Refactoring sticky lines provider and handler

Refactors the sticky lines provider and extract the method to an interface. This is a preparation step for providing a extension point for sticky lines provider.

Author: Christopher-Hermann

bundles/org.eclipse.ui.editors/src/org/eclipse/ui/internal/texteditor/stickyscroll/StickyLinesProvider.java renamed to bundles/org.eclipse.ui.editors/src/org/eclipse/ui/internal/texteditor/stickyscroll/DefaultStickyLinesProvider.java

@@ -24,32 +24,26 @@
 
 /**
  * This class provides sticky lines for the given source code in the source viewer. The
- * implementation is completely based on indentation and therefore should work by default for
- * several languages.
+ * implementation is completely based on indentation and therefore works by default for several
+ * languages.
  */
-public class StickyLinesProvider {
+public class DefaultStickyLinesProvider implements IStickyLinesProvider {
 
-	private final static int IGNORE_INDENTATION= -1;
+	private final static int IGNORE_LINE_INDENTATION= -1;
 
 	private final static String TAB= "\t"; //$NON-NLS-1$
 
-	private int tabWidth= 4;
-
-	/**
-	 * Calculate the sticky lines for the given source code in the source viewer for the given
-	 * vertical offset.
-	 * 
-	 * @param verticalOffset The vertical offset line index of the first visible line
-	 * @param sourceViewer The source viewer containing the source code
-	 * @return A list of sticky lines
-	 */
-	public List<StickyLine> get(int verticalOffset, ISourceViewer sourceViewer) {
-		LinkedList<StickyLine> stickyLines= new LinkedList<>();
+	private StickyLinesProperties fProperties;
 
-		if (verticalOffset == 0) {
-			return stickyLines;
+	@Override
+	public List<StickyLine> getStickyLines(ISourceViewer sourceViewer, StickyLinesProperties properties) {
+		if (sourceViewer.getTopIndex() == 0) {
+			return Collections.emptyList();
 		}
 
+		this.fProperties= properties;
+		LinkedList<StickyLine> stickyLines= new LinkedList<>();
+
 		try {
 			StyledText textWidget= sourceViewer.getTextWidget();
 			int startLine= textWidget.getTopIndex();
@@ -71,7 +65,7 @@ private void calculateStickyLinesForLineNumber(LinkedList<StickyLine> stickyLine
 			String line= textWidget.getLine(i);
 			int indentation= getIndentation(line);
 
-			if (indentation == IGNORE_INDENTATION) {
+			if (indentation == IGNORE_LINE_INDENTATION) {
 				continue;
 			}
 
@@ -91,7 +85,7 @@ private void calculateStickyLinesUnderStickyLineControl(LinkedList<StickyLine> s
 
 			String line= textWidget.getLine(i);
 			int indentation= getIndentation(line);
-			if (indentation == IGNORE_INDENTATION) {
+			if (indentation == IGNORE_LINE_INDENTATION) {
 				continue;
 			}
 
@@ -123,7 +117,7 @@ private int mapLineNumberToSourceViewerLine(int lineNumber, ISourceViewer source
 
 	private int getStartIndentation(int startFromLine, StyledText styledText) {
 		int indentation= getIndentation(styledText.getLine(startFromLine));
-		if (indentation != IGNORE_INDENTATION) {
+		if (indentation != IGNORE_LINE_INDENTATION) {
 			return indentation;
 		} else {
 			int nextContentLine= getIndentation(getNextContentLine(startFromLine, styledText));
@@ -154,21 +148,12 @@ private String getPreviousContentLine(int startFromLine, StyledText styledText)
 
 	private int getIndentation(String line) {
 		if (line == null || line.isBlank()) {
-			return IGNORE_INDENTATION;
+			return IGNORE_LINE_INDENTATION;
 		}
-		String tabAsSpaces= String.join("", Collections.nCopies(tabWidth, " ")); //$NON-NLS-1$ //$NON-NLS-2$
+		String tabAsSpaces= String.join("", Collections.nCopies(fProperties.tabWith(), " ")); //$NON-NLS-1$ //$NON-NLS-2$
 
 		line= line.replace(TAB, tabAsSpaces);
 		return line.length() - line.stripLeading().length();
 	}
 
