- * The main purpose of this class is to enable very easy switching of the - * tracked hint context. Only a call to the {@link #track(IHintContext)} method - * is required. All hint listeners registered into the tracked will - * automatically be switched to listen to the new context instead. - *
- * - *- * The tracker is implemented using HintStack but the - * {@link #addHintContext(IHintContext, int)} and - * {@link #removeHintContext(IHintContext)} methods are disabled by throwing - * {@link UnsupportedOperationException} in both. This is to prevent invalid use - * of the class as it is only meant for tracking a single context and nothing - * more. Otherwise this class functions exactly like {@link IHintStack} and - * {@link IHintObservable} are specified to work. - *
- * - *- * The implementation is thread-safe. - *
- * - *- * Always be sure to {@link #untrack()} any IHintContext that you're tracking - * after the tracker is no longer needed. Otherwise you will most likely have - * invalid listeners within the tracked IHintContext resulting in erroneous - * behavior. - *
- * - * @author Tuukka Lehtonen - */ -public class HintTracker extends HintStack implements IHintTracker { - - private IHintContext ctx; - - public HintTracker() { - } - - public HintTracker(IHintContext ctx) { - addHintContext(ctx, 0); - } - - /* (non-Javadoc) - * @see org.simantics.utils.datastructures.hints.IHintTracker#track(org.simantics.utils.datastructures.hints.IHintContext) - */ - public synchronized final void track(IHintContext ctx) { - IHintContext prevCtx = this.ctx; - if (ctx == prevCtx) - return; - this.ctx = ctx; - - if (ctx != null) { - if (ctx.equals(prevCtx)) { - // remove+add order is necessary in this case. - // add+remove would fail since the hint context would - // already be found in the hint stack. - super.removeHintContext(prevCtx); - super.addHintContext(ctx, 0); - } else { - super.addHintContext(ctx, 0); - if (prevCtx != null) - super.removeHintContext(prevCtx); - } - } else { - if (prevCtx != null) - super.removeHintContext(prevCtx); - } - } - - /* (non-Javadoc) - * @see org.simantics.utils.datastructures.hints.IHintTracker#untrack() - */ - public final void untrack() { - track(null); - } - - @Override - public final void addHintContext(IHintContext hints, int priority) { - throw new UnsupportedOperationException(); - } - - @Override - public final boolean removeHintContext(IHintContext hints) { - throw new UnsupportedOperationException(); - } - +/******************************************************************************* + * Copyright (c) 2007, 2010 Association for Decentralized Information Management + * in Industry THTH ry. + * All rights reserved. This program and the accompanying materials + * are made available under the terms of the Eclipse Public License v1.0 + * which accompanies this distribution, and is available at + * http://www.eclipse.org/legal/epl-v10.html + * + * Contributors: + * VTT Technical Research Centre of Finland - initial API and implementation + *******************************************************************************/ +package org.simantics.utils.datastructures.hints; + +/** + * HintTracker is a helper class for tracking any hints of a single + * IHintContext. + * + *+ * The main purpose of this class is to enable very easy switching of the + * tracked hint context. Only a call to the {@link #track(IHintContext)} method + * is required. All hint listeners registered into the tracked will + * automatically be switched to listen to the new context instead. + *
+ * + *+ * The tracker is implemented using HintStack but the + * {@link #addHintContext(IHintContext, int)} and + * {@link #removeHintContext(IHintContext)} methods are disabled by throwing + * {@link UnsupportedOperationException} in both. This is to prevent invalid use + * of the class as it is only meant for tracking a single context and nothing + * more. Otherwise this class functions exactly like {@link IHintStack} and + * {@link IHintObservable} are specified to work. + *
+ * + *+ * The implementation is thread-safe. + *
+ * + *+ * Always be sure to {@link #untrack()} any IHintContext that you're tracking + * after the tracker is no longer needed. Otherwise you will most likely have + * invalid listeners within the tracked IHintContext resulting in erroneous + * behavior. + *
+ * + * @author Tuukka Lehtonen + */ +public class HintTracker extends HintStack implements IHintTracker { + + private IHintContext ctx; + + public HintTracker() { + } + + public HintTracker(IHintContext ctx) { + addHintContext(ctx, 0); + } + + /* (non-Javadoc) + * @see org.simantics.utils.datastructures.hints.IHintTracker#track(org.simantics.utils.datastructures.hints.IHintContext) + */ + public synchronized final void track(IHintContext ctx) { + IHintContext prevCtx = this.ctx; + if (ctx == prevCtx) + return; + this.ctx = ctx; + + if (ctx != null) { + if (ctx.equals(prevCtx)) { + // remove+add order is necessary in this case. + // add+remove would fail since the hint context would + // already be found in the hint stack. + super.removeHintContext(prevCtx); + super.addHintContext(ctx, 0); + } else { + super.addHintContext(ctx, 0); + if (prevCtx != null) + super.removeHintContext(prevCtx); + } + } else { + if (prevCtx != null) + super.removeHintContext(prevCtx); + } + } + + /* (non-Javadoc) + * @see org.simantics.utils.datastructures.hints.IHintTracker#untrack() + */ + public final void untrack() { + track(null); + } + + @Override + public final void addHintContext(IHintContext hints, int priority) { + throw new UnsupportedOperationException(); + } + + @Override + public final boolean removeHintContext(IHintContext hints) { + throw new UnsupportedOperationException(); + } + } \ No newline at end of file