r/org.eclipse.statet.r.ui/src/org/eclipse/statet/internal/r/ui/editors/RElementCompletionProposal.java - statet/org.eclipse.statet-r - Git at Google

 /*=============================================================================#
  # Copyright (c) 2008, 2020 Stephan Wahlbrink and others.
  #
  # This program and the accompanying materials are made available under the
  # terms of the Eclipse Public License 2.0 which is available at
  # https://www.eclipse.org/legal/epl-2.0, or the Apache License, Version 2.0
  # which is available at https://www.apache.org/licenses/LICENSE-2.0.
  #
  # SPDX-License-Identifier: EPL-2.0 OR Apache-2.0
  #
  # Contributors:
  #     Stephan Wahlbrink <sw@wahlbrink.eu> - initial API and implementation
  #=============================================================================*/

 package org.eclipse.statet.internal.r.ui.editors;

 import java.net.URI;

 import org.eclipse.core.runtime.IProgressMonitor;
 import org.eclipse.jface.text.BadLocationException;
 import org.eclipse.jface.text.IDocument;
 import org.eclipse.jface.text.IInformationControlCreator;
 import org.eclipse.jface.text.IRegion;
 import org.eclipse.jface.text.contentassist.ICompletionProposalExtension5;
 import org.eclipse.jface.text.link.LinkedModeModel;
 import org.eclipse.jface.text.link.LinkedModeUI;
 import org.eclipse.jface.text.link.LinkedPositionGroup;
 import org.eclipse.jface.viewers.StyledString;
 import org.eclipse.swt.graphics.Image;
 import org.eclipse.swt.graphics.Point;
 import org.eclipse.swt.widgets.Shell;

 import org.eclipse.statet.jcommons.lang.NonNullByDefault;
 import org.eclipse.statet.jcommons.lang.Nullable;
 import org.eclipse.statet.jcommons.text.core.SearchPattern;

 import org.eclipse.statet.ecommons.text.ui.BracketLevel.InBracketPosition;

 import org.eclipse.statet.internal.r.ui.rhelp.RHelpInfoHoverCreator;
 import org.eclipse.statet.internal.r.ui.rhelp.RHelpLtkUI;
 import org.eclipse.statet.ltk.core.ElementName;
 import org.eclipse.statet.ltk.ui.ElementLabelProvider;
 import org.eclipse.statet.ltk.ui.sourceediting.assist.AssistInvocationContext;
 import org.eclipse.statet.ltk.ui.sourceediting.assist.ElementNameCompletionProposal;
 import org.eclipse.statet.ltk.ui.sourceediting.assist.InfoHover;
 import org.eclipse.statet.nico.ui.console.InputSourceViewer;
 import org.eclipse.statet.r.core.IRCoreAccess;
 import org.eclipse.statet.r.core.RCodeStyleSettings;
 import org.eclipse.statet.r.core.RCore;
 import org.eclipse.statet.r.core.model.ArgsDefinition;
 import org.eclipse.statet.r.core.model.IRElement;
 import org.eclipse.statet.r.core.model.IRMethod;
 import org.eclipse.statet.r.core.model.RElementName;
 import org.eclipse.statet.r.core.source.RHeuristicTokenScanner;
 import org.eclipse.statet.r.ui.RUI;
 import org.eclipse.statet.r.ui.sourceediting.RAssistInvocationContext;
 import org.eclipse.statet.r.ui.sourceediting.RBracketLevel;
 import org.eclipse.statet.rhelp.core.REnvHelp;
 import org.eclipse.statet.rhelp.core.RHelpManager;
 import org.eclipse.statet.rhelp.core.RPkgHelp;


 @NonNullByDefault
 public class RElementCompletionProposal
 		extends ElementNameCompletionProposal<RAssistInvocationContext, IRElement>
 		implements ICompletionProposalExtension5 {


 	public static class RElementProposalParameters extends ProposalParameters<RAssistInvocationContext> {


 		public final ElementLabelProvider labelProvider;


 		public ElementName replacementName;

 		public IRElement element;


 		public RElementProposalParameters(final RAssistInvocationContext context, final int replacementOffset,
 				final SearchPattern namePattern, final int baseRelevance,
 				final ElementLabelProvider labelProvider) {
 			super(context, replacementOffset, namePattern, baseRelevance);

 			this.labelProvider= labelProvider;
 		}

 		public RElementProposalParameters(final RAssistInvocationContext context, final int replacementOffset,
 				final SearchPattern namePattern,
 				final ElementLabelProvider labelProvider) {
 			super(context, replacementOffset, namePattern);

