匹配不被引号包围的逗号的正则表达式 [英] A regex to match a comma that isn't surrounded by quotes

问题描述

我使用Clojure，所以这是在Java正则表达式的上下文中。

这里是一个示例字符串：

  {：aab，cd，efg，：bab，def，egf，，：cConjecture} 
  

重要的位是每个字符串后的逗号。我想能够用换行符替换为Java的replaceAll方法。符合不包括引号的任何逗号的正则表达式将会执行。

如果我没有遇到问题，我很乐意澄清什么。

编辑：对标题的混乱感到遗憾。我还没有醒得很久。

字符串： {：aab，cd efg，} < - 在这个例子中，最后的逗号将被匹配，但是引号内的逗号不会匹配。

String： {：a 3，：b 3，} < - 每个逗号都匹配。

String {：aabcd，efg：babcedg，e} < - 每个逗号都不匹配。

解决方案

正则表达式：

 ，\s *（？ ] *[^] *）* [^] * $）
  

/ p>

  {：aab，cd，efg，：bab，def，egf，，：cConjecture } 
 ^ ^ 
 ^ ^ 
  

和：

  {：aab，cd efg，} 
 ^ 
 ^ 
  
 
 
 
且不符合逗号：
  {：aabcd，efg：babcedg，e} 
  
如下所示：
  {：aab，\cd efg，} //只有最后一个逗号匹配
  
那么正则表达式解决方案将不起作用。
 
 
 
正则表达式的简要说明：
 ，＃匹配字符'，'
 \s *＃匹配一个空格字符：[\t\\\
\x0B\f\r]，并重复零或多次
（？=＃开始向前看
（＃start捕获组1 
 [^] *＃匹配除之外的任何字符并重复零或多次
＃匹配字符'''
 [^] *匹配任何字符而不是'并重复零或多次
＃匹配字符''
）*＃结束捕获组1并重复零或多次
 [ ^] *＃匹配除之外的任何字符并重复零或多次
 $＃匹配输入结束
）＃end正向前看
  
换句话说：匹配任何在其前面有零或引号为偶数的逗号（直到字符串结尾）。 
 
I'm using Clojure, so this is in the context of Java regexes.

Here is an example string:
{:a "ab,cd, efg", :b "ab,def, egf,", :c "Conjecture"}
The important bits are the commas after each string. I'd like to be able to replace them with newline characters with Java's replaceAll method. A regex that will match any comma that is not surrounded by quotes will do.

If I'm not coming across well, please ask and I'll be happily to clarify anything.

edit: sorry for the confusion in the title. I haven't been awake very long.

String: {:a "ab, cd efg",} <-- In this example, the comma at the end would be matched, but the ones inside the quote would not.

String: {:a 3, :b 3,} <-- Every single comma matches.

String {:a "abcd,efg" :b "abcedg,e"} <-- Every single comma doesn't match.
解决方案
The regex:
,\s*(?=([^"]*"[^"]*")*[^"]*$)
Matches:
{:a "ab,cd, efg", :b "ab,def, egf,", :c "Conjecture"}
                ^                  ^
                ^                  ^
and:
{:a "ab, cd efg",}
                ^
                ^
and does not match a comma in:
{:a "abcd,efg" :b "abcedg,e"}
But when escaped quotes can appear, like so:
{:a "ab,\" cd efg",} // only the last comma should match
then a regex solution won't work.

A brief explanation of the regex:
,            # match the character ','
\s*          # match a whitespace character: [ \t\n\x0B\f\r] and repeat it zero or more times
(?=          # start positive look ahead
  (          #   start capture group 1
    [^"]*    #     match any character other than '"' and repeat it zero or more times
    "        #     match the character '"'
    [^"]*    #     match any character other than '"' and repeat it zero or more times
    "        #     match the character '"'
  )*         #   end capture group 1 and repeat it zero or more times
  [^"]*      #   match any character other than '"' and repeat it zero or more times
  $          #   match the end of the input
)            # end positive look ahead
In other words: match any comma that has zero, or an even number of quotes ahead of it (until the end of the string).

                        
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