org.python.util

Class ConsoleInputStream

java.lang.Object

java.io.InputStream

java.io.FilterInputStream

org.python.util.ConsoleInputStream

All Implemented Interfaces:

java.io.Closeable, java.lang.AutoCloseable

public abstract class ConsoleInputStream
extends java.io.FilterInputStream

This class is intended to replace System.in for use with console libraries that provide a line-oriented input mechanism. The console libraries provide a method to get the next line from the console as a String. Particular sub-classes should wrap this character-oriented method in a definition of getLine().

The libraries JLine and Java Readline have both been used to give Jython line-recall, editing and a line history preserved between sessions. Both deal with the console encoding internally, and interact with the user in terms of a buffer of characters. Our need in Jython is to access a byte-stream encoding the characters, with line-endings, since it is the text layer of the Python io stack, whether we are using the io module or file built-in, that should deal with encoding.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	ConsoleInputStream.EOLPolicy Enumeration used to specify whether an end-of-line should be added or replaced at the end of each line read.

Field Summary

Fields

Modifier and Type	Field and Description
protected static java.nio.ByteBuffer	EMPTY_BUF Empty buffer
protected java.nio.charset.Charset	encoding The character encoding specified in the constructor.
protected java.lang.String	eol The end-of-line String specified in the constructor.
protected ConsoleInputStream.EOLPolicy	eolPolicy The ConsoleInputStream.EOLPolicy specified in the constructor.
protected static java.lang.String	LINE_SEPARATOR Platform-defined end-of-line for convenience

Fields inherited from class java.io.FilterInputStream

in

Method Summary

Modifier and Type	Method and Description
int	available() The number of bytes left unread in the current encoded line.
protected abstract java.lang.CharSequence	getLine() Get one line of input from the console.
void	mark(int readlimit) Mark is not supported.
boolean	markSupported() Mark is not supported.
int	read() Read the next byte of data from the buffered input line.
int	read(byte[] b, int off, int len) Reads up to len bytes of data from this input stream into an array of bytes.
void	reset() Mark is not supported.
long	skip(long n) Skip forward n bytes within the current encoded line.

Methods inherited from class java.io.FilterInputStream

close, read

Methods inherited from class java.lang.Object

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

Field Detail

eolPolicy

protected final ConsoleInputStream.EOLPolicy eolPolicy

The ConsoleInputStream.EOLPolicy specified in the constructor.

eol

protected final java.lang.String eol

The end-of-line String specified in the constructor.

encoding

protected final java.nio.charset.Charset encoding

The character encoding specified in the constructor.

EMPTY_BUF

protected static final java.nio.ByteBuffer EMPTY_BUF

Empty buffer

LINE_SEPARATOR

protected static final java.lang.String LINE_SEPARATOR

Platform-defined end-of-line for convenience

Method Detail

getLine

protected abstract java.lang.CharSequence getLine()
                                           throws java.io.IOException,
                                                  java.io.EOFException

Get one line of input from the console. Override this method with the actions specific to the library in use.

Returns:

Line entered by user

Throws:

java.io.IOException - in case of an error

java.io.EOFException - if the library recognises an end-of-file condition

read

public int read()
         throws java.io.IOException

Read the next byte of data from the buffered input line. The byte is returned as an int in the range 0 to 255. If no byte is available because the end of the stream has been recognised, the value -1 is returned. This method blocks until input data are available, the end of the stream is detected, or an exception is thrown. Normally, an empty line results in an encoded end-of-line being returned.

Overrides:

read in class java.io.FilterInputStream

Throws:

java.io.IOException

read

public int read(byte[] b,
                int off,
                int len)
         throws java.io.IOException,
                java.io.EOFException

Reads up to len bytes of data from this input stream into an array of bytes. If len is not zero, the method blocks until some input is available; otherwise, no bytes are read and 0 is returned. This implementation calls getLine() at most once to get a line of characters from the console, and encodes them as bytes to be read back from the stream.

Overrides:

read in class java.io.FilterInputStream

Throws:

java.io.IOException

java.io.EOFException

skip

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

Skip forward n bytes within the current encoded line. A call to skip will not result in reading a new line with getLine().

Overrides:

skip in class java.io.FilterInputStream

Throws:

java.io.IOException

available

public int available()
              throws java.io.IOException

The number of bytes left unread in the current encoded line.

Overrides:

available in class java.io.FilterInputStream

Throws:

java.io.IOException

mark

public void mark(int readlimit)

Mark is not supported.

Overrides:

mark in class java.io.FilterInputStream

reset

public void reset()
           throws java.io.IOException

Mark is not supported.

Overrides:

reset in class java.io.FilterInputStream

Throws:

java.io.IOException

markSupported

public boolean markSupported()

Mark is not supported.

Overrides:

markSupported in class java.io.FilterInputStream