 			this.labelProvider= labelProvider;
 		}

 		/** Only for context information */
 		public RElementProposalParameters(final RAssistInvocationContext context, final int replacementOffset,
 				final ElementLabelProvider labelProvider) {
 			super(context, replacementOffset, 0);

 			this.labelProvider= labelProvider;
 		}

 	}


 	protected static final int PACKAGE_NAME= 1;
 	protected static final int ARGUMENT_NAME= 2;
 	protected static final int FUNCTION= 3;


 	private static boolean rHelpInfoHoverInitialized;
 	private static @Nullable IInformationControlCreator rHelpInfoHoverCreator;

 	private static @Nullable IInformationControlCreator getRHelpInfoHoverCreator(final AssistInvocationContext context) {
 		if (!rHelpInfoHoverInitialized) {
 			final Shell shell= context.getSourceViewer().getTextWidget().getShell();
 			if (shell != null) {
 				if (RHelpInfoHoverCreator.isAvailable(shell)) {
 					rHelpInfoHoverCreator= new RHelpInfoHoverCreator(InfoHover.MODE_PROPOSAL_INFO);
 				}
 				rHelpInfoHoverInitialized= true;
 			}
 		}
 		return rHelpInfoHoverCreator;
 	}


 	public static class ArgumentProposal extends RElementCompletionProposal {


 		public ArgumentProposal(final RElementProposalParameters parameters) {
 			super(parameters);
 		}


 		@Override
 		protected int getMode() {
 			return ARGUMENT_NAME;
 		}


 		@Override
 		public String getDisplayString() {
 			return getReplacementName().getDisplayName();
 		}

 		@Override
 		public StyledString computeStyledText() {
 			return new StyledString(getReplacementName().getDisplayName());
 		}

 		@Override
 		public Image getImage() {
 			return RUI.getImage(RUI.IMG_OBJ_ARGUMENT_ASSIGN);
 		}

 	}

 	public static class ContextInformationProposal extends RElementCompletionProposal {


 		public ContextInformationProposal(final RElementProposalParameters parameters) {
 			super(parameters);
 		}


 		@Override
 		public boolean isAutoInsertable() {
 			return true;
 		}

 		@Override
 		protected void doApply(final char trigger, final int stateMask,
 				final int caretOffset, final int replacementOffset, final int replacementLength)
 				throws BadLocationException {
 			final ApplyData applyData= getApplyData();

 			applyData.clearSelection();
 			applyData.setContextInformation(new RArgumentListContextInformation(
 					getReplacementOffset(), // allow negative offsets
 					(IRMethod) getElement() ));
 		}

 	}


 	private static final boolean isFollowedByOpeningBracket(final int forwardOffset,
 			final RAssistInvocationContext context) {
 		final RHeuristicTokenScanner scanner= context.getRHeuristicTokenScanner();
 		scanner.configure(context.getDocument());
 		final int idx= scanner.findAnyNonBlankForward(forwardOffset, RHeuristicTokenScanner.UNBOUND, false);
 		return (idx >= 0
 				&& scanner.getChar() == '(' );
 	}

 	private static final boolean isClosedBracket(final int backwardOffset, final int forwardOffset,
 			final RAssistInvocationContext context) {
 		final int searchType= RHeuristicTokenScanner.ROUND_BRACKET_TYPE;
 		int[] balance= new int[3];
 		balance[searchType]++;
 		final RHeuristicTokenScanner scanner= context.getRHeuristicTokenScanner();
 		scanner.configureDefaultPartitions(context.getDocument());
 		balance= scanner.computeBracketBalance(backwardOffset, forwardOffset, balance, searchType);
 		return (balance[searchType] <= 0);
 	}

 	private static final boolean isFollowedByEqualAssign(final int forwardOffset,
 			final RAssistInvocationContext context) {
 		final RHeuristicTokenScanner scanner= context.getRHeuristicTokenScanner();
 		scanner.configure(context.getDocument());
 		final int idx= scanner.findAnyNonBlankForward(forwardOffset, RHeuristicTokenScanner.UNBOUND, false);
 		return (idx >= 0
 				&& scanner.getChar() == '=' );
 	}

 	private static final boolean isFollowedByAssign(final int forwardOffset,
 			final RAssistInvocationContext data) {
 		final RHeuristicTokenScanner scanner= data.getRHeuristicTokenScanner();
 		scanner.configure(data.getDocument());
 		final int idx= scanner.findAnyNonBlankForward(forwardOffset, RHeuristicTokenScanner.UNBOUND, false);
 		return (idx >= 0
 				&& (scanner.getChar() == '=' || scanner.getChar() == '<') );
 	}


 	public RElementCompletionProposal(final RElementProposalParameters parameters) {
 		super(parameters, parameters.replacementName, parameters.element, parameters.labelProvider);
 	}


 	protected IRCoreAccess getRCoreAccess() {
 		return getInvocationContext().getEditor().getRCoreAccess();
 	}

 	protected int getMode() {
 		return (getElement() != null
 						&& (getElement().getElementType() & IRElement.MASK_C1) == IRElement.C1_METHOD) ?
 				FUNCTION : 0;
 	}


