python - 查找另一个字符串后面的第一个匹配项，python regex multiline

Question

我知道有人问了很多这样的问题，但我在使用正则表达式语句来解决我的具体问题时遇到了一些麻烦。

我有大量名称不同但格式完全相同的函数，我需要找到特定函数名称后面的第一个匹配项。

请注意，我正在使用 python 搜索 C 文件。

 writecwp_positionStatus(int      action,
        u_char   *var_val,
        u_char   var_val_type,
        size_t   var_val_len,
        u_char   *statP,
        oid      *name,
        size_t   name_len) {

static long     intval;
static long     old_intval;

switch ( action ) {
    case RESERVE1:
      if (var_val_type != ASN_INTEGER) {
          fprintf(stderr, "write to mib not ASN_INTEGER\n");
          return SNMP_ERR_WRONGTYPE;
      }
      if (var_val_len > sizeof(long)) {
          fprintf(stderr,"write to mib: bad length\n");
          return SNMP_ERR_WRONGLENGTH;
      }
    intval = *((long *) var_val);
      break;

    case RESERVE2:
      break;

    case FREE:
         /* Release any resources that have been allocated */
      break;

    case ACTION:
         /*
          * The variable has been stored in 'value' for you to use,
          * and you have just been asked to do something with it.
          * Note that anything done here must be reversable in the UNDO case
          */
        old_intval = starting_int;
        starting_int = intval;
      break;

    case UNDO:
         /* Back out any changes made in the ACTION case */
         starting_int = old_intval;
      break;

    case COMMIT:
         /*
          * Things are working well, so it's now safe to make the change
          * permanently.  Make sure that anything done here can't fail!
          */
      break;
} return SNMP_ERR_NOERROR;

}

在这个例子中，我想找到第一个“old_intval =starting_int;”遵循函数名称“writecwp_positionStatus”。将会有更多具有相同主体但名称不同的函数。

我的想法是设置一个捕获组来匹配:

(function name)(everything in between including newlines)(line to replace)

我尝试了很多不同的选项，例如，但似乎每次都偏离一点点:

(writecwp_positionStatus\(.*\s)((.*\s)*?)(\s*old_intval = starting_int;)

Answer 1

我建议使用这个正则表达式。

(writecwp_positionStatus[\s\S]*?)old_intval = starting_int;([\s\S]*)

这里的方法是捕获从函数名到要被捕获组 01 替换的语句的所有内容，然后通过捕获组 02 匹配语句后面的所有内容>

\s -> whitespace character (a space, a tab, a line break, or a form feed).
\S -> non-white space character.
*? -> ? after quantifiers makes them lazy/non-greedy.

现在要替换该语句，我们可以使用另一个正则表达式:

\1 >>>I am the replacement<<< \2

这里，

\1 -> Everything before the statement.
\2 -> Everything after the statement.

为了更好地理解，请做实验 here 。我希望这就是您想要的。