Re: Operator precedence and Recursive Descent

graham@maths.su.oz.au (Graham Matthews) writes:
> I once wrote a one routine expression parser. ... I had a table of
> operator precedences. The routine built a parse tree by re-ordering the
> parse tree if the just seen operator was of higher precedence than (I
> think) the root of the existing parse tree.


The Whitesmiths C compilers use something very similar. The original
routine was originally coded in Asm (I think) back in the 70's. Sort of as
"how compact I can write this routine" kind of contest. The C version of
the tree rewriting routine is only about 6 lines or so, a conditional
recursive call embedded in a for loop. Many times I have wished for
comments though ;-).


--
- Richard F. Man (man@labrea.zko.dec.com)
--

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