-	/**
-	 * Sets the with in spaces of a tab in the editor.
-	 * 
-	 * @param tabWidth The amount of spaces a tab is using.
-	 */
-	public void setTabWidth(int tabWidth) {
-		this.tabWidth= tabWidth;
-	}
-
 }

bundles/org.eclipse.ui.editors/src/org/eclipse/ui/internal/texteditor/stickyscroll/IStickyLinesProvider.java

@@ -0,0 +1,53 @@
+/*******************************************************************************
+ * Copyright (c) 2024 SAP SE.
+ *
+ * This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License 2.0
+ * which accompanies this distribution, and is available at
+ * https://www.eclipse.org/legal/epl-2.0/
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ *
+ * Contributors:
+ *     SAP SE - initial API and implementation
+ *******************************************************************************/
+package org.eclipse.ui.internal.texteditor.stickyscroll;
+
+import java.util.List;
+
+import org.eclipse.swt.custom.StyledText;
+
+import org.eclipse.jface.text.source.ISourceViewer;
+
+/**
+ * A sticky lines provider calculates the sticky lines for a given source viewer. The sticky lines
+ * will be displayed in the top area of the editor.
+ * 
+ * TODO move to public package and add since 3.19
+ */
+public interface IStickyLinesProvider {
+
+	/**
+	 * Calculate the sticky lines for the source code of the given sourceViewer. Specific
+	 * properties, such as the <code>tabWidht</code> can be retrieved from the
+	 * <code>properties</code>.
+	 * 
+	 * @param sourceViewer The source viewer containing the source code and information about the
+	 *            first visible line
+	 * @return The list of sticky lines to show
+	 * 
+	 * @see ISourceViewer#getTopIndex()
+	 * @see ISourceViewer#getTextWidget()
+	 * @see StyledText#getTopIndex()
+	 */
+	public List<StickyLine> getStickyLines(ISourceViewer sourceViewer, StickyLinesProperties properties);
+
+	/**
+	 * Properties required to calculate the sticky lines.
+	 * 
+	 * @param tabWith The with of a tab
+	 */
+	record StickyLinesProperties(int tabWith) {
+	}
+
+}

bundles/org.eclipse.ui.editors/src/org/eclipse/ui/internal/texteditor/stickyscroll/StickyScrollingHandler.java

@@ -21,6 +21,7 @@
 import static org.eclipse.ui.texteditor.AbstractDecoratedTextEditorPreferenceConstants.EDITOR_TAB_WIDTH;
 
 import java.time.Duration;
+import java.util.Collections;
 import java.util.List;
 
 import org.eclipse.swt.graphics.Color;
@@ -37,9 +38,10 @@
 import org.eclipse.jface.text.source.IVerticalRuler;
 
 import org.eclipse.ui.internal.editors.text.EditorsPlugin;
+import org.eclipse.ui.internal.texteditor.stickyscroll.IStickyLinesProvider.StickyLinesProperties;
 
 /**
- * A sticky scrolling handler that retrieves stick lines from the {@link StickyLinesProvider} and
+ * A sticky scrolling handler that retrieves stick lines from a {@link IStickyLinesProvider} and
  * shows them in a {@link StickyScrollingControl} on top of the given source viewer.
  */
 public class StickyScrollingHandler implements IViewportListener {
@@ -50,94 +52,95 @@ public class StickyScrollingHandler implements IViewportListener {
 
 	private StickyScrollingControl stickyScrollingControl;
 
-	private int tabWidth;
-
 	private IPropertyChangeListener propertyChangeListener;
 
 	private IPreferenceStore preferenceStore;
 
