PHP正则表达式以匹配HTML标记<a>之外的关键字

Question

我一直在尝试做一个正则表达式来匹配和替换HTML一部分上关键字的出现：我想匹配keyword和<strong>keyword</strong>但是<a href="someurl.html" target="_blank">keyword</a>并且<a href="someur2.html">already linked keyword </a>不应该匹配我只对keyword第一行的匹配（和替换）感兴趣。我想要此操作的原因是将其替换keyword为<a href="dictionary.php?k=keyword">keyword</s>，但仅当keyword它尚未位于<a>标记中时才可以。任何帮助都感激不尽！

Answer 1

$str = preg_replace('~Moses(?!(?>[^<]*(?:<(?!/?a\b)[^<]*)*)</a>)~i',

                    '<a href="novo-mega-link.php">$0</a>', $str);

否定前瞻中的表达式与下一个结束</a>标记匹配，但前提是它首先没有看到开始<a>标记。如果成功，则表示单词Moses在锚元素内，因此超前失败，并且不会发生匹配。

Answer 2

我设法通过以下方式完成了我想做的事情（不使用Regex）：

解析字符串的每个字符

删除所有<a>标签（将它们复制到临时数组并在字符串上保留占位符）

str_replace 新字符串以替换所有关键字

通过原始<a>标签重新填充占位符

如果有人需要，这是我使用的代码：

$str = <<<STRA

Moses supposes his toeses are roses,

but <a href="original-moses1.html">Moses</a> supposes erroneously;

for nobody's toeses are posies of roses,

as Moses supposes his toeses to be.

Ganda <span class="cenas"><a href="original-moses2.html" target="_blank">Moses</a></span>!

STRA;

$arr1 = str_split($str);

$arr_links = array();

$phrase_holder = '';

$current_a = 0;

$goto_arr_links = false;

$close_a = false;

foreach($arr1 as $k => $v)

{

    if ($close_a == true)

    {

        if ($v == '>') {

            $close_a = false;

        } 

        continue;

    }

    if ($goto_arr_links == true)

    {

        $arr_links[$current_a] .= $v;

    }

    if ($v == '<' && $arr1[$k+1] == 'a') { /* <a */

        // keep collecting every char until </a>

        $arr_links[$current_a] .= $v;

        $goto_arr_links = true;

    } elseif ($v == '<' && $arr1[$k+1] == '/' && $arr1[$k+2] == 'a' && $arr1[$k+3] == '>' ) { /* </a> */

        $arr_links[$current_a] .= "/a>";

        $goto_arr_links = false;

        $close_a = true;

        $phrase_holder .= "{%$current_a%}"; /* put a parameter holder on the phrase */

        $current_a++;

    }    

    elseif ($goto_arr_links == false) {

        $phrase_holder .= $v;

    }

}

echo "Links Array:\n";

print_r($arr_links);

echo "\n\n\nPhrase Holder:\n";

echo $phrase_holder;

echo "\n\n\n(pre) Final Phrase (with my keyword replaced):\n";

$final_phrase = str_replace("Moses", "<a href=\"novo-mega-link.php\">Moses</a>", $phrase_holder);

echo $final_phrase;

echo "\n\n\nFinal Phrase:\n";

foreach($arr_links as $k => $v)

{

    $final_phrase = str_replace("{%$k%}", $v, $final_phrase);

}

echo $final_phrase;

输出：

链接数组：

Array

(

    [0] => <a href="original-moses1.html">Moses</a>

    [1] => <a href="original-moses2.html" target="_blank">Moses</a>

)

词组：

Moses supposes his toeses are roses,

but {%0%} supposes erroneously;

for nobody's toeses are posies of roses,

as Moses supposes his toeses to be.

Ganda <span class="cenas">{%1%}</span>!

（上）最终词组（替换为我的关键字）：

<a href="novo-mega-link.php">Moses</a> supposes his toeses are roses,

but {%0%} supposes erroneously;

for nobody's toeses are posies of roses,

as <a href="novo-mega-link.php">Moses</a> supposes his toeses to be.

Ganda <span class="cenas">{%1%}</span>!

最终词组：

<a href="novo-mega-link.php">Moses</a> supposes his toeses are roses,

but <a href="original-moses1.html">Moses</a> supposes erroneously;

for nobody's toeses are posies of roses,

as <a href="novo-mega-link.php">Moses</a> supposes his toeses to be.

Ganda <span class="cenas"><a href="original-moses2.html" target="_blank">Moses</a></span>!

Answer 3

$lines = explode( "\n", $content );

$lines[0] = stri_replace( "keyword", "replacement", $lines[0] );

$content = implode( "\n", $lines );

或者如果您明确想使用正则表达式

$lines = explode( "\n", $content );

$lines[0] = preg_replace( "/keyword/i", "replacement", $lines[0] );

$content = implode( "\n", $lines );