org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/text/java/CompletionProposalCategory.java - jdt/eclipse.jdt.ui - Git at Google

 /*******************************************************************************
  * Copyright (c) 2005, 2012 IBM Corporation and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
  * http://www.eclipse.org/legal/epl-v10.html
  *
  * Contributors:
  *     IBM Corporation - initial API and implementation
  *     Paul Fullbright <paul.fullbright@oracle.com> - content assist category enablement - http://bugs.eclipse.org/345213
  *******************************************************************************/
 package org.eclipse.jdt.internal.ui.text.java;

 import java.net.URL;
 import java.util.ArrayList;
 import java.util.Iterator;
 import java.util.List;

 import org.osgi.framework.Bundle;

 import org.eclipse.core.expressions.EvaluationContext;
 import org.eclipse.core.expressions.EvaluationResult;
 import org.eclipse.core.expressions.Expression;
 import org.eclipse.core.expressions.ExpressionConverter;
 import org.eclipse.core.expressions.ExpressionTagNames;

 import org.eclipse.core.runtime.CoreException;
 import org.eclipse.core.runtime.FileLocator;
 import org.eclipse.core.runtime.IConfigurationElement;
 import org.eclipse.core.runtime.IExtension;
 import org.eclipse.core.runtime.IStatus;
 import org.eclipse.core.runtime.Path;
 import org.eclipse.core.runtime.Platform;
 import org.eclipse.core.runtime.Status;
 import org.eclipse.core.runtime.SubProgressMonitor;

 import org.eclipse.jface.action.LegacyActionTools;
 import org.eclipse.jface.resource.ImageDescriptor;

 import org.eclipse.jface.text.contentassist.ICompletionProposal;
 import org.eclipse.jface.text.contentassist.IContextInformation;

 import org.eclipse.jdt.core.IJavaProject;

 import org.eclipse.jdt.internal.corext.util.Messages;

 import org.eclipse.jdt.ui.text.java.ContentAssistInvocationContext;
 import org.eclipse.jdt.ui.text.java.IJavaCompletionProposalComputer;

 import org.eclipse.jdt.internal.ui.JavaPlugin;


 /**
  * Describes a category extension to the "javaCompletionProposalComputer" extension point.
  *
  * @since 3.2
  */
 public final class CompletionProposalCategory {
 	/** The extension schema name of the icon attribute. */
 	private static final String ICON= "icon"; //$NON-NLS-1$

 	private final String fId;
 	private final String fName;
 	private final IConfigurationElement fElement;
 	/** The image descriptor for this category, or <code>null</code> if none specified. */
 	private final ImageDescriptor fImage;

 	/** The enablement expression for this category, or <code>null</code> if none specified. */
 	private final Expression fEnablementExpression;

 	private boolean fIsSeparateCommand= true;
 	private boolean fIsEnabled= true;
 	private boolean fIsIncluded= true;
 	private final CompletionProposalComputerRegistry fRegistry;

 	private int fSortOrder= 0xffff - 1;
 	private String fLastError= null;

 	CompletionProposalCategory(IConfigurationElement element, CompletionProposalComputerRegistry registry) throws CoreException {
 		fElement= element;
 		fRegistry= registry;
 		IExtension parent= (IExtension) element.getParent();
 		fId= parent.getUniqueIdentifier();
 		checkNotNull(fId, "id"); //$NON-NLS-1$
 		String name= parent.getLabel();
 		if (name == null)
 			fName= fId;
 		else
 			fName= name;

 		IConfigurationElement[] children= fElement.getChildren(ExpressionTagNames.ENABLEMENT);
 		if (children.length == 1) {
 			ExpressionConverter parser= ExpressionConverter.getDefault();
 			fEnablementExpression = parser.perform(children[0]);
 		}
 		else {
 			fEnablementExpression = null;
 		}