 	@Override
 	protected int computeReplacementLength(final int replacementOffset, final Point selection, final int caretOffset, final boolean overwrite) {
 		// keep in synch with RSimpleCompletionProposal
 		final int end= Math.max(caretOffset, selection.x + selection.y);
 		if (overwrite) {
 			final RAssistInvocationContext context= getInvocationContext();
 			final RHeuristicTokenScanner scanner= context.getRHeuristicTokenScanner();
 			scanner.configure(context.getDocument());
 			final IRegion word= scanner.findRWord(end, false, true);
 			if (word != null) {
 				return (word.getOffset() + word.getLength() - replacementOffset);
 			}
 		}
 		return (end - replacementOffset);
 	}


 	@Override
 	protected @Nullable String getValidationPrefix(final int offset) throws BadLocationException {
 		// keep in synch with RSimpleCompletionProposal
 		final int startOffset= Math.max(getReplacementOffset(), 0);
 		if (offset >= startOffset) {
 			final RAssistInvocationContext context= getInvocationContext();
 			final IDocument document= context.getDocument();
 			int nameStartOffset= startOffset;
 			int nameEndOffset= offset;
 			if (nameEndOffset > nameStartOffset && document.getChar(nameStartOffset) == '`') {
 				nameStartOffset++;
 			}
 			if (nameEndOffset > nameStartOffset && document.getChar(nameEndOffset - 1) == '`') {
 				nameEndOffset--;
 			}
 			if (nameEndOffset >= nameStartOffset) {
 				return context.getIdentifierSegmentName(
 						document.get(startOffset, offset - startOffset) );
 			}
 		}
 		return null;
 	}


 	@Override
 	protected void doApply(final char trigger, final int stateMask, final int caretOffset,
 			final int replacementOffset, int replacementLength)
 			throws BadLocationException {
 		final RAssistInvocationContext context= getInvocationContext();
 		final IDocument document= context.getDocument();
 		final ApplyData applyData= getApplyData();

 		final ElementName replacementName= getReplacementName();
 		final int mode= getMode();
 		final boolean assignmentFunction= (mode == FUNCTION)
 				&& replacementName.getNextSegment() == null
 				&& replacementName.getSegmentName().endsWith("<-"); //$NON-NLS-1$
 		final ElementName elementName;
 		if (assignmentFunction) {
 			elementName= RElementName.create(RElementName.MAIN_DEFAULT,
 					replacementName.getSegmentName().substring(0, replacementName.getSegmentName().length() - 2) );
 		}
 		else {
 			elementName= replacementName;
 		}
 		final StringBuilder replacement= new StringBuilder((mode == PACKAGE_NAME) ?
 				elementName.getSegmentName() :
 				elementName.getDisplayName() );
 		int cursor= replacement.length();
 		if (replacementLength > 0 && document.getChar(replacementOffset) == '`' && replacement.charAt(0) != '`') {
 			if (replacement.length() == elementName.getSegmentName().length()
 					&& replacementOffset+replacementLength < document.getLength()
 					&& document.getChar(replacementOffset+replacementLength) == '`') {
 				replacementLength++;
 			}
 			replacement.insert(elementName.getSegmentName().length(), '`');
 			replacement.insert(0, '`');
 			cursor+= 2;
 		}

 		int subMode= 0;
 		int linkedMode= -1;
 		switch (mode) {

 		case FUNCTION:
 			subMode= 1;
 			final IRMethod rMethod= (IRMethod) getElement();

 			if (replacementOffset+replacementLength < document.getLength()-1
 					&& document.getChar(replacementOffset+replacementLength) == '(') {
 				cursor ++;
 				subMode= 10;
 			}
 			else if (!isFollowedByOpeningBracket(replacementOffset + replacementLength, context)) {
 				replacement.append('(');
 				cursor ++;
 				subMode= 11;
 			}
 			if (subMode >= 10) {
 				if (subMode == 11
 						&& !isClosedBracket(replacementOffset, replacementOffset + replacementLength, context)) {
 					replacement.append(')');
 					linkedMode= 2;

