Table-driven top-down parsing

At the end of article <284@ima.UUCP> [by Ken Yap <ken@rochester.arpa>]
        our moderator suggests:


>Most recursive descent compilers are written by hand, ... I'd rather let
>yacc do the work for me. Yacc can parse anything with enough help ...


Top-down, of course, does not necessarily mean recursive descent.
There exist very good generators for table-driven LL(1) [actually SLL(1)]
parsers. Most (though not all) modern languages have usable LL(1)
grammars, and an LL(1) parser has the following very nice properties:


        - Very small tables (typically half the size of SLR tables
                for the same language)
        - Very clean semantics -- easily-understood algorithm and
                data structures
        - Ability to embed semantic routines at arbitrary locations
                within the right-hand side of a production
        - Extremely simple algorithm (Fischer-Milton-Quiring) for
                high-quality, fully automatic syntactic error correction


Michael L. Scott
University of Rochester (716) 275-7745
scott@rochester.arpa
{decvax, allegra, seismo, cmcl2}!rochester!scott
scott%rochester@CSNET-RELAY

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