Package org.antlr.runtime

Class 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 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

      • 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)

      • getNumberOfOnChannelTokens

        public int getNumberOfOnChannelTokens()
        Count EOF just once.