PHP preg_match_all限制 [英] PHP preg_match_all limit

问题描述

我正在使用preg_match_all做很长的图案.

I'm using preg_match_all for very long pattern.

运行代码时，出现此错误:

when run the code, i got this error :

警告:preg_match_all():编译失败:正则表达式在偏移707830处太大

Warning: preg_match_all(): Compilation failed: regular expression is too large at offset 707830

搜索后，我得到了解决方案，所以我应该增加php.ini

After searching, I got the solution, so I should increase value of pcre.backtrack_limit and pcre.recursion_limit in php.ini

但是当我增加值并重新启动apache之后，它仍然遇到相同的问题.我的PHP版本是5.3.8

But after I increase the value and restart my apache, it still got the same problem. My PHP verison is 5.3.8

推荐答案

增加PCRE回溯和递归限制可能会解决此问题，但是当数据大小达到新限制时仍然会失败. (无法通过更多数据很好地扩展)

increasing the PCRE backtrack and recursion limit may fix the problem, but will still fail when the size of your data hits the new limit. (doesn't scale well with more data)

示例:

<?php 
// essential for huge PCREs
ini_set("pcre.backtrack_limit", "23001337");
ini_set("pcre.recursion_limit", "23001337");
// imagine your PCRE here...
?>

要真正解决潜在的问题，您必须优化表达式并将(如果可能的话)将复杂的表达式拆分为部分"，并将一些逻辑移至PHP.我希望您通过阅读示例获得想法.而不是尝试通过单个PCRE直接查找子结构，而是演示了一种更加迭代"的方法，该方法使用PHP越来越深入到结构中.例如:

to really solve the underlying problem, you must optimize your expression and (if possible) split your complex expression into "parts" and move some logic to PHP. I hope you get the idea by reading the example .. instead of trying to find the sub-structure directly with a single PCRE, i demonstrate a more "iterative" approach going deeper and deeper into the structure using PHP. example:

<?php
$html = file_get_contents("huge_input.html");

// first find all tables, and work on those later
$res = preg_match_all("!<table.*>(?P<content>.*)</table>!isU", $html, $table_matches);

if ($res) foreach($table_matches['content'] as $table_match) {  

    // now find all cells in each table that was found earlier ..
    $res = preg_match_all("!<td.*>(?P<content>.*)</td>!isU", $table_match, $cell_matches);

    if ($res) foreach($cell_matches['content'] as $cell_match) {

        // imagine going deeper and deeper into the structure here...
        echo "found a table cell! content: ", $cell_match;

    }    
}

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