// Copyright 2002, FreeHEP.
package org.freehep.util.io;
import java.io.IOException;
import java.io.InputStream;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
/**
* The RoutedInputStream allows the user to add a listener for a certain
* delimited portion of the main inputstream. This portion is marked by a start
* and end marker. The end marker can be null, in which case the portion runs
* from the start marker to the end of the main inputstream. The listener is
* informed via a route (partial inputstream) when input is available. The new
* routed inputstream (route) is supposed to be read to the end or closed, after
* which the main inputstream should be read again. Closing a route will not
* close the original stream, but will discard any bytes up to and including the
* end marker. Returning from a route without reading until the end of the route
* means that the remaining bytes are still available on the main stream.
* Multiple routes can be added, as long as they have different start sequences.
* Start sequences such as "StartA, StartB, StartEmpty" are allowed, but "Start,
* StartOther" are not since they overlap. Start and End markers can be the
* same.
*
* IMPORTANT: inherits from InputStream rather than FilterInputStream so that
* the correct read(byte[], int, int) method is used.
*
* @author Mark Donszelmann
* @version $Id: RoutedInputStream.java 8584 2006-08-10 23:06:37Z duns $
*/
public class RoutedInputStream extends InputStream {
private InputStream in;
private Map routes, listeners;
private byte[] buffer;
private int sob, eob;
private int index;
private int state;
private byte[] start;
private static final int UNROUTED = 0; // the main stream is returned
private static final int ROUTEFOUND = 1; // found a route, but need to
// still return buffer
private static final int ROUTEINFORM = 2; // buffer returned, need to
// inform routelistener
private static final int ROUTED = 3; // the main stream is now routed to
// the route
private static final int CLOSING = 4; // the underlying stream is closed,
// but buffer need to be emptied
private static final int CLOSED = 5; // the main stream is closed
/**
* Creates a RoutedInputStream from the underlying stream.
*
* @param input stream to read
*/
public RoutedInputStream(InputStream input) {
super();
in = input;
routes = new HashMap();
listeners = new HashMap();
// bufferlength has to be more than 1
buffer = new byte[20];
sob = -1;
eob = 0;
index = 0;
state = UNROUTED;
}
/**
* Returns the next byte on this stream, however if a start marker is found,
* the associated route listener is called, which should take over reading
* the stream. In this case this method will, after the route is finished
* reading and closed, return the first byte after the end marker. This of
* course unless that byte is part of the next start marker.
*/
public int read() throws IOException {
int result;
NEWSTATE: while (true) {
switch (state) {
default:
case UNROUTED:
// fill the buffer with one or more bytes
int b = -1;
while (sob != eob) {
if (sob < 0)
sob = 0;
// read a byte from the underlying stream
b = in.read();
if (b < 0) {
// underlying stream closed
state = CLOSING;
continue NEWSTATE;
}
// try to find a start marker
buffer[eob] = (byte) b;
eob = (eob + 1) % buffer.length;
// search for a route
for (Iterator i = routes.keySet().iterator(); i.hasNext();) {
start = (byte[]) i.next();
index = (eob + buffer.length - start.length)
% buffer.length;
if (equals(start, buffer, index)) {
state = ROUTEFOUND;
continue NEWSTATE;
}
}
} // while
// always return what drops from the buffer
// the buffer is one byte longer than the longest start marker,
// so even
// if we find that marker we can still return the byte just in
// front of it.
result = buffer[sob];
sob = (sob + 1) % buffer.length;
return result;
case ROUTEFOUND:
// found a start marker, we still need to return all bytes
// before
// the marker; i.e. from sob to index
if (sob == index) {
state = ROUTEINFORM;
continue NEWSTATE;
}
result = buffer[sob];
sob = (sob + 1) % buffer.length;
return result;
case ROUTEINFORM:
// we inform the routelistener to start reading
state = ROUTED;
Route route = new Route(start, (byte[]) routes.get(start));
// next call will generate callbacks to this read method in
// state ROUTED.
((RouteListener) listeners.get(start)).routeFound(route);
// route listener finished
state = UNROUTED;
if (sob == eob) {
// we restart buffering if the buffer was empty
sob = -1;
eob = 0;
continue NEWSTATE;
}
// FIXME: we need an UNROUTING here which just returns the
// buffer, but does not refill it, in case the reads would
// block...
