/*PGR-GNU*****************************************************************

File: _checkquery.sql

Copyright (c) 2022 ~ Celia Virginia Vergara Castillo

mail: vicky@georepublic.de

------

This program is free software; you can redistribute it and/or modify

it under the terms of the GNU General Public License as published by

the Free Software Foundation; either version 2 of the License, or

(at your option) any later version.

This program is distributed in the hope that it will be useful,

but WITHOUT ANY WARRANTY; without even the implied warranty of

MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the

GNU General Public License for more details.

You should have received a copy of the GNU General Public License

along with this program; if not, write to the Free Software

Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.

********************************************************************PGR-GNU*/

--v3.4

CREATE FUNCTION _pgr_checkquery(

TEXT -- SQL

)

RETURNS TEXT AS

$BODY$

DECLARE

main_sql TEXT;

BEGIN

IF $1 !~ '[[:space:]]' THEN

-- prepared statements no arguments

EXECUTE format($$

SELECT regexp_replace(regexp_replace(statement, %1$L,'','i'),';$','')

FROM pg_prepared_statements WHERE name = %2$L$$,

'.*' || $1 || '\s*as', $1)

INTO main_sql;

IF main_sql IS NULL THEN

RAISE EXCEPTION 'prepared statement "%" does not exist', $1;

END IF;

ELSE

-- normal query

main_sql := $1;

END IF;

BEGIN

EXECUTE format('SELECT * FROM ( %1$s ) AS __a__ limit 1', main_sql);

EXCEPTION WHEN OTHERS THEN

RAISE EXCEPTION '%', SQLERRM USING HINT = $1, ERRCODE = SQLSTATE;

END;

RETURN main_sql;

END;

$BODY$

LANGUAGE plpgsql VOLATILE STRICT;

COMMENT ON FUNCTION _pgr_checkquery(TEXT)

IS 'pgrouting internal function';