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/*
* Copyright (c) 2000, 2020, Oracle and/or its affiliates.
*
* Licensed under the Universal Permissive License v 1.0 as shown at
* http://oss.oracle.com/licenses/upl.
*/
package com.tangosol.io;
import java.io.InputStream;
import java.io.IOException;
/**
* This is an InputStream class that delegates to another InputStream.
* Primarily, this is intended as a base class for building specific-purpose
* InputStream wrappers.
*
* @author cp 2004.09.09
*/
public class WrapperInputStream
extends InputStream
implements InputStreaming
{
// ----- constructors ---------------------------------------------------
/**
* Construct an uninitialized WrapperInputStream.
*/
public WrapperInputStream()
{
}
/**
* Construct a WrapperInputStream that will input from the specified
* InputStream object.
*
* @param in an InputStream object to read from
*/
public WrapperInputStream(InputStream in)
{
setInputStream(in);
}
// ----- accessors ------------------------------------------------------
/**
* Obtain the underlying InputStream.
*
* @return the underlying InputStream
*/
public InputStream getInputStream()
{
return m_in;
}
/**
* Return the underlying InputStream.
*
* @return the underlying InputStream
*
* @throws IllegalStateException if the underlying stream has not been
* specified.
*/
protected InputStream ensureInputStream()
{
InputStream stream = m_in;
if (stream == null)
{
throw new IllegalStateException
("uninitialized WrapperInputStream");
}
return stream;
}
/**
* Specify the underlying InputSream. This method may only be called once
* with a non-null value.
*
* @param in the stream to be wrapped
*
* @throws IllegalStateException if the underlying stream has already been
* specified.
*/
protected void setInputStream(InputStream in)
{
if (m_in == null)
{
m_in = in;
}
else
{
throw new IllegalStateException("InputStream already specified");
}
}
// ----- InputStream methods --------------------------------------------
/**
* Read the next byte of data from the InputStream. The value byte is
* returned as an int in the range 0 to
* 255. If the end of the stream has been reached, the value
* -1 is returned.
*
* This method blocks until input data is available, the end of the stream
* is detected, or an exception is thrown.
*
* @return the next byte of data, or -1 if the end of the
* stream has been reached
*
* @exception IOException if an I/O error occurs
*/
public int read()
throws IOException
{
return ensureInputStream().read();
}
/**
* Read some number of bytes from the input stream and store them into the
* passed array ab. The number of bytes actually read is
* returned.
*
* This method blocks until input data is available, the end of the stream
* is detected, or an exception is thrown.
*
* @param ab the array to store the bytes which are read from the stream
*
* @return the number of bytes read from the stream, or -1
* if no bytes were read from the stream because the end of the
* stream had been reached
*
* @exception NullPointerException if the passed array is null
* @exception IOException if an I/O error occurs
*/
public int read(byte ab[])
throws IOException
{
return ensureInputStream().read(ab);
}
/**
* Read up to cb bytes from the input stream and store them
* into the passed array ab starting at offset
* of. The number of bytes actually read is returned.
*
* This method blocks until input data is available, the end of the stream
* is detected, or an exception is thrown.
*
* @param ab the array to store the bytes which are read from the stream
* @param of the offset into the array that the read bytes will be stored
* @param cb the maximum number of bytes to read
*
* @return the number of bytes read from the stream, or -1
* if no bytes were read from the stream because the end of the
* stream had been reached
*
* @exception NullPointerException if the passed array is null
* @exception IndexOutOfBoundsException if of or
* cb is negative, or of+cb is
* greater than the length of the ab
* @exception IOException if an I/O error occurs
*/
public int read(byte ab[], int of, int cb)
throws IOException
{
return ensureInputStream().read(ab, of, cb);
}
/**
* Skips over up to the specified number of bytes of data from this
* InputStream. The number of bytes actually skipped over may be fewer
* than the number specified to skip, and may even be zero; this can be
* caused by an end-of-file condition, but can also occur even when there
* is data remaining in the InputStream. As a result, the caller should
* check the return value from this method, which indicates the actual
* number of bytes skipped.
*
* @param cb the maximum number of bytes to skip over
*
* @return the actual number of bytes that were skipped over
*
* @exception IOException if an I/O error occurs
*/
public long skip(long cb)
throws IOException
{
return ensureInputStream().skip(cb);
}
/**
* Returns the number of bytes that can be read (or skipped over) from
* this input stream without causing a blocking I/O condition to occur.
* This method reflects the assumed implementation of various buffering
* InputStreams, which can guarantee non-blocking reads up to the extent
* of their buffers, but beyond that the read operations will have to read
* from some underlying (and potentially blocking) source.
*
* @return the number of bytes that can be read from this InputStream
* without blocking
*
* @exception IOException if an I/O error occurs
*/
public int available()
throws IOException
{
return ensureInputStream().available();
}
/**
* Close the InputStream and release any system resources associated with
* it.
*
* @exception IOException if an I/O error occurs
*/
public void close()
throws IOException
{
ensureInputStream().close();
}
/**
* Marks the current read position in the InputStream in order to support
* the stream to be later "rewound" (using the {@link #reset} method) to
* the current position. The caller passes in the maximum number of bytes
* that it expects to read before calling the {@link #reset} method, thus
* indicating the upper bounds of the responsibility of the stream to be
* able to buffer what it has read in order to support this functionality.
*
* @param cbReadLimit the maximum number of bytes that caller expects the
* InputStream to be able to read before the mark
* position becomes invalid
*/
public void mark(int cbReadLimit)
{
ensureInputStream().mark(cbReadLimit);
}
/**
* Rewind this stream to the position at the time the {@link #mark} method
* was last called on this InputStream. If the InputStream cannot fulfill
* this contract, it should throw an IOException.
*
* @exception IOException if an I/O error occurs, for example if this
* has not been marked or if the mark has been
* invalidated
*/
public void reset()
throws IOException
{
ensureInputStream().reset();
}
/**
* Determine if this InputStream supports the {@link #mark} and
* {@link #reset} methods.
*
* @return true if this InputStream supports the mark and
* reset method; false otherwise
*/
public boolean markSupported()
{
return ensureInputStream().markSupported();
}
// ----- data members ---------------------------------------------------
/**
* The underlying InputStream object to use.
*/
private InputStream m_in;
}