Bug 514397 - Provide default autocompletion for generic editorY20170406-1000I20170405-2000

Change-Id: I113fe5ec4faf1fde579dc3400d42041d9e77c9a4
Signed-off-by: Sopot Cela <scela@redhat.com>

2 files changed, 112 insertions, 0 deletions

diff --git a/org.eclipse.ui.genericeditor/src/org/eclipse/ui/internal/genericeditor/DefaultContentAssistProcessor.java b/org.eclipse.ui.genericeditor/src/org/eclipse/ui/internal/genericeditor/DefaultContentAssistProcessor.java
new file mode 100644
index 00000000000..9e47220531e
--- /dev/null
+++ b/org.eclipse.ui.genericeditor/src/org/eclipse/ui/internal/genericeditor/DefaultContentAssistProcessor.java
@@ -0,0 +1,109 @@
+/*******************************************************************************
+ * Copyright (c) 2017 Red Hat Inc. 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:
+ * - Sopot Cela (Red Hat Inc.)
+ *******************************************************************************/
+package org.eclipse.ui.internal.genericeditor;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Set;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+import org.eclipse.jface.text.ITextViewer;
+import org.eclipse.jface.text.contentassist.CompletionProposal;
+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;
+
+/**
+ *
+ * This content assist processor is a default processor which will be present if
+ * no other auto-completion is registered for a given content-type. It splits
+ * the text into 'words' (which are defined as anything in-between
+ * non-alphanumeric characters) and offers them as auto-complete alternatives to
+ * the matching prefix.
+ *
+ * E.g. if your file contains "this is a t^" and you ask for auto-completion at
+ * ^ you will get 'this' as an alternative.
+ *
+ */
+public class DefaultContentAssistProcessor implements IContentAssistProcessor {
+
+	private static final String NON_ALPHANUMERIC_LAST_REGEXP = "[^\\w](?!.*[^\\w])"; //$NON-NLS-1$
+	private static final String NON_ALPHANUMERIC_REGEXP = "[^a-zA-Z0-9]+"; //$NON-NLS-1$
+	private static final Pattern NON_ALPHANUMERIC_LAST_PATTERN = Pattern.compile(NON_ALPHANUMERIC_LAST_REGEXP);
+
+
+	@Override
+	public ICompletionProposal[] computeCompletionProposals(ITextViewer viewer, int offset) {
+		String text = viewer.getDocument().get();
+		String[] tokens = text.split(NON_ALPHANUMERIC_REGEXP);
+
+		//remove duplicates
+		Set<String> tokenSet = new HashSet<String>(Arrays.asList(tokens));
+
+		//wordStartIndex is the index of the last non-alphanumeric before 'offset' in text 'text'
+		int wordStartIndex = findStartingPoint(text, offset);
+		String prefix = text.substring(wordStartIndex, offset);
+
+		List<ICompletionProposal> proposals = new ArrayList<ICompletionProposal>();
+		for (String token : tokenSet) {
+			if ((token==null)||(token.isEmpty())) {
+				continue;
+			}
+			if (token.equals(prefix)) {
+				continue;
+			}
+			if (token.startsWith(prefix)) {
+				String completion = token.substring(prefix.length());
+				CompletionProposal proposal = new CompletionProposal(completion, offset, 0,
+						completion.length(), null,  token, null, null);
+				proposals.add(proposal);
+			}
+		}
+		return proposals.toArray(new ICompletionProposal[proposals.size()]);
+	}
+
+	private int findStartingPoint(String text, int offset) {
+		String substring = text.substring(0, offset);
+		Matcher m = NON_ALPHANUMERIC_LAST_PATTERN.matcher(substring);
+		m.find();
+		return m.end();
+	}
+
+	@Override
+	public IContextInformation[] computeContextInformation(ITextViewer viewer, int offset) {
+		return null;
+	}
+
+	@Override
+	public char[] getCompletionProposalAutoActivationCharacters() {
+		return null;
+	}
+
+	@Override
+	public char[] getContextInformationAutoActivationCharacters() {
+		return null;
+	}
+
+	@Override
+	public String getErrorMessage() {
+		return null;
+	}
+
+	@Override
+	public IContextInformationValidator getContextInformationValidator() {
+		return null;
+	}
+
+}
diff --git a/org.eclipse.ui.genericeditor/src/org/eclipse/ui/internal/genericeditor/ExtensionBasedTextViewerConfiguration.java b/org.eclipse.ui.genericeditor/src/org/eclipse/ui/internal/genericeditor/ExtensionBasedTextViewerConfiguration.java
index 1fe651b32a1..0992d14609b 100644
--- a/org.eclipse.ui.genericeditor/src/org/eclipse/ui/internal/genericeditor/ExtensionBasedTextViewerConfiguration.java
+++ b/org.eclipse.ui.genericeditor/src/org/eclipse/ui/internal/genericeditor/ExtensionBasedTextViewerConfiguration.java
@@ -110,6 +110,9 @@ public final class ExtensionBasedTextViewerConfiguration extends TextSourceViewe
 		contentAssistant.enableColoredLabels(true);
 		contentAssistant.enableAutoActivation(true);
 		this.processors = registry.getContentAssistProcessors(sourceViewer, getContentTypes());
+		if (this.processors.isEmpty()) {
+			this.processors.add(new DefaultContentAssistProcessor());
+		}
 		for (IContentAssistProcessor processor : this.processors) {
 			contentAssistant.addContentAssistProcessor(processor, IDocument.DEFAULT_CONTENT_TYPE);
 		}