$re = '~#PostgreSQL v10+
(?<delimiter>; [;\s]*) #semicolon, followed by semicolons and spaces
| \'(?>[^\']+|\'\')*\' #String Constants
| \b[Ee]\'(?>[^\\\\\']+|\'\'|\\\\.)*\' #String Constants With C-Style Escapes
| (?<stringDollarTag>\$[a-zA-Z\d_]*\$) #Dollar-Quoted String
[^$]*+ #speed improves
.*?
\k<stringDollarTag>
| "(?>[^"]+|"")*"
| #singe-line comment
(?<singeLineComment>-- [^\r\n]*+)
| #multi-line comment
(?<MutilineComment>
/\*
[^*/]*+
(?> [^*/]++
| \*[^/]
| /[^*]
| (?&MutilineComment)
)*+
\*/
)~sxX';
$str = 'CREATE UNIQUE INDEX/*CONCUR-
RENTLY;*/IF NOT EXISTS custom_query_group_name_name_uindex
ON public.custom_query_group_name (lower(name)); ;
;
--CREATE INDEX /*CONCURRENTLY;*/ IF NOT EXISTS custom_query_group_name_name_trigram_index ON public.custom_query_group_name USING GIN (lower(name) gin_trgm_ops);
;
;
;
CREATE INDEX /*CONCURRENTLY*/ IF NOT EXISTS v3_company_name_trigram_index ON public.v3_company USING GIN (lower(name) gin_trgm_ops);
;
-- PostgreSQL
$function$
BEGIN
RETURN ($1 ~ $q$[\\t\\r\\n\\v\\\\]$q$);
END;
$function$;
-- PostgreSQL
SELECT $$Жанна д\'Арк$$, $SomeTag$Жанна д\'Арк$SomeTag$;
SELECT \'abc\\\'\'\\\\def\', "abc\\""\\\\def";
SELECT 123;
';
$subst = "$0";
$result = preg_replace($re, $subst, $str);
echo "The result of the substitution is ".$result;
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php