 					if (assignmentFunction && !isFollowedByAssign(replacementOffset + replacementLength, context)) {
 						replacement.append(" <- "); //$NON-NLS-1$
 						if (linkedMode >= 0) {
 							linkedMode+= 4;
 						}
 					}
 				}

 				final ArgsDefinition argsDef= rMethod.getArgsDefinition();
 				if (argsDef == null || argsDef.size() > 0 || (subMode == 11 && linkedMode < 0)) {
 					applyData.setContextInformation(new RArgumentListContextInformation(replacementOffset + cursor, rMethod));
 				}
 				else {
 					cursor ++;
 					linkedMode= -1;
 				}
 			}
 			break;

 		case ARGUMENT_NAME:
 			if (!isFollowedByEqualAssign(replacementOffset+replacementLength, context)) {
 				final RCodeStyleSettings codeStyle= getRCoreAccess().getRCodeStyle();
 				final String argAssign= codeStyle.getArgAssignString();
 				replacement.append(argAssign);
 				cursor+= argAssign.length();
 			}
 			break;

 		}

 		document.replace(replacementOffset, replacementLength, replacement.toString());
 		applyData.setSelection(replacementOffset + cursor);
 		if (linkedMode >= 0) {
 			createLinkedMode(replacementOffset + cursor - 1, linkedMode).enter();
 		}
 	}

 	private LinkedModeUI createLinkedMode(final int offset, final int mode)
 			throws BadLocationException {
 		final AssistInvocationContext context= getInvocationContext();
 		final IDocument document= context.getDocument();

 		final LinkedModeModel model= new LinkedModeModel();
 		int pos= 0;

 		final LinkedPositionGroup group= new LinkedPositionGroup();
 		final InBracketPosition position= RBracketLevel.createPosition('(', document,
 				offset + 1, 0, pos++);
 		group.addPosition(position);
 		model.addGroup(group);

 		model.forceInstall();

 		final RBracketLevel level= new RBracketLevel(model,
 				document, context.getEditor().getDocumentContentInfo(),
 				position, (context.getSourceViewer() instanceof InputSourceViewer), true);

 		/* create UI */
 		final LinkedModeUI ui= new LinkedModeUI(model, context.getSourceViewer());
 		ui.setCyclingMode(LinkedModeUI.CYCLE_NEVER);
 		ui.setExitPosition(context.getSourceViewer(), offset + (mode & 0xff), 0, pos);
 		ui.setSimpleMode(true);
 		ui.setExitPolicy(level);
 		return ui;
 	}


 	@Override
 	public IInformationControlCreator getInformationControlCreator() {
 		return getRHelpInfoHoverCreator(getInvocationContext());
 	}

 	@Override
 	public @Nullable Object getAdditionalProposalInfo(final IProgressMonitor monitor) {
 		final RHelpManager rHelpManager= RCore.getRHelpManager();
 		final int mode= getMode();

 		Object helpObject= null;

 		switch (mode) {

 		case PACKAGE_NAME: {
 				final ElementName elementName= getReplacementName();
 				if (elementName.getType() == RElementName.SCOPE_PACKAGE) {
 					final String pkgName= elementName.getSegmentName();

 					if (pkgName == null) {
 						return null;
 					}

 					final REnvHelp help= rHelpManager.getHelp(getRCoreAccess().getREnv());
 					if (help != null) {
 						try {
 							helpObject= help.getPkgHelp(pkgName);
 						}
 						finally {
 							help.unlock();
 						}
 					}
 				}
 				break;
 			}

 		default: {
 				final IRElement element= getElement();
 				if (element == null) {
 					return null;
 				}

 				final RElementName elementName= element.getElementName();
 				if (elementName.getType() == RElementName.MAIN_DEFAULT) {
 					RElementName scope= elementName.getScope();
 					if (scope == null && (element.getModelParent() instanceof IRElement)) {
 						scope= element.getModelParent().getElementName();
 					}
 					if (scope == null || !RElementName.isPackageFacetScopeType(scope.getType())) {
 						return null;
 					}
 					final String pkgName= scope.getSegmentName();
 					final String topic= elementName.getSegmentName();

 					if (pkgName == null || topic == null) {
 						return null;
 					}

 					final REnvHelp help= rHelpManager.getHelp(getRCoreAccess().getREnv());
 					if (help != null) {
 						try {
 							final RPkgHelp pkgHelp= help.getPkgHelp(pkgName);
 							if (pkgHelp != null) {
 								helpObject= pkgHelp.getPageForTopic(topic);
 							}
 						}
 						finally {
 							help.unlock();
 						}
 					}
 				}
 				break;
 			}
 		}

