputerDescriptor_reason_instantiation;
246         return new Status(IStatus.ERROR, JavaPlugin.getPluginId(), IStatus.OK, disable + " " + reason, x); //$NON-NLS-1$
247     }
248     
249     private Status createExceptionStatus(RuntimeException   x) {
250         // misbehaving extension - log & disable
251         String   disable= createBlameMessage();
252         String   reason= JavaTextMessages.CompletionProposalComputerDescriptor_reason_runtime_ex;
253         return new Status(IStatus.WARNING, JavaPlugin.getPluginId(), IStatus.OK, disable + " " + reason, x); //$NON-NLS-1$
254     }
255 
256     private Status createAPIViolationStatus(String   operation) {
257         String   disable= createBlameMessage();
258         Object  [] args= {operation};
259         String   reason= Messages.format(JavaTextMessages.CompletionProposalComputerDescriptor_reason_API, args);
260         return new Status(IStatus.WARNING, JavaPlugin.getPluginId(), IStatus.OK, disable + " " + reason, null); //$NON-NLS-1$
261     }
262 
263     private Status createPerformanceStatus(String   operation) {
264         String   disable= createBlameMessage();
265         Object  [] args= {operation};
266         String   reason= Messages.format(JavaTextMessages.CompletionProposalComputerDescriptor_reason_performance, args);
267         return new Status(IStatus.WARNING, JavaPlugin.getPluginId(), IStatus.OK, disable + " " + reason, null); //$NON-NLS-1$
268     }
269 
270     private String   createBlameMessage() {
271         Object  [] args= { getName(), getId() };
272         String   disable= Messages.format(JavaTextMessages.ProposalSorterHandle_blame, args);
273         return disable;
274     }
275     
276     /**
277      * Returns the error message from the described extension, <code>null</code> for no error.
278      * 
279      * @return the error message from the described extension, <code>null</code> for no error
280      */
281     public String   getErrorMessage() {
282         return null;
283     }
284     
285 }
286
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