Class BufferedTokenStream

runtime/JavaScript/src/antlr4/BufferedTokenStream.js:23–384

 * {@link CommonTokenStream}.</p>
 */
export default class BufferedTokenStream extends TokenStream {
	constructor(tokenSource) {

		super();
		// The {@link TokenSource} from which tokens for this stream are fetched.
		this.tokenSource = tokenSource;
		/**
		 * A collection of all tokens fetched from the token source. The list is
		 * considered a complete view of the input once {@link //fetchedEOF} is set
		 * to {@code true}.
		 */
		this.tokens = [];

		/**
		 * The index into {@link //tokens} of the current token (next token to
		 * {@link //consume}). {@link //tokens}{@code [}{@link //p}{@code ]} should
		 * be
		 * {@link //LT LT(1)}.
		 *
		 * <p>This field is set to -1 when the stream is first constructed or when
		 * {@link //setTokenSource} is called, indicating that the first token has
		 * not yet been fetched from the token source. For additional information,
		 * see the documentation of {@link IntStream} for a description of
		 * Initializing Methods.</p>
		 */
		this.index = -1;

		/**
		 * Indicates whether the {@link Token//EOF} token has been fetched from
		 * {@link //tokenSource} and added to {@link //tokens}. This field improves
		 * performance for the following cases:
		 *
		 * <ul>
		 * <li>{@link //consume}: The lookahead check in {@link //consume} to
		 * prevent
		 * consuming the EOF symbol is optimized by checking the values of
		 * {@link //fetchedEOF} and {@link //p} instead of calling {@link
		 * //LA}.</li>
		 * <li>{@link //fetch}: The check to prevent adding multiple EOF symbols
		 * into
		 * {@link //tokens} is trivial with this field.</li>
		 * <ul>
		 */
		this.fetchedEOF = false;
	}

	mark() {
		return 0;
	}

	release(marker) {
		// no resources to release
	}

	reset() {
		this.seek(0);
	}