修改按行相对于标记的位置选择的文件中的行

Question

我在代码中遇到了一点问题，需要一些帮助。

我有一个类似如下的文件：

some lines
some lines
LABEL:
NOP ABC some text - line 1
NOP ABC some text - line 2
NOP ABC some text - line 3
NOP ABC some text - line 4
NOP ABC some text - line 5
NOP ABC some text - line 6
NOP ABC some text - line 7  
NOP ABC some text - line 8 
NOP ABC some text - line 9 
NOP ABC some text - line 10
NOP ABC some text - line 11

现在，我的要求是，一旦LABEL:匹配，我必须跳过下一行(第1行)，并修改接下来的两行，即第2行和第3行，用DEF ABC替换ABC。然后跳过接下来的2行，4和5，并用同样的方法修改接下来的2行，6和7。然后再次跳过接下来的2行，8和9，并修改下面的2行，10和11等等。

我想不出该如何做到这一点。以下是我的代码的相关部分：

while (<>) {

   my $cur_line = $_;
   my $ctv_line = "";

   if ($cur_line =~ /^LABEL/) {

      print "$cur_line";

      my $next_line = <>;
      print "$next_line\n";

      for ($i = 0; $i < 2; $i++) {
         if ($next_line =~ s/NOP\s+ABC/NOP DEF ABC/) {
            $ctv_line = $next_line;
            print "$ctv_line";
         }
      }

      print "$next_line";
      print "next_line";

      for ($i = 0; $i < 2; $i++) {
         if ($next_line =~ s/NOP\s+ABC/NOP DEF ABC/) {
            $ctv_line = $next_line;
            print "$ctv_line";
         }
      }

   }
   else {
      print "$cur_line";
   }
}

Answer 1

您自己的代码的主要问题是，大多数代码只在包含标签的行上执行，因为它在if ($cur_line =~ /^LABEL/) { ... }中，而您想要修改的行在该行之后。

如果您使用$.的值记录标签所在的行号，这是最直接的做法。然后，您可以通过减法找到相对于标签的行号，并且，由于修改具有四个一组的模式，模运算符%将告诉您是否进行替换。

请注意，它现在根据您的注释进行了修改，其中您说要跳过每十行中的两行。

像这样

use strict;
use warnings;
use 5.010;
use autodie;

open my $fh, '<', 'data.txt';

my $label_line;

while (<$fh>) {
   $label_line = $. if /LABEL:/;
   if ($label_line) {
      s/ABC/DEF ABC/ if ( $. - $label_line ) % 10 >= 2;
   }
   print;
}

输出

some lines
some lines
LABEL:
NOP ABC some text - line 1
NOP DEF ABC some text - line 2
NOP DEF ABC some text - line 3
NOP DEF ABC some text - line 4
NOP DEF ABC some text - line 5
NOP DEF ABC some text - line 6
NOP DEF ABC some text - line 7  
NOP DEF ABC some text - line 8 
NOP DEF ABC some text - line 9 
NOP ABC some text - line 10
NOP ABC some text - line 11
NOP DEF ABC some text - line 12
NOP DEF ABC some text - line 13
NOP DEF ABC some text - line 14
NOP DEF ABC some text - line 15
NOP DEF ABC some text - line 16
NOP DEF ABC some text - line 17
NOP DEF ABC some text - line 18
NOP DEF ABC some text - line 19
NOP ABC some text - line 20
NOP ABC some text - line 21
NOP DEF ABC some text - line 22
NOP DEF ABC some text - line 23
NOP DEF ABC some text - line 24
NOP DEF ABC some text - line 25
NOP DEF ABC some text - line 26
NOP DEF ABC some text - line 27
NOP DEF ABC some text - line 28
NOP DEF ABC some text - line 29

Answer 2

使用flip-flop operator确定匹配标签后的行号：

use strict;
use warnings;

while (<DATA>) {
    if (my $range = /LABEL/ .. undef) {
        s/(?=ABC)/DEF / if ($range - 1) % 4 > 1;
    }
    print;
}

__DATA__
some lines
some lines
LABEL:
NOP ABC some text - line 1
NOP ABC some text - line 2
NOP ABC some text - line 3
NOP ABC some text - line 4
NOP ABC some text - line 5
NOP ABC some text - line 6
NOP ABC some text - line 7  
NOP ABC some text - line 8 
NOP ABC some text - line 9 
NOP ABC some text - line 10
NOP ABC some text - line 11

输出：

some lines
some lines
LABEL:
NOP ABC some text - line 1
NOP DEF ABC some text - line 2
NOP DEF ABC some text - line 3
NOP ABC some text - line 4
NOP ABC some text - line 5
NOP DEF ABC some text - line 6
NOP DEF ABC some text - line 7  
NOP ABC some text - line 8 
NOP ABC some text - line 9 
NOP DEF ABC some text - line 10
NOP DEF ABC some text - line 11

漫游规范更新

您在评论中陈述了以下内容：

感谢您的反馈。然而，在我的实际文件中(我只是想展示一个例子)，我必须跳过label之后的下一行，用DEF ABC修改下8行，跳过下2行，然后再次修改下8行。你能告诉我如何做到这一点吗？对不起，我对Perl还不太熟悉。

通过将脚本更改为以下内容，可以轻松接受这一点：

while (<DATA>) {
    if (my $range = /LABEL/ .. undef) {
        s/(?=ABC)/DEF / if ($range - 1) % 10 > 1;
    }
    print;
}