我在处理稍长的字符串时在 preg_replace_callback() 函数中收到 PREG_JIT_STACKLIMIT_ERROR 错误。超过 2000 个字符是无效的(超过 2000 个匹配正则表达式的字符，而不是 2000 个字符串)。
我已经读到它是由效率低下的正则表达式引起的，但我不能让我的正则表达式更简单。这是我的正则表达式:

/\{@([a-z0-9_]+)-(((%?[a-z0-9_]+(:[a-z0-9_]+)*)+)\| (((?R)|.)*)@\}/我们

它应该匹配如下字符串:

1) {@if-statement|echo this|echo otherwise@}

2) {@if-statement:sub|echo this|echo otherwise@}

3) {@if-statement%statament2:sub|echo this@}

也像这样嵌套:

4) {@if-statement|echo this| {@if-statement2|回显这个|否则回显@} @

我试图将其简化为:

/\{@([a-z0-9_]+)-([a-z0-9_]+)\|(((?R)|.)*)@\}/我们

但看起来错误是由 (((?R)|.)*) 部分引起的。有什么建议吗？

测试代码:

$string = '{@if-is_not_logged_homepage|
<header id="header_home">
    <div class="in">
        <div class="top">
            <h1 class="logo"><a href="/"><img src="/img/logo-home.png" alt=""></a></h1>
            <div class="login_outer_wrapper">
                <button id="login"><div class="a"><i class="stripe"><i></i></i>Log in</div></button>
                <div id="login_wrapper">
                    <form method="post" action="{^login^}" id="form_login_global">
                        <div class="form_field no_description">
                            <label>{!auth:login_email!}</label>
                            <div class="input"><input type="text" name="form[login]"></div>
                        </div>
                        <div class="form_field no_description password">
                            <label>{!auth:password!}</label>
                            <div class="input"><input type="password" name="form[password]"></div>
                        </div>
                        <div class="remember">
                            <input type="checkbox" name="remember" id="remember_me_check" checked>
                            <label for="remember_me_check"><i class="fa fa-check" aria-hidden="true"></i>Remember</label>
                        </div>
                        <div class="submit_box">
                            <button class="btn btn_check">Log in</button>
                        </div>
                    </form>
                </div>
            </div>
        </div>
        <div class="content clr">
            <div class="main_menu">
                <a href="">
                    <i class="ico a"><i class="fa fa-lightbulb-o" aria-hidden="true"></i></i>
                    <span>Idea</span>
                    <div>&nbsp;</div>
                </a>
                <a href="">
                    <i class="ico b"><i class="fa fa-user" aria-hidden="true"></i></i>
                    <span>FFa</span>
                </a>
                <a href="">
                    <i class="ico c"><i class="fa fa-briefcase" aria-hidden="true"></i></i>
                    <span>Buss</span>
                </a>
            </div>
            <div class="text_wrapper">

                <div>
                    <div class="register_wrapper">
                        <a id="main_register" class="btn register">Załóż konto</a>
                        <form method="post" action="{^login^}" id="form_register_home">
                            <div class="form_field no_description">
                                <label>{!auth:email!}</label>
                                <div class="input"><input type="text" name="form2[email]"></div>
                            </div>
                            <div class="form_field no_description password">
                                <label>{!auth:password!}</label>
                                <div class="input tooltip"><input type="password" name="form2[password]"><i class="fa fa-info-circle tooltip_open" aria-hidden="true" title="{!auth:password_format!}"></i></div>

                            </div>
                            <div class="form_field terms no_description">
                                <div class="input">
                                    <input type="checkbox" name="form2[terms]" id="terms_check">
                                    <label for="terms_check"><i class="fa fa-check" aria-hidden="true"></i>Agree</label>
                                </div>
                            </div>
                            <div class="form_field no_description">
                                <div class="input captcha_wrapper">
                                    <div class="g-recaptcha" data-sitekey="{%captcha_public_key%}"></div>
                                </div>
                            </div>
                            <div class="submit_box">
                                <button class="btn btn_check">{!auth:register_btn!}</button>
                            </div>
                        </form>
                    </div>
                </div>
            </div>
        </div>
    </div>
</header>
@}';

