Example usage for org.antlr.v4.runtime Parser getTokenFactory

Introduction

In this page you can find the example usage for org.antlr.v4.runtime Parser getTokenFactory.

Prototype

@Override
    public TokenFactory<?> getTokenFactory() 

Source Link

Usage

From source file:com.sample.JavaErrorStrategy.java

License:BSD License

/**
 * Conjure up a missing token during error recovery.
 *
 * The recognizer attempts to recover from single missing symbols. But,
 * actions might refer to that missing symbol. For example, x=ID {f($x);}.
 * The action clearly assumes that there has been an identifier matched
 * previously and that $x points at that token. If that token is missing,
 * but the next token in the stream is what we want we assume that this
 * token is missing and we keep going. Because we have to return some token
 * to replace the missing token, we have to conjure one up. This method
 * gives the user control over the tokens returned for missing tokens.
 * Mostly, you will want to create something special for identifier tokens.
 * For literals such as '{' and ',', the default action in the parser or
 * tree parser works. It simply creates a CommonToken of the appropriate
 * type. The text will be the token. If you change what tokens must be
 * created by the lexer, override this method to create the appropriate
 * tokens./* ww  w  . ja  va2 s.c  o m*/
 */
@NotNull
protected Token getMissingSymbol(@NotNull Parser recognizer) {
    Token currentSymbol = recognizer.getCurrentToken();
    IntervalSet expecting = getExpectedTokens(recognizer);
    int expectedTokenType = expecting.getMinElement(); // get any element
    String tokenText;
    if (expectedTokenType == Token.EOF)
        tokenText = "<missing EOF>";
    else
        tokenText = "<missing " + recognizer.getTokenNames()[expectedTokenType] + ">";
    Token current = currentSymbol;
    Token lookback = recognizer.getInputStream().LT(-1);
    if (current.getType() == Token.EOF && lookback != null) {
        current = lookback;
    }
    return recognizer.getTokenFactory()
            .create(new Pair<TokenSource, CharStream>(current.getTokenSource(),
                    current.getTokenSource().getInputStream()), expectedTokenType, tokenText,
                    Token.DEFAULT_CHANNEL, -1, -1, current.getLine(), current.getCharPositionInLine());
}

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