Path: utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!sun-barr!decwrl!shlump.nac.dec.com!hannah.enet.dec.com!batcheldern From: batcheldern@hannah.enet.dec.com (Ned Batchelder) Newsgroups: comp.lang.postscript Subject: Re: Compiled PostScript Message-ID: <7330@shlump.nac.dec.com> Date: 9 Jan 90 21:47:35 GMT References: <550@jvc.UUCP> <28@macuni.mqcc.mq.oz> <1989Dec31.053812.3410@ico.isc.com> Sender: newsdaemon@shlump.nac.dec.com Reply-To: BatchelderN@hannah.enet.dec.com Distribution: comp Organization: Digital Equipment Corporation Lines: 28 > If these people think that parsing PS and writing grammars is a trivial snap: > > ...[other quotes deleted]... > > then why have we never seen anyone post a BNF for postscript or a > public domain parser? I'll bet it's harder than they think. I think someone just did post a BNF for PostScript, in an earlier article in this thread. Basically, the syntax of PostScript is that you have tokens, and you have procs, which are tokens or procs in curly braces: thing ::= token | { thing* } PSprogram :== thing* Not much of a grammar! It doesn't really shed any light on anything, or help understand the language in any way. Of course, you have to scan the tokens, and that can get a little interesting, what with the "#" notation and all, but that's a lexical issue, which is usually considered separately from syntax. The fact is that as a postfix operator-based language (as opposed to an infix statment-and-expression-based language), PostScript just doesn't lend itself to "parsing". Ned Batchelder, Digital Equipment Corp., BatchelderN@Hannah.enet.DEC.com