Re: Pascal compiler and sets

dallison@bfsec.bt.co.uk (Dave Allison) writes:
>How are sets usually implemented in Pascal? Is there a small limit placed
>on the size of sets? I can think of a number of implementation methods,
>but would like to see how it is normally done so that I dont have to do
>much more work.
>[It is my impression that sets are often limited to 32 members or whatever
>the local word size is. -John]


Back in about 1980, when I was writing my parser generators in Pascal, I
found considerable variation among compilers with respect to set
implementation. I used the 'set' type extensively for things like First
and Follow.


Compiler A placed a small upper limit on the cardinality of the set, so I
used 'packed array of boolean' instead. Compiler B did not pack arrays,
and at 1 byte per element, my set wouldn't fit into the small amount of
available memory. But compiler B had a very high limit on the size of a
set. So my code has two implementations of First and Follow, with and
without sets.


There may be some technique that is more common than others, but I doubt
that there is any truly typical implementation.
--
Jon Mauney mauney@csc.ncsu.edu
Mauney Computer Consulting (919) 828-8053
--

Return to the comp.compilers page.
Search the comp.compilers archives again.