org.antlr.runtime

Interface IntStream

All Known Subinterfaces:

CharStream, TokenStream, TreeNodeStream

All Known Implementing Classes:

ANTLRFileStream, ANTLRInputStream, ANTLRReaderStream, ANTLRStringStream, BufferedTokenStream, BufferedTreeNodeStream, CommonTokenStream, CommonTreeNodeStream, DebugTokenStream, DebugTreeNodeStream, LegacyCommonTokenStream, TokenRewriteStream, UnbufferedTokenStream

public interface IntStream

A simple stream of integers used when all I care about is the char or token type sequence (such as interpretation).

Method Summary

Methods

Modifier and Type	Method and Description
void	consume()
String	getSourceName() Where are you getting symbols from? Normally, implementations will pass the buck all the way to the lexer who can ask its input stream for the file name or whatever.
int	index() Return the current input symbol index 0..n where n indicates the last symbol has been read.
int	LA(int i) Get int at current input pointer + i ahead where i=1 is next int.
int	mark() Tell the stream to start buffering if it hasn't already.
void	release(int marker) You may want to commit to a backtrack but don't want to force the stream to keep bookkeeping objects around for a marker that is no longer necessary.
void	rewind() Rewind to the input position of the last marker.
void	rewind(int marker) Reset the stream so that next call to index would return marker.
void	seek(int index) Set the input cursor to the position indicated by index.
int	size() Only makes sense for streams that buffer everything up probably, but might be useful to display the entire stream or for testing.

Method Detail

consume

void consume()

LA

int LA(int i)

Get int at current input pointer + i ahead where i=1 is next int. Negative indexes are allowed. LA(-1) is previous token (token just matched). LA(-i) where i is before first token should yield -1, invalid char / EOF.

mark

int mark()

Tell the stream to start buffering if it hasn't already. Return current input position, index(), or some other marker so that when passed to rewind() you get back to the same spot. rewind(mark()) should not affect the input cursor. The Lexer track line/col info as well as input index so its markers are not pure input indexes. Same for tree node streams.

index

int index()

Return the current input symbol index 0..n where n indicates the last symbol has been read. The index is the symbol about to be read not the most recently read symbol.

rewind

void rewind(int marker)

Reset the stream so that next call to index would return marker. The marker will usually be index() but it doesn't have to be. It's just a marker to indicate what state the stream was in. This is essentially calling release() and seek(). If there are markers created after this marker argument, this routine must unroll them like a stack. Assume the state the stream was in when this marker was created.

rewind

void rewind()

Rewind to the input position of the last marker. Used currently only after a cyclic DFA and just before starting a sem/syn predicate to get the input position back to the start of the decision. Do not "pop" the marker off the state. mark(i) and rewind(i) should balance still. It is like invoking rewind(last marker) but it should not "pop" the marker off. It's like seek(last marker's input position).

release

void release(int marker)

You may want to commit to a backtrack but don't want to force the stream to keep bookkeeping objects around for a marker that is no longer necessary. This will have the same behavior as rewind() except it releases resources without the backward seek. This must throw away resources for all markers back to the marker argument. So if you're nested 5 levels of mark(), and then release(2) you have to release resources for depths 2..5.

seek

void seek(int index)

Set the input cursor to the position indicated by index. This is normally used to seek ahead in the input stream. No buffering is required to do this unless you know your stream will use seek to move backwards such as when backtracking. This is different from rewind in its multi-directional requirement and in that its argument is strictly an input cursor (index). For char streams, seeking forward must update the stream state such as line number. For seeking backwards, you will be presumably backtracking using the mark/rewind mechanism that restores state and so this method does not need to update state when seeking backwards. Currently, this method is only used for efficient backtracking using memoization, but in the future it may be used for incremental parsing. The index is 0..n-1. A seek to position i means that LA(1) will return the ith symbol. So, seeking to 0 means LA(1) will return the first element in the stream.

size

int size()

Only makes sense for streams that buffer everything up probably, but might be useful to display the entire stream or for testing. This value includes a single EOF.

getSourceName

String getSourceName()

Where are you getting symbols from? Normally, implementations will pass the buck all the way to the lexer who can ask its input stream for the file name or whatever.