我从一位朋友（他现在外出度假）那里得到了一些帮助，但我在 preg_replace 搜索和替换方面遇到了问题。我不知道为什么，但它错误地替换了字符串，这对它应该替换的下一个字符串产生了连锁影响。
这基本上是在模板类中处理模板内的“if”和“else”查询。
function if_statement($a, $b, $if, $type, $else = NULL){
if($type == "1" && is_numeric($a) && is_numeric($b)){
$statement = ($a === $b) ? $if : $else;
} else if($type == "1"){
$statement = ($a == $b) ? $if : $else;
} else if($type == "2"){
$statement = ($a != $b) ? $if : $else;
}
return stripslashes($statement);
}
$output = file_get_contents("template.tpl");
$replace = array(
'#\<if:"\'(.*?)\' == \'(.*?)\'"\>(.*?)\<else\>(.*?)\<\/endif\>#sei',
'#\<if:"\'(.*?)\' == \'(.*?)\'"\>(.*?)\<\/endif\>#sei'
);
$functions = array(
"if_statement('\\1', '\\2', '\\3', '1', '\\4')",
"if_statement('\\1', '\\2', '\\3', '1')"
);
$output = preg_replace($replace, $functions, $output);
echo $output;
模板：
<HTML>
<head>
<meta http-equiv="content-type" content="application/xhtml+xml; charset=UTF-8" />
<title>Site Title</title>
<link rel="stylesheet" type="text/css" media="screen" href="common.css" />
<if:"'{ISADMIN}' == '1'">
<link rel="stylesheet" href="admin-bar.css" type="text/css" media="all" />
</endif>
</head>
<body>
<if:"'{TODAY}' == 'Monday'">Today is Monday<else>Today is not Monday</endif>
<if:"'1' == '2'">1 equals 2!<else>1 doesn't equal 2</endif>
</body>
</html>
当前输出如下：
<HTML>
<head>
<meta http-equiv="content-type" content="application/xhtml+xml; charset=UTF-8" />
<title>Site Title</title>
<link rel="stylesheet" type="text/css" media="screen" href="common.css" />
<link rel="stylesheet" href="admin-bar.css" type="text/css" media="all" />
**</endif>**
</head>
<body>
**<if:"'{TODAY}' == 'Monday'">**Today is Monday
1 doesn't equal 2
</body>
</html>
在上面，粗体/astrix makred 部分不应该出现在输出中，而且今天不是星期一。当管理员登录时，admin-bar.css 文件已正确包含，但由于某种原因未拾取 preg_replace 匹配了一个不正确的东西！因此没有接受第二个
{BRACKET} 标签被正确替换 - 我什至手动将数据放入语句中（只是为了检查），所以它们不是问题......
我不知道为什么，但对我来说，preg_replace 没有找到正确的顺序来替换和执行操作。如果有人能提供一双新的眼睛/伸出援助之手，我将不胜感激。
谢谢！
I've had some help from a friend (who is now away on holiday) but I have a problem with a preg_replace search and replace. I don't know why, but it is replacing strings incorrectly which has had a knock on affect to the next one it should replace.
This basically goes within a template class dealing with 'if' and 'else' queries within the template.
function if_statement($a, $b, $if, $type, $else = NULL){
if($type == "1" && is_numeric($a) && is_numeric($b)){
$statement = ($a === $b) ? $if : $else;
} else if($type == "1"){
$statement = ($a == $b) ? $if : $else;
} else if($type == "2"){
$statement = ($a != $b) ? $if : $else;
}
return stripslashes($statement);
}
$output = file_get_contents("template.tpl");
$replace = array(
'#\<if:"\'(.*?)\' == \'(.*?)\'"\>(.*?)\<else\>(.*?)\<\/endif\>#sei',
'#\<if:"\'(.*?)\' == \'(.*?)\'"\>(.*?)\<\/endif\>#sei'
);
$functions = array(
"if_statement('\\1', '\\2', '\\3', '1', '\\4')",
"if_statement('\\1', '\\2', '\\3', '1')"
);
$output = preg_replace($replace, $functions, $output);
echo $output;
The template:
<HTML>
<head>
<meta http-equiv="content-type" content="application/xhtml+xml; charset=UTF-8" />
<title>Site Title</title>
<link rel="stylesheet" type="text/css" media="screen" href="common.css" />
<if:"'{ISADMIN}' == '1'">
<link rel="stylesheet" href="admin-bar.css" type="text/css" media="all" />
</endif>
</head>
<body>
<if:"'{TODAY}' == 'Monday'">Today is Monday<else>Today is not Monday</endif>
<if:"'1' == '2'">1 equals 2!<else>1 doesn't equal 2</endif>
</body>
</html>
Where the current output will be below:
<HTML>
<head>
<meta http-equiv="content-type" content="application/xhtml+xml; charset=UTF-8" />
<title>Site Title</title>
<link rel="stylesheet" type="text/css" media="screen" href="common.css" />
<link rel="stylesheet" href="admin-bar.css" type="text/css" media="all" />
**</endif>**
</head>
<body>
**<if:"'{TODAY}' == 'Monday'">**Today is Monday
1 doesn't equal 2
</body>
</html>
In the above, the bolded/astrix makred parts shouldn't be there on the output, and also today isn't Monday. While the admin is logged in, the admin-bar.css file has been rightly included, but for some reason isn't picking up the </endif> tag - infact, it looks like it has gone after the <else> tag instead in the next statement ... in other words, preg_replace has matched an incorrect thing! And thus didn't pick up on the 2nd <if> statement.
The {BRACKET} tags are being replaced correctly - I've even manually put data into the statement (just to check), so they aren't the problem...
I don't know why, but to me preg_replace isn't finding the correct sequence to replace and act upon. If anyone could lay a fresh pair of eyes/lend a hand, I would be grateful.
Thanks!
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评论（1）
示例中的第一个(.*?)(.*?)< /code> （其中
在该匹配中，组
$3是您可以通过禁止来避免这种情况这正则表达式使用前瞻断言来跨越
：或者以注释形式（当程序员再次“外出度假”时可能更有帮助）：
第二个正则表达式也应该得到改进：
此外，这些正则表达式应该更快，因为它们更清楚地指定可以匹配和不能匹配的内容，从而避免大量回溯。
The first
<if>in your sample doesn't have an<else>clause. Therefore, when<if:"'(.*?)' == '(.*?)'">(.*?)<else>(.*?)</endif>(where<else>is not optional) is applied to it, it matches all this:In that match, group
$3isYou could avoid that by forbidding the regex to cross over an
</endif>using lookahead assertions:or, in commented form (and possibly more helpful when a programmer again goes "away on holiday"):
The second regex should also be improved:
Also, these regexes should be faster as they specify more clearly what can and cannot be matched, thus avoiding a lot of backtracking.