net.sf.japaki.io
Class RingBuffer

java.lang.Object
  net.sf.japaki.io.RingBuffer

All Implemented Interfaces:

Closeable, ReaderBuffer

public class RingBuffer
extends Object
implements ReaderBuffer

A ring buffer stores the characters read from the input stream in a buffer. The last read characters overwrite the oldest data in the buffer.

Implementation

The buffer stores the last n characters read from the input stream, where n is the buffer's capacity.

• offset is the location of the buffer's first character in the input stream.
• On the left side of the buffer's position are the characters from offset to offset+position.
• On the right hand side are the characters from offset-n+position to offset-1.

Example: Capacity is 100, offset is 300 and position 60. The buffer holds characters 260 to 299 in the right side and from 300 to 359 in the left side of the buffer.

Constructor Summary

RingBuffer(Reader in)
Constructs a new RingBuffer with a default buffer size.

RingBuffer(Reader in, int sz)
Constructs a new RingBuffer.

Method Summary

void	close()
void	free(int pos) Frees the buffer before the specified position.
int	read(char[] cbuf, int off, int len, int pos) Retrieves a sequence of characters as described in read.
String	toString()

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

RingBuffer

public RingBuffer(Reader in,
                  int sz)

Constructs a new RingBuffer.

Parameters:

in - base reader

sz - size to be allocated for the underlying buffer

Throws:

NullPointerException - if in is null

IllegalArgumentException - if the size is a negative integer

RingBuffer

public RingBuffer(Reader in)

Constructs a new RingBuffer with a default buffer size.

Parameters:

in - base reader

Throws:

NullPointerException - if in is null

Method Detail

read

public int read(char[] cbuf,
                int off,
                int len,
                int pos)
         throws IOException

Description copied from interface: ReaderBuffer

Retrieves a sequence of characters as described in read.

Specified by:

read in interface ReaderBuffer

Parameters:

cbuf - Destination buffer

off - Offset at which to start storing characters

len - Maximum number of characters to read

pos - Position, where to start reading in the stream

Returns:

The number of characters read, or -1 if the end of the stream has been reached

Throws:

IOException - If the specified position is not covered by the underlying buffer or if an I/O error occurs

free

public void free(int pos)

Description copied from interface: ReaderBuffer

Frees the buffer before the specified position.

Specified by:

free in interface ReaderBuffer

Parameters:

pos - All characters before this position may no longer be stored in the underlying buffer. Actual behaviour depends on the implementation.

close

public void close()
           throws IOException

Specified by:

close in interface Closeable

Throws:

IOException

toString

public String toString()

Overrides:

toString in class Object