info.aduna.io
Class LookAheadReader

java.lang.Object
  java.io.Reader
      info.aduna.io.LookAheadReader

All Implemented Interfaces:

Closeable, Readable

public class LookAheadReader
extends Reader

A character-stream reader that allows look-aheads to be performed. The reader does not look ahead any more than necesarry, so performing a look ahead of 5 characters means that max. 5 characters will be read into the look ahead buffer. The look ahead buffer grows as needed.

Note that this implementation is not synchronized.

FIXME: implementation does too many array copies. Using a 'sliding window' in the buffer is cheaper.

Field Summary

Fields inherited from class java.io.Reader

lock

Constructor Summary

LookAheadReader(Reader r)
Creates a new LookAheadReader with a initial buffer size of 8 characters.

LookAheadReader(Reader r, int bufSize)
Creates a new LookAheadReader.

Method Summary

int	charAt(int lookAhead) Get the character at the supplied lookAhead.
void	close()
int	fillLABuf(int charsNeeded) Tries to fill the look ahead buffer so that it contains 'charsNeeded' characters.
boolean	moreInput() Checks whether there's more input to read.
boolean	nextInputIgnoreCaseIs(String s) Check whether the next input is equal to the supplied string (case-insensitive).
boolean	nextInputIs(String s) Check whether the next input is equal to the supplied string (case-sensitive).
int	read()
int	read(char[] cbuf, int off, int len)
long	skip(long n)

Methods inherited from class java.io.Reader

mark, markSupported, read, read, ready, reset

Methods inherited from class java.lang.Object

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

Constructor Detail

LookAheadReader

public LookAheadReader(Reader r,
                       int bufSize)

Creates a new LookAheadReader.

Parameters:

r - The reader to do the look ahead on

bufSize - The initial size of the look ahead buffer. Minimum size is 1 (needed for 'moreInput()').

LookAheadReader

public LookAheadReader(Reader r)

Creates a new LookAheadReader with a initial buffer size of 8 characters.

Parameters:

r - The reader to do the look ahead on

Method Detail

nextInputIs

public boolean nextInputIs(String s)
                    throws IOException

Check whether the next input is equal to the supplied string (case-sensitive).

Parameters:

s - The string to compare to the input

Returns:

true if the input is equal to the supplied string, false otherwise

Throws:

IOException - If an I/O error occurred in the current Reader or if the string is longer than the maximum look ahead.

nextInputIgnoreCaseIs

public boolean nextInputIgnoreCaseIs(String s)
                              throws IOException

Check whether the next input is equal to the supplied string (case-insensitive).

Parameters:

s - The string to compare to the input

Returns:

true if the input is equal to the supplied string, false otherwise

Throws:

IOException - If an I/O error occurred in the current Reader or if the string is longer than the maximum look ahead.

charAt

public int charAt(int lookAhead)
           throws IOException

Get the character at the supplied lookAhead. charAt(0) returns the first character to be read.

Returns:

the character at the supplied lookAhead, or -1 if the lookAhead is after the last character in the stream.

Throws:

IOException

moreInput

public boolean moreInput()
                  throws IOException

Checks whether there's more input to read.

Throws:

IOException - If an I/O error occurred in the current Reader

fillLABuf

public int fillLABuf(int charsNeeded)
              throws IOException

Tries to fill the look ahead buffer so that it contains 'charsNeeded' characters. This will succeed, except when the end of the stream has been reached.

Returns:

The number of characters in the buffer

Throws:

IOException

read

public int read()
         throws IOException

Overrides:

read in class Reader

Throws:

IOException

read

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

Specified by:

read in class Reader

Throws:

IOException

skip

public long skip(long n)
          throws IOException

Overrides:

skip in class Reader

Throws:

IOException

close

public void close()
           throws IOException

Specified by:

close in interface Closeable

Specified by:

close in class Reader

Throws:

IOException