Package antlr

Class TokenStreamSelector

java.lang.Object

antlr.TokenStreamSelector

All Implemented Interfaces:

IASDebugStream, TokenStream

public class TokenStreamSelector
extends Object
implements TokenStream, IASDebugStream

A token stream MUX (multiplexor) knows about n token streams and can multiplex them onto the same channel for use by token stream consumer like a parser. This is a way to have multiple lexers break up the same input stream for a single parser. Or, you can have multiple instances of the same lexer handle multiple input streams; this works great for includes.

Field Summary

Fields

Modifier and Type	Field	Description
protected TokenStream	input	The currently-selected token stream input
protected Hashtable	inputStreamNames	The set of inputs to the MUX
protected Stack	streamStack	Used to track stack of input streams

Constructor Summary

Constructors

Constructor	Description
TokenStreamSelector()

Method Summary

Modifier and Type	Method	Description
void	addInputStream(TokenStream stream, String key)
TokenStream	getCurrentStream()	Return the stream from tokens are being pulled at the moment.
String	getEntireText()	Returns the entire text input to the lexer.
TokenOffsetInfo	getOffsetInfo(Token token)	Returns the offset information for the token
TokenStream	getStream(String sname)
Token	nextToken()
TokenStream	pop()
void	push(TokenStream stream)
void	push(String sname)
void	retry()	Abort recognition of current Token and try again.
void	select(TokenStream stream)	Set the stream without pushing old stream
void	select(String sname)

Methods inherited from class java.lang.Object

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

Field Details

inputStreamNames

protected Hashtable inputStreamNames

The set of inputs to the MUX

input

protected TokenStream input

The currently-selected token stream input

streamStack

protected Stack streamStack

Used to track stack of input streams

Constructor Details

TokenStreamSelector

public TokenStreamSelector()

Method Details

addInputStream

public void addInputStream(TokenStream stream,
 String key)

getCurrentStream

public TokenStream getCurrentStream()

Return the stream from tokens are being pulled at the moment.

getStream

public TokenStream getStream(String sname)

nextToken

public Token nextToken()
                throws TokenStreamException

Specified by:

nextToken in interface TokenStream

Throws:

TokenStreamException

pop

public TokenStream pop()

push

public void push(TokenStream stream)

push

public void push(String sname)

retry

public void retry()
           throws TokenStreamRetryException

Abort recognition of current Token and try again. A stream can push a new stream (for include files for example, and then retry(), which will cause the current stream to abort back to this.nextToken(). this.nextToken() then asks for a token from the current stream, which is the new "substream."

Throws:

TokenStreamRetryException

select

public void select(TokenStream stream)

Set the stream without pushing old stream

select

public void select(String sname)
            throws IllegalArgumentException

Throws:

IllegalArgumentException

getEntireText

public String getEntireText()

Description copied from interface: IASDebugStream

Returns the entire text input to the lexer.

Specified by:

getEntireText in interface IASDebugStream

Returns:

The entire text or null, if error occured or System.in was used.

getOffsetInfo

public TokenOffsetInfo getOffsetInfo(Token token)

Description copied from interface: IASDebugStream

Returns the offset information for the token

Specified by:

getOffsetInfo in interface IASDebugStream

Parameters:

token - the token whose information need to be retrieved

Returns:

offset info, or null