 		String icon= element.getAttribute(ICON);
 		ImageDescriptor img= null;
 		if (icon != null) {
 			Bundle bundle= getBundle();
 			if (bundle != null) {
 				Path path= new Path(icon);
 				URL url= FileLocator.find(bundle, path, null);
 				img= ImageDescriptor.createFromURL(url);
 			}
 		}
 		fImage= img;

 	}

 	CompletionProposalCategory(String id, String name, CompletionProposalComputerRegistry registry) {
 		fRegistry= registry;
 		fId= id;
 		fName= name;
 		fElement= null;
 		fEnablementExpression = null;
 		fImage= null;
 	}

 	private Bundle getBundle() {
 		String namespace= fElement.getDeclaringExtension().getContributor().getName();
 		Bundle bundle= Platform.getBundle(namespace);
 		return bundle;
 	}

 	/**
 	 * Checks that the given attribute value is not <code>null</code>.
 	 *
 	 * @param value the element to be checked
 	 * @param attribute the attribute
 	 * @throws CoreException if <code>value</code> is <code>null</code>
 	 */
 	private void checkNotNull(Object value, String attribute) throws CoreException {
 		if (value == null) {
 			Object[] args= { getId(), fElement.getContributor().getName(), attribute };
 			String message= Messages.format(JavaTextMessages.CompletionProposalComputerDescriptor_illegal_attribute_message, args);
 			IStatus status= new Status(IStatus.WARNING, JavaPlugin.getPluginId(), IStatus.OK, message, null);
 			throw new CoreException(status);
 		}
 	}

 	/**
 	 * Returns the identifier of the described extension.
 	 *
 	 * @return Returns the id
 	 */
 	public String getId() {
 		return fId;
 	}

 	/**
 	 * Returns the name of the described extension.
 	 *
 	 * @return Returns the name
 	 */
 	public String getName() {
 		return fName;
 	}

 	/**
 	 * Returns the name of the described extension
 	 * without mnemonic hint in order to be displayed
 	 * in a message.
 	 *
 	 * @return Returns the name
 	 */
 	public String getDisplayName() {
 		return LegacyActionTools.removeMnemonics(fName);
 	}

 	/**
 	 * Returns the image descriptor of the described category.
 	 *
 	 * @return the image descriptor of the described category
 	 */
 	public ImageDescriptor getImageDescriptor() {
 		return fImage;
 	}

 	/**
 	 * Sets the separate command state of the category.
 	 *
 	 * @param enabled the new enabled state.
 	 */
 	public void setSeparateCommand(boolean enabled) {
 		fIsSeparateCommand= enabled;
 	}

 	/**
 	 * Returns the enablement state of the category.
 	 *
 	 * @return the enablement state of the category
 	 */
 	public boolean isSeparateCommand() {
 		return fIsSeparateCommand;
 	}

 	/**
 	 * @param included the included
 	 */
 	public void setIncluded(boolean included) {
 		fIsIncluded= included;
 	}

 	/**
 	 * @return included
 	 */
 	public boolean isIncluded() {
 		return fIsIncluded;
 	}

 	public boolean isEnabled() {
 		return fIsEnabled;
 	}

 	public void setEnabled(boolean isEnabled) {
 		fIsEnabled= isEnabled;
 	}

 	/**
 	 * Returns <code>true</code> if the category contains any computers, <code>false</code>
 	 * otherwise.
 	 *
 	 * @return <code>true</code> if the category contains any computers, <code>false</code>
 	 *         otherwise
 	 */
 	public boolean hasComputers() {
 		List<CompletionProposalComputerDescriptor> descriptors= fRegistry.getProposalComputerDescriptors();
 		for (Iterator<CompletionProposalComputerDescriptor> it= descriptors.iterator(); it.hasNext();) {
 			CompletionProposalComputerDescriptor desc= it.next();
 			if (desc.getCategory() == this)
 				return true;
 		}
 		return false;
 	}

