text parsing function

Hi All,

I am trying to create software that will parse a string of varchar(160) and
write different parts of it into various locations in a database.

My thought process is something like this.
Create one or more functions to parse the data.
Create a trigger function that calls parsing function(s) and writes the data
into the appropriate locations.
Create after trigger on table that contains the entire string.

I have written the first function using pl/pgsql. As one might expect text
processing in pl/pgsql is messy.

Unfortunately I do not know Perl which is probably better suited to the text
munging part of my problem. Is there any penalty for using pl/pgsql for this
function? Given the inputs below does anyone see a problem with my code? Can
anyone suggest a better course of action?

-- Function: func_valid_item(varchar)

-- DROP FUNCTION func_extract_border_id("varchar");

CREATE OR REPLACE FUNCTION func_extract_border_id("varchar")
RETURNS varchar AS
$BODY$
-- A function to extract and check the validity of a border item id.
-- One input argument. description Case insensitive.
DECLARE
v_description ALIAS FOR $1;
v_border_id varchar(20);
BEGIN
SELECT tbl_item.id INTO v_border_id
FROM tbl_item
WHERE lower(tbl_item.id) =
lower(
CASE
-- Check for properly formatted description string.
WHEN lower(v_description)::text
NOT LIKE '%border:%size:%tag:%'
THEN NULL
-- Check for borderless description.
WHEN "substring"(lower(v_description::text),
'border: *none'::text)
IS NOT NULL
THEN NULL
-- Description contains valid border format.
ELSE trim(both
' '
from "substring"( v_description::text,
--source column

"position"(lower(v_description)::text, 'border:'::text) + 7, --start position

"position"(lower(v_description)::text, 'size:'::text) -
("position"(lower(v_description)::text, 'border:'::text) + 7) --string length
)
)
END
);
IF FOUND THEN
RETURN v_border_id;
ELSE
RETURN NULL;
END IF;
END;
$BODY$
LANGUAGE 'plpgsql' STABLE STRICT;

CREATE TABLE tbl_item
(
id varchar(20) NOT NULL,
CONSTRAINT tbl_item_pkey PRIMARY KEY (id)
)
WITHOUT OIDS;

INSERT INTO tbl_item VALUES ('RMFP025BK');
INSERT INTO tbl_item VALUES ('WNY200BK');
INSERT INTO tbl_item VALUES ('TW84NYBK');

Example Input:
SELECT * FROM func_extract_border_id(quote_ident('815 HTPP Black 2in sq
Border: RMFP025BK Size: 7'10" x 16' Tag: None'));

SELECT * FROM func_extract_border_id(quote_ident(' 3000 HTPP Black 4in sq
Border: WNY200BK Size: 17' x 50' Tag: None'));

SELECT * FROM func_extract_border_id(quote_ident(' 1250 HTPP Multi-Color
Bonded 2in sq Border:None Size: 5' X 90' Tag: NONE'));

SELECT * FROM func_extract_border_id(quote_ident(' 3000 HTPP Black 4in sq
Border: WNY200BK Size: 12' x 12'2" Tag: None'));

SELECT * FROM func_extract_border_id(quote_ident(' 1250 HTPP Black Bonded 2in
sq Border: RMFP025BK Size: 39" X 100' Tag: None'));

SELECT * FROM func_extract_border_id(quote_ident(' 1250 HTPP Black Bonded 2in
sq Border: RMFP025BK Size: 83" X 40' Tag: None'));

SELECT * FROM func_extract_border_id(quote_ident(' 500 HTPP Black 1.75in sq
Border: TW84NYBK Size: 12' x 14' Tag: None'));

SELECT * FROM func_extract_border_id(quote_ident(' Netform Net Size: 5' X 32'
W & L Body Length:24''));

SELECT * FROM func_extract_border_id(quote_ident('500WH HTPP White 1.75in sq
Border: WNY200BK Size: 5'x6' Tag: None'));

Kind Regards,
Keith