 		if (Thread.interrupted() || helpObject == null) {
 			return null;
 		}
 		{	final URI url= RCore.getRHelpHttpService().toHttpUrl(helpObject,
 					RHelpLtkUI.INFO_TARGET );
 			if (url != null) {
 				return new RHelpInfoHoverCreator.Data(getInvocationContext().getSourceViewer().getTextWidget(),
 						helpObject, url );
 			}
 		}

 		return null;
 	}

 }
	/*=============================================================================#
	# Copyright (c) 2008, 2020 Stephan Wahlbrink and others.
	#
	# This program and the accompanying materials are made available under the
	# terms of the Eclipse Public License 2.0 which is available at
	# https://www.eclipse.org/legal/epl-2.0, or the Apache License, Version 2.0
	# which is available at https://www.apache.org/licenses/LICENSE-2.0.
	#
	# SPDX-License-Identifier: EPL-2.0 OR Apache-2.0
	#
	# Contributors:
	# Stephan Wahlbrink <sw@wahlbrink.eu> - initial API and implementation
	#=============================================================================*/

	package org.eclipse.statet.internal.r.ui.editors;

	import java.net.URI;

	import org.eclipse.core.runtime.IProgressMonitor;
	import org.eclipse.jface.text.BadLocationException;
	import org.eclipse.jface.text.IDocument;
	import org.eclipse.jface.text.IInformationControlCreator;
	import org.eclipse.jface.text.IRegion;
	import org.eclipse.jface.text.contentassist.ICompletionProposalExtension5;
	import org.eclipse.jface.text.link.LinkedModeModel;
	import org.eclipse.jface.text.link.LinkedModeUI;
	import org.eclipse.jface.text.link.LinkedPositionGroup;
	import org.eclipse.jface.viewers.StyledString;
	import org.eclipse.swt.graphics.Image;
	import org.eclipse.swt.graphics.Point;
	import org.eclipse.swt.widgets.Shell;

	import org.eclipse.statet.jcommons.lang.NonNullByDefault;
	import org.eclipse.statet.jcommons.lang.Nullable;
	import org.eclipse.statet.jcommons.text.core.SearchPattern;

	import org.eclipse.statet.ecommons.text.ui.BracketLevel.InBracketPosition;

	import org.eclipse.statet.internal.r.ui.rhelp.RHelpInfoHoverCreator;
	import org.eclipse.statet.internal.r.ui.rhelp.RHelpLtkUI;
	import org.eclipse.statet.ltk.core.ElementName;
	import org.eclipse.statet.ltk.ui.ElementLabelProvider;
	import org.eclipse.statet.ltk.ui.sourceediting.assist.AssistInvocationContext;
	import org.eclipse.statet.ltk.ui.sourceediting.assist.ElementNameCompletionProposal;
	import org.eclipse.statet.ltk.ui.sourceediting.assist.InfoHover;
	import org.eclipse.statet.nico.ui.console.InputSourceViewer;
	import org.eclipse.statet.r.core.IRCoreAccess;
	import org.eclipse.statet.r.core.RCodeStyleSettings;
	import org.eclipse.statet.r.core.RCore;
	import org.eclipse.statet.r.core.model.ArgsDefinition;
	import org.eclipse.statet.r.core.model.IRElement;
	import org.eclipse.statet.r.core.model.IRMethod;
	import org.eclipse.statet.r.core.model.RElementName;
	import org.eclipse.statet.r.core.source.RHeuristicTokenScanner;
	import org.eclipse.statet.r.ui.RUI;
	import org.eclipse.statet.r.ui.sourceediting.RAssistInvocationContext;
	import org.eclipse.statet.r.ui.sourceediting.RBracketLevel;
	import org.eclipse.statet.rhelp.core.REnvHelp;
	import org.eclipse.statet.rhelp.core.RHelpManager;
	import org.eclipse.statet.rhelp.core.RPkgHelp;