 	/**
 	 * Returns <code>true</code> if the category contains any computers in the given partition, <code>false</code>
 	 * otherwise.
 	 *
 	 * @param partition the partition
 	 * @return <code>true</code> if the category contains any computers, <code>false</code>
 	 *         otherwise
 	 */
 	public boolean hasComputers(String partition) {
 		List<CompletionProposalComputerDescriptor> descriptors= fRegistry.getProposalComputerDescriptors(partition);
 		for (Iterator<CompletionProposalComputerDescriptor> it= descriptors.iterator(); it.hasNext();) {
 			CompletionProposalComputerDescriptor desc= it.next();
 			if (desc.getCategory() == this)
 				return true;
 		}
 		return false;
 	}

 	/**
 	 * @return sortOrder
 	 */
 	public int getSortOrder() {
 		return fSortOrder;
 	}

 	/**
 	 * @param sortOrder the sortOrder
 	 */
 	public void setSortOrder(int sortOrder) {
 		fSortOrder= sortOrder;
 	}

 	/**
 	 * Determines if the project matches any enablement expression defined on the extension.
 	 *
 	 * @param javaProject the Java project against which to test the enablement expression, can be
 	 *            <code>null</code>
 	 * @return <code>true</code> if any enablement expression matches the given project or if the
 	 *         project is <code>null</code> or no enablement expression is specified,
 	 *         <code>false</code> otherwise
 	 * @since 3.8
 	 */
 	public boolean matches(IJavaProject javaProject) {
 		if (fEnablementExpression == null) {
 			return true;
 		}

 		if (javaProject == null) {
 			return false;
 		}

 		try {
 			EvaluationContext evalContext= new EvaluationContext(null, javaProject);
 			evalContext.addVariable("project", javaProject); //$NON-NLS-1$
 			return fEnablementExpression.evaluate(evalContext) == EvaluationResult.TRUE;
 		} catch (CoreException e) {
 			JavaPlugin.log(e);
 		}

 		return false;
 	}

 	/**
 	 * Safely computes completion proposals of all computers of this category through their
 	 * extension. If an extension is disabled, throws an exception or otherwise does not adhere to
 	 * the contract described in {@link IJavaCompletionProposalComputer}, it is disabled.
 	 *
 	 * @param context the invocation context passed on to the extension
 	 * @param partition the partition type where to invocation occurred
 	 * @param monitor the progress monitor passed on to the extension
 	 * @return the list of computed completion proposals (element type:
 	 *         {@link org.eclipse.jface.text.contentassist.ICompletionProposal})
 	 */
 	public List<ICompletionProposal> computeCompletionProposals(ContentAssistInvocationContext context, String partition, SubProgressMonitor monitor) {
 		fLastError= null;
 		List<ICompletionProposal> result= new ArrayList<ICompletionProposal>();
 		List<CompletionProposalComputerDescriptor> descriptors= new ArrayList<CompletionProposalComputerDescriptor>(fRegistry.getProposalComputerDescriptors(partition));
 		for (Iterator<CompletionProposalComputerDescriptor> it= descriptors.iterator(); it.hasNext();) {
 			CompletionProposalComputerDescriptor desc= it.next();
 			if (desc.getCategory() == this)
 				result.addAll(desc.computeCompletionProposals(context, monitor));
 			if (fLastError == null && desc.getErrorMessage() != null)
 				fLastError= desc.getErrorMessage();
 		}
 		return result;
 	}

