org.antlr.v4.runtime.TokenSource Maven / Gradle / Ivy
/*
* 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 source of tokens must provide a sequence of tokens via {@link #nextToken()}
* and also must reveal it's source of characters; {@link CommonToken}'s text is
* computed from a {@link 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 {@link 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 {@link Token} object from your input stream (usually a
* {@link 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();
/**
* Get the line number for the current position in the input stream. The
* first line in the input is line 1.
*
* @return The line number for the current position in the input stream, or
* 0 if the current token source does not track line numbers.
*/
public int getLine();
/**
* Get the index into the current line for the current position in the input
* stream. The first character on a line has position 0.
*
* @return The line number for the current position in the input stream, or
* -1 if the current token source does not track character positions.
*/
public int getCharPositionInLine();
/**
* Get the {@link CharStream} from which this token source is currently
* providing tokens.
*
* @return The {@link CharStream} associated with the current position in
* the input, or {@code null} if no input stream is available for the token
* source.
*/
public CharStream getInputStream();
/**
* Gets the name of the underlying input source. This method returns a
* non-null, non-empty string. If such a name is not known, this method
* returns {@link IntStream#UNKNOWN_SOURCE_NAME}.
*/
public String getSourceName();
/**
* Set the {@link TokenFactory} this token source should use for creating
* {@link Token} objects from the input.
*
* @param factory The {@link TokenFactory} to use for creating tokens.
*/
public void setTokenFactory(TokenFactory factory);
/**
* Gets the {@link TokenFactory} this token source is currently using for
* creating {@link Token} objects from the input.
*
* @return The {@link TokenFactory} currently used by this token source.
*/
public TokenFactory getTokenFactory();
}