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

问题描述

我将ANTLR与Presto语法结合使用，以便解析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 ''
           )*
      '\''
    ;

这对大多数查询都行得通，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

所以我已经修改了String的定义，现在看起来像这样:

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，在我得到上述查询时，这将不起作用

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.知道我该如何处理该查询吗?

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，我能够解决它.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 ''
           )*
      '\''
    ;

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