 	/**
 	 * Safely computes context information objects of all computers of this category through their
 	 * extension. If an extension is disabled, throws an exception or otherwise does not adhere to
 	 * the contract described in {@link IJavaCompletionProposalComputer}, it is disabled.
 	 *
 	 * @param context the invocation context passed on to the extension
 	 * @param partition the partition type where to invocation occurred
 	 * @param monitor the progress monitor passed on to the extension
 	 * @return the list of computed context information objects (element type:
 	 *         {@link org.eclipse.jface.text.contentassist.IContextInformation})
 	 */
 	public List<IContextInformation> computeContextInformation(ContentAssistInvocationContext context, String partition, SubProgressMonitor monitor) {
 		fLastError= null;
 		List<IContextInformation> result= new ArrayList<IContextInformation>();
 		List<CompletionProposalComputerDescriptor> descriptors= new ArrayList<CompletionProposalComputerDescriptor>(fRegistry.getProposalComputerDescriptors(partition));
 		for (Iterator<CompletionProposalComputerDescriptor> it= descriptors.iterator(); it.hasNext();) {
 			CompletionProposalComputerDescriptor desc= it.next();
 			if (desc.getCategory() == this && (isIncluded() || isSeparateCommand()))
 				result.addAll(desc.computeContextInformation(context, monitor));
 			if (fLastError == null)
 				fLastError= desc.getErrorMessage();
 		}
 		return result;
 	}

 	/**
 	 * Returns the error message from the computers in this category.
 	 *
 	 * @return the error message from the computers in this category
 	 */
 	public String getErrorMessage() {
 		return fLastError;
 	}

 	/**
 	 * Notifies the computers in this category of a proposal computation session start.
 	 */
 	public void sessionStarted() {
 		List<CompletionProposalComputerDescriptor> descriptors= new ArrayList<CompletionProposalComputerDescriptor>(fRegistry.getProposalComputerDescriptors());
 		for (Iterator<CompletionProposalComputerDescriptor> it= descriptors.iterator(); it.hasNext();) {
 			CompletionProposalComputerDescriptor desc= it.next();
 			if (desc.getCategory() == this)
 				desc.sessionStarted();
 			if (fLastError == null)
 				fLastError= desc.getErrorMessage();
 		}
 	}

 	/**
 	 * Notifies the computers in this category of a proposal computation session end.
 	 */
 	public void sessionEnded() {
 		List<CompletionProposalComputerDescriptor> descriptors= new ArrayList<CompletionProposalComputerDescriptor>(fRegistry.getProposalComputerDescriptors());
 		for (Iterator<CompletionProposalComputerDescriptor> it= descriptors.iterator(); it.hasNext();) {
 			CompletionProposalComputerDescriptor desc= it.next();
 			if (desc.getCategory() == this)
 				desc.sessionEnded();
 			if (fLastError == null)
 				fLastError= desc.getErrorMessage();
 		}
 	}

 }
	/*******************************************************************************
	* Copyright (c) 2005, 2012 IBM Corporation and others.
	* All rights reserved. This program and the accompanying materials
	* are made available under the terms of the Eclipse Public License v1.0
	* which accompanies this distribution, and is available at
	* http://www.eclipse.org/legal/epl-v10.html
	*
	* Contributors:
	* IBM Corporation - initial API and implementation
	* Paul Fullbright <paul.fullbright@oracle.com> - content assist category enablement - http://bugs.eclipse.org/345213
	*******************************************************************************/
	package org.eclipse.jdt.internal.ui.text.java;

	import java.net.URL;
	import java.util.ArrayList;
	import java.util.Iterator;
	import java.util.List;

	import org.osgi.framework.Bundle;

	import org.eclipse.core.expressions.EvaluationContext;
	import org.eclipse.core.expressions.EvaluationResult;
	import org.eclipse.core.expressions.Expression;
	import org.eclipse.core.expressions.ExpressionConverter;
	import org.eclipse.core.expressions.ExpressionTagNames;

	import org.eclipse.core.runtime.CoreException;
	import org.eclipse.core.runtime.FileLocator;
	import org.eclipse.core.runtime.IConfigurationElement;
	import org.eclipse.core.runtime.IExtension;
	import org.eclipse.core.runtime.IStatus;
	import org.eclipse.core.runtime.Path;
	import org.eclipse.core.runtime.Platform;
	import org.eclipse.core.runtime.Status;
	import org.eclipse.core.runtime.SubProgressMonitor;