-	private StickyLinesProvider stickyLinesProvider;
+	private IStickyLinesProvider stickyLinesProvider;
+
+	private StickyLinesProperties stickyLinesProperties;
 
 	private Throttler throttler;
 
 	private int verticalOffset;
 
 	/**
-	 * Creates a StickyScrollingHandlerIndentation that will be linked to the given source viewer.
-	 * The sticky scrolling will be computed by the default {@link StickyLinesProvider}.
+	 * Creates a StickyScrollingHandler that will be linked to the given source viewer. The sticky
+	 * lines will be provided by the {@link DefaultStickyLinesProvider}.
 	 * 
-	 * @param sourceViewer The source viewer to link the handler
+	 * @param sourceViewer The source viewer to link the handler with
 	 * @param verticalRuler The vertical ruler of the source viewer
 	 * @param preferenceStore The preference store
 	 */
 	public StickyScrollingHandler(ISourceViewer sourceViewer, IVerticalRuler verticalRuler, IPreferenceStore preferenceStore) {
-		this(sourceViewer, verticalRuler, preferenceStore, new StickyLinesProvider());
+		this(sourceViewer, verticalRuler, preferenceStore, new DefaultStickyLinesProvider());
 	}
 
 	/**
-	 * Creates a StickyScrollingHandlerIndentation that will be linked to the given source viewer.
+	 * Creates a StickyScrollingHandler that will be linked to the given source viewer. The sticky
+	 * lines will be provided by the given <code>stickyLinesProvider</code>.
 	 * 
-	 * @param sourceViewer The source viewer to link the handler
+	 * @param sourceViewer The source viewer to link the handler with
 	 * @param verticalRuler The vertical ruler of the source viewer
 	 * @param preferenceStore The preference store
-	 * @param stickyLinesProvider The sticky scrolling computer
+	 * @param stickyLinesProvider The sticky scrolling provider
 	 */
 	public StickyScrollingHandler(ISourceViewer sourceViewer, IVerticalRuler verticalRuler, IPreferenceStore preferenceStore,
-			StickyLinesProvider stickyLinesProvider) {
+			IStickyLinesProvider stickyLinesProvider) {
 		this.sourceViewer= sourceViewer;
 
 		throttler= new Throttler(sourceViewer.getTextWidget().getDisplay(), Duration.ofMillis(THROTTLER_DELAY), this::calculateAndShowStickyLines);
 		this.stickyLinesProvider= stickyLinesProvider;
 
-		StickyScrollingControlSettings settings= loadAndListenForProperties(preferenceStore);
+		listenForPropertiesChanges(preferenceStore);
+		stickyLinesProperties= loadStickyLinesProperties(preferenceStore);
+		StickyScrollingControlSettings settings= loadControlSettings(preferenceStore);
+
 		stickyScrollingControl= new StickyScrollingControl(sourceViewer, verticalRuler, settings, this);
 
 		sourceViewer.addViewportListener(this);
 	}
 
-	private StickyScrollingControlSettings loadAndListenForProperties(IPreferenceStore store) {
+	private void listenForPropertiesChanges(IPreferenceStore store) {
 		preferenceStore= store;
 		propertyChangeListener= e -> {
 			if (e.getProperty().equals(EDITOR_TAB_WIDTH) || e.getProperty().equals(EDITOR_STICKY_SCROLLING_MAXIMUM_COUNT)
 					|| e.getProperty().equals(EDITOR_CURRENT_LINE_COLOR) || e.getProperty().equals(EDITOR_LINE_NUMBER_RULER)
 					|| e.getProperty().equals(STICKY_LINES_SEPARATOR_COLOR)) {
 				if (stickyScrollingControl != null && !sourceViewer.getTextWidget().isDisposed()) {
-					StickyScrollingControlSettings settings= loadSettings(preferenceStore);
+					StickyScrollingControlSettings settings= loadControlSettings(preferenceStore);
 					stickyScrollingControl.applySettings(settings);
-					stickyLinesProvider.setTabWidth(tabWidth);
+					stickyLinesProperties= loadStickyLinesProperties(preferenceStore);
 				}
 			}
 		};
 		store.addPropertyChangeListener(propertyChangeListener);
-		return loadSettings(store);
 	}
 
