Antlr C解析器能从无效令牌中恢复吗

Question

null

Answer 1

您需要使用上面描述的方法重写Match()，并执行解析器的恢复（这是C#伪代码）：

    public override object Match(IIntStream input, int ttype, BitSet follow)
    {
        if (needs recover)
        {
            ... Recover from mismatch, i.e. skip until next valid terminal.
        }

        return base.Match(input, ttype, follow);
    }

此外，还需要从不匹配的令牌中恢复：

    protected override object RecoverFromMismatchedToken(IIntStream input, int ttype, BitSet follow)
    {
        if (needs recover)
        {
            if (unwanted token(input, ttype))
            {

                .. go to the next valid terminal
                .. consume as if ok
                .. return next valid token

            }

            if (missing token(input, follow))
            {
                .. go to the next valid terminal
                .. insert missing symbol and return
            }

            .. othwerwise throw
        }

        .. call base recovery(input, ttype, follow);
    }

如果有其他问题请告诉我。