org.millscript.tools
Class PushbackLinenumberReader

java.lang.Object
  java.io.Reader
      org.millscript.tools.PushbackLinenumberReader

All Implemented Interfaces:

java.io.Closeable, java.lang.Readable

public class PushbackLinenumberReader
extends java.io.Reader

A buffered character stream reader that allows characters to be pushed back and keeps track of line numbers. By default we start line numbers at 1, rather than 0 as is Java.

Due to the implementation, there may be more available push back space than the value specified. However, you are guaranteed to have at least the requested amount of push back space.

This is heavily based on Java's LineNumberReader, PushbackReader and BufferedReader. However PushbackReader fails when you push back an end of file character(-1) as it simply pushes -1 into a char array! Also, although you could construct a PushbackReader on a LineNumberReader, or vice versa, if you push back an end of line you would have a hard time obtaining the correct line number.

Field Summary

Fields inherited from class java.io.Reader

lock

Constructor Summary

PushbackLinenumberReader(java.io.Reader in)

PushbackLinenumberReader(java.io.Reader in, int sz, int pb)
Constructs a new push back line number reader, which will buffer the specified number of characters and have a push back buffer of the given minimum size.

Method Summary

void	close()
int	getLineNumber() Returns the line number for the current position in the file.
void	mark(int readAheadLimit)
boolean	markSupported()
int	read() Reads a single character, returning it as an int.
int	read(char[] cbuf, int off, int len) Read characters into a portion of an array.
java.lang.String	readLine() Reads a line of text.
boolean	ready()
void	reset()
void	setLineNumber(int n) Sets the current line number
long	skip(long n) Skips the requested number of characters.
void	unread(char[] cbuf) Pushes back all the characters in specified buffer.
void	unread(char[] cbuf, int off, int len) Pushes back a specified number of characters from the specified buffer, starting from the specified offset.
void	unread(int ch) Pushes back the specified character.

Methods inherited from class java.io.Reader

read, read

Methods inherited from class java.lang.Object

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

Constructor Detail

PushbackLinenumberReader

public PushbackLinenumberReader(java.io.Reader in)

Parameters:

in - a Reader to fetch characters from

PushbackLinenumberReader

public PushbackLinenumberReader(java.io.Reader in,
                                int sz,
                                int pb)

Constructs a new push back line number reader, which will buffer the specified number of characters and have a push back buffer of the given minimum size.

Parameters:

in - a Reader to fetch characters from

sz - the number of characters to buffer

pb - the minimum number of push back characters

Method Detail

close

public void close()
           throws java.io.IOException

Specified by:

close in interface java.io.Closeable

Specified by:

close in class java.io.Reader

Throws:

java.io.IOException

See Also:

Reader.close()

getLineNumber

public int getLineNumber()

Returns the line number for the current position in the file. i.e. if you've just read a end of line character, the line number will have been incremented. If you've just read a block of characters the line number may have been incremented multiple times.

Returns:

the current line number

mark

public void mark(int readAheadLimit)
          throws java.io.IOException

Overrides:

mark in class java.io.Reader

Throws:

java.io.IOException

See Also:

Reader.mark(int)

markSupported

public boolean markSupported()

Overrides:

markSupported in class java.io.Reader

See Also:

Reader.markSupported()

read

public int read()
         throws java.io.IOException

Reads a single character, returning it as an int. Line terminators are compressed into a single line feed('\n') character. A line is terminated by a line feed('\n'), a carriage return('\r') or a carriage return immediately followed by a line feed('\r\n').

Overrides:

read in class java.io.Reader

Returns:

an int containing the next character code

Throws:

java.io.IOException - if there is a problem reading from the source reader

read

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

Read characters into a portion of an array. This method compresses line endings in the same way as the read method.

Specified by:

read in class java.io.Reader

Parameters:

cbuf - the character buffer to read characters into

off - the position in the character buffer to start placing characters at

len - the maximum number of characters to read

Returns:

the number of characters read

Throws:

java.io.IOException - thrown if there is a problem reading a character from the parent reader

readLine

public java.lang.String readLine()
                          throws java.io.IOException

Reads a line of text. A line is terminated by a line feed('\n'), a carriage return('\r') or a carriage return immediately followed by a line feed.

Returns:

a String holding the line of text read or null if the end of file has been reached.

Throws:

java.io.IOException - if an I/O exception occurs

ready

public boolean ready()
              throws java.io.IOException

Overrides:

ready in class java.io.Reader

Throws:

java.io.IOException

See Also:

Reader.ready()

reset

public void reset()
           throws java.io.IOException

Overrides:

reset in class java.io.Reader

Throws:

java.io.IOException

See Also:

Reader.reset()

setLineNumber

public void setLineNumber(int n)

Sets the current line number

Parameters:

n - an int specifying the new current line number

skip

public long skip(long n)
          throws java.io.IOException

Skips the requested number of characters. This method does not compress line endings like the read method.

Overrides:

skip in class java.io.Reader

Parameters:

n - the number of characters to skip

Returns:

the number of characters skipped

Throws:

java.io.IOException - thrown if there is a problem reading from the parent reader

unread

public void unread(int ch)
            throws java.io.IOException

Pushes back the specified character.

Parameters:

ch - the character to push back. This can include any value returned by read, including the end of line.

Throws:

java.io.IOException - thrown if there is a problem reading from the parent reader

unread

public void unread(char[] cbuf)
            throws java.io.IOException

Pushes back all the characters in specified buffer.

Parameters:

cbuf - the array of characters to unread

Throws:

java.io.IOException - thrown if there is a problem reading from the parent reader

unread

public void unread(char[] cbuf,
                   int off,
                   int len)
            throws java.io.IOException

Pushes back a specified number of characters from the specified buffer, starting from the specified offset.

Parameters:

cbuf - the array of characters to unread

off - the position in the buffer to unread from

len - the number of characters to unread

Throws:

java.io.IOException - thrown if there is a problem reading from the parent reader