$if_counter = 0;

$parsed_view = preg_replace_callback( '/\{@([a-z0-9_]+)-((%?[a-z0-9_]+(:[a-z0-9_]+)*)+)\|(((?R)|.)*)@\}/Us',
        function( $match ) use( &$if_counter ){
            return '<-{'. ( $if_counter ++ ) .'}->';
        }, $string );


var_dump($parsed_view); // NULL

最佳答案

什么是 PCRE JIT ？

Just-in-time compiling is a heavyweight optimization that can greatly speed up pattern matching. However, it comes at the cost of extra processing before the match is performed. Therefore, it is of most benefit when the same pattern is going to be matched many times.

它基本上是如何工作的？

PCRE (and JIT) is a recursive, depth-first engine, so it needs a stack where the local data of the current node is pushed before checking its child nodes... When the compiled JIT code runs, it needs a block of memory to use as a stack. By default, it uses 32K on the machine stack. However, some large or complicated patterns need more than this. The error PCRE_ERROR_JIT_STACKLIMIT is given when there is not enough stack.

通过第一句话，您将了解 JIT 是 PHP [v7.*] PCRE 中默认启用的可选功能。所以你可以很容易地关闭它:pcre.jit = 0(虽然不推荐)

但是，当收到 preg_* 函数的错误代码 #6 时，这意味着 JIT 可能达到堆栈大小限制。

由于捕获组比非捕获组消耗更多的内存(根据聚类的量词类型，打算使用更多的内存):

1. 正在捕获组 OP_CBRA ( pcre_jit_compile.c:#1138 ) -(实际内存不止于此):

case OP_CBRA:
case OP_SCBRA:
bracketlen = 1 + LINK_SIZE + IMM2_SIZE;
break;

1. 非捕获组 OP_BRA ( pcre_jit_compile.c:#1134 ) - (real 内存不止于此):

case OP_BRA:
bracketlen = 1 + LINK_SIZE;
break;

因此，在您自己的 RegEx 中将捕获组更改为非捕获组可以提供正确的输出(我不知道这究竟节省了多少内存)

但似乎您需要捕获组，而且它们是必要的。然后你应该为了性能重写你的正则表达式。回溯几乎是 RegEx 中应该考虑的所有内容。

更新#1

解决方案:

(?(DEFINE)
  (?<recurs>
    (?! {@|@} ) [^|] [^{@|\\]* ( \\.[^{@|\\]* )* | (?R)
  )
)
{@
(?<If> \w+)-
(?<Condition> (%?\w++ (:\w+)*)* )
(?<True> [|] [^{@|]*+ (?&recurs)* )
(?<False> [|] (?&recurs)* )?
\s*@}

Live demo

PHP 代码(观察反斜杠转义):

preg_match_all('/(?(DEFINE)
  (?<recurs>
    (?! {@|@} ) [^|] [^{@|\\\\]* ( \\\\.[^{@|\\\\]* )* | (?R)
  )
)
{@
(?<If> \w+ )-
(?<Condition> (%?\w++ (:\w+)*)* )
(?<True> [|] [^{@|]*+ (?&recurs)* )
(?<False> [|] (?&recurs)* )?
\s*@}/x', $string, $matches);

这是您自己的正则表达式，它经过优化以减少回溯步骤。因此，任何本应由您自己的匹配的内容也将与此匹配。

不遵循嵌套 if block 的正则表达式:

{@
(?<If> \w+)-
(?<Condition> (%?\w++ (:\w+)*)* )
(?<True> [|] [^|\\]* (?: \\.[^|\\]* )* )
(?<False> [|] \X*)?
@}

Live demo

大多数量词都是通过在其后附加 + 来写的(避免回溯)。

关于PHP PREG_JIT_STACKLIMIT_ERROR - 低效的正则表达式，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/39685883/