bbp_make_clickable( string $text )

function bbp_make_clickable( $text ) {
	$r               = '';
	$textarr         = preg_split( '/(<[^<>]+>)/', $text, -1, PREG_SPLIT_DELIM_CAPTURE ); // split out HTML tags
	$nested_code_pre = 0; // Keep track of how many levels link is nested inside <pre> or <code>

	foreach ( $textarr as $piece ) {

		if ( preg_match( '|^<code[\s>]|i', $piece ) || preg_match( '|^<pre[\s>]|i', $piece ) || preg_match( '|^<script[\s>]|i', $piece ) || preg_match( '|^<style[\s>]|i', $piece ) ) {
			$nested_code_pre++;
		} elseif ( $nested_code_pre && ( '</code>' === strtolower( $piece ) || '</pre>' === strtolower( $piece ) || '</script>' === strtolower( $piece ) || '</style>' === strtolower( $piece ) ) ) {
			$nested_code_pre--;
		}

		if ( $nested_code_pre || empty( $piece ) || ( $piece[0] === '<' && ! preg_match( '|^<\s*[\w]{1,20}+://|', $piece ) ) ) {
			$r .= $piece;
			continue;
		}

		// Long strings might contain expensive edge cases ...
		if ( 10000 < strlen( $piece ) ) {
			// ... break it up
			foreach ( _split_str_by_whitespace( $piece, 2100 ) as $chunk ) { // 2100: Extra room for scheme and leading and trailing paretheses
				if ( 2101 < strlen( $chunk ) ) {
					$r .= $chunk; // Too big, no whitespace: bail.
				} else {
					$r .= bbp_make_clickable( $chunk );
				}
			}
		} else {
			$ret = " {$piece} "; // Pad with whitespace to simplify the regexes
			$ret = apply_filters( 'bbp_make_clickable', $ret );
			$ret = substr( $ret, 1, -1 ); // Remove our whitespace padding.
			$r .= $ret;
		}
	}

	// Cleanup of accidental links within links
	return preg_replace( '#(<a([ \r\n\t]+[^>]+?>|>))<a [^>]+?>([^>]+?)</a></a>#i', "$1$3</a>", $r );
}