Add AbstractHigherOrderDataHandle

Abstract superclass for DataHandles that operate over other DataHandles

Author: gab1one

src/main/java/org/scijava/io/handle/AbstractHigherOrderHandle.java

@@ -0,0 +1,113 @@
+/*
+ * #%L
+ * SciJava Common shared library for SciJava software.
+ * %%
+ * Copyright (C) 2009 - 2017 Board of Regents of the University of
+ * Wisconsin-Madison, Broad Institute of MIT and Harvard, Max Planck
+ * Institute of Molecular Cell Biology and Genetics, University of
+ * Konstanz, and KNIME GmbH.
+ * %%
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDERS OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ * #L%
+ */
+
+package org.scijava.io.handle;
+
+import java.io.IOException;
+
+import org.scijava.io.location.Location;
+
+/**
+ * Abstract superclass for {@link DataHandle}s that operate over other
+ * {@link DataHandle}s.
+ *
+ * @author Gabriel Einsdorf
+ */
+public abstract class AbstractHigherOrderHandle<L extends Location> extends
+	AbstractDataHandle<L>
+{
+
+	private final DataHandle<L> handle;
+	private boolean closed;
+
+	public AbstractHigherOrderHandle(final DataHandle<L> handle) {
+		this.handle = handle;
+		set(handle.get()); // provides access to underlying location
+	}
+
+	@Override
+	public boolean isReadable() {
+		return !closed && handle.isReadable();
+	}
+
+	@Override
+	public boolean isWritable() {
+		return !closed && handle.isWritable();
+	}
+
+	@Override
+	public long length() throws IOException {
+		return handle.length();
+	}
+
+	@Override
+	public Class<L> getType() {
+		return handle.getType();
+	}
+
+	@Override
+	public boolean exists() throws IOException {
+		return handle.exists();
+	}
+
+	@Override
+	public void close() throws IOException {
+		if (!closed) {
+			cleanup();
+			closed = true;
+			handle.close();
+		}
+	}
+
+	protected void ensureOpen() throws IOException {
+		if (closed) {
+			throw new IOException("This handle is closed!");
+		}
+	}
+
+	/**
+	 * Clean up data structures after a handle has been closed in the
+	 * {@link #close()} method.
+	 *
+	 * @throws IOException
+	 */
+	protected abstract void cleanup() throws IOException;
+
+	/**
+	 * @return the {@link DataHandle} wrapped by this
+	 *         {@link AbstractHigherOrderHandle}
+	 */
+	protected DataHandle<L> handle() {
+		return handle;
+	}
+
+}