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SciJava Common is a shared library for SciJava software. It provides a plugin framework, with an extensible mechanism for service discovery, backed by its own annotation processor, so that plugins can be loaded dynamically. It is used by downstream projects in the SciJava ecosystem, such as ImageJ and SCIFIO.
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package org.scijava.input;

import java.util.regex.Pattern;

import org.scijava.util.PlatformUtils;

/**
 * A keyboard shortcut, consisting of a {@link KeyCode} plus
 * {@link InputModifiers}.
 * 
 * @author Curtis Rueden
 * @author Barry DeZonia
 */
public class Accelerator {

	/** Actual key pressed. */
	private final KeyCode keyCode;

	/** Key modifiers used. */
	private final InputModifiers modifiers;

	public Accelerator(final KeyCode keyCode, final InputModifiers modifiers) {
		this.keyCode = keyCode;
		this.modifiers = modifiers;
	}

	// -- Accelerator methods --

	public KeyCode getKeyCode() {
		return keyCode;
	}

	public InputModifiers getModifiers() {
		return modifiers;
	}

	// -- Object methods --

	@Override
	public boolean equals(final Object o) {
		if (!(o instanceof Accelerator)) return false;
		final Accelerator acc = (Accelerator) o;
		if (!getModifiers().equals(acc.getModifiers())) return false;
		if (!getKeyCode().equals(acc.getKeyCode())) return false;
		return true;
	}

	@Override
	public int hashCode() {
		return toString().hashCode();
	}

	@Override
	public String toString() {
		final String modString = modifiers.toString();
		final String keyString = keyCode.name();
		if (modString.length() == 0) return keyString;
		return modString + " " + keyString;
	}

	// -- Utility methods --

	/**
	 * Creates an accelerator from the given string representation. The string
	 * must have the following syntax:
	 * 
	 * 	 * 	    <modifiers>* <keyCode>
	 * 
	 * 	    modifiers := alt | altGraph | control | meta | shift
	 * 	    keyCode := {@link KeyCode} field (e.g., COMMA or UP)
	 * 
	 * 
	 * For convenience:
	 * 
	 * "control" may be shortened to "ctrl"
	 * "altGraph" may be shortened to "altGr"
	 * The caret character ('^') is expanded to "control " on non-Mac
	 * platforms, and "meta " (i.e., the Mac command key) on Mac platforms.
	 * 
	 * Here are some example strings:
	 * 
	 * "INSERT"
	 * "control DELETE"
	 * "alt shift X"
	 * "^C"
	 * 
	 * 
	 * @see javax.swing.KeyStroke#getKeyStroke(String) for the syntax from which
	 *      this one is derived.
	 * @see KeyCode for the complete list of special character codes.
	 */
	public static Accelerator create(final String acc) {
		if (acc == null || acc.isEmpty()) return null;

		// allow use of caret for control/command
		// (e.g., "^X" to mean "control X" or "meta X")
		final String a = acc.replaceAll(Pattern.quote("^"), expandedCaret());

		final String[] components = a.split(" ");

		// determine which modifiers are used
		boolean alt = false, altGr = false;
		boolean ctrl = false, meta = false, shift = false;
		for (int i = 0; i < components.length - 1; i++) {
			if (components[i].equalsIgnoreCase("alt")) alt = true;
			else if (components[i].equalsIgnoreCase("altGr") ||
				components[i].equalsIgnoreCase("altGraph"))
			{
				altGr = true;
			}
			else if (components[i].equalsIgnoreCase("control") ||
				components[i].equalsIgnoreCase("ctrl"))
			{
				ctrl = true;
			}
			else if (components[i].equalsIgnoreCase("meta")) meta = true;
			else if (components[i].equalsIgnoreCase("shift")) shift = true;
		}

		final InputModifiers modifiers =
			new InputModifiers(alt, altGr, ctrl, meta, shift, false, false, false);

		// upper case the key code
		final String code = components[components.length - 1].toUpperCase();
		final KeyCode keyCode = KeyCode.get(code);

		return new Accelerator(keyCode, modifiers);
	}

	public static boolean isCtrlReplacedWithMeta() {
		// FIXME: Relocate this platform-specific logic.
		return PlatformUtils.isMac();
	}

	// -- Helper methods --

	private static String expandedCaret() {
		return isCtrlReplacedWithMeta() ? "meta " : "control ";
	}

}