	import org.eclipse.jface.action.LegacyActionTools;
	import org.eclipse.jface.resource.ImageDescriptor;

	import org.eclipse.jface.text.contentassist.ICompletionProposal;
	import org.eclipse.jface.text.contentassist.IContextInformation;

	import org.eclipse.jdt.core.IJavaProject;

	import org.eclipse.jdt.internal.corext.util.Messages;

	import org.eclipse.jdt.ui.text.java.ContentAssistInvocationContext;
	import org.eclipse.jdt.ui.text.java.IJavaCompletionProposalComputer;

	import org.eclipse.jdt.internal.ui.JavaPlugin;


	/**
	* Describes a category extension to the "javaCompletionProposalComputer" extension point.
	*
	* @since 3.2
	*/
	public final class CompletionProposalCategory {
	/** The extension schema name of the icon attribute. */
	private static final String ICON= "icon"; //$NON-NLS-1$

	private final String fId;
	private final String fName;
	private final IConfigurationElement fElement;
	/** The image descriptor for this category, or <code>null</code> if none specified. */
	private final ImageDescriptor fImage;

	/** The enablement expression for this category, or <code>null</code> if none specified. */
	private final Expression fEnablementExpression;

	private boolean fIsSeparateCommand= true;
	private boolean fIsEnabled= true;
	private boolean fIsIncluded= true;
	private final CompletionProposalComputerRegistry fRegistry;

	private int fSortOrder= 0xffff - 1;
	private String fLastError= null;

	CompletionProposalCategory(IConfigurationElement element, CompletionProposalComputerRegistry registry) throws CoreException {
	fElement= element;
	fRegistry= registry;
	IExtension parent= (IExtension) element.getParent();
	fId= parent.getUniqueIdentifier();
	checkNotNull(fId, "id"); //$NON-NLS-1$
	String name= parent.getLabel();
	if (name == null)
	fName= fId;
	else
	fName= name;

	IConfigurationElement[] children= fElement.getChildren(ExpressionTagNames.ENABLEMENT);
	if (children.length == 1) {
	ExpressionConverter parser= ExpressionConverter.getDefault();
	fEnablementExpression = parser.perform(children[0]);
	}
	else {
	fEnablementExpression = null;
	}

	String icon= element.getAttribute(ICON);
	ImageDescriptor img= null;
	if (icon != null) {
	Bundle bundle= getBundle();
	if (bundle != null) {
	Path path= new Path(icon);
	URL url= FileLocator.find(bundle, path, null);
	img= ImageDescriptor.createFromURL(url);
	}
	}
	fImage= img;

	}

	CompletionProposalCategory(String id, String name, CompletionProposalComputerRegistry registry) {
	fRegistry= registry;
	fId= id;
	fName= name;
	fElement= null;
	fEnablementExpression = null;
	fImage= null;
	}

	private Bundle getBundle() {
	String namespace= fElement.getDeclaringExtension().getContributor().getName();
	Bundle bundle= Platform.getBundle(namespace);
	return bundle;
	}

	/**
	* Checks that the given attribute value is not <code>null</code>.
	*
	* @param value the element to be checked
	* @param attribute the attribute
	* @throws CoreException if <code>value</code> is <code>null</code>
	*/
	private void checkNotNull(Object value, String attribute) throws CoreException {
	if (value == null) {
	Object[] args= { getId(), fElement.getContributor().getName(), attribute };
	String message= Messages.format(JavaTextMessages.CompletionProposalComputerDescriptor_illegal_attribute_message, args);
	IStatus status= new Status(IStatus.WARNING, JavaPlugin.getPluginId(), IStatus.OK, message, null);
	throw new CoreException(status);
	}
	}

	/**
	* Returns the identifier of the described extension.
	*
	* @return Returns the id
	*/
	public String getId() {
	return fId;
	}

