🚀 go-pugleaf

In article <550@jvc.UUCP>, lpw@jvc.UUCP (Lance Welsh) writes:
> 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.

The biggest problem is not with the actual parsing per se, it's that
since a PostScript interpreter is actually executing its input stream
(rather than reading a file and then executing it), you cannot statically
analyze a PostScript program (take an 'image' command or a font download,
for example).  This is one of the reasons that the PostScript Document
Structuring Conventions use comments instead of parsing the file.  Comments
are at least unambiguous.

The only way I can see of doing a PostScript compiler is to write an
interpreter which compiles executable arrays once they are constructed
by the interpreter.  I'd probably start with compiling to subroutine-
threaded code, much in the way of a Forth compiler.

Besides, there are several publically available PostScript parsers,
they're just embedded in interpreters: GhostScript, Xps, and so on.

Amanda Walker
Speaker To PostScript
InterCon Systems Corporation
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