	@NonNullByDefault
	public class RElementCompletionProposal
	extends ElementNameCompletionProposal<RAssistInvocationContext, IRElement>
	implements ICompletionProposalExtension5 {


	public static class RElementProposalParameters extends ProposalParameters<RAssistInvocationContext> {


	public final ElementLabelProvider labelProvider;


	public ElementName replacementName;

	public IRElement element;


	public RElementProposalParameters(final RAssistInvocationContext context, final int replacementOffset,
	final SearchPattern namePattern, final int baseRelevance,
	final ElementLabelProvider labelProvider) {
	super(context, replacementOffset, namePattern, baseRelevance);

	this.labelProvider= labelProvider;
	}

	public RElementProposalParameters(final RAssistInvocationContext context, final int replacementOffset,
	final SearchPattern namePattern,
	final ElementLabelProvider labelProvider) {
	super(context, replacementOffset, namePattern);

	this.labelProvider= labelProvider;
	}

	/** Only for context information */
	public RElementProposalParameters(final RAssistInvocationContext context, final int replacementOffset,
	final ElementLabelProvider labelProvider) {
	super(context, replacementOffset, 0);

	this.labelProvider= labelProvider;
	}

	}


	protected static final int PACKAGE_NAME= 1;
	protected static final int ARGUMENT_NAME= 2;
	protected static final int FUNCTION= 3;


	private static boolean rHelpInfoHoverInitialized;
	private static @Nullable IInformationControlCreator rHelpInfoHoverCreator;

	private static @Nullable IInformationControlCreator getRHelpInfoHoverCreator(final AssistInvocationContext context) {
	if (!rHelpInfoHoverInitialized) {
	final Shell shell= context.getSourceViewer().getTextWidget().getShell();
	if (shell != null) {
	if (RHelpInfoHoverCreator.isAvailable(shell)) {
	rHelpInfoHoverCreator= new RHelpInfoHoverCreator(InfoHover.MODE_PROPOSAL_INFO);
	}
	rHelpInfoHoverInitialized= true;
	}
	}
	return rHelpInfoHoverCreator;
	}


	public static class ArgumentProposal extends RElementCompletionProposal {


	public ArgumentProposal(final RElementProposalParameters parameters) {
	super(parameters);
	}


	@Override
	protected int getMode() {
	return ARGUMENT_NAME;
	}


	@Override
	public String getDisplayString() {
	return getReplacementName().getDisplayName();
	}

	@Override
	public StyledString computeStyledText() {
	return new StyledString(getReplacementName().getDisplayName());
	}

	@Override
	public Image getImage() {
	return RUI.getImage(RUI.IMG_OBJ_ARGUMENT_ASSIGN);
	}

	}

	public static class ContextInformationProposal extends RElementCompletionProposal {


	public ContextInformationProposal(final RElementProposalParameters parameters) {
	super(parameters);
	}


	@Override
	public boolean isAutoInsertable() {
	return true;
	}

	@Override
	protected void doApply(final char trigger, final int stateMask,
	final int caretOffset, final int replacementOffset, final int replacementLength)
	throws BadLocationException {
	final ApplyData applyData= getApplyData();

	applyData.clearSelection();
	applyData.setContextInformation(new RArgumentListContextInformation(
	getReplacementOffset(), // allow negative offsets
	(IRMethod) getElement() ));
	}

	}


	private static final boolean isFollowedByOpeningBracket(final int forwardOffset,
	final RAssistInvocationContext context) {
	final RHeuristicTokenScanner scanner= context.getRHeuristicTokenScanner();
	scanner.configure(context.getDocument());
	final int idx= scanner.findAnyNonBlankForward(forwardOffset, RHeuristicTokenScanner.UNBOUND, false);
	return (idx >= 0
	&& scanner.getChar() == '(' );
	}

	private static final boolean isClosedBracket(final int backwardOffset, final int forwardOffset,
	final RAssistInvocationContext context) {
	final int searchType= RHeuristicTokenScanner.ROUND_BRACKET_TYPE;
	int[] balance= new int[3];
	balance[searchType]++;
	final RHeuristicTokenScanner scanner= context.getRHeuristicTokenScanner();
	scanner.configureDefaultPartitions(context.getDocument());
	balance= scanner.computeBracketBalance(backwardOffset, forwardOffset, balance, searchType);
	return (balance[searchType] <= 0);
	}

	private static final boolean isFollowedByEqualAssign(final int forwardOffset,
	final RAssistInvocationContext context) {
	final RHeuristicTokenScanner scanner= context.getRHeuristicTokenScanner();
	scanner.configure(context.getDocument());
	final int idx= scanner.findAnyNonBlankForward(forwardOffset, RHeuristicTokenScanner.UNBOUND, false);
	return (idx >= 0
	&& scanner.getChar() == '=' );
	}

	private static final boolean isFollowedByAssign(final int forwardOffset,
	final RAssistInvocationContext data) {
	final RHeuristicTokenScanner scanner= data.getRHeuristicTokenScanner();
	scanner.configure(data.getDocument());
	final int idx= scanner.findAnyNonBlankForward(forwardOffset, RHeuristicTokenScanner.UNBOUND, false);
	return (idx >= 0
	&& (scanner.getChar() == '=' \|\| scanner.getChar() == '<') );
	}


	public RElementCompletionProposal(final RElementProposalParameters parameters) {
	super(parameters, parameters.replacementName, parameters.element, parameters.labelProvider);
	}


	protected IRCoreAccess getRCoreAccess() {
	return getInvocationContext().getEditor().getRCoreAccess();
	}

	protected int getMode() {
	return (getElement() != null
	&& (getElement().getElementType() & IRElement.MASK_C1) == IRElement.C1_METHOD) ?
	FUNCTION : 0;
	}


