core/plugins/org.eclipse.dltk.ui/src/org/eclipse/dltk/ui/preferences/PreferenceKey.java

/**
 * 
 */
package org.eclipse.dltk.ui.preferences;

import org.eclipse.core.runtime.preferences.IEclipsePreferences;
import org.eclipse.core.runtime.preferences.IScopeContext;
import org.eclipse.ui.preferences.IWorkingCopyManager;

public final class PreferenceKey {

	private final String fQualifier;
	private final String fKey;

	public PreferenceKey(String qualifier, String key) {
		// it is here to declare the parameter precondition, not to check
		// values at runtime.
		assert (qualifier != null);
		assert (key != null);
		fQualifier = qualifier;
		fKey = key;
	}

	public String getName() {
		return fKey;
	}

	private IEclipsePreferences getNode(IScopeContext context,
			IWorkingCopyManager manager) {
		IEclipsePreferences node = context.getNode(fQualifier);
		if (manager != null) {
			return manager.getWorkingCopy(node);
		}
		return node;
	}

	public String getStoredValue(IScopeContext context) {
		return getStoredValue(context, null);
	}

	public String getStoredValue(IScopeContext context,
			IWorkingCopyManager manager) {
		return getNode(context, manager).get(fKey, null);
	}

	public String getStoredValue(IScopeContext[] lookupOrder,
			boolean ignoreTopScope, IWorkingCopyManager manager) {
		for (int i = ignoreTopScope ? 1 : 0; i < lookupOrder.length; i++) {
			String value = getStoredValue(lookupOrder[i], manager);
			if (value != null) {
				return value;
			}
		}
		return null;
	}

	public void setStoredValue(IScopeContext context, String value,
			IWorkingCopyManager manager) {
		if (value != null) {
			getNode(context, manager).put(fKey, value);
		} else {
			getNode(context, manager).remove(fKey);
		}
	}

	/**
	 * @param context
	 * @param value
	 */
	public void setStoredValue(IScopeContext context, String value) {
		setStoredValue(context, value, null);
	}

	@Override
	public int hashCode() {
		return fQualifier.hashCode() ^ fKey.hashCode();
	}

	@Override
	public boolean equals(Object obj) {
		if (obj instanceof PreferenceKey) {
			final PreferenceKey other = (PreferenceKey) obj;
			return fKey.equals(other.fKey)
					&& fQualifier.equals(other.fQualifier);
		}
		return false;
	}

	@Override
	public String toString() {
		return fQualifier + '/' + fKey;
	}

	public String getQualifier() {
		return fQualifier;
	}

	/**
	 * @since 2.0
	 */
	public boolean belongsTo(String qualifier) {
		return fQualifier.equals(qualifier);
	}

}