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/*******************************************************************************
* Copyright (c) 2006, 2008 IBM Corporation and others.
*
* This program and the accompanying materials
* are made available under the terms of the Eclipse Public License 2.0
* which accompanies this distribution, and is available at
* https://www.eclipse.org/legal/epl-2.0/
*
* SPDX-License-Identifier: EPL-2.0
*
* Contributors:
* IBM Corporation - initial API and implementation
*******************************************************************************/
package org.eclipse.equinox.internal.transforms;
import java.io.IOException;
import java.io.InputStream;
/**
* An input stream that is based off of another stream.
* This other stream is provided as needed by an {@link InputStreamProvider} so that the underlying stream is not eagerly loaded.
*/
public class LazyInputStream extends InputStream {
private InputStreamProvider provider;
private InputStream original = null;
/**
* Construct a new lazy stream based off the given provider.
* @param provider the input stream provider. Must not be <code>null</code>.
*/
public LazyInputStream(InputStreamProvider provider) {
if (provider == null)
throw new IllegalArgumentException();
this.provider = provider;
}
private void initOriginal() throws IOException {
if (original == null)
original = provider.getInputStream();
}
public int available() throws IOException {
initOriginal();
return original.available();
}
public void close() throws IOException {
initOriginal();
original.close();
}
public boolean equals(Object obj) {
try {
initOriginal();
return original.equals(obj);
} catch (IOException e) {
throw new RuntimeException(e);
}
}
public int hashCode() {
try {
initOriginal();
return original.hashCode();
} catch (IOException e) {
throw new RuntimeException(e);
}
}
public void mark(int readlimit) {
try {
initOriginal();
original.mark(readlimit);
} catch (IOException e) {
throw new RuntimeException(e);
}
}
public boolean markSupported() {
try {
initOriginal();
return original.markSupported();
} catch (IOException e) {
throw new RuntimeException(e);
}
}
public int read() throws IOException {
initOriginal();
return original.read();
}
public int read(byte[] b, int off, int len) throws IOException {
initOriginal();
return original.read(b, off, len);
}
public int read(byte[] b) throws IOException {
initOriginal();
return original.read(b);
}
public void reset() throws IOException {
initOriginal();
original.reset();
}
public long skip(long n) throws IOException {
initOriginal();
return original.skip(n);
}
public String toString() {
try {
initOriginal();
return original.toString();
} catch (IOException e) {
throw new RuntimeException(e);
}
}
/**
* An interface to be implemented by clients that wish to utilize {@link LazyInputStream}s.
* The implementation of this interface should defer obtaining the desired input stream until absolutely necessary.
*/
public static interface InputStreamProvider {
/**
* Return the input stream.
* @return the input stream
* @throws IOException thrown if there is an issue obtaining the stream
*/
InputStream getInputStream() throws IOException;
}
}
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