PHP - 当被类似的干草堆包围时，干草堆搜索中的针不起作用

Question

任何人都知道如何修改下面的刮板以达到预期的效果：

Array ( [0] => Gold_Needle [1] => Silver_Needle )

代码可以在线运行@http://ideone.com/QATj5a

结果是：

Array ( [0] => this is a bunch of hay hay1= Gold_Needle [1] => Silver_Needle )

想要的结果是：

Array ( [0] => Gold_Needle [1] => Silver_Needle )

Answer 1

使用$starts 和$ends 数组构建一个前瞻正则表达式，如下所示：

(hay1=\h*\K(?:.(?!hay1))*?(?= hay=Gold))|(hay2=\h*\K(?:.(?!hay2))*?(?= hay=Silver))

• RegEx Demo

• Code Demo

代码：

$haystack='Data set 1: hay2= this is a bunch of hay  hay1= Gold_Needle hay=Gold
             Data Set 2: hay2=Silver_Needle hay=Silver';

$needle1_Begin='hay1=';
$needle2_Begin='hay2=';

$needle1_End='hay=Gold';
$needle2_End='hay=Silver';

$starts = array($needle1_Begin,$needle2_Begin);
$ends = array($needle1_End,$needle2_End);

$re = array_reduce($starts, function($res, $e) use (&$ends) {
    $res .= '(' . $e . '\h*\K(?:.(?!' . $e . '))*?(?= ' . current($ends) . '))|';
    next($ends); return $res;} );

$re = '/' . substr($re, 0, -1) . '/';

if (preg_match_all($re, $haystack, $m))
   print_r($m[0]);

输出：

Array
(
    [0] => Gold_Needle
    [1] => Silver_Needle
)