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/*
 * [The "BSD license"]
 *  Copyright (c) 2012 Terence Parr
 *  Copyright (c) 2012 Sam Harwell
 *  All rights reserved.
 *
 *  Redistribution and use in source and binary forms, with or without
 *  modification, are permitted provided that the following conditions
 *  are met:
 *
 *  1. Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *  2. Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 *  3. The name of the author may not be used to endorse or promote products
 *     derived from this software without specific prior written permission.
 *
 *  THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 *  IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 *  OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 *  IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 *  INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 *  NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 *  DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 *  THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 *  (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 *  THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
package org.antlr.v4.runtime;

/** A source of tokens must provide a sequence of tokens via nextToken()
 *  and also must reveal it's source of characters; CommonToken's text is
 *  computed from a CharStream; it only store indices into the char stream.
 *
 *  Errors from the lexer are never passed to the parser.  Either you want
 *  to keep going or you do not upon token recognition error.  If you do not
 *  want to continue lexing then you do not want to continue parsing.  Just
 *  throw an exception not under RecognitionException and Java will naturally
 *  toss you all the way out of the recognizers.  If you want to continue
 *  lexing then you should not throw an exception to the parser--it has already
 *  requested a token.  Keep lexing until you get a valid one.  Just report
 *  errors and keep going, looking for a valid token.
 */
public interface TokenSource {
	/** Return a Token object from your input stream (usually a CharStream).
	 *  Do not fail/return upon lexing error; keep chewing on the characters
	 *  until you get a good one; errors are not passed through to the parser.
	 */
	public Token nextToken();

	public int getLine();

	public int getCharPositionInLine();

	/** From what character stream was this token created?  You don't have to
	 *  implement but it's nice to know where a Token comes from if you have
	 *  include files etc... on the input.
	 */
	public CharStream getInputStream();

	/** Where are you getting tokens from? normally the implication will simply
	 *  ask lexers input stream.
	 */
	public String getSourceName();

	/** Optional method that lets users set factory in lexer or other source */
	public void setTokenFactory(TokenFactory factory);

	/** Gets the factory used for constructing tokens. */
	public TokenFactory getTokenFactory();
}