我正在尝试编写一个正则表达式，可以匹配嵌套的括号，例如：
"(((text(text))))(text()()text)(casual(characters(#$%^^&&#^%#@!&**&#^*!@#^**_)))"
应该匹配像这样的字符串，因为所有嵌套的括号都是关闭的，而不是:
"(((text)))(text)(casualChars*#(!&#*(!))"
不应该，或者更好的选择是至少匹配第一个"(((text)))(text)"部分。
实际上，我的正则表达式是：
$regex = '/( ( (\() ([^[]*?) (?R)? (\)) ){0,}) /x';
这个模式可行：
$pattern = '~ \( (?: [^()]+ | (?R) )*+ \) ~x';
括号内的内容仅用于描述：
"所有不是括号或递归（=其他括号）" 0次或多次
如果您想捕获括号内的所有子字符串，必须将此模式放在前瞻中以获取所有重叠的结果：
$pattern = '~(?= ( \( (?: [^()]+ | (?1) )*+ \) ) )~x';
preg_match_all($pattern, $subject, $matches);
print_r($matches[1]);
(?R)替换为(?1):(?R) -> refers to the whole pattern (You can write (?0) too)
(?1) -> refers to the first capturing group
print_r($matches[0]);），您将看到所有结果都是空字符串。获取 lookahead 内部子模式找到的子字符串的唯一方法是将子模式括在捕获组中。\( [^()]*+ (?: (?R) [^()]* )*+ \)
\1 是指捕获组 1 匹配的内容。(?1) 是指捕获组 1 内部的子模式。你只重复了子模式。 - Casimir et Hippolyte当我发现这个答案时，我无法弄清如何修改模式以适用于我的自定义分隔符，即 { 和 }。所以我的方法是使其更加通用。
$delimiter_wrap = '~';
$delimiter_left = '{';/* put YOUR left delimiter here. */
$delimiter_right = '}';/* put YOUR right delimiter here. */
$delimiter_left = preg_quote( $delimiter_left, $delimiter_wrap );
$delimiter_right = preg_quote( $delimiter_right, $delimiter_wrap );
$pattern = $delimiter_wrap . $delimiter_left
. '((?:[^' . $delimiter_left . $delimiter_right . ']++|(?R))*)'
. $delimiter_right . $delimiter_wrap;
/* Now you can use the generated pattern. */
preg_match_all( $pattern, $subject, $matches );
$delimiter_right 来关闭打开的 $delimiter_left，你就匹配了整个字符串。 - tonix( 时，它将调用自身。当它到达字符串结尾而没有找到相应的 ) 时，它还会检测不匹配的对。function ParseParenthesis(/*string*/ $string, /*function*/ $callback)
{
//Create a new parser object
$parser = new Parser($string);
//Call the recursive part
$result = ParseParenthesisFragment($parser, $callback);
if ($result['close'])
{
return $result['contents'];
}
else
{
//UNEXPECTED END OF STRING
// throw new Exception('UNEXPECTED END OF STRING');
return false;
}
}
递归部分：
function ParseParenthesisFragment(/*parser*/ $parser, /*function*/ $callback)
{
$contents = '';
$level = 0;
while(true)
{
$parenthesis = array('(', ')');
// Jump to the first/next "(" or ")"
$new = $parser->ConsumeUntil($parenthesis);
$parser->Flush(); //<- Flush is just an optimization
// Append what we got so far
$contents .= $new;
// Read the "(" or ")"
$element = $parser->Consume($parenthesis);
if ($element === '(') //If we found "("
{
//OPEN
$result = ParseParenthesisFragment($parser, $callback);
if ($result['close'])
{
// It was closed, all ok
// Update the level of this iteration
$newLevel = $result['level'] + 1;
if ($newLevel > $level)
{
$level = $newLevel;
}
// Call the callback
$new = call_user_func
(
$callback,
$result['contents'],
$level
);
// Append what we got
$contents .= $new;
}
else
{
//UNEXPECTED END OF STRING
// Don't call the callback for missmatched parenthesis
// just append and return
return array
(
'close' => false,
'contents' => $contents.$result['contents']
);
}
}
else if ($element == ')') //If we found a ")"
{
//CLOSE
return array
(
'close' => true,
'contents' => $contents,
'level' => $level
);
}
else if ($result['status'] === null)
{
//END OF STRING
return array
(
'close' => false,
'contents' => $contents
);
}
}
}