Package org.antlr.runtime

Class UnbufferedTokenStream

  • All Implemented Interfaces:
    IntStream, TokenStream
    public class UnbufferedTokenStream
extends LookaheadStream<Token>
implements TokenStream
    A token stream that pulls tokens from the code source on-demand and without tracking a complete buffer of the tokens. This stream buffers the minimum number of tokens possible. It's the same as OnDemandTokenStream except that OnDemandTokenStream buffers all tokens. You can't use this stream if you pass whitespace or other off-channel tokens to the parser. The stream can't ignore off-channel tokens. You can only look backwards 1 token: LT(-1). Use this when you need to read from a socket or other infinite stream.
    See Also:
    BufferedTokenStream, CommonTokenStream

    • Field Detail

      • tokenIndex

        protected int tokenIndex

      • channel

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

    • Constructor Detail

      • UnbufferedTokenStream

        public UnbufferedTokenStream​(TokenSource tokenSource)

    • Method Detail

      • getTokenSource

        public TokenSource getTokenSource()
        Description copied from interface: TokenStream
        Where is this stream pulling tokens from? This is not the name, but the object that provides Token objects.
        Specified by:
        getTokenSource in interface TokenStream

      • toString

        public String toString​(int start,
                       int stop)
        Description copied from interface: TokenStream
        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.
        Specified by:
        toString in interface TokenStream

      • toString

        public String toString​(Token start,
                       Token stop)
        Description copied from interface: TokenStream
        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).
        Specified by:
        toString in interface TokenStream

      • LA

        public int LA​(int i)
        Description copied from interface: IntStream
        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.
        Specified by:
        LA in interface IntStream

      • get

        public Token get​(int i)
        Description copied from interface: TokenStream
        Get a token at an absolute index i; 0..n-1. This is really only needed for profiling and debugging and token stream rewriting. If you don't want to buffer up tokens, then this method makes no sense for you. Naturally you can't use the rewrite stream feature. I believe DebugTokenStream can easily be altered to not use this method, removing the dependency.
        Specified by:
        get in interface TokenStream

      • getSourceName

        public String getSourceName()
        Description copied from interface: IntStream
        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.
        Specified by:
        getSourceName in interface IntStream