	/**
	* Returns the name of the described extension.
	*
	* @return Returns the name
	*/
	public String getName() {
	return fName;
	}

	/**
	* Returns the name of the described extension
	* without mnemonic hint in order to be displayed
	* in a message.
	*
	* @return Returns the name
	*/
	public String getDisplayName() {
	return LegacyActionTools.removeMnemonics(fName);
	}

	/**
	* Returns the image descriptor of the described category.
	*
	* @return the image descriptor of the described category
	*/
	public ImageDescriptor getImageDescriptor() {
	return fImage;
	}

	/**
	* Sets the separate command state of the category.
	*
	* @param enabled the new enabled state.
	*/
	public void setSeparateCommand(boolean enabled) {
	fIsSeparateCommand= enabled;
	}

	/**
	* Returns the enablement state of the category.
	*
	* @return the enablement state of the category
	*/
	public boolean isSeparateCommand() {
	return fIsSeparateCommand;
	}

	/**
	* @param included the included
	*/
	public void setIncluded(boolean included) {
	fIsIncluded= included;
	}

	/**
	* @return included
	*/
	public boolean isIncluded() {
	return fIsIncluded;
	}

	public boolean isEnabled() {
	return fIsEnabled;
	}

	public void setEnabled(boolean isEnabled) {
	fIsEnabled= isEnabled;
	}

	/**
	* Returns <code>true</code> if the category contains any computers, <code>false</code>
	* otherwise.
	*
	* @return <code>true</code> if the category contains any computers, <code>false</code>
	* otherwise
	*/
	public boolean hasComputers() {
	List<CompletionProposalComputerDescriptor> descriptors= fRegistry.getProposalComputerDescriptors();
	for (Iterator<CompletionProposalComputerDescriptor> it= descriptors.iterator(); it.hasNext();) {
	CompletionProposalComputerDescriptor desc= it.next();
	if (desc.getCategory() == this)
	return true;
	}
	return false;
	}

	/**
	* Returns <code>true</code> if the category contains any computers in the given partition, <code>false</code>
	* otherwise.
	*
	* @param partition the partition
	* @return <code>true</code> if the category contains any computers, <code>false</code>
	* otherwise
	*/
	public boolean hasComputers(String partition) {
	List<CompletionProposalComputerDescriptor> descriptors= fRegistry.getProposalComputerDescriptors(partition);
	for (Iterator<CompletionProposalComputerDescriptor> it= descriptors.iterator(); it.hasNext();) {
	CompletionProposalComputerDescriptor desc= it.next();
	if (desc.getCategory() == this)
	return true;
	}
	return false;
	}

	/**
	* @return sortOrder
	*/
	public int getSortOrder() {
	return fSortOrder;
	}

	/**
	* @param sortOrder the sortOrder
	*/
	public void setSortOrder(int sortOrder) {
	fSortOrder= sortOrder;
	}

	/**
	* Determines if the project matches any enablement expression defined on the extension.
	*
	* @param javaProject the Java project against which to test the enablement expression, can be
	* <code>null</code>
	* @return <code>true</code> if any enablement expression matches the given project or if the
	* project is <code>null</code> or no enablement expression is specified,
	* <code>false</code> otherwise
	* @since 3.8
	*/
	public boolean matches(IJavaProject javaProject) {
	if (fEnablementExpression == null) {
	return true;
	}

	if (javaProject == null) {
	return false;
	}

	try {
	EvaluationContext evalContext= new EvaluationContext(null, javaProject);
	evalContext.addVariable("project", javaProject); //$NON-NLS-1$
	return fEnablementExpression.evaluate(evalContext) == EvaluationResult.TRUE;
	} catch (CoreException e) {
	JavaPlugin.log(e);
	}

