Class CommonTokenStream

@param tokenSource A TokenSource instance (usually a Lexer) to pull
    the tokens from.

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

Overrides: object.__init__

Load all tokens from the token source and put in tokens. This is done upon first LT request because you might want to set some token type / channel overrides before filling buffer.

Move the input pointer to the next incoming token. The stream must become active with LT(1) available. consume() simply moves the input pointer so that LT(1) points at the next input symbol. Consume at least one token.

Walk past any token not on the channel the parser is listening to.

Overrides: IntStream.consume

A simple filter mechanism whereby you can tell this token stream to force all tokens of type ttype to be on channel. For example, when interpreting, we cannot exec actions so we need to tell the stream to force all WS and NEWLINE to be a different, ignored channel.

Given a start and stop index, return a list of all tokens in the token type set. Return None if no tokens were found. This method looks at both on and off channel tokens.

Get the ith token from the current position 1..n where k=1 is the first symbol of lookahead.

Overrides: TokenStream.LT

Return absolute token i; ignore which channel the tokens are on; that is, count all tokens not just on-channel tokens.

Overrides: TokenStream.get

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.

Overrides: IntStream.LA

(inherited documentation)

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.

Overrides: IntStream.mark

(inherited documentation)

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.

Overrides: IntStream.release

(inherited documentation)

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.

Overrides: IntStream.size

(inherited documentation)

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.

Overrides: IntStream.index

(inherited documentation)

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.

If marker is None: 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).

Overrides: IntStream.rewind

(inherited documentation)

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.

Overrides: IntStream.seek

(inherited documentation)

Where is this stream pulling tokens from? This is not the name, but the object that provides Token objects.

Overrides: TokenStream.getTokenSource

(inherited documentation)

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.

Overrides: IntStream.getSourceName

(inherited documentation)

Return the text of all tokens from start to stop, inclusive. If the stream does not buffer all the tokens then it can just return "" or null; Users should not access $ruleLabel.text in an action of course in that case.

Because the user is not required to use a token with an index stored in it, we must provide a means for two token objects themselves to indicate the start/end location. Most often this will just delegate to the other toString(int,int). This is also parallel with the TreeNodeStream.toString(Object,Object).

Overrides: TokenStream.toString

(inherited documentation)