On Wed, May 14, 2025 at 10:33:32AM -0400, Nikolaos Chatzikonstantinou wrote: > > Or maybe it is nested shift that is broken: > > $ m4p > > shift(1, 2, 3) > > 2,3 > > shift(shift(1, 2, 3)) > > > > $ > > > > the second one should have output 3, not empty. Maybe that means your > > output of $@ is wrong (conceptually, "1, 2, 3" passed to $* should > > result in "1,2,3"; and passed to $@ should result in "`1',`2',`3'", > > and NOT "``1,2,3''"). > > Thank you! > > I think I fixed this bug in 0.5.4 just now. There were a couple of > things I had gotten wrong, perhaps the most stark was that I was > running the parser on secondary parentheses, giving incorrect results > e.g. for len((2, 3)) (should be 6).
Closer, but you still need to strip a layer of quotes inside unquoted parens: $ m4 define(a,A)define(`echo',`$1')dnl echo((a,b)) (A,b) echo(`(a,b)') (A,b) echo((`a',`b')) (A,b) echo((``a'',``b'')) (a,b) $ m4p define(a,A)define(`echo',`$1')dnl echo((a,b)) (A,b) echo(`(a,b)') (A,b) echo((`a',`b')) (a,b) echo((``a'',``b'')) (`a',`b') At any rate, I can now program m4 iterations - you've made some fast progress at getting the implementation working, even if not efficient. Of course, it is also a demonstration of how much slower your implementation is at the moment: $ cat for.txt define(`forloop', `ifelse($1,1000,,`,$0(incr($1))')') define(`n', `$#') n(forloop(0)) define(`foreach', `ifelse($#,1,+1,`+1$0(shift($@))')') eval(foreach(forloop(0))) On my laptop, I get approximately: m4 1.4.19: 100ms m4 1.4.20: 60ms # Faster, because I improved eval branch-1.6: 10ms # Faster, because I improved shift($@) iteration m4p: 9631ms More importantly, if I double the number in forloop from 1000 to 2000, I see: m4 1.4.19: 270ms # More than double - shift($@) is still O(n^2) m4 1.4.20: 240ms # More than double - shift($@) is still O(n^2) branch-1.6: 10ms # In the noise - overhead of startup dominates the O(n) scaling m4p: 37765ms # Yep, proof that O(n^2) scaling is at work -- Eric Blake, Principal Software Engineer Red Hat, Inc. Virtualization: qemu.org | libguestfs.org