	return false;
	}

	/**
	* Safely computes completion proposals of all computers of this category through their
	* extension. If an extension is disabled, throws an exception or otherwise does not adhere to
	* the contract described in {@link IJavaCompletionProposalComputer}, it is disabled.
	*
	* @param context the invocation context passed on to the extension
	* @param partition the partition type where to invocation occurred
	* @param monitor the progress monitor passed on to the extension
	* @return the list of computed completion proposals (element type:
	* {@link org.eclipse.jface.text.contentassist.ICompletionProposal})
	*/
	public List<ICompletionProposal> computeCompletionProposals(ContentAssistInvocationContext context, String partition, SubProgressMonitor monitor) {
	fLastError= null;
	List<ICompletionProposal> result= new ArrayList<ICompletionProposal>();
	List<CompletionProposalComputerDescriptor> descriptors= new ArrayList<CompletionProposalComputerDescriptor>(fRegistry.getProposalComputerDescriptors(partition));
	for (Iterator<CompletionProposalComputerDescriptor> it= descriptors.iterator(); it.hasNext();) {
	CompletionProposalComputerDescriptor desc= it.next();
	if (desc.getCategory() == this)
	result.addAll(desc.computeCompletionProposals(context, monitor));
	if (fLastError == null && desc.getErrorMessage() != null)
	fLastError= desc.getErrorMessage();
	}
	return result;
	}

	/**
	* Safely computes context information objects of all computers of this category through their
	* extension. If an extension is disabled, throws an exception or otherwise does not adhere to
	* the contract described in {@link IJavaCompletionProposalComputer}, it is disabled.
	*
	* @param context the invocation context passed on to the extension
	* @param partition the partition type where to invocation occurred
	* @param monitor the progress monitor passed on to the extension
	* @return the list of computed context information objects (element type:
	* {@link org.eclipse.jface.text.contentassist.IContextInformation})
	*/
	public List<IContextInformation> computeContextInformation(ContentAssistInvocationContext context, String partition, SubProgressMonitor monitor) {
	fLastError= null;
	List<IContextInformation> result= new ArrayList<IContextInformation>();
	List<CompletionProposalComputerDescriptor> descriptors= new ArrayList<CompletionProposalComputerDescriptor>(fRegistry.getProposalComputerDescriptors(partition));
	for (Iterator<CompletionProposalComputerDescriptor> it= descriptors.iterator(); it.hasNext();) {
	CompletionProposalComputerDescriptor desc= it.next();
	if (desc.getCategory() == this && (isIncluded() \|\| isSeparateCommand()))
	result.addAll(desc.computeContextInformation(context, monitor));
	if (fLastError == null)
	fLastError= desc.getErrorMessage();
	}
	return result;
	}

	/**
	* Returns the error message from the computers in this category.
	*
	* @return the error message from the computers in this category
	*/
	public String getErrorMessage() {
	return fLastError;
	}

	/**
	* Notifies the computers in this category of a proposal computation session start.
	*/
	public void sessionStarted() {
	List<CompletionProposalComputerDescriptor> descriptors= new ArrayList<CompletionProposalComputerDescriptor>(fRegistry.getProposalComputerDescriptors());
	for (Iterator<CompletionProposalComputerDescriptor> it= descriptors.iterator(); it.hasNext();) {
	CompletionProposalComputerDescriptor desc= it.next();
	if (desc.getCategory() == this)
	desc.sessionStarted();
	if (fLastError == null)
	fLastError= desc.getErrorMessage();
	}
	}

	/**
	* Notifies the computers in this category of a proposal computation session end.
	*/
	public void sessionEnded() {
	List<CompletionProposalComputerDescriptor> descriptors= new ArrayList<CompletionProposalComputerDescriptor>(fRegistry.getProposalComputerDescriptors());
	for (Iterator<CompletionProposalComputerDescriptor> it= descriptors.iterator(); it.hasNext();) {
	CompletionProposalComputerDescriptor desc= it.next();
	if (desc.getCategory() == this)
	desc.sessionEnded();
	if (fLastError == null)
	fLastError= desc.getErrorMessage();
	}
	}

	}