org.antlr.v4.runtime.Token.java Source code

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Here is the source code for org.antlr.v4.runtime.Token.java

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/*
 * Copyright (c) 2012-2017 The ANTLR Project. All rights reserved.
 * Use of this file is governed by the BSD 3-clause license that
 * can be found in the LICENSE.txt file in the project root.
 */

package org.antlr.v4.runtime;

/** A token has properties: text, type, line, character position in the line
 *  (so we can ignore tabs), token channel, index, and source from which
 *  we obtained this token.
 */
public interface Token {
    public static final int INVALID_TYPE = 0;

    /** During lookahead operations, this "token" signifies we hit rule end ATN state
     *  and did not follow it despite needing to.
     */
    public static final int EPSILON = -2;

    public static final int MIN_USER_TOKEN_TYPE = 1;

    public static final int EOF = IntStream.EOF;

    /** All tokens go to the parser (unless skip() is called in that rule)
     *  on a particular "channel".  The parser tunes to a particular channel
     *  so that whitespace etc... can go to the parser on a "hidden" channel.
     */
    public static final int DEFAULT_CHANNEL = 0;

    /** Anything on different channel than DEFAULT_CHANNEL is not parsed
     *  by parser.
     */
    public static final int HIDDEN_CHANNEL = 1;

    /**
     * This is the minimum constant value which can be assigned to a
     * user-defined token channel.
     *
     * <p>
     * The non-negative numbers less than {@link #MIN_USER_CHANNEL_VALUE} are
     * assigned to the predefined channels {@link #DEFAULT_CHANNEL} and
     * {@link #HIDDEN_CHANNEL}.</p>
     *
     * @see Token#getChannel()
     */
    public static final int MIN_USER_CHANNEL_VALUE = 2;

    /**
     * Get the text of the token.
     */
    String getText();

    /** Get the token type of the token */
    int getType();

    /** The line number on which the 1st character of this token was matched,
     *  line=1..n
     */
    int getLine();

    /** The index of the first character of this token relative to the
     *  beginning of the line at which it occurs, 0..n-1
     */
    int getCharPositionInLine();

    /** Return the channel this token. Each token can arrive at the parser
     *  on a different channel, but the parser only "tunes" to a single channel.
     *  The parser ignores everything not on DEFAULT_CHANNEL.
     */
    int getChannel();

    /** An index from 0..n-1 of the token object in the input stream.
     *  This must be valid in order to print token streams and
     *  use TokenRewriteStream.
     *
     *  Return -1 to indicate that this token was conjured up since
     *  it doesn't have a valid index.
     */
    int getTokenIndex();

    /** The starting character index of the token
     *  This method is optional; return -1 if not implemented.
     */
    int getStartIndex();

    /** The last character index of the token.
     *  This method is optional; return -1 if not implemented.
     */
    int getStopIndex();

    /** Gets the {@link TokenSource} which created this token.
     */
    TokenSource getTokenSource();

    /**
     * Gets the {@link CharStream} from which this token was derived.
     */
    CharStream getInputStream();
}