org.antlr.runtime
Class CommonTokenStream

java.lang.Object
  org.antlr.runtime.BufferedTokenStream
      org.antlr.runtime.CommonTokenStream

All Implemented Interfaces:

IntStream, TokenStream

Direct Known Subclasses:

TokenRewriteStream

public class CommonTokenStream
extends BufferedTokenStream

The most common stream of tokens where every token is buffered up and tokens are filtered for a certain channel (the parser will only see these tokens). Even though it buffers all of the tokens, this token stream pulls tokens from the tokens source on demand. In other words, until you ask for a token using consume(), LT(), etc. the stream does not pull from the lexer. The only difference between this stream and BufferedTokenStream superclass is that this stream knows how to ignore off channel tokens. There may be a performance advantage to using the superclass if you don't pass whitespace and comments etc. to the parser on a hidden channel (i.e., you set $channel instead of calling skip() in lexer rules.)

See Also:

UnbufferedTokenStream, BufferedTokenStream

Field Summary

protected int

channel Skip tokens on any channel but this one; this is how we skip whitespace...

Fields inherited from class org.antlr.runtime.BufferedTokenStream

lastMarker, p, range, tokens, tokenSource

Constructor Summary

CommonTokenStream()

CommonTokenStream(TokenSource tokenSource)

CommonTokenStream(TokenSource tokenSource, int channel)

Method Summary

void	consume() Always leave p on an on-channel token.
int	getNumberOfOnChannelTokens() Count EOF just once.
protected Token	LB(int k)
Token	LT(int k) Get Token at current input pointer + i ahead where i=1 is next Token.
void	reset()
void	setTokenSource(TokenSource tokenSource) Reset this token stream by setting its token source.
protected void	setup()
protected int	skipOffTokenChannels(int i) Given a starting index, return the index of the first on-channel token.
protected int	skipOffTokenChannelsReverse(int i)

Methods inherited from class org.antlr.runtime.BufferedTokenStream

fetch, fill, get, get, getSourceName, getTokens, getTokens, getTokens, getTokens, getTokens, getTokenSource, index, LA, mark, range, release, rewind, rewind, seek, size, sync, toString, toString, toString

Methods inherited from class java.lang.Object

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

Field Detail

channel

protected int channel

Skip tokens on any channel but this one; this is how we skip whitespace...

Constructor Detail

CommonTokenStream

public CommonTokenStream()

CommonTokenStream

public CommonTokenStream(TokenSource tokenSource)

CommonTokenStream

public CommonTokenStream(TokenSource tokenSource,
                         int channel)

Method Detail

consume

public void consume()

Always leave p on an on-channel token.

Specified by:

consume in interface IntStream

Overrides:

consume in class BufferedTokenStream

LB

protected Token LB(int k)

Overrides:

LB in class BufferedTokenStream

LT

public Token LT(int k)

Description copied from interface: TokenStream

Get Token at current input pointer + i ahead where i=1 is next Token. i<0 indicates tokens in the past. So -1 is previous token and -2 is two tokens ago. LT(0) is undefined. For i>=n, return Token.EOFToken. Return null for LT(0) and any index that results in an absolute address that is negative.

Specified by:

LT in interface TokenStream

Overrides:

LT in class BufferedTokenStream

skipOffTokenChannels

protected int skipOffTokenChannels(int i)

Given a starting index, return the index of the first on-channel token.

skipOffTokenChannelsReverse

protected int skipOffTokenChannelsReverse(int i)

reset

public void reset()

Overrides:

reset in class BufferedTokenStream

setup

protected void setup()

Overrides:

setup in class BufferedTokenStream

getNumberOfOnChannelTokens

public int getNumberOfOnChannelTokens()

Count EOF just once.

setTokenSource

public void setTokenSource(TokenSource tokenSource)

Reset this token stream by setting its token source.

Overrides:

setTokenSource in class BufferedTokenStream