	@Override
	protected int computeReplacementLength(final int replacementOffset, final Point selection, final int caretOffset, final boolean overwrite) {
	// keep in synch with RSimpleCompletionProposal
	final int end= Math.max(caretOffset, selection.x + selection.y);
	if (overwrite) {
	final RAssistInvocationContext context= getInvocationContext();
	final RHeuristicTokenScanner scanner= context.getRHeuristicTokenScanner();
	scanner.configure(context.getDocument());
	final IRegion word= scanner.findRWord(end, false, true);
	if (word != null) {
	return (word.getOffset() + word.getLength() - replacementOffset);
	}
	}
	return (end - replacementOffset);
	}


	@Override
	protected @Nullable String getValidationPrefix(final int offset) throws BadLocationException {
	// keep in synch with RSimpleCompletionProposal
	final int startOffset= Math.max(getReplacementOffset(), 0);
	if (offset >= startOffset) {
	final RAssistInvocationContext context= getInvocationContext();
	final IDocument document= context.getDocument();
	int nameStartOffset= startOffset;
	int nameEndOffset= offset;
	if (nameEndOffset > nameStartOffset && document.getChar(nameStartOffset) == '`') {
	nameStartOffset++;
	}
	if (nameEndOffset > nameStartOffset && document.getChar(nameEndOffset - 1) == '`') {
	nameEndOffset--;
	}
	if (nameEndOffset >= nameStartOffset) {
	return context.getIdentifierSegmentName(
	document.get(startOffset, offset - startOffset) );
	}
	}
	return null;
	}


	@Override
	protected void doApply(final char trigger, final int stateMask, final int caretOffset,
	final int replacementOffset, int replacementLength)
	throws BadLocationException {
	final RAssistInvocationContext context= getInvocationContext();
	final IDocument document= context.getDocument();
	final ApplyData applyData= getApplyData();

	final ElementName replacementName= getReplacementName();
	final int mode= getMode();
	final boolean assignmentFunction= (mode == FUNCTION)
	&& replacementName.getNextSegment() == null
	&& replacementName.getSegmentName().endsWith("<-"); //$NON-NLS-1$
	final ElementName elementName;
	if (assignmentFunction) {
	elementName= RElementName.create(RElementName.MAIN_DEFAULT,
	replacementName.getSegmentName().substring(0, replacementName.getSegmentName().length() - 2) );
	}
	else {
	elementName= replacementName;
	}
	final StringBuilder replacement= new StringBuilder((mode == PACKAGE_NAME) ?
	elementName.getSegmentName() :
	elementName.getDisplayName() );
	int cursor= replacement.length();
	if (replacementLength > 0 && document.getChar(replacementOffset) == '`' && replacement.charAt(0) != '`') {
	if (replacement.length() == elementName.getSegmentName().length()
	&& replacementOffset+replacementLength < document.getLength()
	&& document.getChar(replacementOffset+replacementLength) == '`') {
	replacementLength++;
	}
	replacement.insert(elementName.getSegmentName().length(), '`');
	replacement.insert(0, '`');
	cursor+= 2;
	}

	int subMode= 0;
	int linkedMode= -1;
	switch (mode) {

	case FUNCTION:
	subMode= 1;
	final IRMethod rMethod= (IRMethod) getElement();

	if (replacementOffset+replacementLength < document.getLength()-1
	&& document.getChar(replacementOffset+replacementLength) == '(') {
	cursor ++;
	subMode= 10;
	}
	else if (!isFollowedByOpeningBracket(replacementOffset + replacementLength, context)) {
	replacement.append('(');
	cursor ++;
	subMode= 11;
	}
	if (subMode >= 10) {
	if (subMode == 11
	&& !isClosedBracket(replacementOffset, replacementOffset + replacementLength, context)) {
	replacement.append(')');
	linkedMode= 2;

	if (assignmentFunction && !isFollowedByAssign(replacementOffset + replacementLength, context)) {
	replacement.append(" <- "); //$NON-NLS-1$
	if (linkedMode >= 0) {
	linkedMode+= 4;
	}
	}
	}

