wudsn-ide/com.wudsn.ide.lng/src/com/wudsn/ide/lng/editor/LanguageEditorToggleCommentAction.java

/**
 * Copyright (C) 2009 - 2021 <a href="https://www.wudsn.com" target="_top">Peter Dell</a>
 *
 * This file is part of WUDSN IDE.
 * 
 * WUDSN IDE is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 2 of the License, or
 * (at your option) any later version.
 * 
 * WUDSN IDE is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with WUDSN IDE.  If not, see <http://www.gnu.org/licenses/>.
 */

package com.wudsn.ide.lng.editor;

import java.util.List;
import java.util.ResourceBundle;

import org.eclipse.jface.text.BadLocationException;
import org.eclipse.jface.text.IDocument;
import org.eclipse.jface.text.ITextOperationTarget;
import org.eclipse.jface.text.TextSelection;
import org.eclipse.jface.text.source.SourceViewer;
import org.eclipse.jface.viewers.ISelection;
import org.eclipse.ui.texteditor.TextEditorAction;

import com.wudsn.ide.lng.LanguagePlugin;

/**
 * Action to toggle a comment.
 * 
 * @author Peter Dell
 * @author Andy Reek
 */
final class LanguageEditorToggleCommentAction extends TextEditorAction {

	/**
	 * The owning editor.
	 */
	private final ILanguageEditor editor;

	/**
	 * The editor's source viewer.
	 */
	private final SourceViewer sourceViewer;

	/**
	 * Creates a new instance.
	 * 
	 * @param bundle       The resource bundle, not <code>null</code>.
	 * @param prefix       The resource bundle key prefix, not <code>null</code>.
	 * 
	 * @param editor       The editor, not <code>null</code>.
	 * @param sourceViewer The editor's source viewer.
	 * 
	 */
	LanguageEditorToggleCommentAction(ResourceBundle bundle, String prefix, LanguageEditor editor,
			SourceViewer sourceViewer) {
		super(bundle, prefix, editor);
		if (editor == null) {
			throw new IllegalArgumentException("Parameter 'editor' must not be null.");
		}
		if (sourceViewer == null) {
			throw new IllegalArgumentException("Parameter 'sourceViewer' must not be null.");
		}
		this.editor = editor;
		this.sourceViewer = sourceViewer;
	}

	@Override
	public void update() {
		setEnabled(canModifyEditor());
	}

	@Override
	public void run() {
		IDocument document = sourceViewer.getDocument();
		ISelection selection = sourceViewer.getSelection();
		TextSelection textSelection;
		if (selection instanceof TextSelection) {
			textSelection = (TextSelection) selection;
			boolean isCommented = isCommented(document, textSelection);
			if (isCommented) {
				sourceViewer.doOperation(ITextOperationTarget.STRIP_PREFIX);
			} else {
				sourceViewer.doOperation(ITextOperationTarget.PREFIX);
			}
		}
	}

	/**
	 * Checks, if the selection in the given document is commented fully using one
	 * of the single line comment delimiters.
	 * 
	 * @param document  The document, not <code>null</code>.
	 * @param selection The selection, not <code>null</code>.
	 * 
	 * @return <code>true</code>, if commented.
	 */
	private boolean isCommented(IDocument document, TextSelection selection) {
		if (document == null) {
			throw new IllegalArgumentException("Parameter 'document' must not be null.");
		}
		if (selection == null) {
			throw new IllegalArgumentException("Parameter 'selection' must not be null.");
		}
		try {
			int startLine = selection.getStartLine();
			int endLine = selection.getEndLine();
			for (int line = startLine; line <= endLine; line++) {
				int lineOffset = document.getLineOffset(line);
				int lineLength = document.getLineLength(line);
				String lineText = document.get(lineOffset, lineLength);

				if (!isCommented(lineText)) {
					return false;
				}
			}
		} catch (BadLocationException ex) {
			LanguagePlugin.getInstance().logError("Cannot find location", null, ex);
		}

		return true;
	}

	/**
	 * Checks, if the line is commented using one of the single line comment
	 * delimiters.
	 * 
	 * @param lineText The line text, may be empty, not <code>null</code>.
	 * 
	 * @return <code>true</code>, if commented.
	 */
	private boolean isCommented(String lineText) {

		if (lineText == null) {
			throw new IllegalArgumentException("Parameter 'lineText' must not be null.");
		}

		List<String> singleLineCommentDeliminters;
		singleLineCommentDeliminters = editor.getCompilerDefinition().getSyntax().getSingleLineCommentDelimiters();
		for (String delimiter : singleLineCommentDeliminters) {
			if (lineText.startsWith(delimiter)) {
				return true;
			}
		}
		return false;
	}
}