org.sfj

Class PositionalPushbackReader

java.lang.Object

java.io.Reader

java.io.BufferedReader

java.io.LineNumberReader

org.sfj.PositionalPushbackReader

All Implemented Interfaces:

Closeable, AutoCloseable, Readable

public class PositionalPushbackReader
extends LineNumberReader

This is a basically an infinite pushback Reader, which handles line endings resiliently. It will not be super fast, as all calls end up going through the single char read() method, but it will keep line/column position properly across line endings, across character and line endings being pushed back, etc.

Since it is inifinite, it keeps track of the line lengths of all read lines in a humpty-dumpty linked list, so when newlines are pushed back, the column position is maintained. A similarly linked list is used for pushback chars. I am not certain of the need for a hand rolled linked list for this, but the overhead of boxing seems blah.

End-of-line is denoted by newlines only, and only newlines should be pushed back.

It would have been nice to fit this into PegLeg, as it would be much more efficient for parsing.

Field Summary

Fields inherited from class java.io.Reader

lock

Constructor Summary

Constructors

Constructor and Description
PositionalPushbackReader(Reader r)
PositionalPushbackReader(String source)

Method Summary

Modifier and Type	Method and Description
void	close()
int	getColumnPosition() Position of last read character in the current line.
int	getLineNumber() Line number of last read character.
void	mark(int readAheadLimit)
boolean	markSupported()
void	pushback(int ch) Pushback a character.
int	read() Core method.
int	read(char[] cbuf)
int	read(char[] cbuf, int off, int len)
int	read(CharBuffer target)
String	readLine()
boolean	ready()
void	reset()
void	setLineNumber(int lineNumber)
long	skip(long n)

Methods inherited from class java.io.BufferedReader

lines

Methods inherited from class java.lang.Object

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

Constructor Detail

PositionalPushbackReader

public PositionalPushbackReader(String source)

PositionalPushbackReader

public PositionalPushbackReader(Reader r)

Method Detail

read

public int read()
         throws IOException

Core method. Reads a char, possibly from pushback, return a char, or -1 on end of input.

Overrides:

read in class LineNumberReader

Returns:

char as int, or -1 on end of input.

Throws:

IOException

pushback

public void pushback(int ch)

Pushback a character. Use '\n' newline for end of line. If you pushback a char that was not read, the line number/column position maintanence behavior is undefined.

Parameters:

ch - char to pushback.

skip

public long skip(long n)
          throws IOException

Overrides:

skip in class LineNumberReader

Throws:

IOException

ready

public boolean ready()
              throws IOException

Overrides:

ready in class BufferedReader

Throws:

IOException

reset

public void reset()
           throws IOException

Overrides:

reset in class LineNumberReader

Throws:

IOException

read

public int read(CharBuffer target)
         throws IOException

Specified by:

read in interface Readable

Overrides:

read in class Reader

Throws:

IOException

read

public int read(char[] cbuf)
         throws IOException

Overrides:

read in class Reader

Throws:

IOException

markSupported

public boolean markSupported()

Overrides:

markSupported in class BufferedReader

mark

public void mark(int readAheadLimit)

Overrides:

mark in class LineNumberReader

read

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

Overrides:

read in class LineNumberReader

Throws:

IOException

close

public void close()
           throws IOException

Specified by:

close in interface Closeable

Specified by:

close in interface AutoCloseable

Overrides:

close in class BufferedReader

Throws:

IOException

getColumnPosition

public int getColumnPosition()

Position of last read character in the current line. 1 is the first position.

Returns:

position

getLineNumber

public int getLineNumber()

Line number of last read character. 1 indexed.

Overrides:

getLineNumber in class LineNumberReader

Returns:

line number

setLineNumber

public void setLineNumber(int lineNumber)

Overrides:

setLineNumber in class LineNumberReader

readLine

public String readLine()
                throws IOException

Overrides:

readLine in class LineNumberReader

Throws:

IOException