Article View: net.lang.pascal
Article #113Re: Re: Hash function for Pascal keywords?
From: Bob Dietrich
Date: Fri, 02 Nov 1984 21:30
Date: Fri, 02 Nov 1984 21:30
37 lines
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2317 bytes
> While the Cichelli algorithm works for the reserved words in Pascal (and
> UCSD Pascal) it fails to find a minimal perfect hash function for the
> reserved words in Modula-2.
The keywords 'type' and 'exit' conflict in Modula-2. This is because the hash
function used is:
hash := val[word[1]] + val[word[length]] + length
The hash might be made unique by weighting the value for the first (or last)
character in the hash function. Another approach would be to pick other than
the first and last characters.
>
> I modified the algorithm developed by Cook and Oldehoeft so that it
> terminates when it can not find a perfect minimal hash table.
> Unfortunately I do not have it in UNIX readable form. If you want a
> copy send me email and I can US mail you a Xerox of the listing.
>
> Ian Kaplan
I have a machine-readable copy of the program that also rejects conflicts.
If there's interest, I'll post it again.
Bob Dietrich
Tektronix, Inc.
(503) 629-1727
{ucb or dec}vax!tektronix!robertd uucp address
robertd@tektronix csnet address
robertd.tektronix@rand-relay arpa address
--
Bob Dietrich
Tektronix, Inc.
(503) 629-1727
{ucb or dec}vax!tektronix!robertd uucp address
robertd@tektronix csnet address
robertd.tektronix@rand-relay arpa address
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Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.2 (Tek) 9/12/84; site tektronix.UUCP Path: arc1-ca.pugleaf.net!utzoo!linus!decvax!tektronix!robertd From: robertd@tektronix.UUCP (Bob Dietrich) Newsgroups: net.lang.pascal Subject: Re: Re: Hash function for Pascal keywords? Message-ID: <4042@tektronix.UUCP> Date: Fri, 2-Nov-84 16:30:36 EST Article-I.D.: tektroni.4042 Posted: Fri Nov 2 16:30:36 1984 Date-Received: Sat, 3-Nov-84 21:48:51 EST References: <2487@dartvax.UUCP> <572@loral.UUCP> Organization: Tektronix, Beaverton OR Lines: 37