正则表达式：捕获成对的花括号

Question

我想捕获匹配的花括号。

例如：

Some example text with \added[author]{text with curly braces{some text}..}

Some example text with \added[author]{text without curly braces}

Some example text with \added[author]{text with {}and {} and {}curly braces{some text}..}

Some example text with \added[author]{text with {}and {} and {}curly braces{some text}..} and extented text with curly braces {}

预期输出：

Some example text with text with curly braces{some text}..

Some example text with text without curly braces

Some example text with text with {}and {} and {}curly braces{some text}..

Some example text with text with {}and {} and {}curly braces{some text}.. and extented text with curly braces {}

即我想捕获\added[]{ 和}（它的相对闭合花括号）之间的文本。我的正则表达式的问题是，我不知道如何在相关的花括号之间进行捕获。

我试过了，

       "/\\\\added\\[.*?\\]{(.[^{]*?)}/s"

如果{ 出现在文本中，我知道它会忽略。但我不知道如何创建一个正则表达式来单独获取匹配的花括号。

Answer 1

要匹配成对的大括号，您需要使用recursive subpattern。

---

示例：

$regex = <<<'REGEX'
/
\\added\[.*?\]                # Initial \added[author]

(                             # Group to be recursed on.
    {                         # Opening brace.

    (                         # Group for use in replacement.

        ((?>[^{}]+)|(?1))*    # Any number of substrings which can be either:
                              # - a sequence of non-braces, or
                              # - a recursive match on the first capturing group.
    )

    }                         # Closing brace.
)
/xs
REGEX;

$strings = [
    'Some example text with \added[author]{text with curly braces{some text}..}',
    'Some example text with \added[author]{text without curly braces}',
    'Some example text with \added[author]{text with {}and {} and {}curly braces{some text}..}',
    'Some example text with \added[author]{text with {}and {} and {}curly braces{some text}..} and extented text with curly braces {}'
];

foreach ($strings as $string) {
    echo preg_replace($regex, '$2', $string), "\n";
}

输出：

Some example text with text with curly braces{some text}..
Some example text with text without curly braces
Some example text with text with {}and {} and {}curly braces{some text}..
Some example text with text with {}and {} and {}curly braces{some text}.. and extented text with curly braces {}

Answer 2

在这里，应该可以工作

/\\added\[.*\]\{(.*(?:.*\{.*\}.*)*)\}/gU

说明

/\\added\ 是乳胶标签，

\[.*\]是Latex标签的一个选项，

\{ 左括号，

(.*(?:.*\{.*\}.*)*) 是捕获的文本，在这里我们还防止在我们的目标标签中出现递归 {...} 或多个 {...}，

\} 右括号。​​

策略

我不认为一对括号是一种递归形式

{ { {...} } }
c b a   a b c

我们有一对 a、b 和 c，

但我认为他们是这样的！

{ { {...} } }   
a b c   a b c

见：DEMO

我演示中的最后两个示例也证明它可以正常工作。

重要提示：修饰符 U 假设在此处用于非贪婪量词，否则我的正则表达式将无法正常工作。

Answer 3

使用以下正则表达式：

\\\\added\\[[^\\]]\*][^\\{]\*{((?:(?:[^\\{\\}]\*\\{[^\\}\\{]\*\\})\*||[^\\}]\*)\*)}

Answer 4

使用这个regex

/\\added[^]]*]{([^}]*}[^}]*)}/s

Demo here