/*
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
*
* Copyright 1997-2007 Sun Microsystems, Inc. All rights reserved.
*
* The contents of this file are subject to the terms of either the GNU
* General Public License Version 2 only ("GPL") or the Common
* Development and Distribution License("CDDL") (collectively, the
* "License"). You may not use this file except in compliance with the
* License. You can obtain a copy of the License at
* http://www.netbeans.org/cddl-gplv2.html
* or nbbuild/licenses/CDDL-GPL-2-CP. See the License for the
* specific language governing permissions and limitations under the
* License. When distributing the software, include this License Header
* Notice in each file and include the License file at
* nbbuild/licenses/CDDL-GPL-2-CP. Sun designates this
* particular file as subject to the "Classpath" exception as provided
* by Sun in the GPL Version 2 section of the License file that
* accompanied this code. If applicable, add the following below the
* License Header, with the fields enclosed by brackets [] replaced by
* your own identifying information:
* "Portions Copyrighted [year] [name of copyright owner]"
*
* Contributor(s):
*
* The Original Software is NetBeans. The Initial Developer of the Original
* Software is Sun Microsystems, Inc. Portions Copyright 1997-2006 Sun
* Microsystems, Inc. All Rights Reserved.
*
* If you wish your version of this file to be governed by only the CDDL
* or only the GPL Version 2, indicate your decision by adding
* "[Contributor] elects to include this software in this distribution
* under the [CDDL or GPL Version 2] license." If you do not indicate a
* single choice of license, a recipient has the option to distribute
* your version of this file under either the CDDL, the GPL Version 2 or
* to extend the choice of license to its licensees as provided above.
* However, if you add GPL Version 2 code and therefore, elected the GPL
* Version 2 license, then the option applies only if the new code is
* made subject to such option by the copyright holder.
*/
package org.netbeans.modules.turbo;
import java.util.List;
/**
* SPI, extension point allowing third parties to redefine
* attribute reading and writing. Must be registered
* in default {@link org.openide.util.Lookup}.
* <p>
* It must generally deternime that they
* support given entity key and attribute pair
* and if so then perform action.
* <p>
* Two providers can theoreticaly clash and support
* the same attribute for the same entity key. The
* key point is that attribute meaning must be precisely
* defined guaranteeing that two independent providers
* respond with exactly same value hence making irrelevant
* which one is actually choosen.
* <p>
* Providers should not cache results.
*
* @author Petr Kuzel
*/
public interface TurboProvider {
/**
* Reports if an attribute is supported by the implementation.
*/
boolean recognizesAttribute(String name);
/**
* Reports if the entity identified by key is supported by the implementation.
*/
boolean recognizesEntity(Object key);
/**
* Reads given attribute for given fileobject. No method
* parameter may be referenced after method execution finishes.
*
* @param key identifies source entity, never <code>null</code>
* @param name identifies requested attribute, never <code>null</code>
* @param memoryCache can store speculative results
* @return attribute value or <code>null</code> if it does not exist.
*/
Object readEntry(Object key, String name, MemoryCache memoryCache);
/**
* Writes given attribute. No method
* parameter may be referenced after method execution finishes.
*
* @param key identifies target entity, never <code>null</code>
* @param name identifies attribute, never <code>null</code>
* @param value actual attribute value that should be stored or <code>null</code> for removing it
* @return <code>false</code> on write failure if provider denies the value. On I/O error it
* returns <code>true</code>.
*/
boolean writeEntry(Object key, String name, Object value);
/**
* Provides direct access to memory layer (without
* delegating to providers layer, here source).
*/
public static final class MemoryCache {
private final boolean enabled;
private final List speculative;
private final Memory memory;
private MemoryCache(boolean enabled) {
this.enabled = enabled;
speculative = null;
memory = null;
}
private MemoryCache(Memory memory, List speculative) {
enabled = true;
this.memory = memory;
this.speculative = speculative;
}
/**
* Creates instance intercepting speculative results.
* @param memory implementation
* @param speculative add()s speculative results into it
*/
static MemoryCache createDefault(Memory memory, List speculative) {
return new MemoryCache(memory, speculative);
}
/** T9Y entry point. */
static MemoryCache getTest() {
return new MemoryCache(false);
}
/**
* Writes speculative entry into memory layer.
*/
public void cacheEntry(Object key, String name, Object value) {
if (enabled == false) return;
memory.put(key, name, value);
if (speculative != null) speculative.add(new Object[] {key, name, value});
}
/** Return speculative results <code>[]{FileObject,String,Object}</code> silently inserted into memory */
List getSpeculative() {
return speculative;
}
}
}
|