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| Related articles |
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| [5 earlier articles] |
| Re: Command Line Interpreter sdm7g@elvis.med.virginia.edu (Steven D. Majewski) (2000-07-29) |
| Re: Command Line Interpreter bernfarr@my-deja.com (2000-07-31) |
| Re: Command Line Interpreter gnb@hellcat.itga.com.au (Gregory Bond) (2000-08-04) |
| Re: Command Line Interpreter cfc@world.std.com (Chris F Clark) (2000-08-04) |
| Re: Command Line Interpreter snicol@apk.net (Scott Nicol) (2000-08-04) |
| Re: Command Line Interpreter faj@ericssontelebit.com (Frithiof Jensen) (2000-08-04) |
| Re: Command Line Interpreter tmoog@polhode.com (Tom Moog) (2000-08-05) |
| From: | Tom Moog <tmoog@polhode.com> |
| Newsgroups: | comp.compilers |
| Date: | 5 Aug 2000 21:37:42 -0400 |
| Organization: | Polhode Inc |
| References: | 00-07-055 00-07-069 00-07-093 00-08-004 |
| Keywords: | syntax |
As a long time (former) VMS user I can tell you that it is not VMS DCL
that it resembles, but the VMS Network Control Program (NCP) language
which I believe was created for RSX-11 (RIP) in the early 70s.
You cannot parse this language using traditional lexer/parsers without
hacks. It is not the grammar of the language which is the problem.
It is (a) the feedback from the parser to the lexer required to handle
matching of tokens by using the first unambiguous prefix and (b) the
need to supply descriptions of the allowed input at any point in the
parse, including different descriptions of the same token at different
points in the parse. For example:
set ip 1.2.3.4 subnet 255.255.255.240
The first a.b.c.d has a different help message than the second one.
Tom Moog
Polhode, Inc.
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