Java 标记化 : Treat Anything Separated by an Underscore as One Word

Question

我有一个使用 StreamTokenizer 的非常简单的分词器，它将数学表达式转换为它们的各个组件(如下)。我遇到的问题是，如果表达式中有一个名为 T_1 的变量，它将拆分为 [T,_,1]，我想将其作为 [T_1] 返回。

我曾尝试使用一个变量来检查最后一个字符是否是下划线，如果是，则将下划线附加到 list.Size-1 上，但这似乎是一个非常笨拙且效率低下的解决方案。有没有办法做到这一点？谢谢!

        StreamTokenizer tokenizer = new StreamTokenizer(new StringReader(s));
        tokenizer.ordinaryChar('-'); // Don't parse minus as part of numbers.
        tokenizer.ordinaryChar('/'); // Don't parse slash as part of numbers.
        List<String> tokBuf = new ArrayList<String>();
        while (tokenizer.nextToken() != StreamTokenizer.TT_EOF) //While not the end of file 
        {
            switch (tokenizer.ttype) //Switch based on the type of token
            {
            case StreamTokenizer.TT_NUMBER: //Number
                tokBuf.add(String.valueOf(tokenizer.nval));
                break;
            case StreamTokenizer.TT_WORD: //Word
                tokBuf.add(tokenizer.sval);
                break;
            case '_':
                tokBuf.add(tokBuf.size()-1, tokenizer.sval);
                break;
            default: //Operator
                tokBuf.add(String.valueOf((char) tokenizer.ttype));
            }
        }

        return tokBuf;

Answer 1

这就是你想要的。

tokenizer.wordChars('_', '_');

这使得 _ 可以识别为单词的一部分。

附录:

构建并运行:

public static void main(String args[]) throws Exception {
    String s = "abc_xyz abc 123 1 + 1";
    StreamTokenizer tokenizer = new StreamTokenizer(new StringReader(s));
    tokenizer.ordinaryChar('-'); // Don't parse minus as part of numbers.
    tokenizer.ordinaryChar('/'); // Don't parse slash as part of numbers.
    tokenizer.wordChars('_', '_'); // Don't parse slash as part of numbers.


    List<String> tokBuf = new ArrayList<String>();
    while (tokenizer.nextToken() != StreamTokenizer.TT_EOF) //While not the end of file 
    {
        switch (tokenizer.ttype) //Switch based on the type of token
        {
        case StreamTokenizer.TT_NUMBER: //Number
            tokBuf.add(String.valueOf(tokenizer.nval));
            break;
        case StreamTokenizer.TT_WORD: //Word
            tokBuf.add(tokenizer.sval);
            break;
        default: //Operator
            tokBuf.add(String.valueOf((char) tokenizer.ttype));
        }
    }
    System.out.println(tokBuf);
}

run:
[abc_xyz, abc, 123.0, 1.0, +, 1.0]