## This version doesn't work; the recursive call from coro_enumerate_tree
## winds up yielding.  -- rgr, 7-Oct-06.

## build a complete N-ary tree of the specified depth, with the leaves being
## consecutive integer PMCs from start.
.sub make_nary_tree
	.param int start
	.param int node_width
	.param int depth

	.local pmc result
	if depth goto deeper
	result = new .Undef
	result = start
	inc start
	goto done
deeper:
	result = new .FixedPMCArray
	result = node_width
	dec depth
	.local int i
	i = 0
next:
	if i >= node_width goto done
	($P0, start) = make_nary_tree(start, node_width, depth)
	result[i] = $P0
	inc i
	goto next
done:
	.return (result, start)
.end

## non-coroutine traversal, for debugging.
.sub enumerate_tree
	.param pmc tree_node
	.param int depth :optional
	.param int depth_p :opt_flag

	if depth_p goto have_depth
	depth = 0
have_depth:
	inc depth

	$I0 = isa tree_node, 'FixedPMCArray'
	if $I0 goto recur
	print "[leaf "
	print tree_node
	print "]\n"
done:
	.return ()
recur:
	.local int size, i
	i = 0
	size = tree_node
again:
	if i >= size goto done
	print "[recur: depth "
	print depth
	print ' elt '
	print i
	print "]\n"
	$P1 = tree_node[i]
	enumerate_tree($P1, depth)
	inc i
	goto again
.end

## recursive coroutine to enumerate tree elements, each of which is yielded in
## turn.
.sub coro_enumerate_tree
	.param pmc tree_node
	.param int depth :optional
	.param int depth_p :opt_flag

	if depth_p goto have_depth
	depth = 0
have_depth:
	inc depth

	$I0 = isa tree_node, 'FixedPMCArray'
	if $I0 goto recur
	print "[leaf "
	print tree_node
	print "]\n"
	.yield (tree_node)
	.return ()
recur:
	.local int size, i
	i = 0
	size = tree_node
again:
	if i >= size goto done
	print "[coro recur: depth "
	print depth
	print ' elt '
	print i
	print "]\n"
	$P1 = tree_node[i]
	## [NB:  this recursive call isn't to the clone.  but it's not clear
	## whether that would help.  -- rgr, 7-Oct-06.]
	coro_enumerate_tree($P1)
	inc i
	goto again
done:
	.return ()
.end

.sub main :main
	## make a data structure for traversal.
	.local pmc binary_3
	binary_3 = make_nary_tree(1, 2, 3)
	## enable this to show that make_nary_tree works.
	## enumerate_tree(binary_3)

	## list its contents via coroutine.
	.local pmc coro1
	coro1 = global 'coro_enumerate_tree'
	## [cloning makes it fail later.  -- rgr, 7-Oct-06.]
	## coro1 = clone coro1
loop:
	($P0 :optional, $I0 :opt_flag) = coro1(binary_3)
	unless $I0 goto done
	if null $P0 goto oops
	print $P0
	print "\n"
	goto loop
oops:
	## we should never get here; the coroutine returns either no values, or
	## one value that must be an integer PMC.
	print "oops.\n"
done:
.end