	final ArgsDefinition argsDef= rMethod.getArgsDefinition();
	if (argsDef == null \|\| argsDef.size() > 0 \|\| (subMode == 11 && linkedMode < 0)) {
	applyData.setContextInformation(new RArgumentListContextInformation(replacementOffset + cursor, rMethod));
	}
	else {
	cursor ++;
	linkedMode= -1;
	}
	}
	break;

	case ARGUMENT_NAME:
	if (!isFollowedByEqualAssign(replacementOffset+replacementLength, context)) {
	final RCodeStyleSettings codeStyle= getRCoreAccess().getRCodeStyle();
	final String argAssign= codeStyle.getArgAssignString();
	replacement.append(argAssign);
	cursor+= argAssign.length();
	}
	break;

	}

	document.replace(replacementOffset, replacementLength, replacement.toString());
	applyData.setSelection(replacementOffset + cursor);
	if (linkedMode >= 0) {
	createLinkedMode(replacementOffset + cursor - 1, linkedMode).enter();
	}
	}

	private LinkedModeUI createLinkedMode(final int offset, final int mode)
	throws BadLocationException {
	final AssistInvocationContext context= getInvocationContext();
	final IDocument document= context.getDocument();

	final LinkedModeModel model= new LinkedModeModel();
	int pos= 0;

	final LinkedPositionGroup group= new LinkedPositionGroup();
	final InBracketPosition position= RBracketLevel.createPosition('(', document,
	offset + 1, 0, pos++);
	group.addPosition(position);
	model.addGroup(group);

	model.forceInstall();

	final RBracketLevel level= new RBracketLevel(model,
	document, context.getEditor().getDocumentContentInfo(),
	position, (context.getSourceViewer() instanceof InputSourceViewer), true);

	/* create UI */
	final LinkedModeUI ui= new LinkedModeUI(model, context.getSourceViewer());
	ui.setCyclingMode(LinkedModeUI.CYCLE_NEVER);
	ui.setExitPosition(context.getSourceViewer(), offset + (mode & 0xff), 0, pos);
	ui.setSimpleMode(true);
	ui.setExitPolicy(level);
	return ui;
	}


	@Override
	public IInformationControlCreator getInformationControlCreator() {
	return getRHelpInfoHoverCreator(getInvocationContext());
	}

	@Override
	public @Nullable Object getAdditionalProposalInfo(final IProgressMonitor monitor) {
	final RHelpManager rHelpManager= RCore.getRHelpManager();
	final int mode= getMode();

	Object helpObject= null;

	switch (mode) {

	case PACKAGE_NAME: {
	final ElementName elementName= getReplacementName();
	if (elementName.getType() == RElementName.SCOPE_PACKAGE) {
	final String pkgName= elementName.getSegmentName();

	if (pkgName == null) {
	return null;
	}

	final REnvHelp help= rHelpManager.getHelp(getRCoreAccess().getREnv());
	if (help != null) {
	try {
	helpObject= help.getPkgHelp(pkgName);
	}
	finally {
	help.unlock();
	}
	}
	}
	break;
	}

	default: {
	final IRElement element= getElement();
	if (element == null) {
	return null;
	}

	final RElementName elementName= element.getElementName();
	if (elementName.getType() == RElementName.MAIN_DEFAULT) {
	RElementName scope= elementName.getScope();
	if (scope == null && (element.getModelParent() instanceof IRElement)) {
	scope= element.getModelParent().getElementName();
	}
	if (scope == null \|\| !RElementName.isPackageFacetScopeType(scope.getType())) {
	return null;
	}
	final String pkgName= scope.getSegmentName();
	final String topic= elementName.getSegmentName();

	if (pkgName == null \|\| topic == null) {
	return null;
	}

	final REnvHelp help= rHelpManager.getHelp(getRCoreAccess().getREnv());
	if (help != null) {
	try {
	final RPkgHelp pkgHelp= help.getPkgHelp(pkgName);
	if (pkgHelp != null) {
	helpObject= pkgHelp.getPageForTopic(topic);
	}
	}
	finally {
	help.unlock();
	}
	}
	}
	break;
	}
	}

	if (Thread.interrupted() \|\| helpObject == null) {
	return null;
	}
	{ final URI url= RCore.getRHelpHttpService().toHttpUrl(helpObject,
	RHelpLtkUI.INFO_TARGET );
	if (url != null) {
	return new RHelpInfoHoverCreator.Data(getInvocationContext().getSourceViewer().getTextWidget(),
	helpObject, url );
	}
	}

	return null;
	}

	}