On Fri, Feb 12, 2016 at 2:41 AM, Fabien COELHO <coe...@cri.ensmp.fr> wrote: > > Hello Michaël, > >> + /* the argument list has been built in reverse order, it is fixed >> here */ >> + expr->u.function.args = reverse_elist(args); >> Hm. I may be missing something, but why is that necessary? This is >> basically doing a double-reversion to put all the arguments in the >> correct order when parsing the function arguments. > > This is because the expression list is parsed left to right and the list is > built as a stack to avoid looking for the last argument to append the next > expression, but then the list is in reverse order at the end of parsing, so > it is reversed once to make it right. This way the complexity is kept as > O(n). > > If this is too much I can switch to O(n**2) by appending each expression at > the end of the list.
(this one has been mentioned by Alvaro offlist) Using a pointer to the tail of the list would make the code simple, and save a couple of lines. Another thing that could be considered is also to move list.c and pg_list.h into src/common and reuse that. There are other frontend utilities that emulate the same kind of facilities, have a look for example at the other copycats in pg_dump and pg_basebackup. -- Michael -- Sent via pgsql-hackers mailing list (email@example.com) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers