Table-driven top-down parsing

[jo...@ima.uucp]

At the end of article <2...@ima.UUCP> [by Ken Yap <k...@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
sc...@rochester.arpa
{decvax, allegra, seismo, cmcl2}!rochester!scott
scott%rochester@CSNET-RELAY
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