-	private StickyScrollingControlSettings loadSettings(IPreferenceStore store) {
-		tabWidth= store.getInt(EDITOR_TAB_WIDTH);
-
+	private StickyScrollingControlSettings loadControlSettings(IPreferenceStore store) {
 		int stickyScrollingMaxCount= store.getInt(EDITOR_STICKY_SCROLLING_MAXIMUM_COUNT);
 
 		Color lineNumberColor= new Color(PreferenceConverter.getColor(store, EDITOR_LINE_NUMBER_RULER_COLOR));
 		sourceViewer.getTextWidget().addDisposeListener(e -> lineNumberColor.dispose());
-
 		Color stickyLineHoverColor= new Color(PreferenceConverter.getColor(store, EDITOR_CURRENT_LINE_COLOR));
 		sourceViewer.getTextWidget().addDisposeListener(e -> stickyLineHoverColor.dispose());
-
 		Color stickyLineBackgroundColor= sourceViewer.getTextWidget().getBackground();
-
 		boolean showLineNumbers= store.getBoolean(EDITOR_LINE_NUMBER_RULER);
-
 		Color stickyLineSeparatorColor= null;
 		if (EditorsPlugin.getDefault() != null) {
 			RGB rgb= PreferenceConverter.getColor(store, STICKY_LINES_SEPARATOR_COLOR);
 			ISharedTextColors sharedTextColors= EditorsPlugin.getDefault().getSharedTextColors();
 			stickyLineSeparatorColor= sharedTextColors.getColor(rgb);
 		}
-
 		return new StickyScrollingControlSettings(stickyScrollingMaxCount,
 				lineNumberColor, stickyLineHoverColor, stickyLineBackgroundColor, stickyLineSeparatorColor, showLineNumbers);
 	}
 
+	private StickyLinesProperties loadStickyLinesProperties(IPreferenceStore store) {
+		int tabWidth= store.getInt(EDITOR_TAB_WIDTH);
+		return new StickyLinesProperties(tabWidth);
+	}
+
 	@Override
 	public void viewportChanged(int newVerticalOffset) {
 		if (this.verticalOffset == newVerticalOffset) {
@@ -148,7 +151,10 @@ public void viewportChanged(int newVerticalOffset) {
 	}
 
 	private void calculateAndShowStickyLines() {
-		List<StickyLine> stickyLines= stickyLinesProvider.get(verticalOffset, sourceViewer);
+		List<StickyLine> stickyLines= stickyLinesProvider.getStickyLines(sourceViewer, stickyLinesProperties);
+		if (stickyLines == null) {
+			stickyLines= Collections.emptyList();
+		}
 		stickyScrollingControl.setStickyLines(stickyLines);
 	}
 

tests/org.eclipse.ui.editors.tests/src/org/eclipse/ui/editors/tests/EditorsTestSuite.java

@@ -21,7 +21,7 @@
 
 import org.eclipse.jface.text.tests.codemining.CodeMiningTest;
 
-import org.eclipse.ui.internal.texteditor.stickyscroll.StickyLinesProviderTest;
+import org.eclipse.ui.internal.texteditor.stickyscroll.DefaultStickyLinesProviderTest;
 import org.eclipse.ui.internal.texteditor.stickyscroll.StickyScrollingControlTest;
 import org.eclipse.ui.internal.texteditor.stickyscroll.StickyScrollingHandlerTest;
 
@@ -49,7 +49,7 @@
 
 		StickyScrollingControlTest.class,
 		StickyScrollingHandlerTest.class,
-		StickyLinesProviderTest.class,
+		DefaultStickyLinesProviderTest.class,
 
 		CodeMiningTest.class,
 })