// we return a byte from the buffer and
// let the next call take care of rebuffering, otherwise we may
// block
result = buffer[sob];
sob = (sob + 1) % buffer.length;
return result;
case ROUTED:
// calls end up here when the Route is reading. We should
// return the start marker (in buffer) followed by newly read
// bytes.
if (sob == eob) {
result = in.read();
if (result < 0) {
state = CLOSED;
continue NEWSTATE;
}
} else {
result = buffer[sob];
sob = (sob + 1) % buffer.length;
}
return result;
case CLOSING:
// the underlying stream is closed, no more markers can be found
// thus the rest of the buffer is returned
if (sob == eob) {
state = CLOSED;
continue NEWSTATE;
}
result = buffer[sob];
sob = (sob + 1) % buffer.length;
return result;
case CLOSED:
// all streams are closed
return -1;
} // switch
} // while
}
/**
* Adds a route for given start and end string. The strings are converted
* according to the default encoding to start and end markers (byte[]).
*
* @param start start marker
* @param end end marker
* @param listener listener to inform about the route
*/
public void addRoute(String start, String end, RouteListener listener) {
addRoute(start.getBytes(), (end == null) ? null : end.getBytes(),
listener);
}
/**
* Adds a route for given start and end marker.
*
* If the end marker is null, the route is indefinite, and can be read until
* the main stream ends.
*
* If the start and end marker are equal, the route can be read for exactly
* their length.
*
* @param start start marker
* @param end end marker
* @param listener listener to inform about the route
*/
public void addRoute(byte[] start, byte[] end, RouteListener listener) {
for (Iterator i = routes.keySet().iterator(); i.hasNext();) {
String key = new String((byte[]) i.next());
String name = new String(start);
if (key.startsWith(name) || name.startsWith(key)) {
throw new IllegalArgumentException("Route '" + name
+ "' cannot be added since it overlaps with '" + key
+ "'.");
}
}
routes.put(start, end);
listeners.put(start, listener);
// we make the buffer one longer than the longest start marker, so that
// read() can always return a byte before a marker.
if (start.length > buffer.length - 1) {
byte[] tmp = new byte[start.length + 1];
System.arraycopy(buffer, 0, tmp, 0, buffer.length);
buffer = tmp;
}
}
/**
* Checks if cmp is equal to buf (with start at index) for the length of
* cmp.
*
* @param cmp buffer1 to compare
* @param buf buffer2 to compare
* @param index start index to start compare
* @return true if cmp == buf for length of cmp.
*/
private static boolean equals(byte[] cmp, byte[] buf, int index) {
for (int i = cmp.length - 1; i > 0; i--) {
int j = (index + buf.length + i) % buf.length;
if (buf[j] != cmp[i]) {
return false;
}
}
return buf[(index + buf.length) % buf.length] == cmp[0];
}
/**
* Route which can be read up to and including the end marker.
*
* When you close the route, all bytes including the end marker will be
* read/discarded before returning.
*
* If you just discard the Route, the underlying stream will still return
* you all or part of the bytes of this route.
*
* If the end marker is set to null, the stream can be read until the
* underlying stream ends.
*/
public class Route extends InputStream {
private byte[] start, end;
private byte[] buffer;
private int index;
private boolean closed;
/**
* Creates a route with given start and end marker.
*
* @param start start marker
* @param end end marker
*/
public Route(byte[] start, byte[] end) {
this.start = start;
this.end = end;
if (end != null)
buffer = new byte[end.length];
index = 0;
closed = false;
}
/**
* Returns bytes of this specific route, starting with the start marker,
* followed by any bytes up to and including the end marker.
*
* If the end marker is null, the route is indefinite.
*/
public int read() throws IOException {
if (closed)
return -1;
int b = RoutedInputStream.this.read();
if (b < 0) {
closed = true;
return b;
}
if (end == null)
return b;
buffer[index] = (byte) b;
index = (index + 1) % buffer.length;
closed = RoutedInputStream.equals(end, buffer, index);
return b;
}
/**
* Closes the stream, and discards any bytes up to and including the end
* marker.
*/
public void close() throws IOException {
while (read() >= 0) {
}
;
closed = true;
}
/**
* Returns start marker.
*
* @return start marker
*/
public byte[] getStart() {
return start;
}
/**
* Returns end marker.
*
* @return end marker
*/
public byte[] getEnd() {
return end;
}
}
}
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