RDP parser generator version 1.1 now available

** RDP release version 1.10 flyer. Adrian Johnstone 27 March 1994 **


The first maintenance release of RDP (version 1.1) is now available via
ftp from cscx.cs.rhbnc.ac.uk (134.219.200.45) in directory /pub/rdp. Get
rdp1_1.zip if you are an MS-DOS user or rdp1_1.tar.Z if you are a Unix
user.


If you would like your name added to a mailing list which will keep you up
to date with RDP developments please mail me at the address given at the
end of this message.


Please note that I will be in Madrid (and therefore not reading my email)
for the next two weeks, returning on April 10


** Improvements in this version include **


0. A (very) draft user manual is now included.


1. Very detailed diagnostics given if an LL(1) violation is
      detected, specifying the sub-clauses in error and listing the bad
      tokens.


2. RDP produced C source code is now nicely indented.


3. New PASSES directive supports multiple-pass parsers (such as
      assemblers).


4. New HEX_DOLLAR directive enables Motorla style hexdeimal numbers ($xx)
      in scanner.


5. EOF handling now conforms to ANSI standard (thanks to
      gunnar@fasel.robin.de for pointing this out).


6. OUTPUTFILE now defaults to "rdparser".


7. EOLN_VISIBLE directive superceded by automatic detection of EOLN token.


8. New comment primitives added to support assembler and visible
      comments. COMMENT_VISIBLE directive removed.


9. Bugs in scanner string mode parser fixed.


10. Productions consisting solely of [...] or {...} now handled
        correctly.


11. Toy interpreter now has a full set of control structures.


12. Mini (cut down Toy) language added as a tutorial introduction.


13. Pascal parser now handles null statements.


14. -bfilename switch dropped since new diagnostics reduce the
        need to look at the internal productions. New -e switch dumps
        internal productions to stdout instead.


15. Multiple user command line switches now handled correctly.


16. Force flag removed from default parsers.


17. HELP directive now renamed OPTION.


18. New makefile and project files included.


**** Here follows a thumbnail sketch of RDP ****


RDP - a recursive descent parser generator


RDP compiles attributed LL(1) grammars decorated with C-language semantic
actions into recursive descent compilers. RDP is written in strict ANSI C
and produces strict ANSI C. RDP was developed using Borland C 3.1 on a PC
and has also been built with no problems on Alpha/OSF-1, DECstation/Ultrix
and Sun 4/SunOS hosts all using GCC. The definition of strict ANSI here
means compiling with gcc -Wall -Wstrict-prototypes -fno-common -pedantic
-ANSI and getting no warning messages.


RDP itself and the language processors it generates use standard symbol,
set and scanner modules. The RDP scanner is programmed by loading tokens
into the symbol table at the start of each run.


RDP produces complete runnable programs with built-in help information and
command line switches that are specified as part of the EBNF file. In this
sense RDP output is far more shrink-wrapped than the usual parser
generators which helps beginning students. RDP can generate itself which
is a nice demonstration of the bootstrapping technique used for porting
compilers to new architectures.


I wrote RDP because in October I start giving a course on compiler design.
I don't think the world needs another course on parsing techniques and am
really interested in code generation for exotic processors, so I tried to
produce a compact parser generator that would enable undergraduates to rip
through the syntax and standard code generation parts of the syllabus in a
few weeks, thus leaving me time to get into the black arts of code
scheduling and optimisation.


What you get.


o An implementation of Pascal style set-handling in C.


o A hash-coded symbol table with support for scoping and arbitrary user data


o A programmable high-speed scanner with integrated error handling and
    hooks for macros (RDP is being used to generate assemblers for two novel
    microprocessors in addition to the usual applications of LL(1) parsers).


o The source to a hand-coded version of the RDP translator. RDP checks that
    the source grammar is LL(1) and explains exactly why a non-LL(1) grammar
    is unacceptable. RDP does not attempt to rework a grammar by itself.


o A decorated EBNF file describing RDP that may be processed by the
    hand-coded RDP translator to produce a machine generated version of RDP.
    This is good for boggling undergraduate's minds with.


o A decorated EBNF file describing an interpreter for a language called TOY.


o An EBNF file describing Pascal which generates a parser for
    the Pascal language.


o A pre-built RDP executable for MS-DOS.


o Sources, makefiles and Borland 3.1 project files for everything which
    you may use freely on condition that you send copies of any modifications,
    enhancements and ill-conceived changes you might make back to me so that
    I can improve RDP.


What you don't get.


o Decent manuals. A preliminary draft of the main user manual
    which includes a tutorial introduction to RDP is supplied. Better
    manuals will follow.


o Tutorial information on parsing and compiling (try Wirth's Algorithms +
    Data Structures = Programs, Chapter 5 or your favourite compiler book).


o Warranties. (This code has only just escaped from my personal toolkit.
    I've put a lot of effort into making it fit for others to use, but in
    the very nature of compiler compilers it is hard to test all the angles,
    and the Garbage In - Garbage Out principle holds to the highest degree:
    if you write ill-formed semantic actions you won't find out until you try
    and compile the parser that RDP wrote for you.)


Comments, queries and requests for code to


Dr Adrian Johnstone, CS Dept, Royal Holloway, University of London
Email: adrian@dcs.rhbnc.ac.uk
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