ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/ui/matcher/LetterOrDigitKeyEventMatcher.java

/*=============================================================================#
 # Copyright (c) 2012, 2021 Original NatTable authors 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.
 # 
 # SPDX-License-Identifier: EPL-2.0
 # 
 # Contributors:
 #     Original NatTable authors and others - initial API and implementation
 #=============================================================================*/

package org.eclipse.statet.ecommons.waltable.ui.matcher;

import org.eclipse.swt.SWT;
import org.eclipse.swt.events.KeyEvent;


/**
 * {@link IKeyEventMatcher} implementation that will check if a pressed key 
 * is a letter or digit key, in combination with the configured state mask
 * for the keyboard modifier.
 * <p>
 * Since 1.0.0 this matcher has evolved to match more than only letter or 
 * digit keys. It will now also check for several special characters that
 * are able to be populated to an editor like e.g. the question mark. The
 * following regular expression will be used by this matcher:
 * 
 * <b>[\\.:,;\\-_#\'+*~!?§$%&amp;/()\\[\\]\\{\\}=\\\\\"]</b>
 */
public class LetterOrDigitKeyEventMatcher implements IKeyEventMatcher {

	/**
	 * The state of the keyboard modifier keys at the time
	 * the event was generated, as defined by the key code
	 * constants in class <code>SWT</code>.
	 */
	private final int stateMask;
	
	/**
	 * Will create a new key event matcher that accepts no keyboard
	 * modifiers on typing a key.
	 */
	public LetterOrDigitKeyEventMatcher() {
		this(SWT.NONE);
	}
	
	/**
	 * Will create a new key event matcher that accepts only the given 
	 * keyboard modifiers on typing a key.
	 * @param stateMask The state of the keyboard modifier keys at the time
	 * 			the event was generated, as defined by the key code
	 * 			constants in class <code>SWT</code>.
	 */
	public LetterOrDigitKeyEventMatcher(final int stateMask) {
		this.stateMask= stateMask;
	}

	/* (non-Javadoc)
	 * @see org.eclipse.statet.ecommons.waltable.ui.matcher.IKeyEventMatcher#matches(org.eclipse.swt.events.KeyEvent)
	 */
	@Override
	public boolean matches(final KeyEvent event) {
		return event.stateMask == this.stateMask && isLetterOrDigit(event.character);
	}

	/**
	 * Will check if the given character is a letter or digit character, and moreover
	 * will check special characters that can be typed that will cause a character to
	 * be printed. 
	 * <p>
	 * This method is intended to be used to determine whether a keypress is able to
	 * open an editor, populating the representing character of the key to the editor.
	 * @param character The character to check if it is a letter, digit or
	 * 			specified special character.
	 * @return <code>true</code> if the character is an acceptable character,
	 * 			<code>false</code> if not.
	 */
	public static boolean isLetterOrDigit(final char character) {
		return Character.isLetterOrDigit(character)
				|| Character.valueOf(character).toString().matches(
						"[\\.:,;\\-_#\'+*~!?§$%&/()\\[\\]\\{\\}=\\\\\"]"); //$NON-NLS-1$
	}

}