处理不同的转义序列? [英] Handling different escaping sequences?

问题描述

我使用 ANTLR 和 Presto 语法来解析 SQL 查询.这是我用来解析查询的原始字符串定义:

I'm using ANTLR with Presto grammar in order to parse SQL queries. This is the original string definition I've used to parse queries:

STRING
    : '\'' ( '\\' .
           | ~[\\']       // match anything other than \ and '
           | '\'\''       // match ''
           )*
      '\''
    ;

这适用于大多数查询，直到我看到具有不同转义规则的查询.例如:

This worked ok for most queries until I saw queries with different escaping rules. For example:

select 
table1(replace(replace(some_col,'\\'',''),'\"' ,'')) as features 
from table1

所以我修改了我的字符串定义，现在它看起来像:

So I've modified my String definition and now it looks like:

STRING
    : '\'' ( '\\' .
           | '\\\\'  .  {HelperUtils.isNeedSpecialEscaping(this)}?       // match \ followed by any char
           | ~[\\']       // match anything other than \ and '
           | '\'\''       // match ''
           )*
      '\''
    ;

但是，这不适用于我得到的上述查询

However, this won't work for the query mentioned above as I'm getting

'\\'',''),'

作为单个字符串.对于以下查询，谓词返回 True.知道我该如何处理这个查询吗?

as a single string. The predicate returns True for the following query. Any idea how can I handle this query as well?

谢谢，尼尔.

推荐答案

最后我解决了.这是我使用的表达方式:

In the end I was able to solve it. This is the expression I was using:

STRING
    : '\'' ( '\\\\'  .  {HelperUtils.isNeedSpecialEscaping(this)}?
           | '\\' (~[\\] | . {!HelperUtils.isNeedSpecialEscaping(this)}?)
           | ~[\\']       // match anything other than \ and '
           | '\'\''       // match ''
           )*
      '\''
    ;

这篇关于处理不同的转义序列?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！