正则表达式多行匹配，不包括包含字符串的行

Question

在以下正则表达式中：

EXCLUDE this entire line
include this line
and this as single match
and EXCLUDE this line

我想返回一个包含两行的匹配：

include this line
and this as single match

我想使用EXCLUDE作为字符串，标识不应包含整行。

编辑：如果我可以将第一个匹配项与“EXCLUDE”（或文档末尾以先发生者为准）匹配，那也可以

Answer 1

您可以在正则表达式的匹配项上拆分字符串

^.*\bEXCLUDE\b.*\R

设置了全局和多行标志。

例如，在 Ruby 中，如果变量str保存了字符串

Firstly include this line
EXCLUDE this entire line
include this line
and this as single match
and EXCLUDE this line
Lastly include this line

那么String#split方法可用于生成包含三个字符串的数组。

str.split(/^.*\bEXCLUDE\b.*\R/)
  #=> ["Firstly include this line",
  #    "include this line\nand this as single match",
  #    "Lastly include this line"]

许多语言都有与 Ruby 的split相当的方法或函数。

演示

正则表达式可以分解如下。

^        # match the beginning of a line
.*       # match zero or more characters other than line
         # terminators, as many as possible
\b       # match word boundary
EXCLUDE  # match literal
\b       # match word boundary
.*       # match zero or more characters other than line
         # terminators, as many as possible
\R       # match line terminator
 

Answer 2

使用 pcre 您可以使用\K来获取到目前为止匹配的内容，并首先匹配包含排除的行：

^.*\bEXCLUDE\b.*\K(?:\R(?!.*\bEXCLUDE\b).*)+

正则表达式演示

如果要匹配所有不包含排除的行，则使用连续行：

(?:(?:^|\R)(?!.*\bEXCLUDE\b).*)+

正则表达式演示

或使用跳过失败方法：

^.*\bEXCLUDE\b.*\R(*SKIP)(*F)|.+(?:\R(?!.*\bEXCLUDE\b).*)*

正则表达式演示

Answer 3

您还可以将这些行与EXCLUDE匹配，并使用它将您的文本拆分为您要查找的块：

<?php

$input = 'First include this line
EXCLUDE this entire line
include this line
and this as single match
and EXCLUDE this line
Lastly include this line';

// ^ matches the beginning of a line.
// .* matches anything (except new lines) zero or multiple times.
// \b matches a word boundary (to avoid matching NOEXCLUDE).
// $ matches the end of a line.
$pattern = '/^.*\bEXCLUDE\b.*$/m';

// Split the text with all lines containing the EXCLUDE word.
$desired_blocks = preg_split($pattern, $input);

// Get rid of the new lines around the matched blocks.
array_walk(
    $desired_blocks,
    function (&$block) {
        // \R matches any Unicode newline sequence.
        // ^ matches the beginning of the string.
        // $ matches the end of the string.
        // | = or
        $block = preg_replace('/^\R+|\R+$/', '', $block);
    }
);

var_export($desired_blocks);

在这里演示： https ://onlinephp.io/c/4216a

输出：

array (
  0 => 'First include this line',
  1 => 'include this line
and this as single match',
  2 => 'Lastly include this line',
)