SWT Completion Editor
/*
SWT/JFace in Action
GUI Design with Eclipse 3.0
Matthew Scarpino, Stephen Holder, Stanford Ng, and Laurent Mihalkovic
ISBN: 1932394273
Publisher: Manning
*/
import java.util.HashMap;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import java.util.StringTokenizer;
import org.eclipse.jface.text.BadLocationException;
import org.eclipse.jface.text.Document;
import org.eclipse.jface.text.IDocument;
import org.eclipse.jface.text.ITextListener;
import org.eclipse.jface.text.ITextViewer;
import org.eclipse.jface.text.TextEvent;
import org.eclipse.jface.text.TextViewer;
import org.eclipse.jface.text.contentassist.CompletionProposal;
import org.eclipse.jface.text.contentassist.ContentAssistant;
import org.eclipse.jface.text.contentassist.ContextInformationValidator;
import org.eclipse.jface.text.contentassist.ICompletionProposal;
import org.eclipse.jface.text.contentassist.IContentAssistProcessor;
import org.eclipse.jface.text.contentassist.IContextInformation;
import org.eclipse.jface.text.contentassist.IContextInformationValidator;
import org.eclipse.swt.SWT;
import org.eclipse.swt.events.KeyAdapter;
import org.eclipse.swt.events.KeyEvent;
import org.eclipse.swt.layout.FillLayout;
import org.eclipse.swt.widgets.Composite;
public class Ch5CompletionEditor extends Composite {
private TextViewer textViewer;
private WordTracker wordTracker;
private static final int MAX_QUEUE_SIZE = 200;
public Ch5CompletionEditor(Composite parent) {
super(parent, SWT.NULL);
wordTracker = new WordTracker(MAX_QUEUE_SIZE);
buildControls();
}
private void buildControls() {
setLayout(new FillLayout());
textViewer = new TextViewer(this, SWT.MULTI | SWT.V_SCROLL);
textViewer.setDocument(new Document());
final ContentAssistant assistant = new ContentAssistant();
assistant.setContentAssistProcessor(
new RecentWordContentAssistProcessor(wordTracker),
IDocument.DEFAULT_CONTENT_TYPE);
assistant.install(textViewer);
textViewer.getControl().addKeyListener(new KeyAdapter() {
public void keyPressed(KeyEvent e) {
switch (e.keyCode) {
case SWT.F1:
assistant.showPossibleCompletions();
break;
default:
//ignore everything else
}
}
});
textViewer.addTextListener(new ITextListener() {
public void textChanged(TextEvent e) {
if (isWhitespaceString(e.getText())) {
wordTracker.add(findMostRecentWord(e.getOffset() - 1));
}
}
});
}
protected String findMostRecentWord(int startSearchOffset) {
int currOffset = startSearchOffset;
char currChar;
String word = "";
try {
while (currOffset > 0
&& !Character.isWhitespace(currChar = textViewer
.getDocument().getChar(currOffset))) {
word = currChar + word;
currOffset--;
}
return word;
} catch (BadLocationException e) {
e.printStackTrace();
return null;
}
}
protected boolean isWhitespaceString(String string) {
StringTokenizer tokenizer = new StringTokenizer(string);
//if there is at least 1 token, this string is not whitespace
return !tokenizer.hasMoreTokens();
}
}
class WordTracker {
private int maxQueueSize;
private List wordBuffer;
private Map knownWords = new HashMap();
public WordTracker(int queueSize) {
maxQueueSize = queueSize;
wordBuffer = new LinkedList();
}
public int getWordCount() {
return wordBuffer.size();
}
public void add(String word) {
if (wordIsNotKnown(word)) {
flushOldestWord();
insertNewWord(word);
}
}
private void insertNewWord(String word) {
wordBuffer.add(0, word);
knownWords.put(word, word);
}
private void flushOldestWord() {
if (wordBuffer.size() == maxQueueSize) {
String removedWord = (String) wordBuffer.remove(maxQueueSize - 1);
knownWords.remove(removedWord);
}
}
private boolean wordIsNotKnown(String word) {
return knownWords.get(word) == null;
}
public List suggest(String word) {
List suggestions = new LinkedList();
for (Iterator i = wordBuffer.iterator(); i.hasNext();) {
String currWord = (String) i.next();
if (currWord.startsWith(word)) {
suggestions.add(currWord);
}
}
return suggestions;
}
}
class RecentWordContentAssistProcessor implements IContentAssistProcessor {
private String lastError = null;
private IContextInformationValidator contextInfoValidator;
private WordTracker wordTracker;
public RecentWordContentAssistProcessor(WordTracker tracker) {
super();
contextInfoValidator = new ContextInformationValidator(this);
wordTracker = tracker;
}
public ICompletionProposal[] computeCompletionProposals(
ITextViewer textViewer, int documentOffset) {
IDocument document = textViewer.getDocument();
int currOffset = documentOffset - 1;
try {
String currWord = "";
char currChar;
while (currOffset > 0
&& !Character.isWhitespace(currChar = document
.getChar(currOffset))) {
currWord = currChar + currWord;
currOffset--;
}
List suggestions = wordTracker.suggest(currWord);
ICompletionProposal[] proposals = null;
if (suggestions.size() > 0) {
proposals = buildProposals(suggestions, currWord,
documentOffset - currWord.length());
lastError = null;
}
return proposals;
} catch (BadLocationException e) {
e.printStackTrace();
lastError = e.getMessage();
return null;
}
}
private ICompletionProposal[] buildProposals(List suggestions,
String replacedWord, int offset) {
ICompletionProposal[] proposals = new ICompletionProposal[suggestions
.size()];
int index = 0;
for (Iterator i = suggestions.iterator(); i.hasNext();) {
String currSuggestion = (String) i.next();
proposals[index] = new CompletionProposal(currSuggestion, offset,
replacedWord.length(), currSuggestion.length());
index++;
}
return proposals;
}
public IContextInformation[] computeContextInformation(
ITextViewer textViewer, int documentOffset) {
lastError = "No Context Information available";
return null;
}
public char[] getCompletionProposalAutoActivationCharacters() {
//we always wait for the user to explicitly trigger completion
return null;
}
public char[] getContextInformationAutoActivationCharacters() {
//we have no context information
return null;
}
public String getErrorMessage() {
return lastError;
}
public IContextInformationValidator getContextInformationValidator() {
return contextInfoValidator;
}
}
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