consume method

@override void consume()

Consumes the current symbol in the stream. This method has the following effects:

• Forward movement: The value of {@link #index index()} before calling this method is less than the value of {@code index()} after calling this method.
• Ordered lookahead: The value of {@code LA(1)} before calling this method becomes the value of {@code LA(-1)} after calling this method.

Note that calling this method does not guarantee that {@code index()} is incremented by exactly 1, as that would preclude the ability to implement filtering streams (e.g. CommonTokenStream which distinguishes between "on-channel" and "off-channel" tokens).

@throws IllegalStateException if an attempt is made to consume the end of the stream (i.e. if {@code LA(1)==}{@link #EOF EOF} before calling consume).

Implementation

@override
void consume() {
  bool skipEofCheck;
  if (p >= 0) {
    if (fetchedEOF) {
      // the last token in tokens is EOF. skip check if p indexes any
      // fetched token except the last.
      skipEofCheck = p < tokens.length - 1;
    } else {
      // no EOF token in tokens. skip check if p indexes a fetched token.
      skipEofCheck = p < tokens.length;
    }
  } else {
    // not yet initialized
    skipEofCheck = false;
  }

  if (!skipEofCheck && LA(1) == IntStream.EOF) {
    throw StateError('cannot consume EOF');
  }

  if (sync(p + 1)) {
    p = adjustSeekIndex(p + 1);
  }
}