Removing first-level blocks

Question

Given some text I want remove all text wrapped between { and }. The block may themselves contain some block. How can I do that using PCRE regex?

\\example input:
{a}b{c{d}}e{f{g}h}

\\output:
be

Answer 1

Using regular expression recursion:

\{(?>[^{}]|(?R))*\}

See a regex101 demo

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PHP example:

$input = '{a}b{c{d}}e{f{g}h}';
$output = preg_replace('/\{(?>[^{}]|(?R))*\}/', '', $input);
echo($output); # => be