Re: Is this a new idea?

>[Scanning and parsing can be as much as half of the total time that a
>compiler takes (so says Ken Thompson of his Plan 9 C compiler) and that is
>quite amenable to incremental precalculation. -John]


_Can_ is the operative word here: with our compilers it is not that big a
proportion, but in any case, even parsing is context dependent, i.e. you
can't parse code that contains references to such things as typedefs that
occur earlier in the code, if the typedef is missing or in the middle of
being edited. Lexical analysis can be done to a greater degree on an
incomplete program, although in most C compilers even the lexical phase is
context sensitive.


A pre-parsing scheme combined with a "quick and dirty" code generator
could certainly reduce edit-compile-debug cycle time, but I stand by my
earlier point that increasing machine speed is affecting this more than
incremental compiler technology is likely to.


I like the idea of a syntax-directed editor, but for reasons of minimizing
silly errors (unmatched braces etc.) rather than to speed up compilation.
--
  Clyde Smith-Stubbs | HI-TECH Software, | Voice: +61 7 300 5011
  clyde@hitech.com.au | P.O. Box 103, Alderley, | Fax: +61 7 300 5246
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