Table-driven top-down parsing

uucp (uucp user)
Wed, 10 Dec 86 09:46:07 est

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Table-driven top-down parsing uucp (1986-12-10)
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Newsgroups: mod.compilers
From: uucp (uucp user)
Date: Wed, 10 Dec 86 09:46:07 est

At the end of article <284@ima.UUCP> [by Ken Yap <>]
        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
{decvax, allegra, seismo, cmcl2}!rochester!scott

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