Question

i want to extract the comments out of a string as a block.

e.g. I have a PL/SQL code as:

--comment1 select * from t_table; --i want comment 2; /*i want comment 3 */ --i want comment 4 OPEN data_cur; 

Here, i want all the single line and multiline comments before OPEN data_cur; but after select * from t_table;

i.e. i want a full comment block between two PL/SQL statements.

i want the regex to match the string and form the groups as:

1. SQL statement
2. whole comment block

Can it be done using any regex?

Answer 1

(?ms)^\s*([^\-/\s][^;]+;)((?:(?:\s+/\*(?:.(?!\*/))+.\*/)|(?:\s+\-\-[^\r\n]+))*) 

should do it nicely.
(Note: (?ms) is the way in Java to specify a ‘multi-line’ ‘dot-all’ mode, but I have tested in on RETester and it works)

It can detect 0 or more comments after the select.
Multi line comments are accepted between /* and */ because of the use of a positive lookahead (?:.(?!\*/))+ in a non-capturing group

Update: modified it to detect any ‘non-comment’ line before 0 or many comments.

---

To detect comment1, then statement, then comments:

(?ms)((?:(?:\s+/\*(?:.(?!\*/))+.\*/)|(?:\s+\-\-[^\r\n]+))*)\s*^\s*([^\-/\s][^;]+;)((?:(?:\s+/\*(?:.(?!\*/))+.\*/)|(?:\s+\-\-[^\r\n]+))*) 

Note: I have update in both regexps (the one in the beginning and this one) the statement detection part:

\s*([^\-/][^;]+;) 

to

\s*([^\-/\s][^;]+;) 

Note bis: only the first ‘comments - statement - comments‘ will be detected.
The next blocks will also be detected, but only as : ‘statement - comments‘, then ‘statement - comments‘, and so on. (the comments above a statement are part of the comments below the previous statement)